EARLINET, the European Aerosol Research Lidar Network, is the first aerosol lidar network, established in 2000, with the main goal to provide a comprehensive, quantitative, and statistically significant data base for the aerosol distribution on a continental scale. At present, 23 stations distributed over Europe are part of the network. The EARLINET-ASOS (Advanced Sustainable Observation System) EC Project, starting on the EARLINET infrastructure, will contribute to the improvement of continuing observations and methodological developments that are urgently needed to provide the multi-year continental scale data set necessary to assess the impact of aerosols on the European and global environment and to support future satellite missions. The main objective of EARLINET-ASOS 5-year project, started on 1 March 2006, is to improve the EARLINET infrastructure resulting in a better spatial and temporal coverage of the observations, continuous quality control for the complete observation system, and fast availability of standardized data products. This will be reached by defining and using common standards for instruments, operation procedures, observation schemes, data processing including advanced retrieval algorithms, and dissemination of data. The expected outcome is the most comprehensive data source for the 4-D spatio-temporal distribution of aerosols on a continental scale.

Lidar technique is the most suitable for high vertical and temporal resolution aerosol profiling. In particular the Raman/elastic lidar combined approach allows independent determination of aerosol extinction and backscatter coefficient without any assumption about their relationship. This technique allows the determination of vertical profiles of the lidar ratio, i.e. the ratio of aerosol extinction and backscatter coefficients. In elastic lidar technique an assumption on the lidar ratio profile is needed for the retrieval of aerosol backscatter coefficient. To improve aerosol backscatter coefficient accuracy in the case of pure elastic backscatter lidar, a climatology of lidar ratio values for specific aerosol types is necessary. Five years of systematic lidar ratio measurements have been collected by means of a Raman/elastic lidar system operational at CNR-IMAA, since May 2000 in the framework of EARLINET, the first lidar network for tropospheric aerosol study on continental scale. The dependence of lidar ratio as a function of the altitude is analysed. A climatological analysis of the lidar ratio measurements in the Planetary Boundary Layer (PBL) and for Saharan dust intrusions is carried out. In addition, lidar ratio measurements concerning forest fires and volcanic eruptions are also analyzed.

At ALOMAR (Arctic Lidar Observatory of Middle Atmosphere Research, 69°N, 16°E) an exemplary co-location of tropospheric Lidar, sun-photometer and VHF Radar is used for aerosol investigations. Recently the University of Oslo, the Norwegian Institute for Air Research and the Andøya Rocket Range started to operate a new troposphere Lidar system. The system uses two elastic backscatter channels (1064nm, 355 nm), two polarization channels (532p nm and 532s nm) and a Raman channel (387nm). The co-located sun photometer is of Cimel type and the VHF Radar is operating at 53 MHz. The data from the Cimel instrument are collected in cooperation with a group from Valladolid (Spain) and the Radar is operated by the Institute for Atmospheric Physics from Kühlungsborn. The location of ALOMAR, north of the Arctic Circle and on an island, a few hundred meters from seashore and about 30 km off the continent, makes it ideal for investigations related to Sub-Arctic aerosols. The present paper presents the first results from simultaneous and collocated tropospheric measurements. We compare aerosol stratification derived from Lidar data with simultaneous measurements of total aerosol content, derived from Cimel data in dependence of simultaneous winds, stratified layers and echo power from radar data. Diurnal cycles for both summertime and wintertime are shown.

At the mid-latitude location of Kuehlungsborn (54°N, 12°E) a resonance lidar and a Rayleigh-Mie-Raman (RMR) lidar are operated to observe e.g. the occurrence and particle properties of Noctilucent Clouds (NLC) and to measure continuous temperature profiles from the troposphere to the lower thermosphere. For the temperature profiles the two lidars (RMR lidar and potassium lidar) and three different measurement methods (rotational Raman, Rayleigh/vib. Raman, Doppler resonance) are combined. The profiles are obtained continuously between 1 and 105 km with a temporal and vertical resolution of at least 15 min and 1 km, respectively. Temperature fluctuations due to gravity waves and tides with amplitudes of up to ±20 K are observed. In summer during the cold phases of waves the temperature above 80 km drops occasionally below the frostpoint temperature. However, the mean temperature below 83 km is a few Kelvin above the frost point and only for about two weeks in summer the air becomes continuously supersaturated between 85 and 90 km. Therefore, the existence of NLC ice particles above our site is only allowed in the cold phases of waves. We will present lidar-observations of NLC and temperatures below and above the NLC layer showing the coupling of the NLC to supersaturated air in the mesopause region.

