A method for improving hotspot directional signatures in BRDF models used for MODIS

REMOTE SENSING OF ENVIRONMENT

卷:186

Article

Jiao, Ziti^1,2,3  Schaaf, Crystal B.^4,5  Dong, Yadong^1,2,3  Roman, Miguel⁶  Hill, Michael J.⁷  Chen, Jing M.⁸  Wang, Zhuosen^4,5,6  Zhang, Hu^1,2,3  Saenz, Edward⁴  Poudyal, Rajesh⁹  Gatebe, Charles^6,10  Breon, Francois-Marie¹¹  Li, Xiaowen^1,2,3  Strahler, Alan⁵ 

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

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

[3] Beijing Normal Univ, Beijing Key Lab Environm Remote Sensing & Digital, Beijing 100875, Peoples R China

[4] Univ Massachusetts, Dept Environm Earth & Ocean Sci, Boston, MA 02125 USA

[5] Boston Univ, Ctr Remote Sensing, Dept Earth & Environm, Boston, MA 02215 USA

[6] NASA, Goddard Space Flight Ctr, Terr Informat Syst Lab, Greenbelt, MD USA

[7] Univ North Dakota, Dept Earth Syst Sci & Policy, Clifford Hall,4149 Univ Ave, Grand Forks, ND 58202 USA

[8] Univ Toronto, Dept Geog & Program Planning, 100 St George St,Room 5047, Toronto, ON M55 3G3, Canada

[9] Sci Syst & Applicat Inc, Lanham, MD USA

[10] Univ Space Res Assoc, Columbia, MD USA

[11] CEA, DSM, LSCE, F-91191 Gif Sur Yvette, France

关键词: BRDF;    CAR;    MODIS;    POLDER;    Multiangle remote sensing;    Hotspot signature;    Hotspot kernel;    Hotspot effect;    Linear RTLSR model;    Airborne measurements;   

DOI  :  10.1016/j.rse.2016.08.007

来源: Elsevier

【 摘 要 】

The semi-empirical, kernel-driven, linear RossThick-LiSparseReciprocal (RTLSR) Bidirectional Reflectance Distribution Function (BRDF) model is used to generate the routine MODIS BRDF/Albedo product due to its global applicability and the underlying physics. A challenge of this model in regard to surface reflectance anisotropy effects comes from its underestimation of the directional reflectance signatures near the Sun illumination direction; also known as the hotspot effect. In this study, a method has been developed for improving the ability of the RTLSR model to simulate the magnitude and width of the hotspot effect. The method corrects the volumetric scattering component of the RTLSR model using an exponential approximation of a physical hotspot kernel, which recreates the hotspot magnitude and width using two free parameters (C-1 and C-2, respectively). The approach allows one to reconstruct, with reasonable accuracy, the hotspot effect by adjusting or using the prior values of these two hotspot variables. Our results demonstrate that: (1) significant improvements in capturing hotspot effect can be made to this method by using the invested hotspot parameters; (2) the reciprocal nature allow this method to be more adaptive for simulating the hotspot height and width with high accuracy, especially in cases where hotspot signatures are available; and (3) while the new approach is consistent with the heritage RTLSR model inversion used to estimate intrinsic narrowband and broadband albedos, it presents some differences for vegetation clumping index (CI) retrievals. With the hotspot-related model parameters determined a priori, this method offers improved performance for various ecological remote sensing applications; including the estimation of canopy structure parameters. (C) 2016 Elsevier Inc. All rights reserved.

【 授权许可】

Free