Some of our experimental and theoretical results on optical properties of atmospheric turbulence and light propagation through atmosphere are introduced as follows. 1) A mixed model for the scaling property of high-order structure functions of temperature is proposed to study the turbulence intermittency effect in numerical simulation of light propagation through turbulence. 2) The difference of refractive index structure constant C²_n of atmosphere and light beam wander measured in horizontal and vertical directions suggest that the atmospheric turbulence is not isotopc in many cases. 3) The fluctuation of the scaling exponent of optical turbulence spectrum and light intensity fluctuation spectrum indicate taht the atmospheric turbulence is not a Kolmogorov one in many cases. 4) A general description of turbulence strength is proposed using the variance of the refractive index σ²_n, the outer scale L₀, the scaling power γ and the inner scale l₀. 5) Characteristics of the power spectrum of laser scintillation in atmosphere depend on the laesr beam property, diameter of the receiving aperture, turbulence spectrum in the dissipation range. 6) The intermittency of ligh scintillation is rather stable at different scintillation index for light propagation through turbulence over both land and sea surfaces. 7) The number density of phaser branch points of light wave field in turbulence generally increases with turbulence strength but present large diversity.

The article presents a review of the existing remote snesing methods for experimental study of coherent structures in the fields of temperature, wind speed, refractive index, and admixture concentrations. The physical principles, underlying some methods developed recently are described. The use for these purposes such devices as sodar, lidar, radar, scidar, radiometer, and also occultation techniqes and tomographic techniques is discussed. The advantages and restrictions of different methods, altitude ranges of their applicatbility, and also representativeness of the results obtained are considered. The examples of visualization of vortical, layered and wavy structures and experimental estimates of their parameters are given. The origin of structured turbulence in the atmosphere is discussed. A classification of various forms of coherent structures is offered. Systemization of recently published experimental estimates of their parameters in the lower and middle atmosphere is made.

On the base of the detailed numerical computations by 4-D wave optics code, the scaling laws for estimating the thermal blooming effects on target of the atmospheric propagation of high energy laser, for both horizontal and slant paths are given.

A method of measuring the atmospheric turbulence based on the arrival angle fluctuation of a focused laser beam backscattering is numericallys stimulated. By the paraxial scalar wave equation and a fractal phase-screen algorithm we propose the simulation model for the focused laser beam propagating along a fold path. With a constant Fried length, we separately analyze the arrival angle fluctuation variance's statistical characteristics of the focused laser beam backscattering and the fixed point-source as reference beacon, and obtain the relatively high correlation between them. Moreover, we change the propagation distance; analyze the degree of similarity between them. The simulated results are verified by experimental results.

The effect of atmospheric turbulence on the imaging of a pattern similar to an eye chart composed of LED array, for horizontal propagation of the light over a distance of 1000m, was analyzed at visible wavelenghts using a 355.6 mm telescope. Point Spread Function (PSF) and the images were recorded simlutaneously during the night. The Fried's parameter r₀ was derived from the measured variance of image motion, leading to r₀ values ranging from 5 to 30 cm depending on observing conditions. Very strong image motion and severely degraded images were observed. The relationship between the image resolution and the Fried's parameter is visually shown.

The influence of atmospheric turbulence on partially coherent flat-topped Gaussian beam is investigated in this paper. Partially coherent flat-topped Gaussian beam is expanded as a superposition of independent Hermite-Gaussian modes. Propagation of laser beam through the turubulent atmosphere is numerically studied using phase screen approximation. We deduc two expressions to fit the results of numerical simulation. One describes the dependence of the rms width of the beam on the order number N, the psreading distance and the intensity of turbulence. The other describes the dependence of the coherent length of the beam on that of its initial time and that of turbulence.

Several methods for the retrieval of atmospheric turbulence profile from stellar scintillation measurement are discussed concerning their advantages and shortcomings. Numerical simulations are perforemd aiming at an instrument design. From these simulation results, major parameters that have main influence on the inversion procedure are found, and thus optimal parameters are obtained for the instrument design.

The atmospheric coherent length is an important parameter when study the influence of atmosphere to the light propagation. Two kinds of methods are often used to measure the coherent length. One method uses the optical technique, measure the arrive angle of star objects, another method uses the balloon born thermal-meters, which can get profile of structure constants of refractive index, and then the coherent length can be calculated from the integral of structure constants of refractive index. Because the time scale and space scale are different in these two methods, the results of them are different although the magnitude of results is near. In this paper, a new way to compare the results of two methods above is advised. It is based on the characters of the structure constants of refractive index, and the profile data of balloon born instrument. Not only the average coherent length can be gained, and also the distribution of coherent length can be estimated. So the results of two methods can be compared quite well. The characters of coherent length are also discussed in this paper.

In the past decade interest has focused on the remote analysis of emissions from motor vehicles using spectrometric techniques, driven by recognition of the fact that a very large proportion of the environmental damage done in this way originates with a small percentage of vehicles. Several instrumentation manufacturers now market such devices, and others are developing new technologies that will offer opportunities for enhanced performance and lower cost. In this paper we demonstrate the prototype design of vehicle emission remote sensing system by differential optical absorption spectroscopy (DOAS) and tunable diode laser absorption spectroscopy (TDLAS). In this design, vehicle emissions will be measured when they past a on road remote sensing station while driving along a road. The concentrations of hydrocarbons (HC) and Oxides of Nitrogen (NOx) are measured by DOAS, and the concentrations of Carbon Monoxide (CO) and Carbon Dioxide (CO₂) are measured by TDLAS. The measurement precisions for CO and CO₂ are ±0.25%, and the detection limits for HC and NO are ±250ppm.

A method for the measurements of atmospheric transmittance by FTIR spectrometer is proposed. Calibrating special response of system based on two-point temperature with blackbody, transmittance spectra of CO₂ IR absorption band are analyzed and calculated depending on the measurement data. The CO₂ concentration in atmosphere is acquired after fitting the measured spectra with the line parameter in HITRAN employing NLLS algorithm. The results agree with the standard CO₂ concentration considered in the environmental monitoring. It indicates that the method is feasible for measuring atmospheric transmittance and analyzing gases in quantity.

The spot dancing of the focused laser beam in the turbulent atmosphere was studied using a two dimensional position sensitive photomultiplier tube (PSPMT). The centroid position of the laser spot was evaluated by means of current-dividing center-of-gravity detection. The system has advantage over detector array system in spatial resolution and over the imaging system in dynamic range and sampling rate. Laser propagation experiments were carried out over 1000m path above the sea level and the fluctuations of laser intensity were measured simultaneously. The frequency spectra were calculated by fast Fourier tansform and the standard deviation of the spot dancing were analyzed.

Measurement of Asian dust in the troposphere have been performed with Mie scattering lidars that are Multi-wavelength aerosol lidar (MWA lidar) and Automatic Continuous operated lidar (ACA lidar) at Suwon, Korea (37.2N-127.6E) in the spring of 2000-2004. These lidar systems are based on pulsed Nd:YAG and multi-receiving channels. It consists in two or three mode that MWA lidar are 355 and 532 nm backscatters and 532nm depolarization ratio, and ACA lidar are 532 and 1064 nm backscatters, 532 nm depolarization ratio, and 1064/532 nm aerosol color ratio. During five years (2000-2004) of intensive observation of Asian dust more than 56 episodes and 2,177 vertical profiles were successfully measured. The significant dust in March 2002 to May 2003 showed the dust layers are located in the altitude range of 0.2-3 km. In this case, the depolarization ratio is large than 15% and in some case up to 30%. The ratio of backscattering ratio and the aerosol color ratio are in teh range of 1-5 and 0.3-0.9 respectively. To identify the Asian dust, we retrieved the particle size distribution from the signals of 355nm and 532nm of MWA lidar. In the 12:35-12:40, March 21, 2000, the composition percentage of particle square distribution spectrum of small particles at 0.069-0.225 μm are higher value from 12-39%. Also large particles is lower that are about 17-19% at 0.752μm, 7% at 1.301 μm, and 5% at 2.355μm, respectively. The study of backward trajectory carried out in this episode. The results coincide well with the lidar measurement profiles.

