RECENT PROGRESSES IN ATMOSPHERIC REMOTE SENSING RESEARCHES IN CHINA
QIU Jinhuan and CHEN Hongbin
Institute of Atmospheric Physics, Beijing 100029, China
Progresses of atmospheric remote sensing researches in China during 1999-2003 are summarily introduced in this paper. These researches include: 1) microwave remote sensing of the atmosphere; 2) lidar remote sensing; 3) remote sensing of aerosol optical properties; and 4) other researches relative with the atmospheric remote sensing.
I. MICROWAVE REMOTE SENSING OF THE ATMOSPHERE
(1) Active microwave remote sensing
In recent years, there are great progresses in the development of weather radar hardware. According to the specifications of new generation weather radar systems stimulated by the China Meteorological Administration (CMA), a Doppler weather radar operating in C band named CINRAD/CC has successfully designed by Anhui Sun-Create Electronics CO., Ltd. The radar is a blend of the latest radar and computer technology with valuable experience accumulated by weather analysis experts and radar observers. In the same manufacturing unit are fabricated the C-band conventional and digital radar (JY-16A series) and X-band radar (JY-28 series) mainly for rainfall measurements.
In order to enhance the capability of observing precipitating clouds, a dual-wavelength (X/Ka) and dual-polarization radar has been developed and combined into an active and passive microwave system in the Institute of Atmospheric Physics (IAP) of the Chinese Academy of Sciences (CAS). This undated system has played important role in monitoring and tracking the heavy storm over Beijing in the summer of 2001(Duan et al., 2002).
For obtaining 3-D wind profiles up to lower stratosphere, the Doppler wind profiler radar has been developed by the Institute No.23 of China Aerospace Science and Industry Corporation. The radar system CFL-20, a fully coherent phased array pulsed Doppler radar, is composed of two radars operating at 918 MHz (UHF) and 48 MHz (VHF) respectively. The UHF radar measures the boundary wind field while the VHF radar monitors wind distribution from 2.5 to 25 km. The system can provide the wind profiles in real time in all weather conditions with automatic data processing and display, intelligent monitoring system and several operation modes. A RASS can also be included in the system for temperature measurements in the boundary layer.
A powerful VHF/ST radar, designed by the IAP, operates from time to time in Xianghe Observation Station of IAP for colleting data of wind and its variance profiles between 2-20 km used in the stratosphere-troposphere exchange study. Wuhan Institute of Physics and Mathematics (CAS) also established an MF Doppler radar for mesospheric wind measurement and their Rayleigh and Sodium lidar system is observing quasi-continuously the sodium layer and middle atmospheric density profiles (Lu et al., 2002).
As a milestone in the development history of weather radar network in China, the American NEXRAD (WSR-88D) was introduced in 1998 and then the CINRAD radar was successfully fabricated by a joint company (METSTAR). The CINRAD's radar, almost the most advanced weather radar in use, is so sensitive that it can detect and display clear air returns with unparalleled detail even in the less sensitive volume coverage patterns. It provides many products to weather forecasting experts and other users, such as storm total precipitation, wind velocity and direction, VAD wind profile, wind shear, tornado detection, microburst detection and so on. The establishment of a CINRAD network covering China's continent is under way.
In parallel, during last 4 years there are many researches on the applications of ground-based radar data in weather forecasting, data assimilation experiments, numerical modeling, and so on.
(2) Passive microwave remote sensing
Along with the advance of microwave radiometric technology in China, the passive microwave remote sensing has been applied widely in determining atmospheric precipitable water (PW), liquid water path (LWP), rainfall, and even the temperature profile.
Lei et al. (2001) applied a dual-wavelength microwave radiometer to detect PW and LWP before precipitation passages in Xi'an city from August to November in 1997. The observation results show that there is a sharp increase both in PW and LWP before all precipitation. It is suggested that in the precipitation region there is an accumulation or convergence of PW and cloud liquid water from the plentiful area around. A point to note is these observed phenomena should be considered in the weather nowcasting and modifications.
