Estimation of Terrestrial Albedo from Multiple Reflectance Observations in a Single Day for SGLI Albedo Products Susaki, J.(a*), Ishii, Y.(b), Kuriki, A.(c), Kimura, Y.(d) and Ono, A.(e)
(a) Professor, Graduate School of Engineering, Kyoto University, Japan
(b) Assistant Professor, Graduate School of Engineering, Kyoto University, Japan
(c) Technical Staff, Graduate School of Engineering, Kyoto University, Japan
(d) Student, Graduate School of Engineering, Kyoto University, Japan
(e) Associate Professor, Faculty of Humanities, Tenri University, Japan
Abstract
This paper examines algorithms for estimating terrestrial albedo for the products of the Global Change Observation Mission - Climate (GCOM-C) / Second-generation Global Imager (SGLI), which was launched in December 2017 by the Japan Aerospace Exploration Agency (JAXA). We focused on an approach using parameters derived from a bidirectional reflectance distribution function (BRDF) model. In operational products of the Moderate Resolution Imaging Spectroradiometer (MODIS), kernel-driven BRDF model parameters are estimated from multiple sets of reflectance and they are applied to estimate the land surface albedo. However, one of the challenges in this algorithm is to require multiple reflectance over several or dozens of days in order to achieve robust parapmeter estimation. Instead, another approach has been proposed that estimates the land surface albedo from a single set of reflectance with multi-regression models. The multi-regression models are derived for an arbitrary geometry from datasets of simulated albedo and multi-angular reflectance. Our preliminary experiments using in situ multi-temporal data demonstrated that this algorithm requires information about the land cover of the pixel of interest, and the variance of its estimated albedo is sensitive to the observation geometry. Therefore, in this research, we propose an approach that estimates the land surface albedo from multiple reflectance observed within several hours in a single day. We conducted field measurement in barren land, Tottori Sand Dunes, Japan. We calculated the land surface albedos from those data sets, and compared the albedos with the actual albedos and those obtained using the traditional approach. We found that the error of the albedos estimated by the proposed approach is acceptable. In near future, we^ll examine the performance of the proposed method by using actual satellite images.
