The International Space Station/Japanese Exposure Module (ISS/JEM) borne instrument, the Superconducting
Submillimeter-Wave Limb-Emission Sounder (SMILES), has successfully measured chemical species in the middle
atmosphere between October 2009 and April 2010. We focus on inorganic chlorine species measured inside the
late spring Antarctic vortex, when hydrogen chloride (HCl) was a main component of the total inorganic chlorine
(Cly). Comparisons with other satellite instruments, the Aura Microwave Limb Sounder (MLS) and Atmospheric
Chemistry Experiment Fourier transform spectrometer (ACE-FTS), are also presented to show the SMILES HCl
and chlorine monoxide (ClO) data quality.
A new generation of sub-millimeter-wave receivers employing sensitive SIS (Superconductor-Insulator-
Superconductor) detector technology will provide new opportunities for precise passive remote sensing observation of
minor constituents in atmosphere. Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) was
designed to be onbord the Japanese Experiment Module (JEM) on the International Space Station (ISS) as a
collaboration project of National Institute of Information and Communications Technology (NICT) and Japan Aerospace
Exploration Agency (JAXA). SMILES scheduled to be launch in September 11, 2009 by the H-II Transfer Vehicle
(HTV). Mission Objectives are: i) Space demonstration of superconductive mixer and 4-K mechanical cooler for the
submillimeter limb emission sounding, and ii) global observations of atmospheric minor constituents. JEM/SMILES will
allow to observe the atmospheric species such as O3, H35Cl, H37 Cl, ClO, BrO, HOCl, HO2, and HNO3, CH3CN, and
Ozone isotope species with the precisions in a few to several tens percents from upper troposphere to the mesosphere.
We have estimated the observation capabilities of JEM/SMILES. This new technology may allow us to open new issues
in atmospheric science.
Ice clouds play an important role in the energy budget of the atmosphere as well as in the hydrological cycle.
Currently cloud ice is one of the largest remaining uncertainties in climate models. Large discrepancies arise
from different assumptions on ice cloud properties, in particular on microphysics, which are not sufficiently
constrained by measurements. Passive sub-millimeter wave (SMM) techniques have the potential of providing
direct information on ice content and particle sizes with daily global coverage. Here we introduce a concept for a
compact 2-receiver SMM sensor and demonstrate its capabilities on measurements of ice content, mean particle
size, and cloud altitude.
This work presents clear-sky simulations to study water vapor (H2O) retrieval from a nadir sounder operating in
the TeraHertz (THz) and Far-Infrared (FIR) spectral domains (100-500 cm-1). The THz/FIR retrieval is compared
with retrieval from the mid-InfraRed (IR) 7μm H2O band (1200-2000 cm-1). The THz/FIR observations
are more sensitive in the upper troposphere and lower stratosphere than the IR measurements. On the other
hand, the IR sounder has better performance in the lower troposphere. The retrieval error due to uncertainties
on the temperature profile are of the same order of magnitude in the THz/FIR and IR bands. No significant
retrieval errors from contaminating species have been found. The calculations for several atmospheric scenarios
show that retrieval performances are not only dependent on the H2O abundance but also on the temperature
gradient. Hence, sensitivity in the UT/LS layer, with a low temperature gradient, is poor. The combination of
FIR and IR merges the advantages of both bands, and allows to slightly decorrelate temperature and H2O VMR.
The Geostationary Earth Orbit (GEO) provides a unique opportunity of monitoring tropospheric pollutants on the
regional scale. Thermal InfraRed (TIR) observations (from about 620-2300 cm-1) have two advantages over other
spectral domains: firstly, day/night observations are possible; secondly, numerous molecular species can be observed
simultaneously. However, the sensitivity of TIR observations may be a critical point for the geostationary orbit geometry.
In this study, we present a feasibility study for TIR pollution observations in GEO conditions. The capabilities of
measuring the tropospheric abundance of ozone (O3) and carbon monoxide (CO) are investigated. Limitations of the
sensor sensitivity are also discussed.
