日本地球惑星科学連合2015年大会

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インターナショナルセッション(口頭発表)

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-CG09] Satellite Earth Environment Observation

2015年5月28日(木) 11:00 〜 12:45 301B (3F)

コンビーナ:*沖 理子(宇宙航空研究開発機構)、早坂 忠裕(東北大学大学院理学研究科)、佐藤 薫(東京大学 大学院理学系研究科 地球惑星科学専攻)、佐藤 正樹(東京大学大気海洋研究所)、高橋 暢宏(独立行政法人 情報通信研究機構)、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)、奈佐原 顕郎(筑波大学生命環境系)、中島 孝(東海大学情報理工学部情報科学科)、沖 大幹(東京大学生産技術研究所)、横田 達也(独立行政法人国立環境研究所)、高薮 縁(東京大学 大気海洋研究所)、村上 浩(宇宙航空研究開発機構地球観測研究センター)、岡本 創(九州大学)、座長:可知 美佐子(宇宙航空研究開発機構 地球観測研究センター)

12:30 〜 12:45

[ACG09-25] 海色衛星観測による海洋有光層深度の推定

*平田 貴文1 (1.北海道大学大学院地球環境科学研究院)

キーワード:海色, 衛星観測, 有光層深度, 光合成有効放射

The euphotic depth is defined as a depth where Photosynthetically Available Radiation (PAR) at the sea surface decreased by 1% during its propagation into a water column. While a large amount of ocean colour signal detected by satellite originates from the ocean surface and cannot directly retrieve the euphoric depth, it is a challenge to estimate the euphotic depth by satellite remote sensing. In addition, PAR is defined as the radiance integrated over a range of wavelength (often 400-700nm), while the operational ocean colour satellites only observe the radiance at discrete wavelengths. Thus, it is even a challenge to estimate PAR, hence, the euphotic depth eventually. Furthermore, phytoplankton in the ocean, which is a photosynthetic organism, utilizes radiance at the all solid angles around it for photosynthesis, therefore consideration of radiance at all solid angles is a particular importance in considering the attenuation of PAR when retrieving the euphoric depth, while the ocean colour satellite detects radiance originating only from a certain solid angle, thus showing another challenge. In order to solve these problems for the satellite estimation of the euphotic depth, extensive radiative transfer simulations were conducted. Results show (1) the diffuse attenuation of PAR at the sea surface has a certain relationship with that averaged over euphotic zones, (2) the diffuse attenuation of PAR, which is wavelength-integrated property, can be estimated from an ocean colour measurement at a discrete wavelength, (3) the diffuse attenuation of PAR originating from the all solid angles has a relationship with that of PAR originating from a certain range of solid angles. Using these findings above, a satellite ocean colour algorithm was developed to estimate the euphotic depth. In this presentation, details of the methodology will be demonstrated, and global variability of the euphoric depth will be shown.