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Principle and application of three-band gradient difference vegetation index

Science china Earth Sciences 2005年第2期48卷 241-249页

作者： TANG Shihao, ZHU Qijiang, WANG Jindi, ZHOU Yuyu & ZHAO Feng Research center for Remote Sensing and GIS, Department of Geography, beijing Normal University, beijing 100875, china national satellite meteorological center, china meteorological administration, beijing 100081, china 1. Research center for Remote Sensing and GIS Department of Geography Beijing Normal University 100875 Beijing China 2. national satellite meteorological center China Meteorological Administration 100081 Beijing China

Vegetation index is a simple, effective and experiential measurement of terrestrial vegetation activity, and plays a very important role in qualitative and quantitative remote sensing. Aiming at shortages of current vegetation indices, and starting from the analysis of vegetation spectral characteristics, we put forward a new vegetation index, the three-band gradient difference vegetation index (TGDVI), and established algorithms to inverse crown cover fraction and leaf area index (LAI) from it. Theoretical analysis and model simulation show that TGDVI has high saturation point and the ability to remove the influence of background to some degree, and the explicit functional relation with crown cover fraction and LAI can be established. Moreover, study shows that TGDVI also has the ability to partly remove the influence of thin cloud. Experiment in the Shunyi District, beijing, china shows that reasonable result can be reached using the vegetation index to retrieve LAI. We also theoretically analyzed the reason why the normalized difference vegetation index (NDVI) owns the low saturation point, and show that it is determined by the definition of NDVI and the characteristic of vegetation spectra, and is unavoidable to some degree. Meanwhile, through model simulation, we also indicate that the relationship between simple ratio vegetation index (SR) and LAI closes to a piecewise linear one instead of a linear one, which is mainly caused by the influence of background and different change rates of reflectance in red and infrared bands with LAI increasing.

关键词： vegetation index, remote sensing, LAI, crown cover fraction, remote sensing inversion.

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Ocean color products retrieval and validation around china coast with MODIS

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Acta Oceanologica Sinica 2010年第4期29卷 21-27页

作者： SUN Lingt GUO Maohua WANG Xiaomei Key Laboratory of Radiometric Calibration and Validation for Environmental satellites China Meteorological Administration （LRCVES/CMA） National Satellite Meteorological Center China Meteorological Administration Beijing 100081 China national satellite Ocean Application Service State Oceanic Administration Beijing 100081 China

Waters along china coast are very turbid with high concentrations of suspended sediment nearly all the time,especially at the Hangzhou Bay,the Changjiang （Yangtze） River Estuary and the shoal along Jiangsu *** these turbid and optically complex waters,the standard MODIS ocean color products tend to have invalid *** the water-leaving radiances in the near-infrared （NIR） are significant resulting from the strong scattering of suspended particles,the standard MODIS atmospheric correction algorithm often gets no results or produces significant *** because of the complex water optical properties,the OC3 model used in the standard MODIS data processing tends to get extremely high chlorophyll-a （Chl-a） *** this paper,we present an atmospheric correction approach using MODIS short wave infrared （SWIR） bands based on the fact that water-leaving radiances are negligible in the SWIR region because of the extreme strong absorption of water even in turbid waters.A regional Chl-a concentration estimation model is also constructed for MODIS from in situ *** algorithms are applied to MODIS Aqua data processing in the china coastal *** situ data collected in the Yellow Sea and the East china Sea in spring and autumn,2003 are used to validate the *** good results have been *** is noted that water-leaving reflectance in the NIR bands are significant in waters along the china coast with high sediment *** satellite derived and in-situ reflectance spectra can match in the turbid waters along china coast,and there is relatively good linear relationship between satellite derived and in-situ *** RMSE value of Rrs（λ） is 0.0031 sr ？1 for all the nine ocean color bands （412 to 869 nm）.The satellite-derived Chl-a value is in the reasonable range and the root mean square percentage difference is 46.1%.