LIDAR systems have demonstrated their ability to map aerosol variations throughout the atmospheric column and therefore they have has become a central technology in current strategies for tropospheric aerosol research. Its use is complicated, however, by the fact that the lidar signal contains a convolution of two basic optical properties of the aerosol particles: the backscatter coefficient and the extinction coefficient. A quantitative retrieval of either property requires knowledge of their relationship along the laser path which is referred as lidar ratio. If the lidar ratio can not be measured by high spectral resolution lidar, or Raman lidar, then either an assumed value of LR_a must be used in the lidar retrieval, leading to very large uncertainties in light extinction, or models can be used for determination of LR_a profile. Our research refers to the development of an iterative hybrid regularization technique for elastic backscatter lidar data processing and retrieval of the aerosols optical parameters using the atmospheric model, Mie model and Fernald-Klett, but also Ackermann algorithm for lidar ratio calculation based on relative humidity profile. This study focuses on a numerical investigation about the lidar ratio of tropospheric aerosols characterizing Romanian atmosphere. The model can be also used for other type of atmosphere in order to improve the derivation of aerosols optical parameters from elastic backscatter lidar data when no other information than meteorological data are available.

The remote sensing techniques of Lidar and Sunphotometry are well suited for understanding the optical characteristics of aerosol layers aloft. Lidar has the ability to detect the complex vertical structure of the atmosphere and can therefore identify the existence and extent of aerosols that have undergone long-range transport. Inversion techniques applied to Sunphotometry data can extract information about the aerosol fine and coarse modes. As part of the REALM network (Regional East Atmospheric Lidar Mesonet), routine measurements are made with a vertically-pointing lidar at the Centre For Atmospheric Research Experiments (CARE). In addition, a CIMEL sunphotometer resides at CARE (part of AERONET) yielding an opportunity to achieve an optical climatology of aerosol activity over the site. Environment Canada's mobile lidar facility called RASCAL (Rapid Acqusition SCanning Aerosol Lidar), operating in zenith mode only, was also deployed to Western Canada during the months of March and April, 2005 to provide an opportunity to measure the long-range transport of trans-Pacific pollutants that impact the coastal areas of British Columbia frequently. During that time a long-range transport event was observed on 13-14 of March 2005. Further analysis has shown the event originated from North African dust storms during the period 28 February to 3 March. The optical coherency of these active and passive remote sensors will be presented, along with other supporting observations, for forest fire smoke plumes transported over CARE (in 2003) and the first documented case of Saharan dust to impact Western North America.

We examine the potential, range of application, and limiting factors of a polarization selection technique, recently devised by us, which takes advantage of naturally occurring polarization properties of scattered sky light to minimize the detected sky background signal and which can be used in conjunction with linearly polarized elastic backscatter lidars to maximize lidar receiver SNR. In this approach, a polarization selective lidar receiver is aligned to minimize detected skylight, while the polarization of the transmitted lidar signal is rotated to maintain maximum lidar backscatter signal throughput to the receiver detector, consequently maximizing detected signal to noise ratio. Results presented include lidar elastic backscatter measurements, at 532 nm which show as much as a factor of √10 improvement in signal-to-noise ratio over conventional un-polarized schemes. For vertically pointing lidars, the largest improvements are limited to symmetric early morning and late afternoon hours. For non-vertical scanning lidars, significant improvements are achievable over much more extended time periods, depending on the specific angle between the lidar and solar axes. A theoretical model that simulates the background skylight within the single scattering approximation showed good agreement with measured SNR improvement factors. Diurnally asymmetric improvement factors, sometimes observed, are explained by measured increases in PWV and subsequent modification of aerosol optical depth by dehydration from morning to afternoon. Finally, since the polarization axis follows the solar azimuth angle even for high aerosol loading, as demonstrated using radiative transfer simulations, it is possible to conceive automation of the technique. In addition, it is shown that while multiple scattering reduces the SNR improvement, the orientation of the minimum noise state remains the same.