Cirrus clouds are routinely observed by lidar at Chung-Li (25°N, 121°E). Their optical and microphysical properties are investigated by the height and temperature distributions, optical thickness, extinction, and depolarization ratios. Cirrus clouds with optical thickness smaller than 0.03, which are classified as subvisual cirrus clouds, have high probability of occurrence. Thin cirrus clouds have their optical thickness exponentially correlates with temperature in the region of -60 to -80C. Depolarization ratio is an important property of cirrus clouds. Although depolarization ratio for ice particle is large, vanishing depolarization ratios have been found for some clouds as high as 12 km. Depolarization ratio for all cirrus clouds distributed widely, and thin cirrus clouds near the tropopause above 16 km seem to have limited depolarization ratios. The microphysics of ice particles is discussed.

A Mie lidar was used to make observation of Asian dust over Hefei (31.90° N, 117.16° E) in the every spring from 1998 through 2004. This paper presents main features of vertical distribution and temporal variation of Asian dust extinction coefficient at 532 nm wavelength during the seven years. There were two kinds of vertical distributions of Asian dust extinction coefficients. One indicated that the Asian dust particles intruded into the local boundary layer, causing the very thick dust layer with depth of about 3-4 km. The other showed that the Asian dust passed over Hefei area just above the boundary layer. The aerosol extinction coefficients in the elevated dust layer within the middle troposphere from 3 to 6 km were unusual large. Seasonal average aerosol extinction coefficient profiles showed that larger aerosol extinction coefficients from 1 km to 10 km altitude range were observed in the springtime rather than in any other season.

We conduct network observations using ground-based Mie-scattering lidars in Asian region in cooperation with various research organizations and Universities. Primary purpose of the network is for studying generation and transport of Asian dust, observing air pollution and biomass burning aerosols for atmospheric environment studies, observing aerosol vertical distribution and temporal variation for atmospheric radiation studies and climatology, and for validation of chemical transport models and satellite remote sensors. At present, lidars are operated continuously at twelve locations in Japan, China, Korea, and Thailand. The lidars used in the network are two-wavelength (532 nm and 1064 nm) Mie-scattering lidars having depolarization measurement function at 532nm. Flashlamp-pumped compact Nd:YAG lasers are used as the light source. We developed a method for estimating the extinction coefficient of non-spherical air-pollution aerosols separately using the depolarization ratio. This method is based on a simple assumption that observed aerosols are external mixture of two types of aerosols, but it is practically very useful especially for inter-comparison with chemical transport models. We also studied a method for characterizing aerosols using the depolarization ratio and the wavelength dependence of the backscatter coefficient. Asian dust phenomena were observed with the network since spring of 2001. The frequency of the occurrence of dust events and the vertical distribution characteristics were analyzed. Also, seasonal and year-to-year variations were analyzed. At the same time, transport of dust and air-pollution aerosols were studied by comparing the temporal variation of lidar profiles with chemical transport model results.

The 1064nm Doppler wind lidar with a dual Fabry-Perot etalon based on the edge technique has been developed to measure wind profile in the troposphere. The construction of the lidar system is described in the paper. The dual etalon with high-spectral resolution are used to discriminate the Doppler shift from the aerosol backscattering. The accuracy of the lidar system is analyzed and discussed especially for the etalon parameters. The transmittance curve of the etalon is measured and the results show that the standard deviation of the transmittance will cause the velocity error of 0.5m/s. The lidar system is estimated to measure the wind speed up to 10km with the accuracy of less than 2m/s. The preliminary result of the radial velocity measurements has been obtained.

The Tibet plateau is characterized with its own special highland climate environment. In this paper, the temporal vertical profiles of aerosol extinction/backscattering coefficients, the boundary layer height (BLH) and cloud height during the CAMP-Tibet 2003 autumn and 2004 spring session observations at Naqu BJ site, Tibet are determined with ancillary meteorological parameters, and compared with data at Bejing site.

A new applied differential absorption lidar system for measurement of SO₂ and O₃ in the lower troposphere is developed. The emission wavelengths 289.04, 288.38 and 299.05 nm are obtained by stimulated Raman shifting of a Nd:YAG laser. The concentrations of SO₂ and O₃ have been measured quasi-simultaneously by use of the three wavelengths for compensating measurement results each other. The lidar measurements agree with in situ measurements. The measurement errors, which are primarily attributable to statistical error and variations in atmospheric backscattering intensity during the experiment, are discussed.

One year of continuous measurements of visibility, temperature and relative humidity at the Hong Kong International Airport at Chek Lap Kok (CLK) are combined with the concentrations of the respirable suspended particulates (RSP) measured in Tung Chung near the Airport to extract annual and seasonal characteristics of the aerosols. The knowledge of aerosol characteristics obtained is used in the development of inversion methods for aerosol extinction retrieval from Lidar data. In this paper, the details fo aerosol characteristics and retrieved aersosol extinction profiles are presented. This additional data product requires no additional hardware to the existing Lidar, but only additional computational research efforts. The knowledge of spatil aerosol distributions during haze episodes will be valuable to aviation meteorologists at Chek Lap Kok. Long term visibility studies using Lidar of this kind will help our understanding of the air pollution problem in a coastal urban city like Hong Kong.

Asian dust storms are one of the significant events which influence the environment, climate, as well as land and ocean ecology in East Asian, and at least western Pacific. Understanding these dust storms, about their spatial and temporal variabilities and the characteristics of mineral dust aerosols is of first priority. Owing to limited observation facilities and coarse spatial resolution, so far, our knowledge about Asian dust storms is still very limited, in particular mesoscale structure and mineral dust aerosol's optical depth spectra in severe situation when a lot of instruments are ineffective. In present paper, based on surface meteorological observation relatively high spatial and temporal resolution (about 100 km resolution and 1 hr), we investigated the mesoscale variability of spring dust storms with case study and statistical investigation. Also, base on our solar spectral observation over Beijing, the optical depth spectra of mineral dust aerosols are given with case study and statistics. Comparisons are also made with other related observations in eastern Asia. These results will be useful for estimation of atmospheric dust loading and their transport over eastern part of Northern China.

A reasonable cloud screening algorithm is very important to ensure accuracy of aerosol optical thickness determinations from AERONET database. In this paper, a new cloud screening algorithm is developed. The algorithm uses cloud fraction and a so-called scaling height of the tropospheric aerosol, derived from sunphotometer measurements and surface visibility data, to build the screening criterion. The criterion constraints the scaling height varying in some range. In the condition of no cloud day, the variation range is the monthly-mean scaling height plus 3σ (σ: the standard deviation of scaling height). The larger the cloud fraction is, the smaller the range. The new cloud screening algorithm is used to determine aerosol optical thicknesses from AERONET data measured in Beijing during 2001-2002. According to the application results, the reasonableness of the new algorithm is analyzed.

An eye-safe, mobile micro-pulse Mie lidar system has been established at City University of Hong Kong since November 2002. The system is a co-axial setup with a diode pumped Nd:YAG laser source of 532nm. Since measurements in public areas are required, the system was designed to be eye-safe by operating at a few micro-Joules pulse energy and high repetition rates (1 to 4 kHz) and the beam diameter was expanded to about 3 inches. Since the lower atmosphere is of interest, a co-axial design setup was adopted for improved near range performance. The receiver is a 235mm diameter Schmidt-Cassegrain telescope with a variable iris diaphragm for adjustable field-of-view, allowing for optimal near range or far range measurements. A narrow bandwidth filter (0.3nm) is used to reduce the stron solar radiation. The system is housed in a small van for field measurements at various sites around Hong Kong. Data is inverted using Fernald's method to obtain extinction profiles. Aerosol loading and boundary layer height have been examined at several sites for each season of the year 2003. The boundary layer heights obtained from lidar data measured at City University of Hong Kong are compared with radiosonde data measured at the King's Park meteorological station of the Hong Kong Observatory. In addition, seasonal trends of the maximum mixing height (MMH) measured at City University will be discussed.

The article examines two cases of Beijing atmosphere hazing with natural aerosol reasoned by dust veils (dust haze). Air optical characteristics measured with nefelometer are presented and meteorological parameters and concentration peculiarities ofsoot and ozone for micron and sub-micron aerosol are discussed. Nefelometric measurements were carried out on FAN device which allow to measure the directed dissipation factor at angle of q and wavelength of X 42 0. 52 0. 62 rim and also degree of plane polarization at scattering angle ofp90 for 0. 42 0. 52. Aerosol probes collection is performed simultaneously for determining the aerosol mass with gravimetric method. In both cases air mass intrusion took place at nighttime and it displaced typical smog with high soot submicron aerosol carbon monoxide and carbonic acid gas concentrations. Sharp decrease of that mixtures concentration took place. At the same time high ozone concentrations could be observed. Relative soot concentration in aerosol was very low that is non typical for Benjing conditions. During dust darkness period significant inclination from typical parameters for Benjing aerosol took place. Results of comparison of nefelometric and gravimetric measurements taken at Beijing at several years show that at smog situations typical for the city a strong correlation between nefelometric aerosol concentration measurements and gravimetric ones. At dust haze periods ratios between nefelometric and gravimetric measurements changed greatly. During dust haze correlation between directional flare at 45 deg for wavelengths of 410 nm and 630 nm and degree of linear polarization at 90deg changed that allow FAN Nefelometer data observe dust aerosol transformation processes in conditions of huge megapolis effectively.

