Global-Scale Evaluation of Roughness Effects on C-Band AMSR-E Observations

作者:Wang, S (Wang, Shu)[ 1,2,3 ] ; Wigneron, JP (Wigneron, Jean-Pierre)[ 3 ] ; Jiang, LM (Jiang, Ling-Mei)[ 1,2 ] ; Parrens, M (Parrens, Marie)[ 3,4 ] ; Yu, XY (Yu, Xiao-Yong)[ 1,2 ] ; Al-Yaari, A (Al-Yaari, Amen)[ 3 ] ; Ye, QY (Ye, Qin-Yu)[ 1,2 ] ; Fernandez-Moran, R (Fernandez-Moran, Roberto)[ 3,5 ] ; Ji, W (Ji, Wei)[ 6 ] ; Kerr, Y (Kerr, Yann)[ 4 ]

REMOTE SENSING

卷: 7  期: 5  页: 5734-5757

DOI: 10.3390/rs70505734

出版年: MAY 2015

摘要

Quantifying roughness effects on ground surface emissivity is an important step in obtaining high-quality soil moisture products from large-scale passive microwave sensors. In this study, we used a semi-empirical method to evaluate roughness effects (parameterized here by the Hr parameter) on a global scale from AMSR-E (Advanced Microwave Scanning Radiometer for EOS) observations. AMSR-E brightness temperatures at 6.9 GHz obtained from January 2009 to September 2011, together with estimations of soil moisture from the SMOS (Soil Moisture and Ocean Salinity) L3 products and of soil temperature from ECMWF's (European Centre for Medium-range Weather Forecasting) were used as inputs in a retrieval process. In the first step, we retrieved a parameter (referred to as the a* parameter) accounting for the combined effects of roughness and vegetation. Then, global MODIS NDVI data were used to decouple the effects of vegetation from those of surface roughness. Finally, global maps of the Hr parameters were produced and discussed. Initial results showed that some spatial patterns in the Hr values could be associated with the main vegetation types (higher values of Hr were retrieved generally in forested regions, intermediate values were obtained over crops and grasslands, and lower values were obtained over shrubs and desert) and topography. For instance, over the USA, lower values of Hr were retrieved in relatively flat regions while relatively higher values were retrieved in hilly regions.

通讯作者地址: Wang, S (通讯作者)

Beijing Normal Univ, State Key Lab Remote Sensing Sci, Beijing 100875, Peoples R China.

地址:

[ 1 ] Beijing Normal Univ, State Key Lab Remote Sensing Sci, Beijing 100875, Peoples R China

[ 2 ] Beijing Normal Univ, Sch Geog, Beijing 100875, Peoples R China

[ 3 ] INRA, UMR ISPA 1391, F-33140 Bordeaux Aquitaine, France

[ 4 ] IRD, CNRS, CNES, Ctr Etud Spatiales BIOsphere CESBIO,UMR 5126,UT3, F-31401 Toulouse, France

[ 5 ] Univ Valencia, Fac Phys, Dept Earth Phys & Thermodynam, Climatol Satellites Grp, E-46100 Burjassot, Spain

[ 6 ] Chinese Acad Sci, Inst Remote Sensing & Digital Earth, Beijing 100094, Peoples R China