This PDF file contains the front matter associated with SPIE Proceedings Volume 9607, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

The Orbiting Carbon Observatory-2 (OCO-2) is this first NASA satellite designed to measure atmospheric carbon dioxide (CO2) with the accuracy, resolution, and coverage needed to detect CO2 sources and sinks on regional scales over the globe. OCO-2 was launched from Vandenberg Air Force Base on 2 July 2014, and joined the 705 km Afternoon Constellation a month later. Its primary instrument, a 3-channel imaging grating spectrometer, was then cooled to its operating temperatures and began collecting about one million soundings over the sunlit hemisphere each day. As expected, about 13% of these measurements are sufficiently cloud free to yield full-column estimates of the columnaveraged atmospheric CO2 dry air mole fraction, XCO2. After almost a full year in orbit, the XCO2 product is beginning to reveal some of the most robust features of the atmospheric carbon cycle, including the northern hemisphere spring drawdown, and enhanced values co-located with intense fossil fuel and biomass burning emissions. As the carbon cycle science community continues to analyze these OCO-2 data, information on regional-scale sources (emitters) and sinks (absorbers) as well as far more subtle features are expected to emerge from this high resolution, global data set.

The 35-year Advanced Very High Resolution Radiometer (AVHRR) satellite-instrument data record is critical for studying decadal climate change, provided that the AVHRR sensors are consistently calibrated. Owing to the lack of onboard calibration capability, the AVHRR data need to be adjusted using vicarious approaches. One of the greatest challenges hampering these vicarious calibration techniques, however, is the degrading orbits of the NOAA satellites that house the instruments, or, more specifically, the fact that the satellites eventually drift into a terminator orbit several years after launch. This paper presents a uniform sensor calibration approach for the AVHRR visible (VIS) and nearinfrared (NIR) records using specifically designed NOAA-16 AVHRR-based, top-of-atmosphere (TOA) calibration models that take into account orbit degradation. These models are based on multiple invariant Earth targets, including Saharan deserts, polar ice scenes, and tropical deep-convective clouds. All invariant targets are referenced to the Aqua- MODIS Collection-6 calibration via transfer of the Aqua-MODIS calibration to NOAA-16 AVHRR using simultaneous nadir overpass (SNO) comparisons over the North Pole. A spectral band adjustment factor, based on SCanning Imaging Absorption SpectroMeter for Atmospheric CartograpHY (SCIAMACHY) spectral radiances, is used to account for the spectrally-induced biases caused by the spectral response function (SRF) differences of the AVHRR and MODIS sensors. Validation of the AVHRR Earth target calibration is performed by comparisons with contemporary MODIS SNOs. Calibration consistency between Earth targets validates the historical AVHRR record.

The radiometric stability requirements for ocean color climate data records place tight constraints on the onorbit calibration of ocean color instruments. A major component of the on-orbit calibration methodology for NASA ocean color sensors is the normalization of lunar observations for variations in observing geometry by the USGS ROLO photometric model of the Moon. SeaWiFS made 204 lunar observations over its 13-year mission. 145 radiometric trending observations were made at low phase angles (-8° to -6° and +5° to +10°). 59 additional observations were made at high phase angles (-49° to -27° and +27° to +66° degrees). The NASA Ocean Biology Processing Group has undertaken a reanalysis of residual geometric effects in the SeaWiFS lunar observations. Ratios of SeaWiFS observations to ROLO model predictions were fit with quadratic functions of phase angle and linear functions of sub-spacecraft point and sub-solar point libration longitude and latitude angles. The resulting phase and libration fit coefficients have been used as additional geometric corrections for the SeaWiFS lunar observations. For the low phase angle observations, the phase corrections are 0.16% and the libration corrections are 0.18%. For the low and high phase angle observations, the phase corrections are 1.8% and the libration corrections are 0.22%. These geometric corrections have reduced the overall scatter in the lunar observations, bringing the high phase angle data into family with the low phase angle measurements without impacting the radiometric response in the low phase angle observations.

This article reveals the understanding of informal settlements in Brazil as much as it details the approximate population, the genesis and major impacts on Brazilian society. It also reports, the difficulties faced by local authorities in maintaining cohesive, extensive and above all updated record. Especially taking into account that approximately 17.5% of the population occupies improper locations, according to the formal planning. Because, they are not included in the records dedicated to the territorial organization of the city hall and have more pronounced population density than in cities with urban design. Bringing consequences that exacerbate inequality and the process of social exclusion. In addition, it highlights features of the Airborne Laser Scanner, sensor responsible for laser profiling. Activity contracted by the Municipality of Belo Horizonte, from 2008 coupled with aerophotogrammetric survey that brought a number of advantages including the DEM across the county extension. The study describes a methodology which by treating the laser profiling data with embedded routines in Matlab platform allows the roof eaves registry of buildings in Cluster Cafezal. The author mentions that the strategy when added to the relational database can help to develop an incipient registration.

The University of Arizona Remote Sensing Group (RSG) began outfitting the radiometric calibration test site (RadCaTS) at Railroad Valley Nevada in 2004 for automated vicarious calibration of Earth-observing sensors. RadCaTS was upgraded to use RSG custom 8-band ground viewing radiometers (GVRs) beginning in 2011 and currently four GVRs are deployed providing an average reflectance for the test site. This measurement of ground reflectance is the most critical component of vicarious calibration using the reflectance-based method. In order to ensure the quality of these measurements, RSG has been exploring more efficient and accurate methods of on-site calibration evaluation. This work describes the design of, and initial results from, a small portable transfer radiometer for the purpose of GVR calibration validation on site. Prior to deployment, RSG uses high accuracy laboratory calibration methods in order to provide radiance calibrations with low uncertainties for each GVR. After deployment, a solar radiation based calibration has typically been used. The method is highly dependent on a clear, stable atmosphere, requires at least two people to perform, is time consuming in post processing, and is dependent on several large pieces of equipment. In order to provide more regular and more accurate calibration monitoring, the small portable transfer radiometer is designed for quick, one-person operation and on-site field calibration comparison results. The radiometer is also suited for laboratory calibration use and thus could be used as a transfer radiometer calibration standard for ground viewing radiometers of a RadCalNet site.

The Radiometric Calibration Test Site (RadCaTS) was developed by the University of Arizona in the early 2000s to collect ground-based data in support of the calibration and validation of Earth-observing sensors. It uses the reflectance-based approach, which requires measurements of the atmosphere and surface reflectance. The measurements are used in MODTRAN to determine the at-sensor radiance for a given time and date. In the traditional reflectance-based approach, on-site personnel use an automated solar radiometer (ASR) to measure the atmospheric attenuation, but in the case of RadCaTS, an AERONET Cimel sun photometer is used to make atmospheric measurements. This work presents a comparison between the Cimel-derived atmospheric characteristics such as aerosol optical depth, the Angstrom exponent, and the columnar water vapor, to those derived using a traditional solar radiometer. The top-of-atmosphere radiance derived using the Cimel and ASR measurements are compared using Landsat 8 OLI bands as a test case for the period 2012–2014 to determine if any biases exist between the two methodologies.

The Radiometric Calibration Test Site (RadCaTS) at Railroad Valley Playa, Nevada is being developed by the University of Arizona to enable improved accuracy and consistency for airborne and satellite sensor calibration. Primary instrumentation at the site consists of ground-viewing radiometers, a sun photometer, and a meteorological station. Measurements made by these instruments are used to calculate surface reflectance, atmospheric properties and a prediction for top-of-atmosphere reflectance and radiance. This work will leverage research for RadCaTS, and describe the requirements for an online database, associated data formats and quality control, and processing levels.

NASA Goddard’s Lidar, Hyperspectral and Thermal Imager (G-LiHT) facilitates simultaneous measurements beneficial to variety of applications. Of the suite of “off-the shelf” instruments of G-LiHT, the Visible Near-Infrared (VNIR) Imaging Spectrometer acquires high resolution spectral measurements (1.5 nm resolution) from 0.4 to 1 μm. Goddard Space Flight Center’s Laser for Absolute Measurement of Response (GLAMR) was used to measure the absolute spectral response (ASR) of the G-LiHT’s imaging spectrometer. Continuously tunable lasers coupled to an integrating sphere allow a radiance-based calibration for the detectors at reflective solar wavelengths. GLAMR measurements, covering a wavelength range from 0.58 to 0.99 μm were acquired between July 30 to August 2, 2013. In order to account for the large field-of-view (50°), G-LiHT was rotated in 2 degree increments so that the same area of the sphere is viewed by all detectors. Using this data along with the coincident Silicon trap radiometer measurements, the ASR was computed. The derived calibration parameters for G-LiHT’s Imaging Spectrometer are to be transferred to near-simultaneous measurements of Landsat sensors. Calibration uncertainty of G-LiHT is 1-3% depending spectral region and transferring this traceability to coincident satellite sensors has 3-5% depending on spectral region.

There is a growing interest in the science and user community in the Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) low light detection capabilities at night for quantitative applications such as airglow, geophysical retrievals under lunar illumination, light power estimation, search and rescue, energy use, urban expansion and other human activities. Given the growing interest in the use of the DNB data, a pressing need arises for improving the calibration stability and absolute accuracy of the DNB at low radiances. Currently the low light calibration accuracy was estimated at a moderate 15%-100% while the long-term stability has yet to be characterized. This study investigates selected existing night light point sources from Suomi NPP DNB observations and evaluates the feasibility of SI traceable nightlight source at radiance levels near 3 nW·cm⁻²·sr⁻¹, that potentially can be installed at selected sites for VIIRS DNB calibration/validation. The illumination geometry, surrounding environment, as well as atmospheric effects are also discussed. The uncertainties of the ground based light source are estimated. This study will contribute to the understanding of how the Earth’s atmosphere and surface variability contribute to the stability of the DNB measured radiances, and how to separate them from instrument calibration stability. It presents the need for SI traceable active light sources to monitor the calibration stability, radiometric and geolocation accuracy, and point spread functions of the DNB. Finally, it is also hoped to address whether or not active light sources can be used for detecting environmental changes, such as aerosols.