Clouds can have important effects on light propagation problems such as earth-space communication. The cloud effects may be different due to their occurrence probabilities amounts size distributions and probabilities of cloud-free line-of-sight (P_CFLOS). The volume extinction scattering absorption and backscattering coefficients of clouds as a function of wavelength from 0.4 μm to 4.0 μm are evaluated with the Mie theory. The typical values of the volume extinction coefficients of water clouds vary from 48 to 150 km^-1. The cloud conditions could be monitored with a Total Sky Imager. Cloud occurrence probabilities average amounts and P_CFLOS as functions of elevation angle and time can be estimated from the image.

A ground-based visible all-sky imaging system has been in operation for more than 2 years in Beijing (40°N, 116.5°E) since 2001. Using the 1428 images selected from those obtained from the year 2001 to 2003 we analyzed the spatial and temporal distribution of clouds and their seasonal variation in Beijing in two different ways. Some statistical results show that cloud distribution has some special character. We found that cloud fraction estimated from the all-sky image is relative to its height base-height and position relative to observer of cloud itself. To understand it further and to apply it to other researches of this system we simplified the cloud into two simple types: cube cloud and cylinder cloud for simulation. Then we studied the variation of the cloud fraction with its site on the principle of the equi-angle projection of the fish-eye lens. At the end of the paper the numerical simulation results are presented. Depending on different ratio of width to height cloud fraction has different variation. If ratio value is smaller than threshold value cloud fraction will increase at first and then decrease with the increase of the zenith angle.

Multiband optical polarization measurement can provide the state of polarization and the intensity information of natural scenes. Gradually this technique is practically applied in remote sensing e.g. monitoring of the atmosphere land and environment. Recently an experimental multiband polarized CCD camera (EMPCC) has been built in our laboratory. It can obtain the polarimetric imaging information synchronously and the multispectral data subsequently. We analyze the characteristic of some polarimetric images which were acquired from aerial platform at 3000m high. These multiband polarization images of natural surfaces include soil vegetation water and a variety of man-made objects. We obtain the parameters of degree of linear polarization (DOLP) angle of polarization (AOP) and intensity of the targets by using Stokes parameters. The Stokes parameters can be derived from measured radiant images at three polarization directions. The results indicate that the characteristics of different targets can be discriminated on the basis of polarization images associated with intensity ones. The properties of targets could be enhanced to some extent when we use the DOLP of the aerial image to characterize the natural surfaces. Among these characteristics the shape edge texture and material could be emphasized. These afford a convenience in interpreting the polarization information.

Infrared remote sensing of clouds is one of the main subjects in the field of atmospheric remote sensing from satellites. As its characteristics of intense infrared radiation and absorption the heights of cloud top can generally be derived from the brightness temperature obtained from satellite infrared cloud images and then a series of study about cloud morphologic microphysics and dynamics can be conducted. On the same principle the heights of cloud base can also be determined by sky infrared brightness temperature observations on the ground. Some preliminary studies were made in the past but have not been extended. The reason is that the range of zenith angle is very wide for ground-based remote sensing of cloud base heights. From near horizontal ground up to zenith at different zenith angle the background infrared brightness temperature of clear sky atmosphere is very different it is the function of the atmospheric temperature and humidity profiles as well as the zenith angle. Hence the question must be considered is how to obtain the correct information about the heights of cloud base from sky background brightness temperatures in large variational range. In addition the contributions of aerosols in near ground atmosphere to sky brightness temperatures observed on the ground cannot be neglected. In order to correctly derive cloud base heights from sky brightness temperatures the effect of aerosol layer must be studied seriously. Using radiative transfer equation to study th sensitivities of thermal infrared brightness temperature values observed on the ground to different aerosols and different cloud base heights is an important basic work. In this paper systematic study on the variations of sky infrared brightness temperatures caused by different kinds of clouds under the different kinds of the different intensities (represented by different ground visibilities) of aerosols using MODTRAN 4.0 model is presented. In this study the feasibility of cloud base height remote sensing by ground-based sky infrared brightness temperature observation and the quantitative effects of aerosol layer on it can be found. From the calculated results by model the following can be concluded: 1. For low and middle clouds, the sky thermal infrared brightness temperature observed on the ground is very sensitive to the variations of cloud base height, therefore as the "clear" sky brightness temperature is known it can be used to retrieve and remote sensing of cloud base height. 2. The influence of aerosols (visibilities and aerosol types) above the ground on the sky background brightness temperatures is considerable, it must be corrected. Because the aerosol's influence on brightness temperatures with different zenith angles is fairly clear, it can be corrected very well.

In this paper a method about aerosol particles aerodynamic diameter measurement is introduced. This method is based on the measurement of aerosol particles time-of-flight velocimetry. When aerosol particle passes through two closely spaced elliptic gauss beams two light scattering signals are recorded. For two fixed distance beams the flight velocities of different-size particles are discrepant because of their different inertia. The higher the particle's inertia the slower its exit velocity. Photo detector APD detects the scattering light of particle and yields a double peak signal. The time of flight information is derived from the double peak signal. Then the particle size can be calculated by measuring time signal when particle passes through the two beams. By using standard aerosol particles which are generated by aerosol generator (Model 3450 TSI. Inc.) a calibration curve of the time of flight versus aerodynamic diameter of particle is obtained. As an example the laboratory air size distribution is measured by this system. The experiment result shows the air size distribution presents lognormal distribution which is accorded with the theoretical value. This system is capable ofobtaining high-resolution size distribution of particle in micron magnitude.

An iterative algorithm is presented for the determination of the aerosol optical thickness and the water-leaving radiance simultaneously from SeaWiFS measurements which is based on the wavelength relationships among the water-leaving radiance. The pixel which conforms to the wavelength relationships among the water-leaving radiance can be distinguished during the iterative process. The algorithm was used for the retrieval of the aerosol optical thickness and the water-leaving radiance in the Amoy from the SeaWiFS data. The aerosol optical thickness calculated at wavelength of O.55μm is very close to the values from the Sun-photometer measurements.

Anomolies in the atmospheric methane distribution over Lake Baikal have been studied with a diode gas analyzer having the threshold sensitivity of 0.04 ppm. Local areas, in which the methane concentration two to three times exceeded the background value equal to 2.00 ± 0.16 ppm, were detected.

The measurements of aerosol extinction coefficient profiles and wind vertical structure were conducted by a lidar and a wind profiler respectively at Daxing southern boundary of Beijing in some periods of summer and winter during 2001-2004. The paper will discuss the variation ofaerosol pollutant layer and aerosol particles horizontal transportation by south-north direction at Daxing Beijing.

Methane (CH) and carbon monoxide (CO) total column amounts (TCAs) measured at the Research Institute of Physics of St. Petersburg State University (Russia) were used for: 1. study of temporal variability of CH₄ and CO; 2. identification of source regions of CO and CH₄ using trajectory analysis. CH₄ and CO showed distinct annual cycle with the amplitude of about 3 and 25 respectively. Period of 1999-2002 has a significant decline of CH₄ TCA for the St. Petersburg region. The suggested reason is hot and dry summers of 1998-2002. October 1998-March 1999 is characterized by the strong irregular disturbances of CO TCA. Growth rates of CO TCA have changed at this period from (3.5±2.3)%/yr. (for 1995-1998) up to (-2.1±1.5)%/yr. (for 1999-2002). Enhanced CO and CH₄ TCA levels are observed for air masses originated from the sectors of the North Russia continental Russia and the Eurasia Europe can be classified as moderately polluted territory. Clean air comes from the Baltic Sea Arctic Ocean and Scandinavia. Distribution of CO pollution levels over sectors repeats qualitatively situation for CH₄.

