Estimating Surface Broadband Emissivity of the Taklimakan Desert with FTIR and MODIS Data
LI Huo-qing1, WU Xin-ping2, Ali Mamtimin3, HUO Wen3, YANG Xing-hua3, YANG Fan3, HE Qing3, LIU Yong-qiang1,4*
1. College of Resources and Environmental Sciences, Xinjiang University, Urumqi 830046, China 2. Tazhong Weather Station of Qiemo in Xinjiang, Tazhong 841000, China 3. Institute of Desert Meteorology, China Meteorological Administration, Urumqi 830002, China 4. Key Laboratory of Oasis Ecology (Ministry of Education), Urumqi 830046, China
Abstract：Surface broadband emissivity in the thermal infrared region is an important parameteras for the studies of the surface energy balance. This paper analyzed and offered an equation to estimate the surface broadband emissivity for the spectral domains 8～14 μm against the MODIS data, and then, the distribution characteristic of surface emissivity for Taklimakan Desert was obtained with this equation. Firstly, along two highways crossing the Taklimakan Desert, twenty sample sites were selected and their spectral of broadband emissivity were observed with Fourier Transform Infrared spectrometer (FTIR). Secondly, using the Moderate Resolution Imaging Spectrometer (MODIS) land surface temperature and emissivity product MOD11A1 and MOD11C1, derived emissivities in three thermal infrared channels 29 (8.4～8.7 μm), 31 (10.78～11.28 μm) and 32 (11.77～12.27 μm) and MODIS surface reflectance products MOD09A1, derived reflectance in near-infrared channel 7 (2.105～2.155 μm), developing an empirical regression equation to convert these spectral emissivities and reflectance to a broadband emissivity. The FTIR data were used to determine the coefficients of the regression equation, another part of FTIR data were used to investigate the accuracy of equation. It was found that the equation consist of MODIS channels 29, 31 and 32 has more accuracy; furthermore, the accuracy is improved when channel 7 data was added in the regression equation. The root mean square error (RMSE) and Bias were 0.004 5 and 0.000 1, respectively. Comparing to other six equations originated from literatures, which also estimate the surface broadband emissivity from narrowband emissivities. The RMSE and Bias of our equation are lower one order and two orders of magnitude than other six equations, respectively. Lastly, our equation is applied in the Taklimakan Desert area to build a distribution image of emissivity based on MODIS data. It demonstrates that the emissivity of Taklimakan Desert is in the range of 0.880～0.910 over the central regions, the averaged value is 0.906; The emissivity is in the range of 0.910～0.940 where the areas covered by spare vegetation; The emissivity is in range of 0.950～0.980 where the regions near to the oasis.
李火青1，吴新萍2，买买提艾力·买买提依明3，霍 文3，杨兴华3，杨 帆3, 何 清3，刘永强1，4* . 利用FTIR和MODIS数据估算塔克拉玛干沙漠宽波段地表比辐射率 [J]. 光谱学与光谱分析, 2016, 36(08): 2414-2419.
LI Huo-qing1, WU Xin-ping2, Ali Mamtimin3, HUO Wen3, YANG Xing-hua3, YANG Fan3, HE Qing3, LIU Yong-qiang1,4*. Estimating Surface Broadband Emissivity of the Taklimakan Desert with FTIR and MODIS Data. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2016, 36(08): 2414-2419.
[1] Sellers P J, Randall D A, Collatz G J, et al. Journal of Climate, 1996, 9(4): 676. [2] Jiang G M, Li Z L. Remote Sensing of Environment, 2006, 105: 326. [3] Liang S, Wang K, Zhang X, et al. IEEE Journal of Selected Topics in Applied Earth Observations & Remote Sensing, 2010, 3(3): 225. [4] Hook S J, and Kahle A B. Remote Sensing of Environment, 1996, 56(3): 172. [5] Korb A R, Dybwad P, Wadsworth W, et al. Applied Optics, 1996, 35(10): 1679. [6] Korb A R, Salisbury J W, D’Aria D M, et al. Journal of Geophysical Research: Solid Earth, 1999, 104(B7): 15339. [7] Hori M, Aoki T, Tanikawa T, et al. Remote Sensing of Environment, 2006, 100(4): 486. [8] LIU Yong-qiang，Ali Mamitimin，HUO Wen, et al(刘永强, 艾力·买买提明, 霍 文, 等). Desert and Oasis Meteorology(沙漠与绿洲气象), 2014, 8(3): 1. [9] Liu Y, Mamtimin A, Huo W, et al. Journal of Mountain Science, 2014, 11(6): 1543. [10] Sobrino J A, Raissouni N, Li Z L. Remote Sensing of Environment, 2001, 75(2): 256. [11] Jin M, Liang S. Journal of Climate, 2006, 19(12): 2867. [12] Hulley C C, Hook S J, Baldridge A M. Remote Sensing of Environment, 2010, 114: 1480. [13] Van de Griend A A, Owe M. International Journal of Remote Sensing, 1993, 14(6): 1119. [14] Ogawa K, Schmugge T. Earth Interactions, 2004, 8(7): 1. [15] Tang B H, Wu H, Li C, et al. Optics Express, 2011, 19(1): 185. [16] WANG Xin-sheng, XU Jing, LIU Fei, et al(王新生, 徐 静, 柳 菲, 等). Acta Geographica Sinica(地理学报), 2012, 67(1): 93. [17] Cheng J, Liang S, Yao Y, et al. IEEE Geoscience and Remote Sensing Letters, 2013, 10(2): 401. [18] Weng F, Yan B, Grody N C. Journal of Geophysical Research: Atmospheres (1984—2012), 2001, 106(D17): 20115. [19] Sobrino J A, Jiménez-Muoz J C, Sòria G, et al. IEEE Transactions on Geoscience and Remote Sensing, 2008, 46(2): 316. [20] WANG Xun-ming, DONG Zhi-bao, CHEN Guang-ting(王训明, 董治宝, 陈广庭). Journal of Desert Research(中国沙漠), 2001, 21(1): 56. [21] Wan Z. Remote Sensing of Environment, 2014, 140(1): 36. [22] YAO Yun-jun, QIN Qi-ming, ZHAO Shao-hua, et al(姚云军，秦其明，赵少华，等). Journal of Infrared and Millimeter Waves(红外与毫米波学报), 2011, 30(1): 9. [23] Zhou L, Dickinson R E, Ogawa K, et al. Geophysical Research Letters, 2013, 30(20): 2026. [24] Wilber A C, Kratz D P, Gupta S K. Surface Emissivity Maps for Use in Sutellite Retrievlas of Longwave Radiation. NASA Tech. Publication NASA, 1999. 209362. [25] Wan Z, Dozier J. IEEE Transactions on Geoscience and Remote Sensing, 1996, 34(4): 892. [26] Wan Z, Li Z. IEEE Transactions on Geoscience and Remote Sensing, 1997, 35(4): 980.