This paper provides methodologies developed and implemented by the NASA VIIRS Calibration Support Team (VCST) to validate the S-NPP VIIRS Day-Night band (DNB) and M bands calibration performance. The Sensor Data Records produced by the Interface Data Processing Segment (IDPS) and NASA Land Product Evaluation and Algorithm Testing Element (PEATE) are acquired nearly nadir overpass for Libya 4 desert and Dome C snow surfaces. In the past 3.5 years, the modulated relative spectral responses (RSR) change with time and lead to 3.8% increase on the DNB sensed solar irradiance and 0.1% or less increases on the M4-M7 bands. After excluding data before April 5th, 2013, IDPS DNB radiance and reflectance data are consistent with Land PEATE data with 0.6% or less difference for Libya 4 site and 2% or less difference for Dome C site. These difference are caused by inconsistent LUTs and algorithms used in calibration. In Libya 4 site, the SCIAMACHY spectral and modulated RSR derived top of atmosphere (TOA) reflectance are compared with Land PEATE TOA reflectance and they indicate a decrease of 1.2% and 1.3%, respectively. The radiance of Land PEATE DNB are compared with the simulated radiance from aggregated M bands (M4, M5, and M7). These data trends match well with 2% or less difference for Libya 4 site and 4% or less difference for Dome C. This study demonstrate the consistent quality of DNB and M bands calibration for Land PEATE products during operational period and for IDPS products after April 5^th, 2013.

The last three Apollo lunar missions (15, 16, and 17) carried an integrated photogrammetric mapping system of a Metric Camera (MC), a high-resolution Panoramic Camera, a Star Camera, and a Laser Altimeter. Recently images taken by the MC were scanned by Arizona State University (ASU); these images contain valuable information for scientific exploration, engineering analysis, and visualization of the moon’s surface. Through this article, we took advantage of the large overlaps, the multi viewing, and the high ground resolution of the images taken by the Apollo MC in generating an accurate and trustful surface of the Moon. After computing the positions and orientations of the exposure stations, through rigorous a photogrammetric bundle adjustment techniques, we carried out a two-step matching process that contains hierarchical matching and least squares matching; both steps are implemented in a multi-photo scheme. Our results look very promising and demonstrate the effectiveness of the proposed algorithm in accounting for depth discontinuities, occlusions, and noises.

A main objective of AIRS/AMSU on EOS is to provide accurate sounding products that are used to generate climate data sets. Suomi NPP carries CrIS/ATMS that were designed as follow-ons to AIRS/AMSU. Our objective is to generate a long term climate data set of products derived from CrIS/ATMS to serve as a continuation of the AIRS/AMSU products. We have modified an improved version of the operational AIRS Version-6 retrieval algorithm for use with CrIS/ATMS. CrIS/ATMS products are of very good quality, and are comparable to, and consistent with, those of AIRS.

Synthetic Eigen Vectors (EV) used for the statistical analysis of the PC reconstruction residual of large ensembles of data are a novel tool for the analysis of data from hyperspectral infrared sounders like the Atmospheric Infrared Sounder (AIRS) on the EOS Aqua and the Cross-track Infrared Sounder (CrIS) on the SUOMI polar orbiting satellites. Unlike empirical EV, which are derived from the observed spectra, the synthetic EV are derived from a large ensemble of spectra which are calculated assuming that, given a state of the atmosphere, the spectra created by the instrument can be accurately calculated. The synthetic EV are then used to reconstruct the observed spectra. The analysis of the differences between the observed spectra and the reconstructed spectra for Simultaneous Nadir Overpasses of tropical oceans reveals unexpected differences at the more than 200 mK level under relatively clear conditions, particularly in the mid-wave water vapor channels of CrIS. The repeatability of these differences using independently trained SEV and results from different years appears to rule out inconsistences in the radiative transfer algorithm or the data simulation. The reasons for these discrepancies are under evaluation.

The Atmospheric Infrared Sounder (AIRS) on the EOS Aqua Spacecraft was launched on May 4, 2002. AIRS acquires hyperspectral infrared radiances in 2378 channels ranging in wavelength from 3.7-15.4 um with spectral resolution of better than 1200, and spatial resolution of 13.5 km with global daily coverage. The AIRS is designed to measure temperature and water vapor profiles for improvement in weather forecast accuracy and improved understanding of climate processes. As with most instruments, the AIRS Point Spread Functions (PSFs) are not the same for all detectors. When viewing a non-uniform scene, this causes a significant radiometric error in some channels that is scene dependent and cannot be removed without knowledge of the underlying scene. The magnitude of the error depends on the combination of non-uniformity of the AIRS spatial response for a given channel and the non-uniformity of the scene, but is typically only noticeable in about 1% of the scenes and about 10% of the channels. The current solution is to avoid those channels when performing geophysical retrievals. In this effort we use data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument to provide information on the scene uniformity that is used to correct the AIRS data. For the vast majority of channels and footprints the technique works extremely well when compared to a Principal Component (PC) reconstruction of the AIRS channels. In some cases where the scene has high inhomogeneity in an irregular pattern, and in some channels, the method can actually degrade the spectrum. Most of the degraded channels appear to be slightly affected by random noise introduced in the process, but those with larger degradation may be affected by alignment errors in the AIRS relative to MODIS or uncertainties in the PSF. Despite these errors, the methodology shows the ability to correct AIRS radiances in non-uniform scenes under some of the worst case conditions and improves the ability to match AIRS and MODIS radiances in non-uniform scenes.

Simultaneous Nadir Observations (SNOs) contain thousands of pairs of observations taken within 8 km and 10 minutes. SNOs have been very useful for comparisons in polar conditions. But classic SNO pairing criteria have very low yield in the tropics, making these SNOs less useful for investigating instrument performance for hotter scenes or scenes with high contrast. We introduce a modified methodology, which finds pairs of matched spectra in a wider angular range but is restricted to the tropics. We illustrate this with AIRS and CrIS data. Insight into instrument differences is gained from statistical distributions of the residual differences between the matched pairs. A sample analysis compares AIRS and CrIS brightness temperature at 900 cm-1 as function of scene brightness temperature. The proposed method may be applicable to matchups of other sensors on different spacecraft.

Modern infrared spectrometers contain many detectors. The Atmospheric Infrared Sounder (AIRS) has 4482 infrared detectors. The Cross-track Infrared Sounder (CrIS) (a Fourier Transform Spectrometer) has 27. This paper examines issues related to multiple detectors and describes their impact on calibration and data analysis, using examples from AIRS and CrIS. The potential differences among detectors are not limited to dead channels. They can include: noise characteristics, spatial response, illumination through the optical system, and exposure to radiation. The more detectors in an instrument, the more important it is for both the hardware and data analysis software designers to be prepared to handle such differences. Techniques used to mitigate these effects are described in this paper.

Landsat-8 and its two Earth imaging sensors, the Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) have been operating on-orbit for 2 1/2 years. The OLI radiometric calibration, which is monitored using on-board lamps, on-board solar diffusers, the moon and vicarious calibration techniques has been stable to within 1% over this period of time. The Coastal Aerosol band, band 1, shows the largest change at about 1% over the period; all other bands have shown no significant trend. OLI bands 1- 4 show small discontinuities in response (+0.1% to 0.2%) beginning about 7 months after launch and continuing for about 1 month associated with a power cycling of the instrument, though the origin of the recovery is unclear. To date these small changes have not been compensated for, but this will change with a reprocessing campaign that is currently scheduled for Fall 2015. The calibration parameter files (each typically covering a 3 month period) will be updated for these observed gain changes. A fitted response to an adjusted average of the lamps, solar and lunar results will represent the trend, sampled at the rate of one value per CPF.

The Operational Land Imager (OLI), on board the Landsat-8 satellite, is a pushbroom sensor with nearly 7000 detectors per band, divided between 14 separate modules. While rigorously characterized prior to launch, the shear number of individual detectors presents a challenge to maintaining the on-orbit relative calibration, such that stripes, bands and other artifacts are minimized in the final image products.

On-orbit relative calibration of the OLI is primarily monitored and corrected by observing an on-board primary solar diffuser panel. The panel is the most uniform target available to the OLI, though as observed but the OLI, it has a slope across the field of view due to view angle effects. Just after launch, parameters were derived using the solar diffuser data, to correct for the angular effects across the 14 modules. The residual discontinuities between arrays and the detector-to-detector uniformity continue to be monitored on a weekly basis.

The observed variations in the responses to the diffuser panel since launch are thought to be due to real instrument changes. Since launch, the Coastal/Aerosol (CA) and Blue bands have shown the most variation in relative calibration of the VNIR bands, with as much as 0.14% change (3-sigma) between consecutive relative gain estimates. The other VNIR bands (Green, Red and NIR) initially had detectors showing a slow drift of about 0.2% per year, though this stopped after an instrument power cycle about seven months after launch. The SWIR bands also exhibit variability between collects (0.11% 3-sigma) but the larger changes have been where individual detectors’ responses change suddenly by as much as 1.5%.