The difficulties encountered in microwave radiometric observations in the rainy atmosphere were investigated by Wei et al. (2001). They introduced a scheme to correct the effect of liquid water on the antenna system and a method for retrieving PW and LWP and presented a statistical analysis of microwave radiometer measurements in the rainy atmospheres. The results indicate that when rain rate R is less than 20 mm/h, there always exists the possibility to obtain PW and LWP measurements. In the statistical sense, some parameters like precipitation effectiveness and potentiality were obtained from the ground-based microwave radiometer observations.
(1) Active remote sensing
Dou and Testud did a study on the application of stereo-radar analysis to the spaceborne rain radar. Due to the currently technical constrains, the space-based precipitation radar has to work at the rain attenuated wavelength to satisfy the requirements of high spatial resolution, wide coverage, large dynamic range of rainfall measurements and accurate point precipitation measurements. The stereo-radar analysis is used in a procedure to correct the attenuated reflectivity field with the apparent reflectivity observed by radars along the two viewing angles and to retrieve the specific attenuation coefficient field. They studied by simulation the influence of non-uniform beam filling effect due to the implementation of the spaceborne means on the stereo-radar analysis.
The precipitation characteristics over the Tibetan Plateau were synthetically investigated by Fu et al. (2002) using TRMM products of 2A25 from Precipitation Radar (PR) and 1B11 from TMI. Their investigation shows that in the Tibet region stratiform precipitation is a dominant type according to NASA/GFSC PR algorithm. Statistics show that area fraction ratio of stratiform to convective rains is at least 20. Even in summer, the ratio reaches to 10. As a result, stratiform rains form much more rainfall than convective rains, the former being at least 2 times larger than the latter. In their investigation were also compared the vertical profiles of precipitation and corresponding TMI brightness temperatures (TBs) between these two types of rain.
A method was proposed by Chen (2002) to determine liquid water path (LWP) from microwave attenuation by clouds along the satellite-earth surface path. He conducted an investigation on the optimal choice of channels, observation modes, and error analysis. The results show that (a) in principle, the proposed method can provide LWP measurements with much better accuracy than the available (passive) satellite remote sensing; (b) the method with dual-or triple-channel combination can simultaneously measure precipitable water (PW), LWP, and ice water path (IWP); and (c) if combined with the available satellite remote sensing techniques, it would more efficiently yield global datasets of LWP, PW, and IWP.
(2) Passive remote sensing
By using the physico-statistical method, Chen (2000) developed a retrieval algorithm for determining cloud LWP over oceans from SSMI measurements. A simple relation w as obtained between the LWP and the difference of TBs in cloudy and clear atmospheres from the simulation dataset with a radiative transfer model. In his algorithm, only the relationship LWP-△TB in channel of vertically polarized 37 GHz (37V) is used because it has smaller rms errors. The TB at 37V in ‘clear' atmosphere can be derived through a relationship with TB at 19V obtained by regression of SSM/I observation data in really clear atmospheres. Comparison of LWP results retrieved from the SSM/I measurements by the proposed algorithm and other two algorithms shows that Chen's retrieval algorithm yields quite reliable retrievals of cloud liquid water path over oceans.
Fu and Liu (2002) also developed a cloud LWP retrieval algorithm optimized for the tropical atmospheric conditions for the Airborne Imaging Microwave Radiometer (AIMR) measurements during the 1999 observation period of the INDEX Radiative transfer modeling and error analysis were conducted for guide selection of AIMR channels used for the LWP retrievals. Results show that the horizontal polarization channels outperform the vertical polarization channels at both 37 and 90 GHz. Additionally, for LWP less than 300 g/m2, the best results are expected from the 90 GHz horizontal polarization channel, while the 37 GHz horizontal polarization channel performs better for higher LWP values. On the basis of these findings, they formulated the LWP retrieval algorithm from the combination of retrievals of 37 and 90 GHz horizontal polarization channels. Results of several indirect validation show that in nearly clear condition the LWP retrievals have a rms error of about 28 g/m2 but without bias.