With wavelengths in the order of the size of typical ice cloud particles and therefore being sensitive to ice clouds,
the Terahertz (THz) region is expected to bear a high potential concerning measuring ice cloud properties, in
particular microphysical parameters. In this paper we give an introduction to the characteristics of atmospheric
THz radiation between 0-5THz (wavelengths >60 μm and wavenumber<170 cm-1 respectively) as well as ice
cloud optical properties and cloud effects in the THz region. Using radiative transfer model simulations we
analyze the sensitivity of THz spectra to ice content and particle size. For tropical cases cloud effects in the
order of 0.1 K/(g/m2) are found. Assuming instrumental sensitivities of typically around 1K these effects allow
for detection of clouds with columnar ice content of 10 g/m2. It is demonstrated that submillimeter (SMM)
instruments are sensitive to particles with sizes larger than 100 μm, while THz observations potentially can
measure particles as small as 10 μm.
Here we present a Principal Components (PCs) method of retrieval of the HDO/H2O vertical profile using atmospheric
radiances observed from space by sensor like IMG as well as atmospheric transmittance spectra observed by ground
based FTIR. The method is based on the expansion of the retrieved profile on eigenvectors of covariance matrix of
model profiles extracted from the isotopic Atmospheric General Circulation Model (AGCM). A priori information of
covariance matrix compensates partially the lack of information containing in weighting functions for HDO in lower
atmospheric layer (0-1 km) and layers above 10 km. Error estimation of the retrieval scheme was made using closed
model computations with synthetic spectra ofIMG and known sets of T, H20, HDO profiles and its value is within 8% -
70% for vertical profile and not greater than l8% for columnar value of HDO/H20 ratio. The method was applied to
IMG/ADEOS spectra measured over the ocean in clear sky conditions. Latitudinal distributions ofHDO/H20 profile and
columnar HDO/H20 ratio are retrieved over Pacific Ocean for the time interval from winter of 1996 to summer of 1997.
The retrieved HDO/H20 from IMG/ADEOS data and simulated with isotopic AGCM are in a good agreement.
FTIR is Poker Flat high resolution ground based Fourier transform spectrometer for up-looking observation of
atmosphere in the spectral range from 750-4300 cm-1 with resolution 0.0019 cm-1 and high signal to noise ratio. The
spectrometer is located at the Poker Flat Research Range (Altitude 0.61km; latitude 65.11N; longitude 147.42W) of the
Geophysical Institute at the University of Alaska Fairbanks. Poker Flat FTS is operating from 1999, observation modes
are atmospheric emission and solar radiation absorption. The measured atmospheric traiismittances are supported by
sonde observations of T and water vapour profiles. The HDO/H20 PCs retrieval method was also adapted for using the
high spectral resolution atmospheric transmittances observed by FTIR. Linear regression of PCs of the HDO/H20
profiles was obtained in this case. Error estimation of the retrieval scheme was made using closed model computations
with synthetic spectra ofthe FTIR and known sets of T, H20, HDO profiles and its value is within 6% - 67% for vertical
profile but not greater than lO% for columnar value of HDO/H20 ratio. As an example, HDO/H20 vertical profiles were
retrieved using a few samples of FTIR spectra observed at the Poker Flat Research Range from 2000 to 2004 and
compared with isotope AGCM outputs for Alaska's atmosphere.
A submillimeter wave limb emission sounder, that is to be aboard the Japanese Experiment Module (JEM, dubbed as 'KIBO') at the International Space Station, has been designed. This payload, Superconducting Submillimeter-wave Limb Emission Sounder (SMILES), is aimed at global mappings of stratospheric trace gasses by means of the most sensitive submillimeter receiver ever operated in space. Such sensitivity is ascribed to a Superconductor-Insulator- Superconductor (SIS) mixer, which is operated at 4.5 K in a dedicated cryostat combined with a mechanical cooler. SMILES will observe ozone-depletion-related molecules such as ClO, HCl, HO2, HNO3, BrO and O3 in the frequency bands at 624.32 - 626.32 GHz, and 649.12 - 650.32 GHz. A scanning antenna will cover tangent altitudes from 10 to 60 km in every 53 seconds, while tracing latitudes from 38S to 65N along its orbit. This global coverage makes SMILES a useful tool of observing the low- and mid-latitudinal areas as well as the Arctic peripheral region. The molecular emissions will be detected by two units of acousto-optic spectrometers (AOS), each of which has coverage of 1.2 GHz with a resolution of 1.8 MHz. This high-resolution spectroscopy will allow us to detect weal emission lines attributing to less-abundant species.