The mechanisms behind these changes are not well understood but in order to minimize impact to the users, the OLI relative calibration is updated on a quarterly basis in order to capture changes over time.

The Operational Land Imager (OLI) routinely acquires calibration datasets involving various targets such as the solar diffusers collects, Pseudo Invariant Calibration Sites (PICS), and Lunar collects. This paper focus on stray light analysis of the lunar collects made through the lifetime of the mission. The analysis done on the lunar collects is used to estimate stability of stray light levels from which the stability or built up of contamination is demonstrated.

The Thermal Infrared Sensor (TIRS) onboard Landsat 8 was tasked with continuing thermal band measurements of the Earth as part of the Landsat program. From first light in early 2013, there were obvious indications that stray light was contaminating the thermal image data collected from the instrument. Traditional calibration techniques did not perform adequately as non-uniform banding was evident in the corrected data and error in absolute estimates of temperature over trusted buoys sites varied seasonally and, in worst cases, exceeded 9 K error. The development of an operational technique to remove the effects of the stray light has become a high priority to enhance the utility of the TIRS data. This paper introduces the current algorithm being tested by Landsat’s calibration and validation team to remove stray light from TIRS image data. The integration of the algorithm into the EROS test system is discussed with strategies for operationalizing the method emphasized. Techniques for assessing the methodologies used are presented and potential refinements to the algorithm are suggested. Initial results indicate that the proposed algorithm significantly removes stray light artifacts from the image data. Specifically, visual and quantitative evidence suggests that the algorithm practically eliminates banding in the image data. Additionally, the seasonal variation in absolute errors is flattened and, in the worst case, errors of over 9 K are reduced to within 2 K. Future work focuses on refining the algorithm based on these findings and applying traditional calibration techniques to enhance the final image product.

The most interaction between humankind and water occurs in coastal and inland waters (Case 2 waters) at a scale of tens or hundred of meters, but there is not yet an ocean color product at this spatial scale. Landsat 8 is a promising candidate to address the remote sensing of these kinds of waters due to its improved signal-to-noise ratio (SNR), spectral resolution, 12-bit quantization, and high spatial resolution. Standard atmospheric correction algorithms developed for heritage ocean color instruments (e.g. MODIS, SeaWiFS) require a sufficient SNR in two bands where the water-leaving signal is negligible, which is not always possible, particularly for Landsat 8's bands. The model-based empirical line method (MoB-ELM) atmospheric algorithm for Landsat 8 imagery does not rely on this assumption. In this work, we evaluate the performance of this algorithm. We compare the MoB-ELM algorithm with in situ data and with three standard atmospheric correction algorithms. The results from our algorithm are comparable with the standard algorithms in some bands when comparing remote-sensing reflectances. When compared with in situ remote-sensing reflectance, the MoB-ELM perform similar to the standard algorithm in most cases. A comparison of retrieved chlorophyll-a concentration was perform as well, showing that the MoB- ELM outperforms the rest at high concentrations commonly found in Case 2 waters. These results show that our atmospheric correction algorithm allows one to use Landsat 8 to study Case 2 waters as an alternative to heritage ocean color satellites.

The Landsat program has collected imagery of the Earth for the past 40 years. Although both Landsat 7 and 8 are currently operating on-orbit, the next generation Landsat mission is already being planned. Concept studies for this mission include reproducing the Landsat 8 design (mainly push-broom imaging architecture). The definition of science requirements is an important step towards the development of instrument specifications. At this early stage, a re-evaluation of the Landsat requirements is beneficial since they might be flexible enough to relax in some areas to possibly save on manufacturing costs or may need to be tightened in other areas to produce better science products. The investigations presented here focused on spatial aliasing and spectral banding effects. The specifications of these two key performance requirements were taken from the Landsat 8 Operational Land Imager (OLI) sensor as a starting point for the analyses. They were then adjusted to determine their effects on the final image products through the use of standard radiometry equations and synthetic Earth scene data. The results of the modeling efforts for these two requirements concepts are presented here and could be used as a template for future instrument studies.

The Clouds and the Earth’s Radiant Energy System (CERES) scanning radiometer is designed to measure reflected solar radiation and thermal radiation emitted by the Earth. Five CERES instruments are currently taking active measurements in-orbit with two aboard the Terra spacecraft (FM1 and FM2), two aboard the Aqua spacecraft (FM3 and FM4), and one aboard the S-NPP spacecraft (FM5). The CERES instrument uses three scanning thermistor bolometers to make broadband radiance measurements in the shortwave (0.3 – 5.0 micrometers), total (0.3 - >100 micrometers) and water vapor window (8 – 12 micrometer) regions. An internal calibration module (ICM) used for in-flight calibration is built into the CERES instrument package consisting of an anodized aluminum blackbody source for calibrating the total and window sensors, and a shortwave internal calibration source (SWICS) for the shortwave sensor. The ICM sources, along with a solar diffusor called the Mirror Attenuator Mosaic (MAM), are used to define shifts or drifts in the sensor response over the life of the mission. In addition, validation studies are conducted to understand any spectral changes that may occur with the sensors and assess the pointing accuracy of the instrument, allowing for corrections to be made to the radiance calculations in CERES data products. This paper covers the observed trends in the internal and solar calibration data, discusses the latest techniques used to correct for sensor response, and explains the validation studies used to assess the performance and stability of the instrument.

Aqua MODIS, the second MODIS instrument of the NASA Earth Observation System, has operated for over thirteen years since launch in 2002. MODIS has sixteen thermal emissive bands (TEB) located on two separate cold focal plane assemblies (CFPA). The TEB are calibrated using onboard blackbody and space view observations. MODIS CFPA temperature is controlled by a radiative cooler and heaters in order to maintain detector gain stability. Beginning in 2006, the CFPA temperature gradually varies from its designed operating temperature with increasing orbital and seasonal fluctuations, with the largest observed impacts on the TEB photoconductive (PC) bands. In Aqua Collection 6 (C6), a correction to the detector gain due to the CFPA temperature variation is applied for data after mid-2012. This paper evaluates the impact of the CFPA temperature variation on the TEB PC band calibration through comparisons with simultaneous nadir overpasses (SNO) measurements from the Infrared Atmospheric Sounding Interferometer (IASI) and Atmospheric Infrared Sounder (AIRS). Our analysis shows that the current L1B product from mid-2011 to mid-2012 is affected by the CFPA temperature fluctuation. The MODIS-IASI comparison results show that no drift is observed in PC bands over the CFPA temperature variation range. Similarly, in the MODIS-AIRS comparison, bands 31-34 show nearly no trend over the range of CFPA temperature while a slight drift in bands 35-36 are seen from the comparison results.

The MODerate-resolution Imaging Spectroradiometer (MODIS) is a legacy Earth remote sensing instrument in the National Aeronautics and Space Administration (NASA) Earth Observing System (EOS). The first MODIS instrument was launched in December 1999 on board the Terra spacecraft. MODIS has 36 bands, among which bands 20-25 and bands 27-36 are thermal emissive bands covering a wavelength range from 3.7μm to 14.2μm. It has been found that there are severe contaminations in Terra bands 27-30 (6.7 μm – 9.73 μm) due to crosstalk of signals among themselves. The crosstalk effect induces strong striping artifacts in the Earth View (EV) images and causes large long-term drifts in the EV brightness temperature (BT) in these bands. An algorithm using a linear approximation derived from on-orbit lunar observations has been developed to correct the crosstalk effect for them. It was demonstrated that the crosstalk correction can substantially reduce the striping noise in the EV images and significantly remove the long-term drifts in the EV BT in the Long Wave InfraRed (LWIR) water vapor channels (bands 27-28). In this paper, the crosstalk correction algorithm previously developed is applied to correct the crosstalk effect in the remaining LWIR bands 29 and 30. The crosstalk correction successfully reduces the striping artifact in the EV images and removes long-term drifts in the EV BT in bands 29-30 as was done similarly for bands 27-28. The crosstalk correction algorithm can thus substantially improve both the image quality and the radiometric accuracy of the Level 1B (L1B) products of the LWIR PV bands, bands 27-30. From this study it is also understood that other Terra MODIS thermal emissive bands are contaminated by the crosstalk effect and that the algorithm can be applied to these bands for crosstalk correction.

Terra (T) MODerate-resolution Imaging Spectroradiometer (MODIS), a heritage Earth observing sensor has completed 15 years of operation as of December 18 2014. T-MODIS has 36 spectral channels designed to monitor the land, ocean, and atmosphere. The long term climate data record from T-MODIS is an important dataset for global change monitoring. Sixteen of the spectral channels fall in the Mid (M) (3.7-4.5μm) to Long (L) (6.7-14.1μm)Wave InfraRed (M/LWIR) wavelengths, which are also referred to as the Thermal Emissive Bands (TEBs). To date the TEBs have very satisfactory performance which is attributed to the scan-by-scan calibration using an on-board BlackBody whose temperature is traceable to the NIST temperature standards. However, with an aging instrument, it was observed from 2010 onwards that the Photo Voltaic LWIR channels (Bands 27-30) have suffered significantly from electronic crosstalk. This is mainly due to the deterioration of the electronic circuits of the relevant bands in the LWIR Focal Plane Array (FPA). In this paper, we report the characterization of the electronic crosstalk in the above-mentioned bands using the well characterized test site such as Dome Concordia (C). Such characterization can be used to reduce the effects of crosstalk when implemented in the future Level 1B reprocessing and thereby increasing the radiometric fidelity of the concerned bands.

