Effects of Smoothed BRDF on Multi-angle Albedo Retrievals

¹ Liaoning Technical University, College of Surveying and Mapping and Geographic Science, 123000 Fuxin, China
² Xinjiang Institute of Ecology and Geography, CAS, 830011 Urumqi, China
³ Research Center for Ecology and Environment of Central Asia, CAS, 830011 Urumqi, China
⁴ University of Chinese Academy of Sciences, 100049 Beijing, China
⁵ Xinjiang University, 830046 Urumqi, China
⁶ Shenyang Gas Group Co. Ltd., 110000 Shenyang, China
⁷ RIOH Automobile Testing & Certification Technology Co. Ltd, 101103 Beijing, China

^* Corresponding author: 471910043@stu.lntu.edu.cn

Abstract

BRDF as the intrinsic feature of surface targets, is an important parameter required by albedo inversion from multi-angle observations, especially for satellite data suit with less directional measurements. Several studies have shown up to introduce BRDF priori knowledge into albedo retrievals at different scale by spatial or temporal smoothing. Thus, it is necessary to further understand what’s the influence induced by BRDF smoothing on albedo retrieval. This work investigated effects of smoothed BRDF on albedo magnitude through case studies over North America region using operational MCD43A&C BRDF products respectively smoothed in spatial and temporal scales. Our results show that BRDF of seasonal DBF samples smoothed from daily to monthly can lead to apparent relative difference to smoothed values of 10.97%, 9.42%, 8.24% and detectable absolute differences of 0.0172, 0.0095 and 0.0035 on related albedo respectively at Near Infrared, Short Wave and Visible broadband. The spatial smoothing of BRDF from 500m to 5600m results in relative differences to smoothed values of 17.38%, 14.38%, 27.23% and absolute differences of 0.0250, 0.0139, 0.0052 for the inversed albedo at above three broadbands.