JEM/SMILES (superconducting SubMIllimeter-wave Limb-Emission Sounder) is currently under development to demonstrate a submillimeter-wave sounder with extremely high sensitivity on the platform of the Japanese Experiment Module (JEM). In the submillimeter region, this is the first mission in space using a low-noise 4K cooled receiver, which is expected to give new observations for radicals in the stratosphere such as BrO. One of the most unique characteristics of the JEM/SMILES observation is its high sensitivity in detecting atmospheric limb emissions in the submillimeter wave range. The purpose of SMILES is global monitoring of the radicals which play important roles in the stratospheric system. We are now using the newly developed JEM/SMILES simulator to model observed spectra (including the characteristics of the SMILES sensor) and simulate the retrieval performance. Some preliminary results of the simulation are obtained in view of the scientific targets of JEM/SMILES.
In order to estimate measurement capability of the Superconducting Submillimter-Wave Limb-Emission Sounder (SMILES) on the Japanese Experiment Module (JEM) of the International Space Station (ISS) and to clarify the scientific impacts of the JEM/SMILES, we are developing the JEM/SMILES simulator. The simulator consists of the forward model and the inversion model. The forward model calculates a brightness temperature by applying the radiative transfer formula to a limb sounding geometry and simulates the effects of the JEM/SMILES sensor characteristics including optics superconductor-insulator-superconductor (SIS) mixers, Acousto-Optical Spectrometer (AOS), and so on, to it. Because it is important to estimate the effects of the sensor for the retrieval, we develop carefully simulated sensor model. The forward model also calculates weighting functions of molecular, the temperature, the pressure and so on. This paper describes how the brightness temperature and weighting functions are calculated in the forward model and how the effects of the sensor are taken into account in the simulator, and finally shows how the optical estimation method (OEM) is applied to our retrieval model.
KEYWORDS: Spectroscopy, Adaptive optics, Acousto-optics, Interference (communication), Charge-coupled devices, Analog electronics, Signal to noise ratio, Spectroscopes, Quantization, Data modeling
An acousto-optical spectrometer (AOS) is employed in order to meet scientific mission objectives of submillimeter-wave limb-emission sounder (SMILES) to be aboard the Japanese Experiment Module (JEM) of the International space station (ISS). The capability of multi channel detection with AOS is suitable for observing multi chemical species in a wide frequency region. Wide noise dynamic range enables us to obtain the spectra without unnecessary increase of system noise, suggesting a good combination of AOS with low noise front end system of SMILES> Several technical concerns relating to important instrumental characteristics of AOS are discussed and expected performance of the spectrometers to be used in the JEM/SMILES mission are over viewed.
KEYWORDS: Space operations, Data processing, Data centers, Algorithm development, Data archive systems, Multiplexing, Satellites, Data backup, Binary data, Relays
Superconducting sub-millimeter-wave limb-emission sounder (SMILES) using 4K Superconductor-Insulator-Superconductor (SIS) detector for ISS/JEM is under development. Spectrum of 600 GHz regions will be acquired using acousto-optics spectrometer (AOS). The high sensitivity of SMILES will enable us to measure O3, ClO without enhancement, BrO, Hcl, HO2, HNO3 from 10 to 60 km. This paper describes a current plan of data retrieval algorithms (L0, L1, L2 and L3), ground data system, data validation and data distribution.
A submillimeter limb-emission sounder, that is to be aboard the Japanese Experiment Module (JEM, dubbed as KIBO) at the International Space Station, has been designed. This payload, Superconducting Submillimeter-wave Limb-emission Sounder (SMILES), is aimed at global mappings of stratospheric trace gases by means of the most sensitive submillimeter receiver ever operated in space. Such sensitivity is ascribed to a Superconductor-Insulator- Superconductor (SIS) mixer, which is operated at 4.5 K in a dedicated cryostat combined with a mechanical cooler. SMILES will observe ozone-depletion-related molecules such as ClO, Hcl, HO2, HNO3, BrO and O3 in the frequency bands at 624.32-626.32 GHz and 649.12-650.32 GHz. A scanning antenna will cover tangent altitudes from 10 to 60 km in every 53 seconds, while tracing the latitudes form 38 S to 65 N along its orbit. This global coverage makes SMILES a useful tool of observing the low- and mid- latitudinal areas as well as the Arctic peripheral region. The molecular emissions will be detected by two units of acousto-optic spectrometers (AOS), each of which has coverage of 1.2 GHz with a resolution of 1.8 MHz. This high-resolution spectroscopy will allow us to detect weak emission lines attributing to less-abundant species.
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