, MODIS PROGRESS IN GEOGRAPHY. PWV [11], PWV 4.12 mm [12] MOD07 PWV. (Surface Vapor Pressure,SVP),SVP (Pprecipitable Water Va 鄄 SVP, PWV SVP.

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1 PROGRESS IN GEOGRAPHY Vol.29, No.9 Sept., 2010 MODIS (, ) :, MODIS MOD07, , 1 1 R : ;MODIS; ; 1 0.5%, MODIS, MOD07, PWV [11], PWV 4.12 mm [12],, [1-3] MOD07 PWV SVP ( ), PWV, SVP, SVP,, (Surface Vapor Pressure,SVP),SVP (Pprecipitable Water Va 鄄 por,pwv) 20, PWV SVP, PWV 2.1 [4] ; (1), [5-6] 4, 8, PWV SVP , 3000 m [7],, [8-10] 535 mm 37 PWV SVP, (1), ,,,, : ; : BAC34B06, 2006BAB04A16,, 2 :,, GIS huangyh@lreis.ac.cn

2 PWV=scale DN+offset (3) 1 :PWV (cm);scale 0.001;off 鄄 Fig.1 The study area and the location of field observation stations set 0, [0,20],-9999, , : 1, 3.1 (1) [2] : PWV SVP e s =0.6108exp T 17.27T [4] T T (1), MOD07 SVP, 37 :e s (kpa);t ( ) e s GIS PWV PWV PWV 3 RH, (2) : e=e s RH (2), 37 :e (kpa); e s, PWV, (kpa);rh (%) MODIS NASA- 1 MOD07 (PWV) EOS MODIS Tab.1 The correlation coefficient between PWV MOD07, 3 PWV in MOD07 and field observed SVP (Total Column Precipitable Water Vapor) PWV (Precipitable Water Vapor High) PWV (Precipitable Water Vapor Low), 5 5 MOD07 PWV MODIS 3 (0.940 μm)2 (0.865 μm μm) Gao LOWTRAN, [11],Seemann MOD07, l K, 412 mm [12] MOD07 2, HDF(Hierarchical Data Format) IDL PWV PWV PWV, Albers Geotiff 3 MOD07, 12,, DN (3) : MOD07 (1) 1,MOD07 PWV 0.862; PWV, PWV

3 9 : MODIS , PWV, PWV H PWV (hpa);pwv T PWV 0.907, 37 (hpa), 3 PWV SVP 2 R 2, PWV PWV PWV 0.839, 3.1, 28.3% ,,3 PWV SVP, PWV, PWV, 37 (2), 2,, PWV 3.2 SVP,R , 2.778, 11.8%, 17% PWV SVP PWV, (5) :, 2 SVP= PWV MODIS L PWVL (5), :SVP (mm),pwv L PWV(hPa),, PWV 3 (2) (6) : (1) MOD07 3 PWV 3 2,SVP=0.002 PWV L PWVL 2, PWV L (6) PWV PWV :SVP (mm),pwv L PWV R 2 PWV(hPa) , 2 PWV Tab.2 The details of the constructed evaluation modles, 3 PWV 3 PWVÂPWVÃ PWVÄ, , PWVÄ 55.1% 33.8% 29.4% PWV 30%, 3 PWV 3, (4) SVP=1.9 PWV L PWV H PWV T (4) :SVP (mm);pwv L PWV (hpa); RÁ /% SVP=0.568PWVÂ (PWVÂ) (PWVÃ) SVP=1.399PWVÃ (PWVÄ) Y=2.316PWVÄ SVP=1.9PWVÄ+0.255PWVÃ+0.03PWVÁÂ PWVÂ SVP= PWVÂÃ+0.973PWVÂ PWVÃ SVP=-0.104PWVÃ+2.899PWVÃ PWVÄ SVP=-0.129PWVÄÃ+4.024PWVÄ SVP=0.002PWVÄ-0.17PWVÄÃ PWVÄ (PWV L ) (SVP) Fig.2 Scatter and fitting curve of PWVL and SVP