Fourier transform infrared (FuR) spectrometer with its high radiometric reproducibility wavelength accuracy signal-to-noise ratio and spectral resolution has been established as an ideal tool for air pollutants detection in city. Because most pollutant gases exhibit significant absorptivities in infrared spectral regions FTIR system can measure their hyper-spectral absorption signatures analyze the composition and provide the concentration estimation. The flexibility of airborne FTIR system in combination with its great detectable distance makes it even more suitable for the detection of pollutant cloud. This paper focuses on the detection principle of airborne pollutants and concemed signal processing techniques such as the establishment of spectral database pro-processing and characteristic extraction identification and classification for spectral signals pollution evaluation simulation techniques and etc.

Nitrogen Dioxide (NO₂) column density was studied by solar spectroscopic method. In the retrieval of NO₂ column density the Kitt Peak Solar Flux Atlas provides a standard reference of the extraterrestrial solar spectrum. However in order to eliminate the Fraunhofer features from the solar spectrum the ground-level solar spectrum needs to be re-scaled for wavelength correction and resolution matching to the reference Kitt Peak Solar spectrum. The analysis procedure becomes much simplified if both the reference and the ground-level solar spectra are captured by the same instrument. A portable miniature charge-coupled device (CCD) spectrometer was employed to acquire both the reference and ground-level solar spectra. The reference spectrum was captured in Xinjiang (42.107°N 83.750°E), the People's Republic of China during a flight in a plane. The altitude ofthe reference solar spectrum is 11 meters above the sea level. The ground-level solar spectrum was acquired in the campus of City University of Hong Kong (22.336°N, 114.173°E) using a computer-controlled solar tracker. By analyzing the solar spectra obtained at two different locations and altitudes NO₂ total column density can be deduced.

Results of measurements of vertical distribution and column abundance of NO₂ at Zvenigorod Research Station of the Institute of Atmospheric Physics since 1990 are presented. Measurements are done during morning and evening twilight at solar zenith angles 84-96 with a zenith-viewing spectrophotometer in spectral range 435-450 nm. A vertical distribution of NO₂ constituted by NO₂ abundances in 5 km thick layers and in the thin near-surface layer is retrieved as a solution of an inverse problem using Chahine method. The column NO₂ abundance is obtained as a sum of layer abundances. Random errors of retrieved NO₂ profiles are estimated with the help of a special statistical method based on randomization of measured slant column abundances. Measurements show that stratospheric NO₂ is a subject to diurnal day-to-day intra-seasonal annual and interannual variations. A linear negative trend in the stratosphere column NO₂ abundance has also been estimated. The NO₂ abundance in the lower troposphere is strongly affected by pollution episodes. Regular variations and statistical characteristics of the NO₂ abundance in the near-surface layer have been determined.

Based on standard Umkehr inversion algorithm the ozone vertical profiles have been retrieved from the Dobson Umkehr observations of Beijing. The corrections are made for aerosols in the process of inversion and the retrieved results have been improved. By using the derived profiles the characteristics and trends of ozone vertical distributions of Beijing during 1990-2002 are studied. The results imply that the ozone concentrations between 10.3 and 23.5km were unusually low during the fall of 1992 and the spring of 1993 and at the same time the total ozone underwent a marked decline. During the period 1990-2002 the total ozone decreased slightly but the trends of change of ozone concentrations at different altitudes were different.

We measured the high resolution absorption spectroscopy of water vapor between 7599cm^-1 and 7615cm^-1 by narrow linewidth DFB diode laser and kilometers order long path White cell. We observed the minimum detectable absorption of the 10^-26 cm/molecular line strength. The measured line parameters show excellent agreements with the values from HITRAN2000 database. The 7600.133 cm^-1 line of water vapor listed in HITRAN2000 database was not observed we think the line is inexistent. Seven new weak lines unlisted in HITRAN2000 database were observed which may belong to the isotope H₂¹⁸0 molecular.

Measurements of CO and H₂0 total content in the atmosphere by using ground-based solar spectroscopic system were conducted in Beijing since 1992. Measurements have been done every year during time period of late autumn and early winter when the heating activities started in the most places of Northern China. So the impact of human activities on CO variation can be assessed based on the obtained results. Brief description of the used spectroscopic method is introduced. Some variation characteristics of CO and H₂O total content in the atmosphere over Beijing the background value of CO content in Beijing area and variation trend of CO and H₂0 content in the last 8 years are given and discussed in this paper. Results show evident daily and seasonal variations of CO and H₂O content and heating activities in Northern China have a remarkable influence on CO content in the atmosphere. On average CO total content in the atmosphere over Beijing area maintains a high level (about 0.130-0.150 atm-cm) all along and no clear annual variation tendency of CO column content was observed since 1996 in Beijing area.

A portable sensor based on tunable diode laser for remote sensing of methane (CH₄) leakage at a wavelength of 1.65 μm was developed. Wavelength modulated spectroscopy technology is also applied. It was found that the sensor can detect a 10 cm³ min^-1 city-gas leak with a sensor output equivalent to the range-integrated concentration over 100 ppm-mn.

Monocyclic aromatic hydrocarbons are regarded as one of the most important classes of hydrocarbons in the atmosphere since they are a potential risk for human health and play a key role for photochemical smog formation. Differential Optical Absorption Spectroscopy (DOAS) has been widely used for many trace gases monitoring in the atmosphere however he analysis of aromatic compounds is difficult and the spectral structures from interfering absorbers (e.g. O₂) should be very careful to separate correctly. This paper describes a spectral evaluation technique of aromatic compounds from DOAS measurement and summarizes the results of field measurements of benzene toluene xylene (BTX) in Chinese cities Beijing (2000) Shanghai (2001) and Hefei (2002). High concentrations of BTX were observed in Beijing and Shanghai whereas low concentrations in Hefei. This study will provide useful information to help understanding air pollution and atmospheric chemistry processes in urban areas ofChina and thereby contributes towards an improved pollution control strategy in Chinese cities.

Dioxins (polychiorinated dibenzo-p-dioxin/furan congeners) are the most toxic chemicals among the by-products emitted from combustion processes in trace amounts. Since the concentration of dioxins in flue gas is far beyond the detection limits of today's on-line methods the idea of using surrogate compounds of dioxins for fast measuring come up. Many evidences confirm that chlorobenzenes (monochlorobenze and some polychiorinated benzenes) are the suitable surrogates for on-line measuring of the dioxins in the flue gas by laser mass spectrometry. In this paper we present the principles of laser mass spectrometry. The 1+1 two-photon Resonant Enhanced Multiphoton Ionization (REMPI) spectra of monochlorobenzene in the range 240≈250nm are studied. The measurement shows that monochlorobenzene has the highest ionization efficiency excited at 248.6nm in this wavelength range and the detection limit of monochlorobenzene at ppb(v/v) concentration is obtained. The REPMI-MS properties of monochlorobenzene in this wavelength range provide useful information of practical measurements on mixtures.

On-road motor vehicle emissions have been estimated being the single largest contributor of major atmospheric pollutants worldwide. The amount of motor vehicles in Beijing has rapidly grown in the past few years and will increase even more noticeably in the near future. It is therefore clearly required that a targeted approach to identifying the grossly polluting vehicles will have maximum impact on reducing the detrimental effects of the emissions. In this paper we will introduce an on-road motor vehicle exhaust emission monitor built by our group. This monitor was fabricated with tunable diode laser absorption spectroscopy (TDLAS) technique. On-road remote sensing of CO and CO₂ of the motor vehicle exhaust emissions on Xueyuan road and at Dayangfang motorway toll station in Beijing were performed with this monitor. Analysis of the results shows that only 73.4% on-road motor vehicles are clean. Among the rest more than 15% are heavy gross polluters which should be warn for repair or removed from service.

For joint retrieval of vertical distributions of both air density and ozone concentration in the mesosphere which are two of the most important atmospheric parameters in this region a retrieval scheme is suggested by using satellite limb scan observation at two UV wavelengths i. e. 265 nm and 296 nm. The retrieval scheme is the modification of the LSUV method by Aruga and Heath with two UV wavelengths and two atmospheric parameters. Feasibility study was made based on simulated limb scan radiances computed with a single scattering radiative transfer algorithm of spherical geometry developed by the present authors and the inversion technique. Results of the simulations show that it is feasible to retrieve air density and ozone concentration vertical distributions on a global basis from satellite UV limb scan over the altitude range of 50-100 km with 1-km intervals as well as the SME measurements of air density and ozone indicate the rationality of the present retrieval method.