The combined data from a ground-based dual wavelength (1.35 and 0.8 cm) microwave radiometer and the TRMM/TMI were used to retrieve the cloud liquid water amount over the Shouxian County of Anhui Province by Yao et al. (2001). Based on the statistical regression, the retrieval algorithm for LWP was deduced using only the brightness temperature data in 85 GHz-V channel. Analysis results show that (a) there exists a threshold of 0.4 mm cloud LWP in the area, and (b) when the LWP is larger than this threshold, the precipitation will occur. There appears a noticeable increase (decrease) in PW and LWP before (after) the precipitation.
II. LIDAR REMOTE SENSING OF THE ATMOSPHERE
This section introduces main developments on lidar technique and its application in China during 1999-2003.
1. Lidar Measurements of Ozone, Cloud and Aerosol
A four-wavelength lidar system has been recently developed in Institute of Atmospheric Physics (IAP) for monitoring 10-40 km ozone profile, 2-40 km aerosol profile and high cloud optical property (Qiu et al, 2002a, 2002b). It contains a XeCl excimer laser with output energy of about 120 mJ at 308 nm, a Nd-YAG laser with three operating wavelengths of 355 nm, 532 nm and 1064 nm, and a 1m-receiving telescope. There are four analog-detection channels and two photon-counting channels. Three among four analog channels are used for detections of the 532 nm backscattering (two for polarization detection), and another is for the 355 nm radiation. Two photon-counting channels of 308 nm and 355 nm are for ozone measurements. Two examples of ozone and aerosol measurement results by the lidar are shown in Figs.1-2.
Figure1 shows a comparison of the ozone concentration profile measured by the lidar in October 16, 2001 with that by balloon-borne ECC. A good agreement between both profiles is obtained, especially in the height range from 10 km to 20 km. As shown in Fig.2, there is an aerosol layer ranging from about 4km to 10 km, where the lidar-measured aerosol extinction coefficient profiles during 20:07-20:36 of April 7, 2000 look like a typical normal distribution with the coefficient maximum value at about 8km. On April 6, 2000 a very strong duststorm passed over Beijing area, and on April 7 no cloud was observed. So, the aerosol layer may be a mineral particle layer, transported from remote desert areas.
Ozone concentration (cm/km)
Fig.1. A comparison between ozone concentration profiles by lidar and balloon (ECC).
Fig.2. Aerosol extinction coefficient profiles measured by the four-wavelength lidar during a duststorm event on April 7, 2000.
In addition, Hu's group in Anhui Institute of Optics and Mechanics (AIOFM) used a NASA-made Multiple Pulse Lidar (MPL) to detect aerosol extinction coefficient profiles in the troposphere over Beijing area (Hu et al., 2002). Bai et al. (2000) used a Japan-made Nd:YAG Lidar to measure the optical properties of stratospheric and tropospheric aerosols over Lhasa area.
2. Lidar Measurements of Temperature, Moisture and Wind Profiles
Lidar is a potential means for remote sensing of four basic meteorological parameters, i.e. temperature, moisture, pressure and wind in the clear atmosphere, being free of a radiosonde.
Li et al. (2001) developed a Raman lidar system for monitoring water vapor profile. By using the lidar, water vapor mixing ratio is measured over the city of Hefei. In their study, the characteristics and the errors of typical water vapor mixing ratio profiles detected by the lidar are analyzed.
Two kinds of lidars for wind measurements are developed in China. One is incoherent Doppler wind lidar, developed by Liu et al. (1997) in Qingdao Ocean University for measurements of the tropospheric wind. The lidar uses an iodine vapor filter to separate the Mie and Rayleigh scattering components, and it discriminates the Doppler shift frequency by using double edge technique. Based on the Doppler lidar, now Liu's group is developing a high spectral resolution lidar (HSRL) system for simultaneous measurements of wind and aerosol optical properties. As shown in simulations presented by Liu et al. (2003), the error of wind velocity below an altitude of 20 km is smaller than 2 m/s, and the error of the aerosol backscattering coefficients is smaller than 30% if HSRL is employed in the night. In the daytime, the lidar system can remotely sense wind velocity and aerosol backscattering coefficients within an altitude of 10 km with the same accuracy. Another kind of wind lidar, developed in IAP, uses a correlation-analysis technique (Yang, 1999).