4 PWV L 3 R , mm 2.777, 11.0%,, MOD07 4 PWV L 4, ArcGIS 3-6, 5 MOD07 PWV (SVP) hpa, (PWV L ) SVP Fig.3 The estimation of SVP of the 2nd day in SVP Fig.4 The estimation of SVP of the 34th day in SVP Fig.5 The estimation of SVP of the 77th day in SVP Fig.6 The estimation of SVP of the 99th day in 2009

5 9 : MODIS SVP SVP, SVP, MOD07 3-6,,, SVP,,,1 5 hpa, 4 17 hpa,, 37 SVP, 7 SVP SVP SVP Fig.7 Comparison of the estimated and field observed values 7, 7, SVP,1: , R , SVP :1 21.8%,, ;2MOD %, 5 ; 3, 5 MODIS 5 5 (MOD07), [1] Nishida K, Nemani R R, Glassy J M, et al. Development, of an evapotranspiration index from Aqua/MODIS for mon 鄄 MOD07 PWV, itoring surface moisture status. IEEE Transactions on Geo 鄄 science and Remote Sensing, 2003, 41(2): 1-9., [2],,,.. :, 2005: PWV [3] Iziomona M G, Mayer H, Matzarakis A. Downward atmo 鄄 spheric longwave irradiance under clear and cloudy skies: MOD Measurement and parameterization. Journal of Atmospher 鄄 , ic and Solar-Terrestrial Physics, 2003,65(10): , 1, [4],.,., 1996, 20(5): [5].., 2004, 30 MOD07 (2): 9-11., [6] Reber E E, Swope J R. On the correlation of the total precipitable water in a vertical column and absolute hu 鄄, midity at the surface. Journal of Applied Meteorology,

6 , 11(2): [10] Idso S B. Atmospheric attenuation of solar radiation. Jour 鄄 [7],,,. nal of the Atmospheric Sciences, 1969, 26 (12): , , 33(11): [11] Gao B C, Kaufman Y J. Water vapor retrievals using [8] Karalis J D. Precipitable water and its relationship to sur 鄄 face dew point and vapor pressure in Athens. Journal of Applied Meteorology, 1974, 13(1): Moderate Resolution Imaging Spectroradiometer (MODIS) near-infrared channels. Journal of Geophysical Research, 2003, 108(D13): [9] Monteith J L. An empirical method for estimating long 鄄 wave radiation exchanges in the British Isles. Quarterly Journal of the Royal Meteorological Society, 1961, 87 (372): [12] Seemann S W, Li J, Menzel W P. Operational retrieval of atmospheric temperature, moisture and ozone from MODIS infrared radiances. Journal of Applied Meteorology, 2003, 42(8): Estimation of the Surface Vapor Pressure Based on the MODIS Images HUANG Yaohuan, JIANG Dong, ZHUANG Dafang, FU Jingying (Data Center for Resources and Environmental Sciences, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing ) Abstract: Surface vapor pressure (SVP) is a highly significant variable for physically based ecosystem, hydrology and climate modeling without available regional spatially representative data currently. Conventional field observation SVP data is spatial discontinuous and time-consuming, so MODIS images are used to estimate the mean daily SVPin the Haihe River basin. Firstly, correlation analysis is taken and it is found that there are significant correlations between the dataset of precipitable water vapor low in MOD07 images and field observed SVP. Secondly, comparison of the models based on correlation analysis shows that second -order polynomial regression is the most suitable one for evaluating SVP in the Haihe river area. Finally, a series of MOD07 images from January to April of 2009 are used to validate the proposed second-order polynomial model. The result shows that the estimated value is close to the observed value, and their slope and R 2 of 1:1 line analysis are and 0.83, respectively. The results indicated that the proposed PWV -SVP model is effective for obtaining SVP data at a regional scale. Key words: surface vapor pressure; MODIS; Haihe River; precipitable water vapor :,,,. MODIS., 2010, 29(9):