Jet Propulsion Laboratory currently operates lidar systems at Table Mountain Facility (TMF), California (34.4°N, 117.7°W at 2300m) and Mauna Loa Observatory (MLO), Hawaii (19.5°N, 155.6°W at 3400m) under the Network for the Detection of Atmospheric Composition Change (NDACC, formerly NDSC). To complement existing NDACC lidars at TMF, which acts as a primary site for inter-comparisons, a new water vapor and temperature lidar has begun routine operation with typically 3-4 nightly profiles per week. As water vapor is a key greenhouse gas, and is highly variable on annual and seasonal cycles, accurate long term measurements are necessary for predictions of climate change and to increase our understanding of the atmospheric processes it contributes to. The new TMF lidar has demonstrated high spatial and temporal resolution, with a high degree of optimization being achieved over the past year, although the authors believe further improvement may yet be possible. The lidar has been designed for accuracies of 5% up to 12km in the free troposphere with the capability to measure to the tropopause and lower stratosphere with accuracies of 1 ppm. It is anticipated that the data sets produced will be used for Aura validation and for incorporation into NDACC archives. Validation results for the optimized system are presented with intercomparisons using Vaisala RS92-K radiosondes.

We present the design and preliminary results of a water vapor Raman lidar, developed explicitly for meteorological applications. The lidar was designed for Meteoswiss as a fully automated, eye-safe instrument for routine water vapor measurements in the troposphere. The lidar is capable of day and nighttime vertical profiling of the tropospheric water vapor with 15 to 30 min temporal resolution. The daytime operation is achieved by decreasing the solar background employing the narrow field-of-view, narrow-band technique. The daytime vertical operational range exceeds 4 km, while the nighttime range is above 7.5 km. The lidar receiver is built on a compact multi-telescope configuration coupled with fibers to a grating polychromator used for spectral separation and partial background suppression. An additional "near range" fiber in one of the telescopes increases the signal level in the near range and allows water vapor retrieval starting from 100 m. The water vapor mixing ratio is retrieved using the ratio of the water vapor and the nitrogen Raman signals. An additional detection channel for oxygen Raman signal is used for aerosol correction.

The vertical distributions of the water vapor mixing ratio (w) were measured by Raman lidar at the Meteorological Research Institute, Japan, in 2000 to 2004. The measured values were compared with those obtained with radiosondes, hygrometers on the meteorological observation tower, and Global Positional System (GPS) antennas. The values of w obtained with the lidar agreed within 9% with those obtained with the Meisei RS2-91 radiosonde for w > 0.5 g/kg^-1. However, they were systematically higher than those obtained with the Vaisala RS80-A radiosonde for that region. The vertical variations of w obtained with the lidar were similar to those obtained with the Meisei RS-01G and Meteolabor Snow White radiosondes for w > 0.3 g/kg^-1. The temporal variations of w obtained with the lidar were similar to those obtained with the hygrometers at heights between 50 and 213 m on the tower, although the absolute values differed systematically due to the incomplete overlap of the laser beam and the receiver's field of view at the lower heights. The precipitable water vapor content obtained with the lidar generally agreed with those obtained with GPS, except for the period when the large spatial inhomogeneity of w was present.

Open-air explosive activities are carried out by a variety of institutions, including government agencies and private organizations. These activities result in debris plumes that contain elements of the explosive package as well as substantial amounts of entrained environmental materials. While Lidar monitoring technology for these situations has been around for years we developed a unique, interactive, post-experiment Lidar Data Analysis Toolset (LIDATO) that allows the expert user to determine the location, backscatter intensity distribution, volume, and boundaries for general debris plumes at any given time. This is true with the exception of the early development and transport of the plume where the plume is typically opaque to the Lidar and only the plume edge facing the Lidar system can be mapped. For this reason we incorporated video coverage using multiple cameras. While the analysis of the video is handled separately we used the resulting plume position data and combined them with the LIDATO results. The data-fusion product refines the separately gained results and increases the data set accuracy in all aspects for the early stages of the explosion.