The present paper describes the challenging diffuser design and verification activities of TNO under contract of a customer for an earth observation instrument with observation conditions that require feasible BRDF under large angles of incidence of up to 70° with respect to the surface normal. Not only the design though but also the verification of the diffuser performance under such angles including “out-of-plane”, i.e. angle theta detection of the scattered light, was an essential activity to be executed. In this paper we will summarize the R&D activities with respect to diffuser design and verification that were recently carried out at TNO and present its applicability to current and future earth observation missions with challenging observation conditions and thus challenging diffuser requirements under high illumination angles.

A Light-Emitting Diode (LED)-driven integrating sphere light source has been fabricated and assembled in the NASA Goddard Space Flight Center (GSFC) Code 618 Biospheric Sciences Laboratory’s Calibration Facility. This light source is a 30.5 cm diameter integrating sphere lined with Spectralon. A set of four LEDs of different wavelengths are mounted on the integrating sphere’s wall ports. A National Institute of Standards and Technology (NIST) characterized Si detector is mounted on a port to provide real-time monitoring data for reference. The measurement results presented here include the short-term and long-term stability and polarization characterization of the output from this LED-driven integrating sphere light source. As an initial application, this light source is used to characterize detector/pre-amplifier gain linearity in light detection systems. The measurement results will be presented and discussed.

This work describes the development of an improved vacuum compatible flat plate radiometric source used for characterizing and calibrating remote optical sensors, in situ, throughout their testing period. The original flat plate radiometric source was developed for use by the VIIRS instrument during the NPOESS Preparatory Project (NPP). Following this effort, the FPI has had significant upgrades in order to improve both the radiometric throughput and uniformity. Results of the VIIRS testing with the reconfigured FPI are reported and discussed.

The Visible Infrared Imaging Radiometer Suite (VIIRS) on-board the first Joint Polar Satellite System (JPSS) completed its sensor level testing on December 2014. The JPSS-1 (J1) mission is scheduled to launch in December 2016, and will be very similar to the Suomi-National Polar-orbiting Partnership (SNPP) mission. VIIRS instrument was designed to provide measurements of the globe twice daily. It is a wide-swath (3,040 km) cross-track scanning radiometer with spatial resolutions of 370 and 740 m at nadir for imaging and moderate bands, respectively. It covers the wavelength spectrum from reflective to long-wave infrared through 22 spectral bands [0.412 μm to 12.01 μm]. VIIRS observations are used to generate 22 environmental data products (EDRs). This paper will briefly describe J1 VIIRS characterization and calibration performance and methodologies executed during the pre-launch testing phases by the independent government team, to generate the at-launch baseline radiometric performance, and the metrics needed to populate the sensor data record (SDR) Look-Up-Tables (LUTs). This paper will also provide an assessment of the sensor pre-launch radiometric performance, such as the sensor signal to noise ratios (SNRs), dynamic range, reflective and emissive bands calibration performance, polarization sensitivity, bands spectral performance, response-vs-scan (RVS), near field and stray light responses. A set of performance metrics generated during the pre-launch testing program will be compared to the SNPP VIIRS pre-launch performance.

The JPSS-1 VIIRS instrument completed sensor level testing, including spectral characterization, at the Raytheon El Segundo facility in 2014. Spectral subject matter experts (SMEs) of the VIIRS DAWG have reviewed and analyzed the spectral measurements leading to a Version 1 release of JPSS-1 VIIRS relative spectral response (RSR) data in June 2015. The analysis demonstrates that all bands are well characterized with minor performance specification non-compliances in a few bands similar to those seen on S-NPP VIIRS. A major reduction in the out-of-band response (compared to that seen for S-NPP) has been realized through the redesign of the JPSS-1 VIIRS integrated filter assembly for the warm focal plane bands. An EAR99 restricted DAWG Version 1 release consisting of detector and band average (over all detectors) in-band + out-of-band RSR for all VIIRS bands is available on the NASA JPSS-1 eRoom limited access site and replaces the previous Version 0 Beta release.

The polarization sensitivity of the Visible/NearIR (VISNIR) bands in the Joint Polar Satellite Sensor 1 (J1) Visible Infrared Imaging Radiometer Suite (VIIRS) instrument was measured using a broadband source. While polarization sensitivity for bands M5-M7, I1, and I2 was less than 2.5 %, the maximum polarization sensitivity for bands M1, M2, M3, and M4 was measured to be 6.4 %, 4.4 %, 3.1 %, and 4.3 %, respectively with a polarization characterization uncertainty of less than 0.38%. A detailed polarization model indicated that the large polarization sensitivity observed in the M1 to M4 bands is mainly due to the large polarization sensitivity introduced at the leading and trailing edges of the newly manufactured VISNIR bandpass focal plane filters installed in front of the VISNIR detectors. This was confirmed by polarization measurements of bands M1 and M4 bands using monochromatic light. Discussed are the activities leading up to and including the two polarization tests, some discussion of the polarization model and the model results, the role of the focal plane filters, the polarization testing of the Aft-Optics-Assembly, the testing of the polarizers at the National Aeronautics and Space Administration’s (NASA) Goddard center and at the National Institute of Science and Technology (NIST) facility and the use of NIST’s Traveling Spectral Irradiance and Radiance responsivity Calibrations using Uniform Sources (T-SIRCUS) for polarization testing and associated analyses and results.

The polarization sensitivity of the Joint Polar Satellite System (JPSS) J1 Visible Infrared Imaging Radiometer Suite (VIIRS) measured pre-launch using a broadband source was observed to be larger than expected for many reflective bands. Ray trace modeling predicted that the observed polarization sensitivity was the result of larger diattenuation at the edges of the focal plane filter spectral bandpass. Additional ground measurements were performed using a monochromatic source (the NIST T-SIRCUS) to input linearly polarized light at a number of wavelengths across the bandpass of two VIIRS spectral bands and two scan angles. This work describes the data processing, analysis, and results derived from the T-SIRCUS measurements, comparing them with broadband measurements. Results have shown that the observed degree of linear polarization, when weighted by the sensor’s spectral response function, is generally larger on the edges and smaller in the center of the spectral bandpass, as predicted. However, phase angle changes in the center of the bandpass differ between model and measurement. Integration of the monochromatic polarization sensitivity over wavelength produced results consistent with the broadband source measurements, for all cases considered.

The Visible and Infrared Imaging Radiometer Suite (VIIRS) collects Earth science data continually in a sun-synchronous orbit. VIIRS raw data records (RDRs) are processed by ground software to generate a variety of environmental data records (EDRs). Over open ocean, ground software produces measurements of chlorophyll concentration based on subsurface reflectance estimates. Considering that about 90% of the top of the atmosphere (TOA) radiance reaching a sensor over open ocean can be attributed to atmosphere or surface reflectance, it is possible to introduce large chlorophyll estimate errors by ignoring ordinarily small contributions due to polarization sensitivity. For chlorophyll determination, instrument polarization sensitivity measurements are used in combination with atmospheric models to compensate for polarization phenomenon. VIIRS ground software does not compensate for polarization phenomenon when processing land scenes. It is therefore natural to consider the impacts of ignoring VIIRS polarization phenomenon for land surface reflectance estimates. In this work, pre-flight polarization sensitivity characterization data is used in conjunction with a polarized atmospheric propagation model to analyze potential impacts on retrieved TOA reflectance. Impacts are analyzed across several collection conditions, including ground surface type, atmospheric visibility, general atmospheric profile and collection geometry. Actual pre-flight characterization data is used for both NPP and J1 VIIRS.

The Visible/Infrared Imaging Radiometer Suite (VIIRS) is a key sensor on the Suomi National Polar-orbiting Partnership (NPP) satellite in orbit as well as for the upcoming Joint Polar Satellite System (JPSS). VIIRS collects Earth radiometry and imagery in 22 spectral from 0.4 to 12.5 μm. Radiometric calibration of the reflective bands in the 0.4 to 2.5 μm wavelength range is performed by measuring the sunlight reflectance from Solar Diffuser Assembly (diffuser is Spectralon®). Spectralon® is known to solarize due to sun UV exposure at the blue end of the spectrum (~0.4 – 0.6+ μm) as seen by laboratory tests as well as on orbit data from MODIS and NPP. VIIRS uses a Solar Diffuser Stability Monitor (SDSM) to monitor the change in the Solar Diffuser reflectance in the 0.4 – 0.94 μm wavelength range to correct the calibration constants. The SDSM measures the ratio of sun light reflecting from the Solar Diffuser to a direct view of the sun. As the intensity of the light reaching the SDSM in both Solar Diffuser view and sun view is a function of the sun’s angle of incidence (AOI), the SDSM response to sun AOI has to be characterized. This paper presents details of the test setup including an extended collimated source simulating the sun across all SDSM bands. The prelaunch characterization results for the JPSS-1 (J1) VIIRS SDSM are presented. Comparison with NPP on orbit yaw maneuver SDSM results shows similar behavior demonstrating that the J1 test successfully characterized the SDSM response to sun AOI.

