NDLI: An approach to improve hot spot effect for the MODIS BRDF/Albedo algorithm

Content Provider	IEEE Xplore Digital Library
Author	Ziti Jiao Yadong Dong Xiaowen Li
Copyright Year	2013
Description	Author affiliation: Sch. of Geogr., Beijing Normal Univ., Beijing, China (Ziti Jiao; Yadong Dong; Xiaowen Li)
Abstract	The RossThick-LiSparse-Reciprocal (RTLSR) Bidirectional Reflectance Distribution Function (BRDF) model has been developped to derive the operational Moderate Resolution Imaging Spectroradiometer (MODIS) BRDF/Albedo product due to its simplicity and the underlying physics; however, early research showed that this model deficiency mainly comes from its underestimation of the hotspot directional signatures near the Sun's illumination direction. In this paper, we developed an approach to improve the hot spot effect for the RTLSR model by improving the volumetric scattering kernel with an exponential approximation of the hot spot kernel (Chen and Cihlar, 1997). Compared with the RTLSR model and the further-developed model that modify the hotspot directional signatures of RTLSR model based on the calculation of an overlay function of the intersection of viewed and sunlit leaf areas (Jupp and Strahler, 1991, thereafter named RTJLSR), this newly-corrected model that modifies the hot spot effect of RTLSR model based on the theory of calculation of a canopy gap size distribution function (Chen and Leblanc, 1997, thereafter named RTCLSR) preserves the linear form of kernel-driven model, but flexibly adjust hotspot magnitude and width through two additional parameters C1 and C2. Initial validation result with airborne cloud absorption radiometer (CAR) data shows that the RTCLSR model can significantly improve the model-observation fits in hotspot region. In near future, we will focus on determining C1/C2 values from spaceborne POLDER BRDF database provided by the POSTEL Service Centre. With C1/C2 are predetermined, the newly-correctly RTCLSR model is promissing for global application with a minor update from the RTLSR model.
Sponsorship	IEEE Geosci. Remote Sens. Soc.
Starting Page	3037
Ending Page	3039
File Size	173549
Page Count	3
File Format	PDF
ISBN	9781479911141
ISSN	21536996
DOI	10.1109/IGARSS.2013.6723466
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2013-07-21
Publisher Place	Australia
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Kernel Scattering Atmospheric modeling Lighting Data models Bidirectional control MODIS hotspot BRDF kernel-driven
Content Type	Text
Resource Type	Article

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