The Tenth Symposium on Polar Science/Ordinary sessions: [OM] Polar Meteorology and Glaciology, Wed. 4 Dec. / Entrance Hall (1st floor) , National Institute of Polar Researc

Makoto Kuji

Masahiro Hori

Naho Nakatsuji

Sara Hirose

National Institute of Polar Research Repository

Characteristics of cloud fractions from satellite observations along the ship track of R/V Shirase∗Naho Nakatsuji1, Sara Hirose1, Makoto KUJI1 and Masahiro Hori21Nara Women’s University2Earth Observation Research Center, Japan Aerospace Exploration AgencyClouds have an important role in the earth climate system in terms of radiation budget. They have cooling and warming effectson solar and terrestrial radiations, respectively. Their radiative impacts depend on the cloud amount, optical thickness, particlesize, top and bottom heights, and so on. Satellite observation is one of the most suitable approaches to understand the cloudproperties on a global scale. However, it is not easy to observe cloud properties because their spatiotemporal variations are verylarge, and then the reliability on the cloud products from satellite is not necessarily high (IPCC 2013). It is therefore requiredto validate the cloud products retrieved from satellites. There are a lot of validation sites over land, but we do not have enoughvalidation sites over ocean, even though ocean extends about 70% of the earth surface. Therefore, shipborne observation is oneof the possible counterparts for the spaceborne platforms over the oceans.R/V Shirase performed the Antarctic cruise between Japan and Antarctica from 12 November 2017 to 12 April 2018 during the59th Japanese Antarctic Research Expedition (JARE 59). Cloud fractions were estimated from R/V Shirase observations withwhole-sky camera, ceilometer and eye after JARE 55 (Kuji et al. 2018). 0 20 40 60 80 100 0  20  40  60  80  100RMSE=31.7, MB=-24.4R=0.77, N=51y=0.37*x+8.99Himawari [%]Whole sky camera [%]Figure 1. Scatter plot of daily- averaged cloud fractionsestimated with Himawari-8 versus the whole-sky camerain JARE 59. Solid and dotted line are regression and one-to-one line, respectively. RMSE, MB, R and N repre-sent root-mean-square-error, mean bias, correlation coef-ﬁcient and total number, respectively.JAXA retrieves cloud properties using Advanced Himawari Imager (AHI)onboard Himawari-8, which is a geostationary meteorological satel-lite launched by Japan Meteorological Agency (JMA) in 2014 (Besshoet al. 2016). The cloud products such as cloud optical thicknessand cloud types are available in every 10 min in Himawari Monitor(http://www.eorc.jaxa.jp/ptree/index.html). The product level ver. 1 wasused in this study.Therefore we tried to investigate the cloud characteristics from Himawari-8 observation along the track of R/V Shirase . We estimated cloud fractionbased on the cloud optical thickness and compared it with the R/V Shiraseobservation. A pixel is considered cloudy when the cloud optical thicknessabove R/V Shirase is greater than 0. The cloud fraction was deﬁned as afrequency of cloud appearance, that is, the ratio of cloudy to total effectivepixels. Figure 1 shows a scatter plot of daily-averaged cloud fractions es-timated with Himawari-8 versus the whole-sky camera in JARE 59. Thecorrelation coefﬁcient of Himawari-8 versus the whole-sky camera werehigh with 0.77.In this study, cloud characteristics from Himawari-8 observations is inves-tigated along the ship track of R/V Shirase observation for the validation.We are going to improve the estimation of the cloud fraction. In future,the cloud properties from GCOM-C/SGLI observation will be also investi-gated and validated along the track of R/V Shirase .ReferencesBessho, K., K. Date, M. Hayashi, A. Ikeda, T. Imai, H. Inoue, Y. Kumagai, T. Miyakawa, H. Murata, T. Ohno, A. Okuyama, R.Oyama, Y. Sasaki, Y. Shimazu, K. Shimoji, Y. Sumida, M. Suzuki, H. Taniguchi, H. Tsuchiyama, D. Uesawa, H. Yokota,and R. Yoshida, 2016: An introduction to Himawari-8/9 - Japan’s new-generation geostationary meteorological satellites.J. Meteor. Soc. Japan, 94, 151-183.IPCC, 2013: Climate Change 2013: The Physical Science Basis. Cambridge University Press, 1535 pp.Kuji, M., A. Murasaki, M. Hori, M. Shiobara, 2018: Cloud Fractions Estimated from Shipboard Whole-Sky Camera andCeilometer Observations between East Asia and Antarctica. J. Meteor. Soc. Japan, 96, 201-214.

Characteristics of cloud fractions from satellite observations along the ship track of R/V Shirase

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Characteristics of cloud fractions from satellite observations along the ship track of R/V Shirase

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