During JPSS-1 VIIRS testing at Raytheon El Segundo, a larger than expected radiometric response nonlinearity was discovered in Day-Nigh Band (DNB). In addition, the DNB nonlinearity is aggregation mode dependent, where the most severe non-linear behavior are the aggregation modes used at high scan angles (<~50 degree). The DNB aggregation strategy was subsequently modified to remove modes with the most significant non-linearity. We characterized the DNB radiometric response using pre-launch tests with the modified aggregation strategy. The test data show the DNB non-linearity varies at each gain stages, detectors and aggregation modes. The non-linearity is most significant in the Low Gain Stage (LGS) and could vary from sample-to-sample. The non-linearity is also more significant in EV than in calibration view samples. The HGS nonlinearity is difficult to quantify due to the higher uncertainty in determining source radiance. Since the radiometric response non-linearity is most significant at low dn ranges, it presents challenge in DNB cross-stage calibration, an critical path to calibration DNB’s High Gain Stage (HGS) for nighttime imagery. Based on the radiometric characterization, we estimated the DNB on-orbit calibration accuracy and compared the expected DNB calibration accuracy using operational calibration approaches. The analysis showed the non-linearity will result in cross-stage gain ratio bias, and have the most significant impact on HGS. The HGS calibration accuracy can be improved when either SD data or only the more linearly behaved EV pixels are used in cross-stage calibration. Due to constrain in test data, we were not able to achieve a satisfactory accuracy and uniformity for the JPSS-1 DNB nighttime imagery quality. The JPSS-1 DNB nonlinearity is a challenging calibration issue which will likely require special attention after JPSS-1 launch.

This paper presents a robust method for determining the calibration coefficients in polynomial calibration equations, and discusses the corresponding calibration uncertainties. An attenuator method that takes into account all measurements with and without an attenuator screen was used to restrict the impact of the absolute calibration of the light source. The originally proposed procedure attempts to simultaneously determine all unknowns nonlinearly using polynomial curve fitting. The newly proposed method divides the task into two simpler parts. For example, in the case of a quadratic calibration equation, the first part becomes a quadratic equation solely for the transmittance of attenuator, which has an analytical solution using three or four sets of measurements. Additionally, it is straightforward to determine the median value and the standard deviation of the transmittance from the solutions using all combinations of measured data points. In conjunction, the second part becomes a linear fit, with the ratio of the zeroth-order to first-order calibration coefficients as the intercept and the ratio of the second-order to first-order calibration coefficients as the slope. These ratios are unaffected by the absolute calibration of the light source and are then used in the calibration equation to calculate the first-order calibration coefficient. How the new method works is straightforward to visualize, which makes its results easier to verify. This is demonstrated using measurements from the Joint Polar Satellite System (JPSS) J1 Visible Infrared Imaging Radiometer Suite (VIIRS) reflective solar bands (RSB) pre-launch testing.

The remote sensing system engineering process often makes use of modeling and simulation tools to flow down specifications to subsystems and components, and/or to predict performance given a particular set of defined capabilities. A persistent question in the development and use of such tools is that of appropriate level of fidelity. In this paper we look at one problem area encountered in the simulation of panchromatic and other broadband imaging systems, that of accounting for spectrally varying resolution over the band. An established method for treating this variation is that of the polychromatic optical transfer function (OTF), but this technique imposes a measure of complexity on the simulation tool software architecture, as well as on users who must subsequently interact with it. We present a methodology for assessing the required level of fidelity for this problem and show that under some conditions it appears possible to forgo the polychromatic OTF formalism, or else to treat it with less than full rigor, with minimal loss in accuracy.

The performance of an optical system depends on the characteristics manufacturing errors of the mirrors, including aberrations on the primary mirror. When designing a system and evaluating its expected performance, the exact nature of the aberrations is not known beforehand, so approximations and simplifying assumptions need to be made. A common assumption is that aberrations of the primary mirror take the form of correlated Gaussian peaks and valleys about the ideal (perfectly spherical) primary mirror. The effect of such correlated Gaussian imperfections can be calculated in an average sense, using the optical quality factor (OQF) to modify the diffraction-limited modulation transfer function (MTF). Alternatively, a single instantiation of the aberrations can be added as phase variations to the pupil function, followed by calculation of the MTF. In this paper we compare these two methods of modeling the effects of correlated Gaussian aberrations on the MTF and point spread function (PSF). We explore the parameter space within which the OQF approximation is valid and the range of possible MTFs resulting from individual instantiations of the aberrations.

The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission addresses the need to observe highaccuracy, long-term climate change trends and to use decadal change observations as a method to determine the accuracy of climate change. A CLARREO objective is to improve the accuracy of SI-traceable, absolute calibration at infrared and reflected solar wavelengths to reach on-orbit accuracies required to allow climate change observations to survive data gaps and observe climate change at the limit of natural variability. Such an effort will also demonstrate National Institute of Standards and Technology (NIST) approaches for use in future spaceborne instruments. The current work describes the results of laboratory and field measurements with the Solar, Lunar for Absolute Reflectance Imaging Spectroradiometer (SOLARIS) which is the calibration demonstration system (CDS) for the reflected solar portion of CLARREO. SOLARIS allows testing and evaluation of calibration approaches, alternate design and/or implementation approaches and components for the CLARREO mission. SOLARIS also provides a testbed for detector technologies, non-linearity determination and uncertainties, and application of future technology developments and suggested spacecraft instrument design modifications. Results of laboratory calibration measurements are provided to demonstrate key assumptions about instrument behavior that are needed to achieve CLARREO’s climate measurement requirements. Absolute radiometric response is determined using laser-based calibration sources and applied to direct solar views for comparison with accepted solar irradiance models to demonstrate accuracy values giving confidence in the error budget for the CLARREO reflectance retrieval.

EUMETSAT supports operational meteorology and climate monitoring with its mandatory programmes, in the geostationary and polar sun-synchronous orbits. Optional programmes support further tasks like altimetry and oceanography. Satellite data from other agencies’ satellites which are of interest to the user community are provided through third party programmes. This paper provides an overview over current EUMETSAT programmes, and the status and plans of future systems. This includes the mandatory geostationary and polar systems, as well as third party and Oceanography missions. Programmes currently under development are the Meteosat Third Generation and EPS Second Generation programmes and also the Oceanography missions related to Jason and Copernicus. Related services are addressed as well.

Consistently collecting the earth’s climate signatures remains a priority for world governments and international scientific organizations. Architecting a long term solution requires transforming scientific missions into an optimized robust ‘operational’ constellation that addresses the collective needs of policy makers, scientific communities and global academic users for trusted data. The application of new tools offers pathways for global architecture collaboration. Recent rule-based expert system (RBES) optimization modeling of the intended NPOESS architecture becomes a surrogate for global operational climate monitoring architecture(s). These rulebased systems tools provide valuable insight for global climate architectures, by comparison/evaluation of alternatives and the sheer range of trade space explored. Optimization of climate monitoring architecture(s) for a partial list of ECV (essential climate variables) is explored and described in detail with dialogue on appropriate rule-based valuations. These optimization tool(s) suggest global collaboration advantages and elicit responses from the audience and climate science community. This paper will focus on recent research exploring joint requirement implications of the high profile NPOESS architecture and extends the research and tools to optimization for a climate centric case study. This reflects work from SPIE RS Conferences 2013 and 2014, abridged for simplification^{30, 32}. First, the heavily securitized NPOESS architecture; inspired the recent research question - was Complexity (as a cost/risk factor) overlooked when considering the benefits of aggregating different missions into a single platform. Now years later a complete reversal; should agencies considering Disaggregation as the answer. We’ll discuss what some academic research suggests. Second, using the GCOS requirements of earth climate observations via ECV (essential climate variables) many collected from space-based sensors; and accepting their definitions of global coverages intended to ensure the needs of major global and international organizations (UNFCCC and IPCC) are met as a core objective. Consider how new optimization tools like rule-based engines (RBES) offer alternative methods of evaluating collaborative architectures and constellations? What would the trade space of optimized operational climate monitoring architectures of ECV look like? Third, using the RBES tool kit (2014) demonstrate with application to a climate centric rule-based decision engine - optimizing architectural trades of earth observation satellite systems, allowing comparison(s) to existing architectures and gaining insights for global collaborative architectures. How difficult is it to pull together an optimized climate case study - utilizing for example 12 climate based instruments on multiple existing platforms and nominal handful of orbits; for best cost and performance benefits against the collection requirements of representative set of ECV. How much effort and resources would an organization expect to invest to realize these analysis and utility benefits?

The Suomi National Polar Orbiting Partnership (S-NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) employs a large number of temperature and voltage sensors (telemetry points) to monitor instrument health and performance. We have collected data and built tools to study telemetry and calibration parameters trends. The telemetry points are organized into groups based on locations and functionalities. Examples of the groups are: telescope motor, focal plane array (FPA), scan cavity bulkhead, radiators, solar diffuser and Solar Diffuser Stability Monitor (SDSM). We have performed daily monitoring and long-term trending studies. Daily monitoring processes are automated with alarms built into the software to indicate if pre-defined limits are exceeded. Long-term trending studies focus on instrument performance and sensitivities of Sensor Data Record (SDR) products and calibration look-up tables (LUTs) to instrument temperature and voltage variations. VIIRS uses a DC Restore (DCR) process to periodically correct the analog offsets of each detector of each spectral band to ensure that the FPA output signals are always within the dynamic range of the Analog to Digital Converter (ADC). The offset values are updated based on observations of the On-Board Calibrator Blackbody source. We have performed a long-term trend study of DCR offsets and calibration parameters to explore connections of the DCR offsets with onboard calibrators. The study also shows how the instrument and calibration parameters respond to the VIIRS Petulant Mode, spacecraft (SC) anomalies and flight software (FSW) updates. We have also shown that trending studies of telemetry and calibration parameters may help to improve the instrument calibration processes and SDR Quality Flags.