关键词： ocean color atmospheric correction chlorophyll-a MODIS china coastal region validation

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Response of remotely sensed Normalized Difference Water Deviation Index to the 2006 Drought of eastern Sichuan Basin

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Science china Earth Sciences 2008年第5期51卷 748-758页

作者： ZHANG WenJiang1, LU QiFeng2, GAO ZhiQiang3 & PENG Jian4 1 School of Water Resource and Hydropower, Sichuan University, Chengdu 610065, china 2 national satellite meteorological center, china meteorological administration, beijing 100081, china 3 Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, beijing 100101, china 4 School of Environmental Sciences, Peking University, beijing 100871, china 1. School of Water Resource and Hydropower Sichuan University Chengdu 610065 China 2. national Statellite meteorological center China Meteorological Administration Beijing 100081 China 3. Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China 4. School of Environmental Sciences Peking University Beijing 100871 China

One of the most serious droughts in last century occurred in eastern Sichuan Basin in the summer of 2006 (hereinafter called the Drought). The response of Moderate Resolution Imaging Spectroradiometer (MODIS, boarding on NASA satellites of Terra and Aqua) to the Drought was analyzed in order to reach one practicable monitoring solution for regional soil moisture. Temporal process and spatial extension of the Drought were firstly estimated with ground meteorological and hydrological observations. Then, for the whole region of Sichuan and Chongqing, the remotely sensed Normalized Difference Water In- dex (NDWI) for the summers of 2001―2006 were calculated based on 8-day composite MODIS products, which were further used to construct a new water index (Normalized Difference Water Deviation Index, NDWDI) to examine the sensitivity of remote sensing in the Drought. The study showed that the NDWDI is more sensitive to regional drought than other absolute-soil-moisture-based indices. With the new index, the study extracted the spatial-temporal characteristics of the 2006 Drought, and explored its developing and withdrawing processes, which agreed with related statistics. Compared with ground method of drought observation, the NDWDI-based remote sensing solution of this paper is more pref- erable and practicable in that the local soil properties of water consumption and supply are implicitly taken into account, and the spatial representativity limit of ground observation is circumvented to a degree as satellite remotely senses the earth surface in a way of two-dimensional pixel matrix. So, the NDWDI-based method can be used to monitor regional soil water stress situation more practically and efficiently.

关键词： Sichuan Basin drought Normalized Difference Water Deviation Index response of remote sensing regional scale

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A New Approach to the On-Orbit Evaluation of Point Spread Function of Thermal Infrared Images With Applications to FY-2 satellite Products

A New Approach to the On-Orbit Evaluation of Point Spread Fu...

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作者： Qiang Guo,Changjun Yang,and Caiying Wei the national satellite meteorological center,china meteorological administration,beijing 100081,china,the Key Laboratory of Radiometric Calibration and Validation for Environmental satellite,china meteorological administration,beijing 100081,china

Spatial characteristics of thermal infrared(TIR) images are generally described by image-derived point spread function(IDPSF) for sampled imaging *** investigators working on IDPSF on-orbit evaluation focus on visible and near-infrared images and pay little attention on TIR ones,the reason of which lies on the fact that the assumption of an observed target with an ideal step profile is not suitable for TIR band. A new approach for TIR images is proposed here based on a more common slope-profile model,where the transition features, i.e.,the sample number(N) and the beginning position of slope interval,are extracted from the observed *** results show that the estimation performance will be increased, with lower noise level as well as higher system modulation transfer function value at half of normalized spatial frequency(MTF) or smaller *** a good performance system with noise squared-root variance(SRV) no more than 1.0 count and MTF between 0.3 and 0.4,the relative error between simulated and estimated MTF\s is less than 20%.The IDPSF of FY-2C satellite TIR band is estimated,and the derived MTF0.5 is properly close to on-ground testing *** image quality of FY-2C TIR band has been improved by using Wiener filtering and the estimated IDPSF,which eventually benefits the cloud detection product with more detectable low fractus and increased detection accuracy by about 1%in *** a step-profile target as a special case of this model,the proposed approach is also suitable for visible and near-infrared images.

关键词： Index Terms—Infrared imaging optical image processing optical transfer functions.

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A LAI Inversion Algorithm Based on Directional Reflectance

A LAI Inversion Algorithm Based on Directional Reflectance

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中国气象学会2004年年会

作者： Tang Shihao~(12) (1 national satellite meteorological center, china meteorological administration, beijing 100081, china 2 Remote Sensing and GIS Research center, Department of Geography, beijing Normal University, beijing 100875, china)