Plants constantly interact with environment, mainly, by means of photosynthesis and soil nutrition. The state of plant photosynthetic apparatus that reflects the general physiological state of a plant, can be analyzed remotely on a basis of laser-induced fluorescence using a fluorescence lidar. In this respect, a fluorescence lidar can be a technical means of remote sensing of the effects on vegetation including chemical soil pollution. Among a series of applications, of interest is development of a lidar technique for detecting the effects of oil products and mechanical disturbances. This paper is devoted to the application of the fluorescence lidar technique to monitoring mechanical and chemical impacts on the woody vegetation typical of Siberia. A physical basis of this technique is the red fluorescence of chlorophyll of green plants excited by the second harmonic (532 nm) of Nd:YAG laser. Red fluorescence of plants consists of two bands centered at 685 and 740 nm which is conditioned by functioning of two photosystems. As in situ experiments show, the indicated photosystems and, respectively, the fluorescence on these bands respond differently to feeding disturbances and mechanical impacts, making the increase in the fluorescence intensity informative. Time criteria of fluorescence characteristics were obtained at single and multiple effects on the vegetation. The paper describes a lidar system that meets the requirements for detecting the effects on vegetation.

This paper examines the steady state and time resolved emission spectroscopy of Tm³⁺ doped and Tm³⁺-Ho³⁺, Tm³⁺-Yb³⁺ co-doped tellurite fibers for mid-IR fiber laser design which find applications for lidar. These doped fibers show promising properties for compact and tunable laser sources in the visible and mid-IR when pumped at 800 nm, 980 nm and 1480 nm which can be used for remote chemical sensing and atmospheric monitoring. Tellurite glass has a lower cut-off phonon energy than silica glass and is more environmentally stable than fluoride glass, and coupling these properties with its high rare-earth ion solubility and high refractive index make this glass a very interesting material in which to study the fluorescence properties of these rare earth ions. We have measured the mid-IR fluorescence properties in varying lengths of multi-mode and single-mode fiber for the ³H₄-³H₆ (~1.85 μm), ³H₄-³F₄ (~1.46 μm) transitions in Tm³⁺ and the ⁵I₇-⁵I₈ (~2.05 μm) transition in Ho³⁺. We have also measured the visible emission from these fibers due to excited state absorption (ESA) as there is blue and green emission in Tm³⁺ and Tm³⁺-Ho³⁺ doped fibers respectively when pumped at 800 nm, and strong red and blue emission in the Tm³⁺-Yb³⁺ when pumped at 980 nm. These results in fiber are compared to bulk glass results and are used to describe the pumping schemes and energy transfer mechanisms of these rare earth ions in tellurite fiber.

Laser wind velocimeters work by monitoring the Doppler shift induced on the backscattered light by aerosols that are present in the air. Recently there has been a growing interest in the scientific community for developing systems operating at wavelengths near 1.5 μm and based on all-fibre lasers configuration. In this paper, we propose a new all-fibre laser source that is suitable for Doppler velocimetry in aircraft safety applications. The all-fibre laser has been specifically conceived for aircraft safety application. Our prototype has a conveniently narrow linewidth (9 kHz) and is modulated and amplified through an all fibre Master Oscillator Power Amplifier (MOPA) configuration. According to the measurements, we performed the final characteristics of the laser consist in a maximum peak power of 2.7 kW and an energy of 27 μJ energy per pulses of 10 ns at 30 kHz repetition rate. The only limiting factor of these performances is the Stimulated Brillouin Scattering.

Forest fires can be the cause of serious environmental and economic damages. For this reason a considerable effort has been directed toward the forest protection and fire fighting. In the early forest fire detection, Lidar technique present considerable advantages compared to the passive detection methods based on infrared cameras currently in common use, due its higher sensitivity and ability to accurately locate the fire. The combustion phase of the vegetable matter causes a great amount of water vapour emission, thus the water molecule behaviour will be studied to obtain a fire detection system ready and efficient also before the flame propagation. A first evaluation of increment of the water vapour concentration compared to standard one will be estimated by a numerical simulation. These results will be compared with the experimental measurements carried out into a cell with a CO₂ Dial system, burning different kinds of vegetable fuel. Our results and their comparison will be reported in this paper.

