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Characterization of Remote Sensing Albedo Over Sloped Surfaces Based on DART Simulations and In Situ Observations
Author(s) -
Wu Shengbiao,
Wen Jianguang,
You Dongqin,
Hao Dalei,
Lin Xingwen,
Xiao Qing,
Liu Qinhuo,
GastelluEtchegorry JeanPhilippe
Publication year - 2018
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2018jd028283
Subject(s) - albedo (alchemy) , remote sensing , skylight , radiative transfer , environmental science , solar zenith angle , dart , shortwave , atmospheric radiative transfer codes , zenith , bidirectional reflectance distribution function , visibility , terrain , atmospheric sciences , geology , meteorology , reflectivity , optics , geography , physics , archaeology , performance art , computer science , art history , art , programming language , cartography
In situ albedo measurement over sloped surfaces is pivotal to a wide range of remote sensing applications, such as the estimation and evaluation of surface energy budget at regional and global scales. However, existing albedo measurements over rugged terrain are limited and controversial and remain a major challenge. In this paper, two commonly measured broadband albedos, which depend on incoming/outgoing geometric conditions, were characterized over sloped surfaces and illustrated. These albedos are the horizontal/horizontal sloped surface albedo (HHSA) and inclined/inclined sloped surface albedo (IISA). The 3‐D Discrete Anisotropic Radiative Transfer (DART) model simulations over varying slopes were utilized to quantify differences in the albedos. In particular, the effects of the slope, aspect, the solar zenith angle, and the proportion of diffuse skylight were investigated. The results show that absolute (relative) biases between HHSA and IISA are significant, reaching up to 0.026 (61.8%), 0.134 (62.4%), and 0.114 (62.3%) in the visible, near‐infrared, and shortwave broadbands, respectively. In addition, the diurnal cycle differences between HHSA and IISA were also compared using DART simulations and in situ observations over four typical slopes. Comparisons reveal that topographic parameters (e.g., slope and aspect) and atmospheric conditions (e.g., diffuse skylight and atmospheric visibility) are the primary factors, while the optical and structural parameters have a smaller effect.