Environmental Data Records (EDR) from the Visible Infrared Imaging Radiometer Suite (VIIRS) have a need for Reflective Solar Band (RSB) calibration errors of less than 0.1%. Throughout the mission history of VIIRS, the overall instrument calibrated response scale factor (F factor) has been calculated with a manual process that uses data at least one week old and up to two weeks old until a new calibration Look Up Table (LUT) is put into operation. This one to two week lag routinely adds more than 0.1% calibration error. In this paper, we discuss trending the solar diffuser degradation (H factor), a key component of the F factor, improving H factor accuracy with improved bidirectional reflectance distribution function (BRDF) and attenuation screen LUTs , trending F factor, and how using RSB Automated Calibration (RSBAutoCal) will eliminate the lag and look-ahead extrapolation error.

The NASA Ocean Biology Processing Group (OBPG) has continued monitoring the SNPP VIIRS on-orbit calibration since the derivation of the calibration for Reprocessing 2014.0 of the VIIRS ocean color data set. That calibration was based on solar and lunar observations through July 2014. Updates to the R2014.0 calibration include: 1) the addition of solar and lunar observations through May 2015; 2) the extension of the lunar libration corrections to incorporate sub-solar point corrections in addition to sub-spacecraft point corrections; 3) the implementation of a shortwave infrared (SWIR) band lunar and solar calibration; and 4) the absolute calibration of the solar observations using solar diffuser measurements. The SWIR band lunar calibration shows residual libration effects. Comparison of the lunar and solar time series yields lunar-derived adjustments to the solar calibration. The solar calibration time series show RMS residuals per band of 0.066–0.17%. The lunar calibration time series show RMS residuals per band of 0.072–0.23%. The solar and lunar time series show RMS differences per band of 0.10–0.23%. The VIIRS on-orbit calibration stability is comparable to that achieved for heritage instruments (SeaWiFS, Aqua MODIS). The quality of the resulting ocean color products is sufficient for incorporation of the VIIRS data into the long-term NASA ocean color data record.

During the first few years of the Suomi National Polar-orbiting Partnership (NPP) mission, the NASA Ocean Color calibration team continued to improve on their approach to the on-orbit calibration of the Visible Infrared Imaging Radiometer Suite (VIIRS). As the calibration was adjusted for changes in ocean band responsitivity, the team also estimated a theoretic residual error in the calibration trends well within a few tenths of a percent, which could be translated into trend uncertainties in regional time series of surface reflectance and derived products, where biases as low as a few tenths of a percent in certain bands can lead to significant effects. This study looks at effects from spurious trends inherent to the calibration and biases that arise between reprocessing efforts because of extrapolation of the timedependent calibration table. With the addition of new models for instrument and calibration system trend artifacts, new calibration trends led to improved estimates of ocean time series uncertainty. Table extrapolation biases are presented for the first time. The results further the understanding of uncertainty in measuring regional and global biospheric trends in the ocean using VIIRS, which better define the roles of such records in climate research.

The accuracy of pre-launch VIIRS response versus scan angle (RVS) characterization is vitally important to the quality of calibrated radiance products. The RVS correct the optical system’s scan angle dependency with respect to the calibrator scan angle. In this document, we describe the methodology used in JPSS-1 RSB RVS characterization and the efficacy of MODTRAN5 in water vapor correction. The RVS is characterized using a 2^nd order polynomial fit over the measured scan angles. The results show high fitting accuracy for all bands except for M9 due to water vapor absorption. To improve M9 RVS, MODTRAN®5 is used to correction water vapor absorption variation during the RVS measurements. This correction greatly reduced M9 RVS characterization uncertainty with a RVS that is up to 0.4% difference compared with RVS prior to water vapor correction.

Observations of stars can be used to calibrate the radiometric performance of the Day/Night Band (DNB) of the Suomi-NPP instrument VIIRS. Bright stars are normally visible in the Space View window. In this paper, we describe several potential applications of stellar observations with preliminary results for several. These applications include routine trending of the gain of the highand mid-gain stages of the DNB and trending the gain ratio between those stages. Many of the stars observed by the VIIRS DNB have absolute flux curves available, allowing for an absolute calibration. Additionally, stars are visible during scheduled lunar roll observations. The electronic sector rotations applied during the scheduled lunar observations greatly increases the sky area recorded for a brief period, increasing the observing opportunities. Additionally, the DNB recorded data during the spacecraft pitch maneuver. This means the deep sky was viewed through the full Earth View. In this situation, thousands of stars (and the planet Mars) are recorded over a very short time period and over all aggregation zones. A possible application would be to create a gain curve by comparing the instrument response to the known apparent stellar brightness for a large number of stars of similar spectral shape. Finally, the DNB is especially affected the mirror degradation afflicting VIIRS. The degradation has shifted peak of the relative spectral response (RSR) of the DNB the blue and the effective band pass has been slightly reduced. The change in response for hot stars (effective temperatures of over 30,000 K) due to this degradation will differ by about 10 percent from the response change of cool stars (below 3500 K).

Both MODIS and VIIRS instruments use a solar diffuser (SD) for their reflective solar bands (RSB) on-orbit calibration. On-orbit changes in SD bi-directional reflectance factor (BRF) are tracked by a solar diffuser stability monitor (SDSM) using its alternate measurements of the sunlight reflected off the SD panel and direct sunlight through a fixed attenuation screen. The SDSM calibration data are collected by a number of filtered detectors, covering wavelengths from 0.41 to 0.94μm. In this paper we describe briefly the Terra and Aqua MODIS and S-NPP VIIRS SDSM on-orbit operation and calibration activities and strategies, provide an overall assessment of their SDSM on-orbit performance, including wavelength-dependent changes in the SDSM detector responses and changes in their SD BRF, and discuss remaining challenging issues and their potential impact on RSB calibration quality. Due to different launch dates, operating configurations, and calibration frequencies, the Terra and Aqua MODIS and S-NPP VIIRS SD have experienced different amount of SD degradation. However, in general the shorter the wavelength, the larger is the SD on-orbit degradation. On the other hand, the larger changes in SDSM detector responses are observed at longer wavelengths in the near infrared (NIR).

To radiometrically calibrate its reflective solar bands, the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the Suomi National Polar-orbiting Partnership satellite observes a sunlit onboard solar diffuser (SD). The degradation factor of the SD bidirectional reflectance distribution function (BRDF) is determined by an onboard solar diffuser stability monitor (SDSM). We improve the accuracy of the measured SD BRDF degradation factor in four ways. First, we remove the bias in the previously computed relative product of the SD screen transmittance and the BRDF at t 0 (when the BRDF degradation just started) τ R/SD, _eff BRDF(t₀). The bias is introduced by the angular dependence of the SD BRDF degradation factor. Second, to computeτ R/SD, _eff BRDF(t₀), we use both the yaw maneuver and a small portion (~ 3 months) of regular on-orbit data. Third, we average the computed degradation factors over a large angular range of an orbit, reducing the impact of the solar power and detector gain noise. And fourth, we center the average of computed degradation factor at a fixed angle relative to the SD surface normal vector to remove the variation due to the dependence of the degradation factor on solar radiation energy incident angle. We fit the degradation factor to a smooth function of time and use the fitting residuals to estimate the accuracy of the degradation factors measured by the SDSM on a per orbit basis.

To radiometrically calibrate its reflective solar bands, the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the Suomi National Polar-orbiting Partnership (SNPP) satellite observes a sunlit onboard solar diffuser (SD). Once on orbit, the bidirectional reflectance distribution function (BRDF) of the SD degrades over time. The degradation factor is determined by an onboard solar diffuser stability monitor (SDSM). However, the central wavelengths (414 to 929 nm) of the SDSM detectors do not cover the VIIRS short wave infrared (SWIR) bands which have central wavelengths from 1238 to 2257 nm. Although it is known that at wavelengths longer than 1 m the SD BRDF degrades at a much slower rate, the degradation at some of the SWIR bands’ central wavelengths may still be non-negligible as Ocean Color products often require a radiometric calibration stability of at least 0.1%. To access the SD BRDF degradation factor in the SWIR bands wavelength region, we investigate a phenomenological model and apply the model to determine the degradation factor in the SWIR bands wavelength region.

The Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the Suomi National Polar-orbiting Partnership satellite performs radiometric calibration of its reflective solar bands (RSBs) primarily by observing an onboard solar diffuser (SD). The SD optical scattering property is measured by a bidirectional reflectance distribution function (BRDF). Once on orbit, the BRDF degrades over time and the degradation factor is determined by an onboard solar diffuser stability monitor (SDSM) which observes the Sun and the sunlit SD at almost the same time. We showed in a previous SPIE paper that the BRDF degradation factor is angle dependent. Consequently, due to that the SDSM and the VIIRS telescope SD views have very different angles, applying the BRDF degradation factor determined from the SDSM without any adjustments to the VIIRS RSB calibration can result in large systematic errors. In addition, the BRDF angular dependence impacts the determination of the SD screen transmittance viewed by both the SDSM detectors and the VIIRS telescope. We first use yaw maneuver data to determine the product of the SD attenuation screen transmittance and the BRDF at the initial time (when the BRDF just started to degrade) viewed by the VIIRS telescope, removing the impact of the SD BRDF degradation factor angular dependence over satellite orbits. By attributing the large bumps observed in the initially computed VIIRS detector gains for the M1-M4 bands to the angular dependence of the BRDF degradation factor and matching the computed VIIRS detector gains from the SD and the lunar observations, we find the relation between the BRDF degradation factors in the VIIRS telescope and SDSM SD view directions.