＜正＞Leaf area index (LAD is an important ecological and environmental parameter. The current remote sensing inversion methods of leaf area index can mainly（?）e grouped into two classes: vegetation index based methods and remote sensing physical model based methods. In this paper, a new LAI retrieval method is developed. The algorithm borrows ideas from the principles and methods of ground LAI measurements, and adopts a new frame which differs from traditional remote sensing LAI inversion methods. First, the relationship between LAI and directional gap fraction is derived from the definition of LAI. Then, directional gap fraction is acquired from remote sensing bidirectional reflectance distribution function （BRDF） product. This acquisition is obtained by the use of a kernel driven model and a large scale directional gap fraction algorithm. At last, the large scale LAI is calculated through angle integrations. This algorithm has been applied to get LAI distribution of china in the middle of July, 2002. The ground data acquired from two field experiments conducted in Changbai Mountain and Qiiian Mountain, china, are used to validate the algorithm. In order to resolve the scale change problem between high resolution grouad observation and low resolution remote sensing data, two high resolution remote sensing images almost ha, ing the same resolutions with ground measurements are used as transitions. In order to proceed, we first bulid an empirical relationship between measured LAI and high resolution reflectance. Then, we get high resolu ion LAI distribution according to that relation. The LAI value of a low resolution pixel is calculated from the areal weighted sum of high resolution LAIs composing the low resolution pixel. Our results show that the algo（?）ithm has a high precision. Factors that may influence the precision of the algorithm are also discussed in this paper.

关键词： LAI MODIS BRDF ALBEDO Gap fraction

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DETECTING TROPICAL CYCLONE WATER VAPOR TRANSPORTATION WITH THE TRMM AND ADVANCED MICROWAVE SOUNDING UNIT(AMSU)

DETECTING TROPICAL CYCLONE WATER VAPOR TRANSPORTATION WITH T...

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作者： WangXin~1 FangXiang~(1,2) Qiu Hong~1 Zhu Yuanjing~2 1 national satellite meteorological center of china meteorological administration, beijing,china,100081 2 Department of Atmospheric Science,School of Physics,Peking University, beijing,china,100871

The AMSU-B data contain the vertical distribution of the retrieved water vapor from satellite brightness temperature. The tropical cyclone Matsa event in 2005 formed from the northwest pacific is analysised by combining the AMSU-B water vapor fields with the latent *** show the combination the TRMM latent heating data in the heavy precipitation area around TC,we find heat release is one of the most important factors to impact TC intensity,especially to the long-life and land load *** there is a time delay between the low level water vapor convergence and the middle layer latent heat,which will improve the real-time forecast of tropical cyclones.

关键词： Index Terms—One two three four five

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Operational retrieval of Asian sand and dust storm from FY-2C geostationary meteorological satellite and its application to real time forecast in Asia

Operational retrieval of Asian sand and dust storm from FY-2...

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“2010年北京气象学会中青年优秀论文评选”学术研讨会

作者： X.Q.Hu~(1,3),N.M.Lu~1,T.Niu~2,and P.Zhang~1 1 Key Laboratory of Radiometric Calibration and Validation for Environmental satellites(KLRCV),national satellite meteorological center,china meteorological administration(NSMC/CMA),beijing 100081,china 2 Centre for Atmosphere Watch & Services(CAWAS),Chinese Academy of meteorological Sciences,china meteorological administration(CMA),beijing 100081,china 3 Institute of remote sensing applications,Chinese Academy of Sciences,beijing 100101,china

This paper describes an operational retrieval algorithm for the sand/dust storm(SDS) from FY-2C/SVISSR (Stretched-Visible and Infrared Spin-Scan Radiometer) developed at the national satellite meteorological center (NSMC) of *** algorithm,called Dust Retrieval Algorithm based on Geostationary Imager(DRAGI), is based on the optical and radiative physical properties of SDS in mid-infrared and thermal infrared spectral regions as well as the observation of all bands in the geostationary imager, which include the Brightness Temperature Difference (BTD) in split window channels,Infrared Difference Dust Index(IDDI) and the ratio of middle infrared reflectance to visible *** also combines the visible and water vapor bands observation of the geostationary imager to identify the dust clouds from the surface targets and meteorological *** output product is validated by and related to other dust aerosol observations such as the synoptic weather reports,surface visibility,aerosol optical depth(AOD) and ground-based PM *** the SDS-IDD product and a data assimilation scheme,the dust forecast model CUACE/Dust achieved a substantial improvement to the SDS predictions in spring 2006.

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Operational retrieval of Asian sand and dust storm from FY-2C geostationary meteorological satellite and its application to real time forecast in Asia

Operational retrieval of Asian sand and dust storm from FY-2...