Sulfur dioxide is a highly toxic air contaminant that harms human health and damages the environment. It is easily converted to sulfuric acid which is the major component in acid rain and to sulfate particles. Coal-burning power plants are the main sources of SO₂ pollution. It is necessary to evaluate the emissions from industry for emission reduction strategies. Passive DOAS method has been successfully applied in volcanic plume and atmosphere monitoring because of its advantage of relative simple system with no light source. Here we report the measurement of SO₂ total flux from a chimney in plant area in Hefei city (China) with a compact passive DOAS system. The system consists of a small telescope pointing zenith direction and a fibre-coupled OceanOptics USB2000 spectrometer. In the measurement the system was mounted on a mobile platform moving under the plume approximately perpendicular to the plume transport direction and the spectra of the zenith direction were recorded. By combining the integrated gas concentration over the plume cross section with wind velocity data SO₂ flux was estimated.

In the beginning ofnineties, scientists from the A.M. Obukhov Institute ofAtmospheric Physics, Russian Academy of Sciences started in collaboration with the Institute ofthe Atmoapheric Physics, Chinese Academy of Sciences systematical studies ofthe air pollution in the atmosphere over Beijing. In the fall of 1992 and 1996-2003 and in the summer of 1999, specroscopic measurements ofthe carbon monoxide content in the atmospheric column and local measurements of concentration of CO, black carbon, and submicrometer aerosol concentration in the surface layer were carried out in the north part of Beijing [Wang, 2001].

MODIS a moderate-resolution imaging spectroradiometer instrument on board EOS-AM1 and PM1 has 36 spectral bands amongst which only 9.6 μm band sensitively traces atmospheric ozone. To produce total ozone inversion one requirement is via temperature and pressure profiles a popular requirement of mass-calculation which could now be argued not a literally convenient idea. Thus in this paper I try my hand at a new method through firstly overall bands' correlative statistics and analysis based on MODIS high-precision data source in spectral radiation to materialize "similar TRIPLET" spectral data combination method. Then it comes to us a need to attain a solid cooperative optimization and thirdly with forgoing output a process is introduced here of spectrum differential calculation leading to final total ozone inversion.

The one of the most important technique of satellite ocean color remote sensing is the radiance measurement accuracy because the water leaving radiance is only about 5% to 10% of the total radiance arrived at sensor at the satellite altitude. It is necessary to guarantee the accuracy of water leaving radiance measurement of about 5%(relative error) to meet the reversed accuracy of ocean color factors (such as chlorophyll suspended material and so on) within relative error about 30 in open sea (Case I water). When sensor has been in the orbit it is important to take orbit calibration to make up some deficits of the pre-launch calibration in the laboratory. Two kinds of data could be used for orbit calibration one is in-situ measurement date so-called in-situ field calibration and another is other satellite data with higher radiance measurement accuracy so called crossing-calibration. China has launched the third spaceship SZ-3 in March 2002. The main remote sensing sensor is the Chinese Moderate Imaging Spectroradiometer (CMODIS) which has total 34 channels (30 channels of 2Onm interval in the spectral range of 0.403-1.O43μm and four infrared channels with 2.15-2.25um, 8.4-8.5um, 10.3-11.3um and 11.5-12.5um. Following SZ-3 China had the first ocean color satellite HY-1A in May of the same year whose main sensor is for ocean color measurement, called as Chinese Ocean Color and Temperature Scanner, COCTS, providing 8 visible and near-infrared channels similar to SeaWiFS. In this paper, first, the methodology and procedure of satellite cross-calibration are discussed in detail, with taking an example of CMODIS. Then the results of this orbit cross-calibrated by American ocean sensor, Sea Wide Field-of-View Sensor (SeaWiFS), for CMODIS and COCTS are presented with comparing the normarization from pre-lunched Lab-calibration and in-situ measurement.

Thermal infrared images from the NOAA AVHRR taken over 12 years between 1991 and 2002 have been used to study the sea surface front ofthe South China Sea Warm Current in the southern Taiwan Strait. Information about the location length width and strength of the front has been retrieved. The temporal and spatial variations of the front have been discussed.

China launched its own ocean color satellite HY-1A in May 2002. One of the onboard sensors COCTS has 10 channels including 8 visible and near-infrared bands for ocean color and 2 thermal infrared bands for sea surface temperature which has the advantage to estimate ocean primary production (OPP). In this paper first a satellite model of ocean primary production developed from in-situ data sets of China Sea was introduced with focus on the analysis of modeling vertical chlorophyll distribution and photosynthesis quantum yield. Second we test the reliability of this model with in situ data and compare it with other primary production models. Finally satellite-derived ocean primary production of China Sea was generated with HY-1A/COCTS data and the results show that COCTS data has a good capability to estimate ocean primary production in general.

The calculation of Rayleigh scattering radiance is the first step of the atmospheric correction of ocean color remote sensing which affects the quality of atmospheric correction significantly. This paper studies how the satellite attitude affects the accuracy of the Rayleigh scattering radiance calculation. Satellite attitude affects the geometry angles of the sun and sensor directly and then affects the Rayleigh scattering radiance. The results show that roll angle affects Rayleigh scattering calculation most and the relative error of Rayleigh scattering radiance calculation is up to 10 as the roll angle is 2.5°. However the effects of the pitch angle and yaw angle are very small and the relative error of Rayleigh scattering radiance calculation is less than 1% as the pitch angle or yaw angle is 2.5°. The results also show that in order to achieve the 1% accuracy goal of the Rayleigh scattering radiance calculation the satellite roll angle should be less than if the satellite attitude isn't corrected in the data pre-processing stage of ocean color remote sensing.

On the basis of retrieving clear-day LST (Land Surface Temperature) with single time/dual channels SWA (Split-Window Algorithm) by using GMS 5 satellite observation. To establish LST database the regression equation are established for LST by using GMS/IR data and some surface meteorological parameters as input. The preliminary results show that the present results are better than those from several modified SWAs. Applied GMS 5 data from 1998-2OOO to East Asia and in particular to several representative land surface types including Talimu Basin (Gobi desert) Tibetan Plateau Hunshandake Sands (mid-latitude savanna) Northern Plain of China and Southern China the fundamental characteristics of the diurnal seasonal and interannual variation of LST are analyzed and discussed in detail.

Monitoring and restoration the water quality of lake need proper water quality parameters. Traditional measurement of water quality requiring laborious laboratory work is expensive and time consuming. Hyperspectral measurement can offer fast and easy way for estimating trophic status. Hyperspectral data on 7-8 March 2004 and water chemical data from 1997 to 2003 was used for retrieval of water quality parameters. The quantification of spectra with water quality parameters: chlorophyll a suspended solids total nitrogen(TN) total phosphorus(TP) chemical oxygen demand(COD) secchi depth(SD) were regressed. Results showed that the reflectance ratio of R702/R685 R6201R53 1 and R554/R675 had high correlations with the concentration of chlorophyll a suspended solids and total phosphorus respectively TN COD can be calculated from TP or Chi a for good relations between them SD is negatively correlated with suspended solids concentration total phosphorus (TP) (less than 0. 25 mg/L) linearly correlated with logarithm chlorophyll a concentration trophic status index (TSI) exponentially correlated with COD concentration.

The Zhejiang-Fujian coastal front is an important front in the East China Sea. The frontal parameters have been measured using an improved front-following algorithm with Advanced Very High Resolution Radiometer (AVHRR) data. The Frontal parameters including position width mean SST SST difference and gradient of the front have been retrieved.

This paper describes the survey of Zhoushan archipelago and Ningbo depth port group in east China Zhejiang province using TM/ETM+ SPOT ERS-2 SAR and NOAA-AVHRR remotely sensed data and the general data. TM/ETM+ and SPOT remote sensing images are used to obtain the information of ports status shoreline types and storage field. Images of ERS-2 SAR are applied to survey the oceanic environment factors such as front and internal wave. TM/ETM+ and NOAA-AVHRR data are employed to detect the suspend sediment. Finally based on the survey results the assessment ofthe depth port resource of the study area is brought out.