Measurements of thermal profiles in the stratosphere and mesosphere with Rayleigh scattering lidar are made in Anhui Institute of Optics and Mechanics (AIOFM), presented by Wu et al. (2002), and Wuhan Institute of Physics & Mathematics (WIPM), Chinese Academy of Sciences (Zheng et al., 1999). In Wu et al.'s study, two kinds of algorithms for calculating temperature are proposed, and thermal profiles obtained by the Rayleigh Lidar agree very well with satellite UARS/HALOE and radiosonde observations. In the Zheng et al.'s study, the atmospheric density profile ranging from 30 to 70 km and the temperature profile from 30 to 60 km over Wuhan were measured by the lidar.
3. Lidar Measurements of Trace Pollution Gases
A new mobile lidar to monitor atmospheric pollution in the troposphere is recently developed by Zhang group in AIOFM (Zhang et al., 2001, 2002). The lidar can measure SO2, NO2, O3 and aerosol profiles with the maximum ranges of 3km, 4km, 3km and 5km, and the minimum monitoring concentrations of 4 ppb, 20 ppb, 4 ppb and 0.05 /km, respectively. Its highest measurement resolution is 7.5 m.
III. REMOTE SENSING OF AEROSOL OPTICAL PROPERTIES
The atmospheric aerosol is receiving more and more concern because of its significant climate forcing and the atmospheric correction of space-borne remote sensing (Mao et al., 2002; Menon, 2002; Charlson et al., 1992; Penner et al., 1994). It is found that sulfate aerosol, carbonaceous aerosol and mineral dust have a substantial climatic forcing in clear sky which is comparable with the effect of greenhouse gases. But the estimates are still uncertain in quantity. Among all reasons, lack of information of aerosol optical properties, especially its absorption, is a significant one (Penner et al., 1994). In order to enrich aerosol information, many Chinese investigators have made great efforts to develop remote sensing methods of aerosol optical properties and to use them in determining the properties of aerosols in China. These developments are introduced as follows.
1. Satellite Remote Sensing of Aerosol Optical Properties
There has been a long history of ground-based observations of atmospheric aerosol optical properties by sunphotometer. The ground-based measurement, however, can not provide aerosol parameters over large areas. Satellite remote sensing is the sole means to determine aerosol properties in the global scale. In fact, in the last 30 years, research on satellite remote sensing of aerosols has made important progress. At present, there are two main methods for the remote sensing. One is occultation method in which stratospheric aerosol extinction coefficient profile is determined by measuring the attenuated solar direct radiation at sunrise and sunset with radiometer. It has a shortcoming to determine the tropospheric aerosol optical properties. The other is to retrieve atmospheric column aerosol optical depth from outgoing sky radiance measured in space, which is mainly applied under the situation of ocean underlying surface. In the case of land surface, its reflectance is very complicated, and it is generally bigger than that of ocean, and so it has stronger effect on upward sky radiance. Therefore, satellite remote sensing of aerosols over land remains some questions, especially in the case of a high-reflectance surface. It is very important to develop available and reliable methods of satellite remote sensing of aerosols over land, and in recent years some Chinese researchers have made their efforts to developing. These developments include:
(1) Based on the vegetation reflectance properties from near ultra-violet to near infrared and the extraterrestrial radiance sensitivity to vegetation reflectance and atmospheric Aerosol Optical Depth (AOD), Qiu (1999) proposed a method for satellite synthetic remote sensing of the surface reflectance and AOD by using a corresponding iteration-correlation inversion algorithm.
(2) Based on an analysis of sky radiance distribution on aerosol optical properties and surface albedo, Zhao and Mao (1999) developed a method for simultaneous retrievals of AOD, aerosol single scattering albedo and surface albedo from the radiance and visible channel data of GMS5.
(3) By simulating the sensitivity of GMS5 apparent reflectance to the surface reflectance and AOD, Mao et al. (2001) developed a method to determine AOD over lake from GMS5 data. Some comparisons of the GMS5 measurements with sunphotometer measurements showed that the relative error of monthly mean AOD at 533.6 nm is less than 30%. This method is further developed to measure AODs over 25 lakes in China (Zhang et al., 2003).