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第七届全国优秀青年气象科技工作者学术研讨会

作者： X. Q. Hu1,3, N. M. Lu1, T. Niu2, and P. Zhang1 1Key Laboratory of Radiometric Calibration and Validation for Environmental satellites (KLRCV), national satellite meteorological center, china meteorological administration (NSMC/CMA), beijing 100081, china 2Centre for Atmosphere Watch & Services (CAWAS), Chinese Academy of meteorological Sciences, china meteorological administration (CMA), beijing 100081, china 3Institute of remote sensing applications, Chinese Academy of Sciences, beijing 100101, china

This paper describes an operational retrieval algorithm for the sand/dust storm （SDS） from FY-2C/SVISSR （Stretched-Visible and Infrared Spin-Scan Radiometer） developed at the national satellite meteorological center （NSMC） of china. This algorithm, called Dust Retrieval Algorithm based on Geostationary Imager （DRAGI）, is based on the optical and radiative physical properties of SDS in mid-infrared and thermal infrared spectral regions as well as the observation of all bands in the geostationary imager, which include the Brightness Temperature Difference （BTD） in split window channels, Infrared Difference Dust Index （IDDI） and the ratio of middle infrared re?ectance to visible re?ectance. It also combines the visible and water vapor bands observation of the geostationary imager to identify the dust clouds from the surface targets and meteorological clouds. The output product is validated by and related to other dust aerosol observations such as the synoptic weather reports, surface visibility, aerosol optical depth （AOD） and ground-based PM10 observations. Using the SDS-IDD product and a data assimilation scheme, the dust forecast model CUACE/Dust achieved a substantial improvement to the SDS predictions in spring 2006.

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Spatiotemporal variations in mid-upper tropospheric methane over china from satellite observations

Spatiotemporal variations in mid-upper tropospheric methane ...

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作者： ZHANG Xing Ying~(1,2*),BAI WenGuang~1,ZHANG Peng~1 & WANG WeiHe~1 1 Key Laboratory of Radiometric Calibration and Validation for Environmental satellites,national satellite meteorological center,china meteorological administration,beijing 100081,china 2 State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry,Institute of Atmospheric Physics,Chinese Academy of Sciences,beijing 100029,china

Spaceborne measurements by the Atmospheric Infrared Sounder(AIRS) on the EOS/Aqua satellite provide a global view of methane (CH) distribution in the mid-upper troposphere(MUT-CH).The focus of this study is to analyze the spatiotemporal variations in MUT-CH over china from 2003 to *** of AIRS CH products versus Fourier transform infrared profiles demonstrates that its RMS error is mostly less than 1.5%.A typical atmospheric methane profile is found that shows how concentrations decrease as height increases because of surface *** found that an important feature in the seasonal variation in CH is the two peaks that exist in summer and winter in most parts of china,which is also observed in in-situ measurements at Mt. Waliguan,Qinghai Province,china(36.2879°N 100.8964°E,3810 m).Also,in the summer,only one peak existed in western and southern china since there are no more significant anthropogenic sources in winter than at any other time of the *** analysis of the deseasonahzed time-series of AIRS CH in three fixed pressure layers of AIRS from 2003 to 2008 indicates that CH in the Northern Hemisphere has increased abruptly since 2007,with no significant increase occurring before *** increase in china is generally more significant than in other areas around the world,which again correlates with in-situ measurements at ***.

关键词： satellite remote sensing mid-upper tropospheric methane sptiotemporal variation

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Relationship between the Asian-Pacific oscillation and the tropical cyclone frequency in the western North Pacific

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Science china Earth Sciences 2008年第3期51卷 380-385页

作者： ZHOU BoTao1, CUI Xuan2 & ZHAO Ping3 1 Laboratory for Climate Studies, national Climate center, china meteorological administration, beijing 100081, china 2 national meteorological center, china meteorological administration, beijing 100081, china 3 Chinese Academy of meteorological Sciences, china meteorological administration, beijing 100081, china 1. Laboratory for Climate Studies National Climate Center China Meteorological Administration Beijing 100081 China 2. national meteorological center China Meteorological Administration Beijing 100081 China 3. Chinese Academy of meteorological Sciences China Meteorological Administration Beijing 100081 China

The relationship between the Asian-Pacific oscillation (APO) and the tropical cyclone frequency over the western North Pacific (WNP) in summer is preliminarily investigated through an analysis of ob- served data. The result has shown clearly that APO is significantly and positively correlated to the tropical cyclone frequency in the WNP. If APO is above (below) the normal in summer, more (less) tropical cyclones will tend to appear in the WNP. The present study also addresses the large-scale at- mospheric general circulation changes underlying the linkage between APO and the WNP tropical cy- clone frequency. It follows that a positive phase of summer APO is concurrent with weakened as well as northward and eastward located western Pacific subtropical high (WPSH), low-level convergence and high-level divergence, and reduced vertical zonal wind shear in the WNP, providing favorable envi- ronment for the tropical cyclone genesis, and thus more tropical cyclones will come into being, and vice versa.

关键词： Asian-Pacific oscillation western North Pacific tropical cyclone atmospheric circulation

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