Both MODIS and VIIRS use a solar diffuser (SD) to calibrate their reflective solar bands (RSB), covering wavelengths from 0.41 to 2.3 μm. On-orbit changes of the SD bi-directional reflectance factor (BRF) are tracked by an on-board solar diffuser stability monitor (SDSM). The current SDSM design only covers the spectral range from 0.41 to 0.93 μm. In general, the SD degradation is strongly wavelength-dependent with larger degradation occurring at shorter wavelengths, and the degradation in the SWIR region is expected to be extremely small. As each mission continues, however, the impact due to SD degradation at SWIR needs to be carefully examined and the correction if necessary should be applied in order to maintain the calibration quality. For Terra MODIS, alternative approaches have been developed and used to estimate the SD degradation for its band 5 at 1.24 μm and a time-dependent correction has already been applied to the current level 1B (L1B) collection 6 (C6). In this paper, we present different methodologies that can be used to examine the SD degradation and their applications for both Terra and Aqua MODIS and S-NPP VIIRS SWIR calibration. These methodologies include but not limited to the use of lunar observations, Pseudo Invariant Calibration Sites (PICS), and deep convective clouds (DCC). A brief description of relative approaches and their use is also provided in this paper.

Lunar observations have been regularly scheduled for the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard the Suomi National Polar-orbiting Partnership (S-NPP) satellite since its launch on October 28th, 2011. In reference to the ROLO irradiance model, the detector gain coefficient or F-factor can be derived from these lunar observations for the reflective solar bands (RSB). Unlike its predecessor Moderate Resolution Imaging Spectroradiometer (MODIS), the Moon and the on-board solar diffuser (SD) are viewed by VIIRS detectors at the same angle of incidence (AOI) to the half angle mirror (HAM). Eliminating the impact from the variation in the instrument response to the HAM AOI, this design allows the detector gain changes tracked by the Moon and the SD to be directly compared. In this paper, we update the lunar F-factors from the scheduled lunar calibration. The long-term trends of the lunar F-factor trending and the SD F-factor trending still agree in general for all RSBs. We also calculate the lunar F-factor at detector level and compare the detector dependency of the lunar F-factor and the SD F-factor. For a few RSBs at shorter wavelengths, a bias of up to 1% between the two has been identified. Using the detector-dependent lunar F-factors will decrease the retrieved Earth view radiance of lower-number detectors in relative to higher-number detectors than the SD F-factors. The inconsistency indicates systematic bias between the lunar and SD calibration approaches.

The VIIRS radiometric calibration approach relies on views of space above the earth limb to estimate a “zero offset” which is subtracted from the other instrument views (earth, solar diffuser, on board black body). This zero offset estimation is compromised when the Moon lies within the space view. The current calibration approach has a conservative method to determine when the space view is contaminated or potentially contaminated by the Moon. We outline a new approach to detecting lunar contamination, and for estimating the zero offset for contaminated scans. Our approach offers the potential to greatly reduce the number of scans classified as lunar contaminated and thus of lower quality due to the alternate calibration process used in the current operational approach. Thus, such an alternative approach could increase the number of nominal, high quality VIIRS scans available for science analyses.

Since launch, lunar observations have been performed on a regular basis for the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard the Suomi National Polar-orbiting Partnership (S-NPP) satellite. Unlike its predecessor Moderate Resolution Imaging Spectro-radiometer (MODIS), VIIRS has no on-board calibrator to perform its on-orbit spatial characterization. Therefore, the methodologies for spatial characterization using the Moon that have been developed for MODIS are extended for VIIRS. One of the key spatial parameters is the band-to-band registration (BBR) in both along-scan and along-track directions. While the lunar BBR results can satisfactorily demonstrate that the longterm stability of VIIRS BBR meets the design requirement specification of ±0.1 M-band pixels, seasonal oscillations have been observed in BBR trending, mostly noticeable between the visible/near infrared bands and short/middle wave infrared bands. This paper investigates the cause of this oscillation and proposes a new algorithm to reduce it. It is identified that the oscillation is correlated with the orientations of the lunar images that rotate from event to event. After figuring out an approach to quantify the rotation and compensate its impact, current BBR algorithm is improved and the seasonal oscillation in the BBR results is significantly reduced from up to ±0.05 M-band pixels to less than ±0.01 Mband pixels. With suppressed seasonal oscillation, the actual BBR including its long-term drift can be determined more accurately.

The Soumi-NPP Visible Infrared Imaging Radiometer Suite (VIIRS) was launched on October 28th, 2011 and its Sensor Data Record (SDR) product reached maturity status in March of 2014. Although the VIIRS SDR products are declared at the validated maturity level, there remain issues such as residual stripings in some thermal bands along with the scan direction. These horizontal striping issues in the Thermal Emissive Bands (TEB) were reflected in the sea surface temperature (SST) products. The observed striping magnitude can reach to 0.2 K, especially at the band M14 and M15. As an independent source of calibration, the Solar Diffuser (SD) is utilized in this study. The SD is originally designed for the Reflective Solar Band (RSB), however, it is assumed to be thermally stable at the time of SD observation. For each detector, a linear slope is developed by Integrated Calibration and Validation System (ICVS), which is applied on converting digital number (DN) to radiance unit. After the conversion, detector based noise analyses in VIIRS band M15 and M16 are performed on in-scan and scan-by-scan SD responses. Since SD radiance varies within an orbit, the noise calculation must be derived from the neighborhood Allan deviation. The noise derived Allan deviation shows that detector 1 and 2 in band M15 and detector 9 in band M16 have higher noise content compared to other detectors.

Calibration and validation play an essential role during the acquisition and processing of satellite data for Earth Observing System satellites in addition to being an integral part of maintaining scientific values of archived satellite data. The Advanced Spaceborne Thermal Emission and Reflection and Radiometer (ASTER) and Moderate Resolution Imaging Spectroradiometer (MODIS) are two of five sensors onboard the Terra platform. ASTER has a swath width of 60 km with 8 spectral bands in the visible and near infrared (VNIR) and thermal infrared (TIR) spectral range with a spatial resolution of 15-m (bands 1-3) and 90-m (bands 10-14), respectively while MODIS has a swath width of 2300 km with 36 spectral bands from visible to infrared spectral range with a spatial resolution of 250 m (bands 1-2), 500 m (bands 3-7), and 1 km (bands 8-36). ASTER is the ‘zoom’ lens and MODIS is the ‘keystone’ instrument for Terra; they provide quantitative measurements of various earth system variables to the scientific and to the broader community. The simultaneous view of the sensors simplifies the intercomparison between them and the current work relies on the use of the Railroad Valley Playa test site to reduce uncertainties caused by spatial heterogeneity and spectral differences in the sensors. The fact that Railroad Valley is a calibration test site for ASTER ensures that ASTER was tasked at a higher rate over this area providing more scenes for an intercomparison. The study compares ASTER L1B data for the three VNIR bands reprocessed with recent calibration updates and MODIS 02 Collection 6 data products for the similar bands. No correction for geometry angle is needed and coincident 3-km by 3-km regions are used to reduce the impact of spatial heterogeneity. A correction for spectral differences between the sensors is applied based on seasonal averages of EO-1 Hyperion spectral range. Results indicate that the calibrated radiance products from the two sensors agree to within the combined absolute uncertainties. There is no statistically significant temporal trend between the two and this should allow the correction between the two to within 0.5% over the 10 years studied here.

The MODerate-resolution Imaging Spectroradiometer (MODIS) is one of the primary instruments in the fleet of NASA’s Earth Observing Systems (EOS) in space. Terra MODIS has completed 15 years of operation far exceeding its design lifetime of 6 years. The MODIS Level 1B (L1B) processing is the first in the process chain for deriving various higher level science products. These products are used mainly in understanding the geophysical changes occurring in the Earth’s land, ocean, and atmosphere. The L1B code is designed to carefully calibrate the responses of all the detectors of the 36 spectral bands of MODIS and provide accurate L1B radiances (also reflectances in the case of Reflective Solar Bands). To fulfill this purpose, Look Up Tables (LUTs), that contain calibration coefficients derived from both on-board calibrators and Earth-view characterized responses, are used in the L1B processing. In this paper, we present the implementation mechanism of the electronic crosstalk correction in the Photo Voltaic (PV) Long Wave InfraRed (LWIR) bands (Bands 27-30). The crosstalk correction involves two vital components. First, a crosstalk correction modular is implemented in the L1B code to correct the on-board Blackbody and Earth-View (EV) digital number (dn) responses using a linear correction model. Second, the correction coefficients, derived from the EV observations, are supplied in the form of LUTs. Further, the LUTs contain time stamps reflecting to the change in the coefficients assessed using the Noise Equivalent difference Temperature (NEdT) trending. With the algorithms applied in the MODIS L1B processing it is demonstrated that these corrections indeed restore the radiometric balance for each of the affected bands and substantially reduce the striping noise in the processed images.

The paper presents the new approach that includes technique, scheme and instruments for precise calibration of space-borne and airborne visible infrared imaging radiometers (VIIRs). The key component of this technique is the precise uniform light source based on optically-interconnected integrating spheres. The light source contains several (5…11) primary integrating spheres of small diameters which are installed on a secondary integrating sphere of bigger diameter. The initial light sources – halogen lamps or light emitted diodes are installed inside the primary integrating spheres. These spheres are mounted on the secondary integrating sphere. The radiation comes from the primary integrating spheres to the secondary one through diaphragms which diameters can be varied. The secondary integrating sphere has an output aperture where uniform radiance emits. As a result the output radiance can be varied in extremely wide range – up to 800 W/(st·m²) with dynamic range 1 000 000 – without any change of spectral characteristics. Non-uniformity of the radiance distribution throughout the output aperture can be smaller 0.5 % because the secondary integrating sphere is illuminated uniformly and it does not contain lamps inside. The paper discusses the requirements to calibration system, the application of this light source in calibration procedures, metrological aspects of radiometric calibration.