Ground-based measurements of land surface temperature as measured by Platinum resistance thermometer partly buried in the soil surface radiation temperature measured by infrared thermometer and near surface air temperature measurements at Gaize (32.30°N 84.06°E 4420 m) on the western Tibetan Plateau from January 2001 to December 2003 were compared with Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) products (Version 4) produced by the generalized split-window (MOD11A1) and the day/night LST algorithm (MOD11B1). A comparison of LSTs shows that the LSTs produced by the day/night LST algorithm agree quite well with ground-based surface temperature and surface radiation temperature measurements with a mean difference of zero and root mean square errors being less than 1 K. MODIS LST retrieved by the day/night LST algorithm is found to be 2.2 K less than the air temperature at 0. 5 m above the surface. Compared to that produced by the day/night LST algorithm the LST produced by the generalized spit-window LST algorithm is underestimated by 1.9 K.

To illustrate the relationship between nutrients of Taihu Lake and growth of algal three ecological model were introduced: 1)OECD management model 2)Monod equation 3)logistic equation. Based on these models of lake eutrophication good relationships between nutrients concentration and chlorophyll-a were found. Taking advantage of the consistent correlation to estimate nutrient concentration in Taihu Lake from CMODIS chl-a image was possible.

In recent years hyperspectral remote sensing has been widely used in the applications of geology agriculture forest ocean etc. This work assessed the feasibility of hyperspectral technique in coastal zone remote sensing. Data was acquired by Operational Modular Imaging Spectrometer (OMIS). Field spectrum of each class was measured and analyzed to extract certain spectral feature. We proffer a hybrid decision tree classification algorithm combined with optimum spectral features of class pairs to every tree node and step by step classified out coastal vegetation water body rocky shore sand beach mudflat and artificial objects etc. The results show that hyperspectral data can be used to classify coastal landscape more accurate than multispectral image.

There are usually three calculation methods of normalized water-leaving radiance in use of in-water radiometric profile data the local linear regression method is the commonly used one for its simple principle and processing. However this method need manual selection of the regression depth interval the results are mostly affected by subjective factors of processors which can lead to 5%-45% errors with different depth intervals selected. In this paper a statistical method is introduced that calculates all the results of linear regression in the sub-interval of selected depth interval removing the exceptional values of them and the mean of remained values is best result. The other advantage of this method is that we can find the best regression depth intervals in use of the result. At last the author compares the results of processes of three measurements: in-water radiometric profile measurement above-water radiance measurement and the reversion produce of SeaWiFS data at the same time and site the results show that this statistical method is available and looking Es(O⁺.λ) on as the validation of extrapolation of Ed(O^-,λ) is incorrect.

The airborne test experiment validates the function of remote sensor before on-oribt which has important meaning for satellite remote sensing. The sun glint is the most important factor that affects the data quality of airborne test experiment. In order to avoid the sun glint and improve the data quality it needs to select the optimal fly route before the airborne test experiment. This paper simulates the sun glint radiative image with inputed the in-remote sensor atmosphere and water parameters using the radiative transfer theory in atmosphere and ocean. Based on the generated sun glint radiative images can select the optimal fly route will improve the data availability significantly in the airborne test experiment and reduce the waste of manpower and material resources in the airborne test experiment.

Over the past two decades algal blooms appear to have increased in frequency intensity and geographic distribution. Algal blooms have caused harmful effects on the marine ecological balance even to human health. Monitor programs especially trending toward including continuous data collection by in situ detectors for example remote sensing is in emergently demand. In this research NDVI imagery obtained from MODIS satellite data combined with SST and chl-a proved to be a sensitive measure of phytoplankton amount providing a means of improving the detection and delineation of algal blooms.

Quantative parameters of urban environment impact on the thermal state of the atmospheric boundary layer are presented in the paper. Temperature profiles up to the height of 600 m were obtained in a continuous series of measurements by stationary and mobile microwave temperature profilers MTP-5 in Moscow (Russia) and in Nigny Novgorod (Russia). The influence of a large city on the parameters of the urban heat island (UHI) was estimated for the cases ofthe stationary atmospheric processes and for the frontal passage conditions. Two types of UHI were identified from the temperature profile measurements the warmer dome of urban heat at all levels and the low dome in combination with a lens of coal air above it. The time stability of the UHI illustrates sharp differences in the daily temperature change at different levels. The strongest UHI appears in the morning and at night. The accumulation of pollution and water in urban air accurse at this time and the UHI reaches maximum intensity. At the daytime UHI is broken down or remains only in the lower 300 meters. The temperature profiles data from the mobile profiler showed a big irregularity of UHI inside the city.

Cloud liquid water path (L) (i.e. vertically integrated cloud liquid water) is an important parameter in meteorology and cloud physics. However the actual measurements of L are too limited to build and validate the retrieval algorithm. The space-borne microwave radiometer is the most powerful tool for monitoring the distribution and variation of L on global scale. The Advanced Microwave Scanning Radiometer on EOS (AMSR-E) is a high-powered space-borne microwave radiometer. This paper combines the physico-statistical method of Chen with the microwave radiative transfer model developed by Wentz. A linear regression relationship of L versus the difference of brightness temperature (ΔT_B) between cloudy and clear atmospheres is built and a preliminary retrieval result is given. This algorithm has two advantages. Firstly it only uses the T_B measurements of two channels (i.e. a retrieval channel and a low frequency channel) while the ocean algorithm needs all channels' T_B measurements to retrieve L. Secondly the resolution of L can arrive at 12km while the one derived from Special Sensor Microwave/Imager (SSM/I) is 27km. This algorithm is valid for clear and cloudy skies and for light rain up to about 2 mm/h. Numerical comparative study shows that this algorithm is feasible in general although the result needs a modification.

Multiparameter (multifrequency and/or multipolarization) synthetic aperture radar (SAR) data collected by JPL AIRSAR and SIR-C are used to analyze ocean features such as ocean waves oil slicks ship wakes ocean fronts and underwater topography in the China Seas. Suggestions to the choices of frequency and polarization for the mapping of these features are given based on the analyses.

The paper is intended to retrieve atmospheric temperatures from AMSU soundings by a combined physical-statistical scheme and a regression model is established on weighting functions of AMSU channels 3-14 calculated by the Liebe model (Liebe 1981, 1985) and the normalized weighting functions are employed as its constraints and the optimal solution is obtained by appropriately adjusting the constraints. Results show that when nadir AMSU samples are adopted the constrained regression algorithm yields higher retrieval accuracy with the root-mean-square error of 0.4 K (1.0 K) below (at and above) 100 hPa. By the same algorithm a limb adjustment is made of off-nadir fields of view. For atmospheric sounding channels 4l4 (frequencies of 52.8-57.29 GHz) the maximum deviation is thereby decreased to 0.9 K from -l5-5 K. Retrieved temperatures are utilized to investigate the warm-core structures of 15 tropical cyclones making landfall in China mainland during 2002 and 2003 indicating that retrievals have ability to reveal clearly the structure and better correlativity of the temperature anomaly to the surface central wind speeds and the sea-level central pressures ofcyclones. As a reference therefore the correlation is of utility to forecasting.

A study on sensitivity of TMI brightness temperatures (Tbs) to the different vertical profiles of hydrometeor in precipitating cloud has been made by using a microwave radiative transfer model VDISORT. The different hydrometeor profiles are obtained from the simulations of precipitating convective cloud by means of a sophisticated meso-scale meteorological model MM5. The results show that at high frequency scattering effect of ice crystal and graupel are stronger than that of snow among the ice phase hydrometeors. When changing the ice phase water content the corresponding scattering coefficient has significant change however the extinction coefficient with obvious change is found only for changing ice crystal content. The analyses show that the Tbs at TMI high frequency calculated by the VDISORT model are very sensitive to the ice crystal concentration and much less sensitive to the snow and graupel concentrations. In addition comparison of measured and calculated TMI Tbs indicates that the MM5 might produce too much snow and less ice crystal content in the convective cloud for medium or heavy rainfall.

GPS technology provides a new powerful approach for measuring atmospheric water vapor. In this paper the experiment of observing integrated atmospheric water vapor or the precipitable water (PW) using ground-based GPS receivers performed in southwestern region of China is presented. Zenith total delay (ZPD) data are collected in a GPS network consisting of 10 stations. Time series ofwater vapor in one hour bins for 10 months is retrieved. The results of 3 stations in southwestern region affected by many monsoons show that the water vapor has large variability in spatial and temporal scales. The water vapor derived from GPS is compared with retrievals from the radiosondes. The GPS PW agrees well with data from radiosondes which indicates GPS PW are correct at this locations. The difference of PW from them is larger when the humidity is higher and more variable in summer. The results of comparison with the NCEP reanalysis PW data show that they are consistent with each other. In the mountain areas where observations are few PW from GPS can be used to validate the PW from numerical model analyses. Finally long-term monitoring water vapor using ground-based GPS is discussing.