We present a novel concept design of a differential absorption LIDAR for open path trace gas sensing in the atmosphere. To perform a range-resolved gas sensing we propose to arrange a set of retroreflectors in the laser beam path to measure a differential absorption in adjacent sections. In validation experiments we used a pulsed DFB quantum cascade laser fabricated by Alpes Lasers. The laser was excited with 200-ns current pulses with a repetition rate of 10 kHz. The frequency chirp rate was found to increase from 7.7 to 1.0 cm^-1/μs as peak injection current was increased from 7.1, to 7.8 A. We utilized the frequency chirp at laser substrate temperature of 24.0 °C to scan the 967.0 - 968.5 cm^-1 spectral interval containing the absorption lines of CO₂ and NH3. We detected ~ 0.25 ppmv of NH₃ in nitrogen at atmospheric pressure using a double-pass gas cell with an effective absorption path of 2.4 m. Digital filtering of the spectra was shown to be effective in eliminating a high-frequency noise. To demonstrate range-resolved capabilities of the sensor we used two retroreflectors inserted into the laser beam. A differential absorption of CO₂ at 967.7 cm^-1 was measured with the gas cell placed in one of the sections. Our experiments indicate that the frequency chirped LIDAR can be used for open path spectroscopy of NH₃ over the ranges up to ~ 1 km with a spatial resolution of ~ 30 m and detection limit of ~ 20 ppbv per a 30-m section.

A simple method for estimating the gas emission flux by spot source fields based on IR laser measurements and atmospheric diffusion models is presented. The method is based on a proper arrangement of the optical links around the emission area, over which the determination of the gas integral concentration is required. The first objective of such measurements is to tune the parameters of a basic diffusion model in order to estimate, as second objective, the gas emission flux by applying the tuned model to experimental measurements. After discussing the proposed model and method, experimental data obtained from some CO₂-rich natural discharges in Tuscany (Central Italy) are presented

The extinction-to-backscatter ratio (S_a) is an important parameter used in the determination of the aerosol extinction and subsequently the optical depth from lidar backscatter measurements. We outline the algorithm used to determine S_a for the Cloud and Aerosol Lidar and Infrared Pathfinder Spaceborne Observations (CALIPSO) lidar. S_a for the CALIPSO lidar will either be selected from a look-up table or calculated using the lidar measurements depending on the characteristics of aerosol layer. Whenever suitable lofted layers are encountered, S_a is computed directly from the integrated backscatter and transmittance. In all other cases, the CALIPSO observables: the depolarization ratio, δ, the layer integrated attenuated backscatter, β', and the mean layer total attenuated color ratio, γ, together with the surface type, are used to aid in aerosol typing. Once the type is identified, a look-up-table developed primarily from worldwide observations, is used to determine the S_a value. The CALIPSO aerosol models include desert dust, biomass burning, background, polluted continental, polluted dust, and marine aerosols.

Joint efforts by the National Aeronautics and Space Administration (NASA), the Department of Defense, and industry partners are enhancing the capability of airborne wind and turbulence detection. The Airborne Coherent Lidar for Advanced In-Flight Measurements (ACLAIM) was flown on three series of flights to assess its capability over a range of altitudes, air mass conditions, and gust phenomena. This paper describes the observation of mountain waves and turbulence induced by mountain waves over the Tehachapi and Sierra Nevada mountain ranges (California, USA) by lidar onboard the NASA Airborne Science DC-8 airplane. The examples in this paper compare lidar-predicted mountain waves and wave-induced turbulence to subsequent aircraft-measured true airspeed. Airplane acceleration data is presented describing the effects of the wave-induced turbulence on the DC-8 airplane. Highlights of the lidar-predicted airspeed from the two flights show increases of 12 meters per second (m/s) at the mountain wave interface and peak-to-peak airspeed changes of 10 m/s and 15 m/s in a span of 12 seconds in moderate turbulence.

