View angle effects on MODIS snow mapping in forests

REMOTE SENSING OF ENVIRONMENT

卷:118

Article

Xin, Qinchuan¹  Woodcock, Curtis E.¹  Liu, Jicheng²  Tan, Bin³  Melloh, Rae A.⁴  Davis, Robert E.⁴ 

[1] Boston Univ, Dept Geog & Environm, Boston, MA 02215 USA

[2] NOAA NESDIS STAR, IM Syst Grp, Rockville, MD 20852 USA

[3] NASA, Goddard Space Flight Ctr, Greenbelt, MD 20770 USA

[4] Engn Res & Dev Ctr, Cold Reg Res & Engn Lab, Hanover, NH 03755 USA

关键词: Remote sensing;    MODIS;    Snow cover;    View angle effect;   

DOI  :  10.1016/j.rse.2011.10.029

来源: Elsevier

【 摘 要 】

Binary snow maps and fractional snow cover data are provided routinely from MODIS (Moderate Resolution Imaging Spectroradiometer). This paper investigates how the wide observation angles of MODIS influence the current snow mapping algorithm in forested areas. Theoretical modeling results indicate that large view zenith angles (VZA) can lead to underestimation of fractional snow cover (FSC) by reducing the amount of the ground surface that is viewable through forest canopies, and by increasing uncertainties during the gridding of MODIS data. At the end of the MODIS scan line, the total modeled error can be as much as 50% for FSC. Empirical analysis of MODIS/Terra snow products in four forest sites shows high fluctuation in FSC estimates on consecutive days. In addition, the normalized difference snow index (NDSI) values, which are the primary input to the MODIS snow mapping algorithms, decrease as VZA increases at the site level. At the pixel level. NDSI values have higher variances, and are correlated with the normalized difference vegetation index (NDVI) in snow covered forests. These findings are consistent with our modeled results, and imply that consideration of view angle effects could improve MODIS snow monitoring in forested areas. (C) 2011 Elsevier Inc. All rights reserved.

【 授权许可】

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