(4) Based on the characteristics of the upwelling solar radiance from cloud-shadow surface, Duan (2001) proposed a new dark-subject method to retrieve AOD from satellite data.
(5) Han (1999) proposed a method to retrieve optical properties of aerosols over grassland from satellite data of outgoing scalar and polarized radiance.
2. Broadband Solar Radiation Methods for Aerosol Retrievals
In recent years, some researchers have paid great attentions to develop the broadband extinction methods to retrieve AOD from pyrheliometer data and their applications (Gueymard 1998; Molineaus et al. 1998; Luo et al. 2001; Qiu 1998, 2000, 2001; Zhou et al. 1998), being impelled mainly from two aspects of reasons. At first, AOD is an important and convenient parameter for studies of atmospheric pollution, aerosol radiation-climate effect and so on. In the other hand, there is a worldwide pyrheliometer network for broadband direct solar radiation observations, and high-quality historic broadband radiation data can be traced back to the 1880s (Stothers 1996). Therefore, the quantitative method to retrieve AOD from pyrheliometer data is very useful.
In a Qiu's earlier study (1998) a method to determine the 0.75 mm AOD from the pyrheliometer data is proposed. Considering the effect of uncertainty in the aerosol size distribution on the AOD retrieval, Qiu (2001) developed a new broadband extinction method to retrieve the AOD. In the method, a parameterized expression of the ‘equivalent' wavelength, at which AOD is equal to Broadband AOD (BAOD), is developed, and then the l-wavelength AOD is determined in terms of the ‘equivalent' wavelength and the BAOD. In addition, an approach to determine both the Ångström wavelength index and the AOD from pyrheliometer data with large solar zenith angles is proposed. These methods all need to input solar zenith angle cosine (m0). Pyrheliometer data are usually recorded in the format of hourly/daily/monthly accumulated radiation. During the accumulated period the solar zenith angle is variable, and hence a problem is how to select a suitable m0 for the AOD retrieval. Due to highly variable and random cloud cover distribution, there may often be cloud effect on the accumulated direct solar radiation, especially in two cases of daily/monthly pyrheliometer data. For these reasons, some available approaches to use hourly/daily/monthly accumulated radiation data for the AOD retrievals are developed (Qiu and Yang, 2002c; Qiu 2003).
In the other hand, based on diffuse-direct method to retrieve aerosol imaginary part developed by Herman et al. (1975), Wei and Qiu (1998, 1999) developed a broadband diffuse method for the imaginary part retrieval from paranometer data. The paranometer used in China has a shading ring to shade direct solar radiation to yield the diffuse radiation, and the shaded light scattering effect is corrected. Considering the uncertainty in the correction, Qiu et al. (2002d) improved the broadband diffuse radiation method. The first improvement is to determine diffuse radiation from combined pyrheliometer and paranometer data in order to avoid shading ring correction. Secondly, some available approaches to input relative parameters are presented.
3. Optical Properties of Aerosols in China
In recent years, researches on optical properties of aerosols over China mainly focus on such three aspects as: (1) long-term variation characteristics and distinct-distribution properties of AODs in China; (2) aerosol imaginary part and its single scattering albedo characteristics; and (3) aerosol extinction coefficient profiles over some areas, especially first one.
(1) Aerosol optical depth characteristics
By using broadband extinction method, Qiu and Yang (2000) studied variation characteristics of atmospheric optical depths in North China during 1980-1994. As shown in the study, during 1980-1994 the AODs show an increased trend, and in the winter the trend is stronger, and there is an evident Pinatubo effect on the AODs in China.
By using a method improved from Qiu's broadband extinction method, Luo et al. (2001) retrieved and analyzed AODs over 46 meteorological stations in China during 1961-1990. It is found that the yearly and monthly averaged AODs of the total 46 stations from 1961 to 1990 have a significant increasing trend. And mean AODs over the 46 stations were also given. Furthermore, Luo et al. (2002) analyzed spatial distribution of AODs over China during 1961-1990.