The Vaisala Ceilometer CL31 is a compact and low-cost all-weather lidar designed to report cloud base height and vertical visibility. It works 24 hours a day in fully-automated, hands-off operation mode. Its enhanced optical and electronic concept enables it for tasks that go far beyond its standard duties. Four different areas will be treated in the scope of this paper. 1. Mixing height assessment from attenuated backscatter profiles. 2. Comparison of particulate matter concentration, near-range ceilometer backscatter, and extinction reported by a ceilometer. 3. Backscatter profiles from a ceilometer that was installed for one year in an industrial area pointing in a nearly horizontal direction were evaluated in respect of possibilities to monitor chimney plumes, spray caused by cars driving on a wet road, and other phenomena. 4. The standard profile report frequency of the CL31 ceilometer is 0.5 Hz. If the measuring range is reduced to 100 m, the profile report frequency can be raised to 100 Hz, opening new fields of application like the investigation of falling hailstones.

In the present paper, we show application examples of united generalized methodology for atmospheric lidar assessment, which uses the dimensionless-parameterization as a core component. It is based on a series of our previous works where the problem of universal parameterization over many lidar technologies were described and analyzed from different points of view. A methodology of spatial-angular filtering efficiency was used for comparison of different receiving system designs on the criterion of stability against background radiation. The dimensionless parameterization concept applied to photodetectors of remote sensing instruments allowed predicting the lidar receiver performance in presence of sky background. The approach can be widely used to evaluate a broad range of lidar system capabilities for a variety of lidar remote sensing applications, as well as to serve as a basis for selection of appropriate lidar system parameters for a specific application. Such a methodology provides generalized, uniform and objective approach for the evaluation of a broad range of lidar types and systems (aerosol, Raman, DIAL), operating on different targets (backscatter or topographic) and under intense sky background conditions, and can be used within the lidar community to compare different lidar instruments.

Trace gases are components of the Earth's atmosphere influencing weather and climate significantly. They play an important role in atmosphere's chemistry. Ground-based and airborne Differential-Absorption-Lidar-Systems (DIAL) designed for atmospheric investigations are operated since 20 years. Based on the long-term experience in development and operation, the DLR Lidar group initiated a new airborne water vapour Lidar experiment which will perform its first test flight in 2006. Software simulation is one of the major tools for the development of such complex opto-electronic systems. It allows the optimization of system parameters and observation conditions, the development and test of data processing software and the estimation of the capabilities of the sensor system in terms of product quality. The paper describes the physical basics and the DLR DIAL concept. The simulations' end results are presented.

Differential absorption lidar (DIAL) has proved to be an important tool for remote sensing of trace gases in the atmosphere. As DIAL systems are affected by various noise factors such as atmospheric turbulence, target speckle, detection noise and so on, the measured concentration is corrupted by noise, and cannot be estimated accurately. However, when observations, predictions, estimations, and various covariance of Kalman filter algorithm are decomposed into lower resolution levels, due to filtering effects of wavelet transform, noise can be restrained while behavior of concentration is exposed. In this paper, a novel multiresolution Kalman filter algorithm is applied to estimate the path-integrated concentration (CL) from DIAL time series data where measurements are available at only one resolution level, and uses the stationary wavelet transform (SWT) as a means for mapping data between different resolution levels. The algorithm was evaluated for a variety of synthetic lidar data created with a program designed to model the various noise sources, including atmospheric turbulence, reflective speckle, and detection noise, which affect lidar signals. The simulation results show that our algorithm is effective in improving the measurement accuracy of gas concentration in DIAL and performs better than Kalman filtering and SWT visually and quantitatively.