The low gain stage of VIIRS Day/Night Band (DNB) on Suomi-NPP is calibrated using onboard solar diffuser. The calibration is then transferred to the high gain stage of DNB based on the gain ratio determined from data collected along solar terminator region. The calibration transfer causes increase of uncertainties and affects the accuracy of the low light radiances observed by DNB at night. Since there are 32 aggregation zones from nadir to the edge of the scan and each zone has its own calibration, the calibration versus scan angle of DNB needs to be independently assessed. This study presents preliminary analysis of the scan-angle dependence of the light intensity from bridge lights, oil platforms, power plants, and flares observed by VIIRS DNB since 2014. Effects of atmospheric path length associated with scan angle are analyzed. In addition, other effects such as light changes at the time of observation are also discussed. The methodology developed will be especially useful for JPSS J1 VIIRS due to the nonlinearity effects at high scan angles, and the modification of geolocation software code for different aggregation modes. It is known that J1 VIIRS DNB has large nonlinearity across aggregation zones, and requires new aggregation modes, as well as more comprehensive validation.

Overhauser magnetometer, a kind of weak-magnetic measurement system based on the Overhauser effect, has been widely used in satellite magnetic survey, aeromagnetic survey and other engineering and environmental applications. Overhauser magnetometer plays an important role in the application of magnetic field measurement for its advantages of low power consumption and high accuracy. Weak field magnetic resonance is usually limited by the signal to noise ratio (SNR). In order to improve the SNR of Overhauser magnetometer, noise characteristics of Overhauser magnetometer sensor are investigated in this paper. A background noise model of Overhauser magnetometer sensor is presented. The calculated results indicate that the noise power spectral density shows a band-limited white noise characteristic. The maximum value of the noise power spectral density observed at the resonant frequency. The measured results coincide with the calculated results. The correlation between the SNR and the matched resistance is investigated by using the noise model. The calculated results demonstrate that large matched resistance is beneficial to improve the SNR of the sensor. When matched resistance is larger than 100kΩ, the SNR tends to be a constant. On the premise of stability, the sensor will achieve the optimal SNR when the matched resistance is around 100kΩ. This investigation is beneficial to improve noise performance of Overhauser magnetometer sensor.

As a precision instrument to measure the earth magnetic field, proton magnetometer is widely used in different fields such as geological survey, buried objects detection and earth field variations. Due to poor signal to noise ratio (SNR) of the system, proton magnetometer suffers from low sensitivity which directly affects the performance. In order to increase the sensitivity, we present an improved proton magnetometer. First, the effect of matching resistance on Q value is discussed to enhance SNR, and high matching resistance has been chosen to improve the Q value of the resonant circuit. Second, noise induced by pre-amplifier is investigated in order to obtain low noise signal, and we adopt the JFET with noise figure less than 0.5dB as the pre-amplifier. Third, by using band-pass filter, low-noise output signal is obtained. Fourth, the method of period measurement based on CPLD is employed to measure frequency of the square wave shaped from the output sinusoidal signal. High precision temperature compensate crystal oscillator (TCXO) has been used to improve the frequency measurement accuracy. Last, experimental data is obtained through field measurements. By calculating the standard deviation, the sensitivity of the improved proton magnetometer is 0.15nT for Earth’s magnetic field observation. Experimental results show that the new magnetometer is sensitive to earth field measurement.

MODIS (Moderate Resolution Imaging Spectroradiometer) is a key sensor aboard the Terra (EOS AM) and Aqua (EOS PM) satellites. MODIS collects data in 36 spectral bands and generates over 40 data products for land, atmosphere, cryosphere and oceans. MODIS bands 1 and 2 have nadir spatial resolution of 250 m, compared with 500 m for bands 3 to 7 and 1000 m for all the remaining bands, and their measurements are crucial to derive key land surface products. This study evaluates the calibration performance of the Collection-6 L1B for both Terra and Aqua MODIS bands 1 and 2 using three vicarious approaches. The first and second approaches focus on stability assessment using data collected from two pseudo-invariant sites, Libya 4 desert and Antarctic Dome C snow surface. The third approach examines the relative stability between Terra and Aqua in reference to a third sensor from a series of NOAA 15-19 Advanced Very High Resolution Radiometer (AVHRR). The comparison is based on measurements from MODIS and AVHRR Simultaneous Nadir Overpasses (SNO) over a thirteen-year period from 2002 to 2015. Results from this study provide a quantitative assessment of Terra and Aqua MODIS bands 1 and 2 calibration stability and the relative calibration differences between the two sensors.

Suomi NPP VIIRS SWIR band M11 (2.25 μm) has larger radiometric uncertainty compared to the rest of the reflective solar bands. This is due to a number of reasons including prelaunch calibration uncertainties. One of the most commonly used technique to verify the radiometric stability and accuracy of VIIRS is by intercomparing it with other well calibrated radiometers such as MODIS. However one of the limitations of using MODIS is that VIIRS band M11 RSR doesn’t overlap with MODIS bands at all. Thus the accuracy of intercomparison relies completely on how well the spectral differences are analyzed over the given target. Since desert sites have higher reflectance and more flat spectra, this study uses desert sites to analyze M11 radiometric performance. In order to better match the RSR between instruments, we have chosen Landsat 8 OLI SWIR band 2 (2.20 μm) to perform intercomparison. This is mainly because OLI SWIR band 2 fully covers the VIIRS band M11 even though OLI has much wider RSR compared to VIIRS. The study suggests that there exists large radiometric inconsistency between VIIRS M11 and OLI, on the order of 5%. The impact due to spectral differences is estimated and accounted for using EO-1 Hyperion observations and MODTRAN.

Recent pre-launch measurements performed on the Joint Polar Satellite System (JPSS) J1 Visible Infrared Imaging Radiometer Suite (VIIRS) using the NIST T-SIRCUS monochromatic source have provided wavelength dependent polarization sensitivity for select spectral bands and viewing conditions. Measurements were made at a number of input linear polarization states (twelve in total) and initially at thirteen wavelengths across the bandpass (later expanded to seventeen for some cases). Using the source radiance information collected by an external monitor, a spectral responsivity function was constructed for each input linear polarization state. Additionally, an unpolarized spectral responsivity function was derived from these polarized measurements. An investigation of how the centroid, bandwidth, and detector responsivity vary with polarization state was weighted by two model input spectra to simulate both ground measurements as well as expected on-orbit conditions. These measurements will enhance our understanding of VIIRS polarization sensitivity, improve the design for future flight models, and provide valuable data to enhance product quality in the post-launch phase.

The next-generation geostationary meteorological satellite of the Japan Meteorological Agency (JMA), Himawari-8, entered operation on 7 July 2015. Himawari-8 features the new 16-band Advanced Himawari Imager (AHI), whose spatial resolution and observation frequency are improved over those of its predecessor MTSAT-series satellites. These improvements will bring unprecedented levels of performance in nowcasting services and short-range weather forecasting systems. In view of the essential nature of navigation and radiometric calibration in fully leveraging the imager’s potential, this study reports on the current status of navigation and calibration for the AHI. Image navigation is accurate to within 1 km, and band-to-band co-registration has also been validated. Infrared-band calibration is accurate to within 0.2 K with no significant diurnal variation, and is being validated using an approach developed under the GSICS project. Validation approaches are currently being tested for the visible and near-infrared bands. In this study, two of such approaches were compared and found to produce largely consistent results.

The urban impervious surface, an important part in the city system, has a great influence on theecologicalenvironment in urban areas. The coverage of it is an important indicator for the evaluation ofurbanization. TheRemotesensing data has prominent features such as information-rich and accurate and it can provide data basis for large area extraction of impervious surface. GF-1 satellite is the first satellite of high-resolution earth observation system in China. With the homemade GF-1 satellite remote sensing image date as a resolution, this research, by the combination of V-I-S model and linear spectral mixture model, has first made estimation on the impervious surface of Tianjin City and then employed the remote sensingimage date with high resolution to test the precision of the estimated results. The results not only show that this method will make high precision available, but also reveal that Tianjin City has a wide coverage of impervious surface in general level, especially a high coverage rate both in the center and the coastal areas. The average coverage of impervious surface of the Tianjin city is very high and the coverage of impervious surface in the center and the coastal areas of Tianjin city reach seventy percent.City managers can use these data to guide city management and city planning.

The Day/Night Band (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard Suomi National Polar-orbiting Partnership (Suomi-NPP) represents a major advancement in night time imaging capabilities. The VIIRS DNB sensor is affected by stray light. Straylight effect on the DNB instrument is due to solar illumination entering the optical path after the satellite passes through the day-night terminator projected on Earth’s surface. It results in an overall increase in the recorded radiance values. This effect is more significant during solstice. After the launch of Suomi-NPP in October 2011, there was a gray haze in radiance images observed by DNB due to straylight, and straylight correction has been implemented to remove this effect. This study performs vicarious validation of straylight correction for VIIRS DNB band using Dome C in Antarctic. Nadir observations of these high latitude regions by VIIRS are selected during perpetual night season, i.e. from April to July during the year 2014 under various lunar phases. The dependence of observed radiance over Dome C on lunar phases and the cross-comparison between DNB observations for events with/without straylight are shown in this paper. This paper presents an effective method to assess the performance of straylight correction for VIIRS DNB in Southern Hemisphere.