Some researches on GMS5 remote sensing of aerosol optical depths over 25 lakes in China are contributed by Mao's Group (Mao et al., 2002; Zhang et al., 2003). Based on TOMS/AI and aerosol optical depth data freely provided by NASA/TOMS aerosol group, Xia (2002) analyzed the temporal and spatial distribution characteristics of aerosol, especially dust aerosol in north of China. Trend analysis of dust aerosol concentration shows distinct spatial distribution in north China, from west to east, decline magnitude decreases slowly.
In addition, Shang et al. (2002a, 2002b) used some multi-wavelength sunphotometers to measure AODs over Beijing and Damxung region, the Tiberan Plateau.
(2) Aerosol imaginary part and its single scatter albedo characteristics
By using broadband radiation method, Wei and Qiu (2000) retrieved aerosol imaginary part (AIP) in Beijing during 1992 from paranometer. The retrieval results show that the monthly mean AIPs in January, February and December are 0.053, 0.064 and 0.050, respectively, being larger than those in other months. Latter, by using an improved broadband radiation method, Qiu and Yang (2002) retrieved and analyzed AIP and aerosol single scattering albedo in Beijing and Shenyang during 1993-2000 from joint pyrheliometer and paranometer data. It is shown that the in Beijing yearly mean AIP and aerosol scattering albedo change from 0.021 to 0.026 and from 0.816 to 0.85 during 1993-2000, and total mean AIP and albedo are 0.0234 and 0.833, respectively. In Shenyang, AIPs during 1993-1996 are evidently larger than those during 1997-2000, and total mean AIP and albedo are 0.0336 and 0.782, respectively. There is the (larger AIP) stronger absorption of the aerosol in Shenyang.
(3) Aerosol extinction coefficient profiles
Hu's group used a NASA-made Multiple Pulse Lidar (MPL) to detect aerosol extinction coefficient profiles in the troposphere over Beijing areas (Hu et al., 2002), and Bai et al. (2000) used a Japan-made Nd:YAG Lidar to measure the optical properties of stratospheric and tropospheric aerosols over Lhasa areas.
IV. OTHER REMOTE SENSING RESEARCHES
Apart from the above three aspects, during 1999-2003 Chinese scientists have also received some significant progresses in the remote sensing researches of ozone, lightning, radiation and so on.
Xia et al. (2001) developed a new method for inferring total ozone and aerosol optical thickness from multispectral extinction measurements using eigenvalue analysis. By using about 20 years of Dobson and TOMS data, Bian et al. (2002) analyzed the variation characteristics of total atmospheric ozone in Beijing and Kunming. It is shown that the long-term change trends for 1979 (or 1980)-2000 period are –0.642 DU/year and –0.009 DU /year respectively in Beijing and Kunming. In addition, there are significant QBO signals both in Beijing (mid latitude) and Kunming (low latitude).
Chen (1999) commended research progresses in GPS measurements of atmospheric temperature, moisture and wind profiles, Chen and Lu (2001) reviewed main developments in spaceborne measurements of lightning.
Wang et al. (2001) developed a new parameterization method for retrieving surface UVB irradiance and erythemal UVB radiative dose rate. This method is based on a simple concept: the earth-atmosphere system can be equivalent to three layers: absorption layer by ozone, scattering layer containing air molecules, cloud and aerosol particles, and the surface reflecting. The surface UVB irradiance and erythemal UVB dose rate can be expressed by the effective transmission of the ozone layer and united reflectivity due to the scattering layer and the surface. An actual application has been performed using satellite observations, and the results are compared with the surface observations, showing a good agreement.
In addition, some radiation models are developed for remote sensing applications. These models include a new model of surface BRDF-atmospheric coupled radiation (Qiu, 2001b), a modified Delta-Eddington approximation for solar radiation (Qiu, 1999), a parameterized atmospheric correction model (Qiu, 2001c), and a simple jet more accurate model to calculate solar radiative flux in the inhomogeneous atmosphere (2002e).
