日本地球惑星科学連合2018年大会

講演情報

[EE] ポスター発表

セッション記号 A (大気水圏科学) » A-CG 大気水圏科学複合領域・一般

[A-CG36] 衛星による地球環境観測

2018年5月24日(木) 10:45 〜 12:15 ポスター会場 (幕張メッセ国際展示場 7ホール)

コンビーナ:沖 理子(宇宙航空研究開発機構)、本多 嘉明(千葉大学環境リモートセンシング研究センター)、高薮 縁(東京大学 大気海洋研究所、共同)、松永 恒雄(国立環境研究所地球環境研究センター/衛星観測センター)、Allen HL Huang (University of Wisconsin Madison)

[ACG36-P10] Dependence on Spectral Reflectance of Surface Properties at Railroad Valley Playa for GOSAT/GOSAT-2 Vicarious Calibration

*荒井 武彦1松永 恒雄1 (1.国立環境研究所 地球環境研究センター 衛星観測研究室)

キーワード:温室効果ガス、GOSAT、レールロードバレー、代替較正

GOSAT and the next generation GOSAT-2 satellites estimate the concentration of greenhouse gases, and distribution of aerosol and cloud by observing solar light reflection and radiation from surface and atmosphere of the Earth. A bidirectional reflectance distribution function (BRDF) is required for the estimation because the surface reflectance of solar light varies with the observation geometry and the surface condition. The purpose of this study is to search for an appropriate BRDF model of Railroad Valley playa, Nevada (RRV) for the sensor calibration of GOSAT. We measured the radiance factor of RRV by varying with solar incident angles and observed angles using a spectroradiometer (FieldSpec4, ASD Inc.) mounted on a one-axis goniometer. The surface sands were shifted to several sizes of grain (75, 125, 250, 500, and 1000 μm). We determined the Hapke parameters (Hapke, 2012) as the BRDF for the observed radiance factor of the sands by the least squares fitting with the free parameters of a single scattering albedo, an asymmetric factor, a shadow hiding opposition effect parameter, and a mean slope angle. This result indicates that the albedo was varied with the grain size and its physical state of the surface. Therefore, detail measurements of the surface properties at local sites, such as a filling factor, are significant to determine the precise albedo of the calibration site.