Synthetic aperture radar (SAR) remote sensing ofthe ocean from space in China began in the early 1990s. This paper presents the research and marine applications of synthetic aperture radar technique in China. Research activities in SAR remote sensing range from basic research to technique development. Basic research has been focused on studies of SAR imaging mechanisms. Technique development has been given to methodology for extracting information about sea surface waves internal waves water bottom topography and ship detection. Applications of SAR data include the study of oceanic phenomena and coastal environmental monitoring. Some examples are presented. Future research and applications are discussed.

A matchup dataset that contains the SSM/I measurements from F14 satellite and the columnar water vapor (CWV) radiosoundings taken in or near the China Sea was established to cover the period from April 1998 to June 1999. CWVs retrieved from two statistical and two semistatistical retrieval algorithms were compared to radiosonde CWVs using the matchup dataset. It is indicated that the root-mean-square (RMS) error of these retrievals relative to the radiosonde data ranges from 4.483 kg m^-2 to 10.180 kg m^-2. Three improved algorithms were developed and validated using the matchup dataset. It is demonstrated that these improved algorithms can be applied to the China Sea for retrieving CWV from the SSM/I with better accuracies relative to the four typical existing algorithms.

The image spectrum ofthe Chinese airborne synthetic aperture radar (SAR) has been simulated using a simulation model based on the closed nonlinear integral transformation. The results of the simulation have been used to study the ocean wave imaging mechanism. The ability of the Chinese airborne SAR to observe ocean waves in the China Seas is discussed.

A combining retrieval method of radio occultation measurements is presented. Vertical profiles of water vapor and temperature are retrieved from radio occultation bending angles with a new method combining the artificial neural network and iterative method. We used a feedforward full-connected network based on the back-propagation algorithm to retrieve the water vapor profiles in the troposphere. The network was trained by paired bending angle and water vapor pressure profiles from CHAMP. The month latitude altitude and bending angle were used as the input vectors and the water vapor pressure as the output vector. The profile of water vapor pressure retrieved by the ANN was applied to the iterative procedure that exploits the constrains on temperature and water vapor pressure mandated by the ideal gas law and the equation ofhydrostatic equilibrium. The vertical distribution of temperature was calculated.

Wind wind stress and drag coefficient of ocean surface are very important parameters in the studies of ocean and atmospheric dynamics especially in that of air-sea interaction. It is shown in this paper that wind wind stress and drag coefficient of ocean surface can be measured remotely with high resolution by synthetic aperture radar (SAR). A model has been developed based on SAR imaging mechanisms of ocean surface capillary waves and short gravity waves. A Radarsat SAR image of coastal ocean of south of Hainan Island has been used to calculate wind stress and drag coefficient. Good results have been achieved.

Since late 1980s there have been a series of satellite-borne microwave (MW) radiometers operated for remote sensing of water-related parameters in particular for rainfall observation among them SSMII on DMSP TMI on TRMM and AMSR-E on AQUA are well known instruments. A lot of retrieval schemes have been published for operational and research purposes. Inter-comparison of different retrieval algorithms and their products is an important task for their reliable application with enough accuracy. In this paper we will compare some algorithms for SSM/I products over West Pacific area. The methodology is mainly focusing on the comparison of retrieved hourly rain rate at the spatially and temporally collocated area statistical results and case study will be given.

In 2000 Frank Wentz and Thomas Meissner described a model function for the microwave radiometer's brightness temperature of the ocean and intervening atmosphere. The oceanic and atmospheric parameters are the sea surface temperature the near-surface wind speed the columnar water vapor and the columnar cloud liquid water. We analyzed the sensitivity between the geophysical parameters and the microwave radiometer's brightness temperature with the model function. First we find that the sensitive bands of the sea surface temperature are 6.93GHz v-pol and 10.65GHz v-pol; the sensitive bands ofthe near-surface wind speed are 6.93GHz h-pol, 10.65GHz h-pol, 18.7GHz h-pol, 23.8GHz h-pol, and 36.5GHz h-pol; the sensitive bands of the columnar water vapor are 18.7GHz v-pol, 18.7GHz h-pol, 23.8GHz v-pol, 23.8GHz h-pol, 36.5GHz v-pol and 36.5GHz h-pol; the sensitive bands of the columnar cloud liquid water are 36.5GHz v-pol and 36.5GHz h-pol. Second we find that the brightness temperature is sensitive to incidence angle variations. One-degree error in specifying incidence angle produces a 2.5K error in brightness temperature. The 2.5K errors in brightness temperature produce 5K errors in sea surface temperature and 4.5m/s error in near-surface wind speed. Third we find that brightness temperature is not sensitive to the sea surface salinity in the 6 to 37 GHz band.

A technique is developed to plan and conduct lidar profiling of temperature and humidity by the DIAL (differential absorption lidar) method in the lower troposphere. The technique proposed has been tested in the near JR region when designing a meteorological lidar based on the Ti:Sapphire laser. The DIAL and correlation methods were used in the meteolidar complex for measurements of the main atmospheric parameters: temperature humidity wind velocity and direction. The possibility of this lidar complex for remote determination of the main meteorological parameters is investigated. The accuracy ofthe measurements is estimated.

The method and technology of the photoacoustic gas analysis enables highly sensitive investigations of CO₂ gas exchange different biosystems. The CO₂ evolution by some plants exposed to elevated concentration of pollutants and CO₂ emissen from the wood of tree rings at low air pressure is studied. All measurements have been performed using the photoacoustic gas analyzer with the tunable CW CO₂-laser.

Based on the laser desorption/ionization an experimental prototype of laser single particle time-of-flight mass spectrometer (TOFMS) was designed and constructed in our laboratory. Particles are inhaled directly from ambient air into a sampling inlet consisting of a short capillary nozzle and a two-stage differential pumping system. The particles are accelerated to different velocities depending on their aerodynamic diameter through free expansion of the air. The velocity of each particle is measured through two cross-positioned diode laser beam. A UV laser is fired at the exact time when the particle arrives at its focal zone to desorb/ionize the particle. The ions each firing generated are analyzed by a linear TOFMS and recorded automatically on a personal computer. The initial testing experiments including size calibration and practical measurements showed that the instrument is capable of analyzing the aerodynamic diameter and chemical constitutes of individual particle in real time. The information at single particle level allows each particle to be traced to its original source and provides immediate sense of atmospheric phenomena.

In the past decade interest has focused on the remote analysis of emissions from motor vehicle using spectrometric techniques driven by recognition of the fact that a very proportion of the environmental damage done in this way originates with a small percentage of vehicles. In this paper a remote sensing system designed to measure air-pollutant emission from on-road motor vehicles is described. The system uses a tunable infrared laser differential absorption spectrometer and a technique of UV DOAS. It has been shown to be able to measure CO, C0₂ NO, HC and the dust emissions from on-road individual vehicles. Excellent detection sensitivity is obtained with measure precision.

Metastable transfer emission spectronmetry (MTES) has been shown to be an extremely sensitive method for the determination of trace metals. In this work it was shown that MTES can also be used as a sensitive method for the determination of SO₂ EDF and capillary sampling system were employed to determine the detection limit of the flowing afterglow system on the SO2 detection. The characteristic emission lines of SO₂ (^~a³B₁ → ^~X¹A₁) are used to detect the concentration of SO₂ and also can be used to identify SO₂ from other S-containing molecules such as CS₂. In addition S0₂ in a flowing tube has been detected down to 45μg m^-3 by means of metastable N₂ (A³Σ_U⁺) energy transfer emission spectroscopy. The linear measurement range is from 0.045 to 0.8 mg m^-3. The capability of metastable transfer emission spectroscopy in the quantitative determination of S0₂ has been evaluated. And the lowest detection limit of S0₂ in the dilution gas N₂ has been confirmed to be about 10 times as much as that in the air because of the great consumption of N₂ (A³Σ_u⁺) by 0₂.