Bai Yubo, Shi Guangyun, K. Tamura, Y. Iwasaka, 2000, Lidar observations of atmospheric aerosol optical properties over Lhasa, Chinese J. Atmos. Sci., 24, 559-567.
Bian Yangliang, Chen Hongbin, Zhao Yangliang and Lu Daren, 2002, Variation features of total atmospheric ozone in Beijing and Kunming based on Dobson and TOMS data, Adv. Atmos. Sci., 19, 279-286.
Charlson, R. J., Schwartz, S. E., Hales, J. M., Cess, R. D., Coakley, J. A., Hansen, Jr. J. E., Hofmann, D. J., 1992. Climate forcing by anthropogenic aerosols. Science 255, 423-429.
and Lu Daren, 2001, A review on spaceborne sounding of lightning, Acta Meteorologica Sinica, 59, 58-380.
Chen Hongbin, 2000: A retrieval algorithm for deriving liquid water path from space-borne microwave radiometric measurements. J. Remote Sensing, 4(3), 165-171 (in Chinese).
Chen Hongbin, 2002: A concept for measuring liquid water path from microwave attenuation along the satellite-Earth path. Chinese J. Atmos. Sci., 26(4), 402-408.
Dou, X.K. and J. Testud, 1999: The application of stereo-radar analysis to the spaceborne raine radar. Acta Meteor. Sinica, 57(3), 358-366 (in Chinese with English abstract).
Duan Mingzheng, 2001, Simultaneous retrieval of atmospheric aerosol optical thickness and surface albedo over land by using polarized radiance as well as solar radiance from satellite measurement, Ph.D. dissertation.
Gueymard, C, 1998: Turbidity determination from broadband irradiance measurements: a detailed multicoefficient approach, J. Appl. Meteor., 37, 414-435.
Han Zhigang, 2000, Satellite remote sensing of aerosol optical properties over grass by using polarized radiance, Ph.D. dissertation.
Herman, B. M., Browning, S. R., De Luisi, J. J., 1975, Determination of the effective imaginary term of the complex refractive index of atmospheric dust by remote sensing: the Diffuse-Direct radiation method. J. Atoms. Sci. 32: 918-925.
Hu Huanling, Xie Chenbo, Yan Fengqi, Qiu Xiangshuang angYu Tong, 2002, Lidar, measurements of aerosol-layer near the ground with actual extinction-backscatter-ratio in BAPIE, Proceedings of 21th ILRC, Quebec, Canada, 161-164.
Lei, H.C., C. Wei, Z.L. Sun, L. Gu, and L. Yan, 2001: Microwave radiometric measurement of water vapor and cloud liquid water before rainfall. Q. J. Appl. Meteor. 12(suppl.), 73-78 (in Chinese with English abstract) (in Chinese).
Li Tao, Qi Fudi, Jin Chuanjia, Yue Guming, Hu Huanling and Zhou Jun, 2000, Raman lidar system for the measurements of water vapor mixing ratio in the atmosphere, Chinese J. Atmos. Sci., 24, 843-854.
Liu Jintao, Chen Weibiao, and Liu Zhishen, 2003, A Simulation of Simultaneously measuring Wind and Aerosol Optical Properties Using High Spectral Resolution Lidar, Chinese J. Atmos. Sci., 27, 115-122.
Liu Zhishen, Chen Weibiao et al., 1997, An incoherent Doppler lidar for grouned-based atmospheric wind profiling, Appl. Phys. B., 64, 561-566.
Lu, D.R., F. Yi, J.Y. Xu, 2002: Advances on study of middle and upper atmosphere and their coupling with lower atmosphere. Chinese J. Space Sci., 22(supl.), 111-119.
Luo Yunfeng, Lu Daren, Zhou Xieji, Li Weilian and He Qing, 2001, Characteristics of the spatial distribution and yearly variation of aerosol optical depth over China in last 30 years, J. Geophy. Res.106, D13, pp.14501-14513, 2001.
Luo Yunfeng, Lu Daren, Zhou Xieji, Li Weilian, 2002, Analyses on the spatial distribution of aerosol optical depth over China in recent 30 years, Chinese J. Atmos. Sci., 26, 721-730.