Implementation of the pure-vibrational Raman spectra lidar method for simultaneous measurements of atmospheric water-vapour, aerosol extinction and backscatter coefficients is reported. A Q-switched Nd:YAG laser provides the three elastic wavelengths of 1064, 532 and 355 nm while the return signal is collected by a 40-cm aperture telescope. A spot-to-spot fiber bundle conveys the light from the telescope focal plane to a specific polychromator especially simulated and designed with care on minimizing optical losses and physical dimensions. The reception field of view, which is limited by the fiber bundle characteristics, is the same for all wavelengths. By means of four customised dichroic filters and beam splitters, light is separated into the three elastic wavelengths (355, 532, 1064 nm) as well as the 386.7- and 607.4-nm N₂-Raman-shifted wavelengths, and the 407.5-nm H₂O-Raman-shifted wavelength. Signal detection is achieved by using avalanche photodiodes at 1064 and 532 nm and analog acquisition while photomultiplier tubes and fast photon counting acquisition at the rest of the wavelengths. A specific design of the optoelectronics of the receiving channels is controlled by a distributed CPU thanks to a user-friendly LabView^TM interface. User-configurable scanning tools are built-in, but can also be customized. In this work an overview of the system though particularly geared to the polychromator unit is presented as well as a power link-budget assessment, which is to include simulation of end-to-end transmissivities, will be discussed for the main channels involved. The first measurements have already been made at 1064, 532, and 607.4 nm.

Atmopheric turbulence is one of the important correction factors to evaluate the earth's surface using a sinsor on a satellite. CO₂ and aerosol are selected as factors of turbulence. The effects of turbulence caused by CO₂ and aerosol on the light reflected from the earth's surface are estimated by measuring the degradation of spatial coherence of light in a chamber in which atmospheric turbulence is generated. Dry ice is used to generate carbon dioxide gas. degradation of spatial coherence is measured in relation to the increase of CO₂. Turbulence caused by aerosol is measured by density of smoke cigarettes. The spatial coherence of light in the chamber degrades in relation to the increase of aerosol and as a result the turbulence increases. The relation between the turbulence and the degree of spatial coherence is explained in a formula.

Fringe technique is preferred to edge technique of wind measurement in troposphere for a direct-detect Doppler wind lidar. However, most fringe-technique based Doppler lidar systems have been developed to date are based on conventional Fabry-perot interferometer. The purpose of this paper is to introduce our development of fringe-technique lidar based on Fizeau interferometer in which the signal can be detected more conveniently using commercial linear detector. The pre-development of the lidar system is described including interferometer's optimum design, the frequency stabilization of Fizeau interferometer and the choice of multi-anode detector. In additional, the wind error of the system is simulated with taking account of Rayleigh noise. Results shows that the wind error can be less than 0.56m/s under 5 km with 30s integral time.

A compact diode-pumped, injection-seeded and frequency- tripled Nd:YAG laser was developed for a mobile, direct detection Doppler wind lidar system. The laser is configured with the master oscillator power amplifier (MOPA). The oscillator consists of E-O Q-switched, thermal stability, diode pumped cavity. The oscillator is injection seeded by a monolithic, diode-pumped Nd:YAG seeder laser with power of 200mW. The technique of resonance detection is used to lock slave laser frequency in order to satisfy with the mobile environment. The output laser from oscillator is single-way amplified. Frequency triple is realized with a Type II KTP crystal and Type I BBO. The laser can be working on single frequency without mode jumping. The output pulse is about 15 ns at 355 nm, the linewidth is reached to the limit of Fourier transfer. The output energy is 100 mJ of 1064 nm at 100 Hz, and the beam quality is about M² of 1.3 at both directions. The frequency- triple efficiency is over than 30%. After a long time test, the laser will be installed on a mobile lidar system.

A lidar system for determination of vertical profiles of the aerosol extinction coefficient, operating with 355 nm and 532 nm laser wavelengths, is presented. Lidar measurements will be performed within the European collaboration named EARLINET-ASOS and data will be used as a part of the assessment of a method for prediction of the observation range of optical systems in the atmosphere, based on meteorological weather forecast models. The lidar system has been extended with a detector channel for elastic scattering at 532 nm and Raman scattering from N₂ at 387 and 607 nm to enable determination of the aerosol extinction coefficient. Extinction coefficients and backscatter coefficients will later be compared to corresponding values received from meteorological predictions of atmospheric aerosols. The aerosols prediction will be calculated using weather forecast model (HIRLAM) together with a forward dispersion model in the chemical transport model MATCH. Atmospheric scattering calculations (Mie-calculations) will give extinction and backscatter coefficients so comparison can be with lidar measurements. The design of the lidar system and the first measurements will be presented.