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(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-CG09] Satellite Earth Environment Observation

2015年5月27日(水) 18:15 〜 19:30 コンベンションホール (2F)

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)

18:15 〜 19:30

[ACG09-P01] CALIPSO観測データを用いた静止衛星split-window観測による雲頂高度推定手法の開発

*西 憲敬1濱田 篤2広瀬 民志3 (1.福岡大学理学部、2.東京大学大気海洋研究所、3.千葉大学CEReS)

We released a database of cloud top height and visible optical thickness (CTOP) with one-hour resolution over the tropical western Pacific and Maritime Continent, by using infrared split-window data of the geostationary satellites (MTSAT) (http://database.rish.kyoto-u.ac.jp/arch/ctop/). We made lookup tables for estimating cloud top height only with geostationary infrared observations by comparing them with the direct cloud observation by CloudSat (Hamada and Nishi, 2010, JAMC). We picked out the same-time observations by MTSAT and CloudSat and regressed the cloud top height observation of CloudSat back onto 11 micro m brightness temperature (Tb) and the difference between the 11 micro m Tb and 12 micro m Tb of MTSAT. The database contains digital data and quick look images from Jul 2005 to real time and the area in 85E-155W (MTSAT2) and 20S-20N.
Though the CTOP dataset is particularly useful for the upper tropospheric clouds, it has one serious problem. The cloud radar onboard CloudSat cannot well detect the optically thin cirrus clouds composed of small ice crystals and misses a certain part of cirriform clouds in the upper troposphere. In order to overcome this weakness, we are now making next version of the CTOP by using the lidar data (CALIOP) onboard CALIPSO satellite. One problem on the use of lidar observation is that they observe very thin cirrus formed around the tropopause. The main purpose of CTOP dataset is to provide the top height of clouds that originate from cloud clusters including cumulonimbus and nimbostratus, not of in-situ cirrus clouds formed near the tropopause. To exclude the very thin tropopause cirrus, we define cloud-top height of CALIOP observation as the height at which the optical depth accumulated from the cloud top is 0.2, instead of the CALIOP cloud top itself. With this criterion we can succeed in estimating the top height of cirruiform clouds, but it has another problem for thick clouds like cumulonimbus. For such clouds, the height of accumulated optical depth 0.2 is considerably lower than the real cloud top, possibly due to rather small number of large cloud particles near the top. Therefore, the estimation using CloudSat data is closer to the real top for the thick clouds, while that using CALIOP data is closer for cirriform clouds. So we are now making a lookup table with using both CloudSat and CALIPSO data to estimate cloud-top heights both for thick and thin clouds seamlessly.