Study of the Microwave Emissivity Characteristics of Vegetation over the Northern Hemisphere
SHI Li-juan1, 2, QIU Yu-bao1*, SHI Jian-cheng3
1. Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences，Beijing 100094, China 2. School of Geomatics, Liaoning Technical University, Fuxin 123000, China 3. Institute for Computational Earth System Science, University of California, Santa Barbara, CA 93106-3060, USA
Abstract：The microwave emissivity is a function of structure, water content, and surface roughness, and all these factors have obvious seasonal variations. In the present study, the half-month averaged emissivities in summer and winter of 2003 over the vegetation of Northern Hemisphere were estimated using Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) combined with IGBP (International Geosphere-Biosphere Project labels) land classification data. Then the emissivities of vegetation land covers at different frequencies, the polarization and their seasonal variations were analyzed respectively. The results show that the emissivities of vegetation increase with the increase in frequencies, and decline with the frequency increasing over snow region. In summer, the vegetation emissivity at V-polarization of 89 GHz is larger than 0.944, and all emissivities are relatively stable and the RMSE of time series emissivity variation is less than 0.007 2. In winter, emissivities decrease over snow covered area, especially for higher frequencies. Furthermore, with the increase in vegetation density, the emissivities increase and emissivity polarization difference decreases.
Key words：Land emissivity;Emissivity polarization difference;Vegetation;Winter and summer
石利娟1, 2，邱玉宝1*，施建成3 . 北半球植被冬夏两季微波发射率特征分析 [J]. 光谱学与光谱分析, 2013, 33(05): 1157-1162.
SHI Li-juan1, 2, QIU Yu-bao1*, SHI Jian-cheng3 . Study of the Microwave Emissivity Characteristics of Vegetation over the Northern Hemisphere . SPECTROSCOPY AND SPECTRAL ANALYSIS, 2013, 33(05): 1157-1162.
[1] English S J. Journal of Applied Meteorology, 1999, 38(10)：1526. [2] Qiu Yubao, Guo Huadong, Shi Jiancheng, et al. IGARSS，2012, 4664. [3] Prigent C, Aires F. Journal of Geophysical Research, 2001, 106(D18): 20665. [4] Cordisco E, Prigent C, Aires F. Journal of Geophysical Research. 2006, 111, doi: 10.1029/2005JD00 6773. [5] Xiang X, Smith E A. Journal of Hydrology, 1997, (188-189): 330. [6] Shi J C, Jiang L M, Zhang L X, et al. IEEE Transactions on Geoscience and Remote Sensing, 2006, 44(11): 3145. [7] Prigent C, Rossow W B, Matthews E. Journal of Geophysical Research, 1997, 102(D18)：21867. [8] Prigent C, Aires F, Rossow W B. Journal of Geophysical Research, 2003, 108: 4310. [9] Karbou F, Prigent C, Eymard L, et al. IEEE Transactions on Geoscience and Remote Sensing, 2005, 43(5): 948. [10] Galantowicz J F, Moncet J L, Liang P. Journal of Geophysical Research, 2011, 116(D17105): 1. [11] Norouzi H, Temimi M, Rossow W B, et al. Hydrology and Earth System Sciences, 2011, 8: 5667. [12] Norouzi H, Rossow W, Temimi M, et al. Remote Sensing of Environment, 2012, 123: 470. [13] Pan G D, Wang C, Wang H M, et al. IGRASS, 2000, 2(24-28): 923. [14] Qiu Y B, Shi J C, Hallikainen M T. IGARSS，2008, 2: 749. [15] Shi Lijuan, Qiu Yubao. IGARSS, 2012, 678. [16] Prigent C, Aires F, Rossow W B. American Meteorological Society，2007, 87(11): 157. [17] Sume A, Mtzler C, Huppi R, et al. Microwave Radiometer and Scatterometer Measurements of Vegetation. FOA-Report C30494-3.2, 1988, Linkoping, Sweden. [18] Wegmuller U, Matzler C, Weise T. Absorption von Mikrowellen in Nadelbaumen. Auftragsstudie zuhanden der PTT, 1993, Institute of Applied Physics, University of Bern. [19] Mtzler C. Meteorology and Atmospheric Physics, 1994, 54：241. [20] Karam M A, Fung A K, Lang R H, et al. IEEE Transactions on Geoscience and Remote Sensing, 1992, 30(4)：767. [21] Choudhury B J. International Journal of Remote Sensing, 1989, 10：1579.