Mao Jietai, Liu Li and Zhang Junhua, 2001, GMS5 remote sensing of aerosol optical thickness over Chaohu lake, Acta Meteorogica Sinica,, 59, 351-359.
Mao Jietai,, Zhang Junhua and Wang meihu, 2002, summary comment on research of atmospheric aerosol in China, Acta Meteorogica Sinica, 60, 625-634.
Menon S., Hansen, J., Nazarenko L., Luo Y., 2002, Climate Effects of Black Carbon Aerosols in China and India, Science, 297, 2250-2253.
Molineaux B., P. Ineichen And N. O¢Neill, 1998: Equivalence of pyrheliometric and monochromatic aerosol optical depths at a single key wavelength, Appl. Opt., 37, 7008-7018.
Penner, J. E., R. J. Charlson, J. M. Hales, N. S. Laulainen, R. Leifer, T. Novakov, J. Ogren, L. F. Radke, S. E. Schwartz, and L. Travis, 1994: Quantifying and minimizing uncertainty of climate forcing by anthropogenic aerosols. Bull. Am. Meteorol. Soc., 75., 375-400
Qiu Jinhuan, 1998a, A method to determine atmospheric aerosol optical depth using total direct solar radiation, J. Atmos. Sci, 55, 734-758.
Qiu Jinhuan,, 1999a, A method for spaceborne synthetic remote sensing of aerosol optical depth and vegetation reflectance, Adv. Atmos. Sci., 15, 17-30.
Qiu Jinhuan,, Qiu Jinhuan, 1999b, Modified Delta-Eddington approximation for solar reflectance, transmission, and absorption calculation, J. Atmos. Sci., 56, 2955-2961.
Qiu Jinhuan,, and Yang Liquan, 2000: Variation characteristics of atmospheric aerosol optical depths and visibility in North Chana during 1980-1994, Atmospheric Environment, 34, 603-609.
Qiu Jinhuan,, 2001, Broadband extinction method to determine atmospheric aerosol optical properties, Tellus, 53B, No.1, 72-82.
Qiu Jinhuan,, Qiu Jinhuan, 2001b, An improved model of surface BRDF- atmospheric coupled radiation, IEEE, 2001，39, 181-187.
Qiu Jinhuan,, 2001c，A parameterized atmospheric correction model and its application simulation for satellite remote sensing, J. Remote Sensing, 5, 401-406.
Qiu Jinhuan,, Zheng Siping, Huang Qirong, Xia Qirong, Yang Liquan, Wang Wenming, Pan Jidong and Sun Jinhui, 2002a, Lidar measurements of cloud and aerosol in the upper troposphere in Beijing, Chinese J. Atmos. Sci., 27, 1-7.
Qiu Jinhuan,, Zheng Ping, Xia Qilin, Huan Qirong, Sun Jinhui, Wang Wenming, Pan Jidong and Yang Liquan, 2002b, Proceedings of 21th ILRC, Quebec, Canada, 401-402.
Qiu Jinhuan,, Yang Liquan, 2002c, A study of retrieving aerosol optical depth from day- or hour-exposed broadband solar direct radiation, Chinese J. Atmos. Sci., 26, 449-458.
Qiu Jinhuan,,Yang Liquan, 2002d, Broadband radiation methods to determine aerosol optical depth and imaginary part of its refractive index and their applications, SPIE 3rd International Asia-Pacific Symposium on remote sensing of Atmosphere, Environment, and Space, Hongzhou, China.
Qiu Jinhuan, 2002e, A simple jet more accurate model to calculate solar radiative flux in the inhomogeneous atmosphere, Adv. Atmos Sci., 19, 433-447
Stothers, R. B., 1996: Major optical depth perturbations to the stratosphere from volcanic eruptions: pyrhelimetric period, 1881-1960, J. Geophys. Res., 101(D), 3901-3920.
Wang Pucal, Lu Daren, Li Zhanqing, 2001, A Parameterization Method for Retrieving Surface UVB Radiation from Satellite, Chinese J. Atmos. Sci., 1-13.