Satellite remote sensing is an efficient and economic measurement for earth observation which has become a major information resource. With the exponential increasing satellite information it is necessary to design and construct a stable and automatic operational data processing system suitable for different satellites to meet the requirement of marine application. This paper focused on design and construction of a satellite data processing system (SatDPS) for multi-satellites such as FY- 1 CID NOAAI 2/14/1 5/16/1 7 and EOSIMODIS (AQUA TERRA). According to software engineering principle an object-oriented program was designed and modeled. Furthermore some special data processing techniques have been developed including multi satellite combination processing programming collaboration of hardware and software Windows sockets mechanism embedded database and SQL etc. The system has been constructed and tested for half a year in Second Institute of Oceanography State Oceanic Administration which can automatically provide the remote sensing products for marine application such as sea surface temperature chlorophyll concentration suspended material concentration diffusing attenuation coefficient of 490 nm Secchi Disk depth vegetation index optical thickness and so on. The result shows that the constructed system is suitable to process multi-satellites for marine operational application.

This paper is about cavity enhanced absorption spectroscopy (CEAS) experiment with a tunable narrow line width continuous wave DFB diode laser and it was used to measure the weak absorption band of carbon dioxide in the near infrared region. The absorption spectrum was extracted from the measurement of light intensity that leaks out of an optical cavity which was consisted of two high reflectivity mirrors separated at a distance about 34cm. In the experiment the optical cavity was scanned continuously and the laser radiation was coupled into the optical cavity via accidental coincidences of laser frequency with one of the multitude modes of the optical cavity. A wavemeter was used simultaneously to record the accurate wavelength of the DFB diode laser radiation. Absorption spectrum of vibrational combination band of carbon dioxide near 6358.65cm^-1 has been obtained. An absorption sensivity of about 3.6 x 10^-7 cm^-1 has been achieved. The experimental results indicate that cavity enhanced absorption spectroscopy can be used as a high sensitive direct absorption spectroscopy technology.

The absorption spectra of CH₄ around 1.31 μm have been observed by wavelength modulation absorption spectroscopy technique employed with a tunable diode laser at different pressure. The overtone spectra of CH₄ around 1.31 μm and the corresponding spectral parameters (i.e. positions intensities self-broadening coefficients) are presented. The intensity of the weakest line detected is 1.306x10^-26 cm^-1/(molecule-cm^-2) at the pressure of 0.077 Torr with a corresponding absorption of l.174x10^-7.

This study determined the potential of wavelet-based analysis for extracting spectral features of hyperspectral reflectance signals. The dyadic discrete wavelet transform is proposed for feature extraction from a high dimensional data space. The wavelet's inherent multi-resolution properties are discussed in terms related to multi-spectral and hyperspectral remote sensing. Wavelet can focus on the local structure of the signal through adjusting the scale parameter in the course of focusing. So we can find the singularities and the inflexions of the original signal. The absorption strips are thus detected consequently with the local wavelet transform modulus (absolute value) maxima. The results show a superior performance of the proposed wavelet-based features that are more meaningful for spectral feature extraction when compared to conventional methods.

Raman frequency shifter is a useful method extending laser wavelength the first Stokes of CH₄, H₂, and D₂ pumped by the fourth harmonic of Nd:YAG laser can be used in DIAL measurement of the trace gases. The stability and energy of SRS are related to focal length of lens active gas pressure input energy buffer gas elements and pressure. We detect the stability and energy of the first Stokes line under pure active and mixture with Ar or He. From our experiment the stability of pure CH₄, H₂ are almost same under different pressure however the stability of pure D₂ changes with pressure. The energy conversion efficiency on Si is different among pure gas (CH₄, H₂, D₂). Furthermore the optimal output energy of the first Stokes line of CH₄, H₂, D₂ are got independently at moderate active gas pressure mixing with moderate buffer pressure.

The quality of polarimetric images deduced from three different angle radiometric images depends greatly on the accuracy of the images registration. The researches indicate that image misregistration with 1110th order of magnitude of a pixel can introduce artifacts in polarization images. Typically translation rotation and scaling are the main image deformations to be corrected. It is desirable to have a registration algorithm that corrects translations rotations and scaling to 0th of a pixel just based on analytical automated calculation without user intervention. This paper presents an automated image registration algorithm by using wavelet transform technique. The algorithm relies on the local wavelet transform modulus maxima of the images. Examples of images registered with this algorithm are presented. The results testify this method is effective to correct the image misregistration of three different angle radiometric images.

The fourth harmonic (266nm) of a pulsed Nd: YAG laser is used to pump Raman cells filled with D₂ and D₂/He. The dependences of the energy conversion efficiency of stimulated Raman scattering radiations upon the system parameters such as the pump energy pressure of pure D2 and partial pressure of He in D₂/He mixture were experimentally studied. The maximum energy conversion efficiency of the first Stokes radiation (S₁, 289.O4nm) reaches 22.1% in D₂/He. The conditions to improve the energy conversion efficiency of Si were found. The results have been used to optimize the laser transmitter system for a S0₂ differential absorption lidar (S0₂-DIAL).

Photodiode Array (PDA) detector is a key component of Optical Multiple Analyzer (OMA). The present paper reported the design of low-noise thermoelectrically-cooled Photodiode Array detector and its performance test and analysis in practice. It shows that our designed PDA detector has the advantages of small size low noise and constant temperature etc. and settles for the demands of high precision spectrum analysis.

DOAS technique provides a more representative picture of air quality and typical urban exposures over traditional point monitoring equipments it has been widely used for urban air quality monitoring in China. Most commercial DOAS instruments presently used for air quality monitoring adopt photomultiplier and scanning slit as detector which is called slotted disk (SD) detector. In contrast with the SD detector Photodiode Array can overcome the problem of scintillation noise caused by atmospheric turbulence and reduce photon noise. We report here a new type UV-visible DOAS system based on photodiode array. The properties of the system including offset dark current noise linearity of the detector and resolution stray light ofthe spectrometer are described. Field observations of a number of pollutants (e.g. S0₂, NO₂, 0₃ and HCHO) were performed in the urban area of Beijing City during August 2004. The measurement results show that the system fulfils automatic ambient air monitoring with high time resolution and sufficient sensitivity.

A measurement experiment of horizontal visibility was conducted by using a micro pulse lidar (MPL) at Hefei Airport during March of 2003. Segment-average method is used for processing the data measured by MPL. A visibility-meter and an OPC were running simultaneously at same site. The results show that the visibility measured by MPL is of a positive correlation with the ones measured simultaneously by a visibility-meter and a negative correlation with the total number of particles measured by OPC which indicates that it is feasible for MPL to measure the visibility.

As one of the most versatile tools lidar plays an important role in the field of the atmospheric and environmental probing for its special properties of fine resolution continual operation long-range and wide scanning. The most important parameter of lidar is the signal-to-noise ratio (SNR) and it not only shows the ability in remote sensing but also gives some instructions in designing of lidar. But there is still not a suitable and scientific way to calculate the lidar's signal-to-noise ratio in practice. Under this circumstance the new and reasonable method is present from the experience in lidar working and its data processing and the analyses of main influencing factors are also made on real lidar data.

The temperature dependent of the ratio between second and first harmonic signals in wavelength modulation spectroscopy was experimentally measured. The results show the ratio decrease with the temperature increase the temperature increase from 30°C to 50°C the ratio decrease about 5%, the results is consistent with theoretical calculation. As increasing the temperature of the CO gas the ratio between second and first harmonic signals is the straight line parallel displaces downwards. Therefore the measuring concentration can be corrected by using a calibrated temperature curve in practice sensor application. The results are useful for the application of the diode laser sensor ofthe ratio detection type.

This paper describes the passive remote method and its instrumental realization based on microwave radiometry for express diagnostics of radioactive elements in the atmosphere. The formation of ionized atoms and molecule in the atmosphere as result of radioactive emissions and the photochemical processes resulting in background radiation power are discussed. Analysis of the microwave radiation due to ionization and dissociation of atmospheric components interacting with radioactive elements is carried out. The photochemical processes resulting in background microwave radiation power are considered. Electron density formed in the emission plume from an atomic power station is estimated for β-active nuclides ⁴¹Ar, ¹³³Xe, ⁸⁵Kr, ¹³¹I, because they are main part of emissions from the atomic power stations and nuclei reprocessing plants. The influence of atmospheric conditions on such processes is estimated for different stratification of atmospheric parameters. As an example the results of natural experiment of detecting the atomic hydrogen radiation in the plume of emissions of nuclear cycle processing plants are presented.

The DOAS system is a synthetical system that combines optics mechanics electricity and computer technologies in it. The Multi-Path DOAS system that we developed is of great sensibility and lower measure limits. Advanced controlling and signal detection technology are applied in the system. This paper briefly summarizes the principle and the realization ofthe electrical control and signal detection in DOAS system