著者

MIYAMOTO Yoshiaki SATO Yousuke NISHIZAWA Seiya YASHIRO Hisashi SEIKI Tatsuya NODA Akira T.

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2020-051, (Released:2020-07-09)

被引用文献数

1

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This study proposes a new energy balance model to determine the cloud fraction of low-level clouds. It is assumed that the horizontal cloud field consists of several individual cloud cells having a similar structure. Using a high–resolution simulation dataset with a wide numerical domain, we conducted an energy budget analysis. It is shown that the energy injected into the domain by surface flux is approximately balanced with the energy loss due to radiation and advection due to large–scale motion. The analysis of cloud cells within the simulated cloud field showed that the cloud field consists of a number of cloud cells with similar structures. We developed a simple model for the cloud fraction from the energy conservation equation. The cloud fraction diagnosed using the model developed in this study was able to quantitatively capture the simulated cloud fraction.

著者

OHNO Tomoki NODA Akira T. SATOH Masaki

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2020-054, (Released:2020-07-20)

被引用文献数

7

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The impacts of the saturation adjustment type approach to sub-grid-scale (SGS) ice clouds in a turbulent closure scheme on the high clouds and their response to global warming were investigated based on the radiative–convective equilibrium experiments (RCEs). This was motivated by the fact that the time scale of ice condensation is several orders of magnitude longer than that for liquid water. The RCEs were conducted with uniform sea surface temperatures over the spherical domain for the Earth's radius without rotation using an explicit cloud microphysics and a non-hydrostatic icosahedral atmospheric model. This study revealed that suppressing the phase change effect associated with the SGS ice condensation on the buoyancy of the SGS turbulence could cause approximately a 20 % reduction of the total high cloud covers and a significantly different response of high cloud amounts to global warming due to the change in static stability near high clouds, which leads to weaker vertical heat transport at a sub-grid scale there. Since the typical value of the time scale of the ice-phase cloud is much longer than that for liquid water and the ice supersaturation is in general, using the saturation adjustment type approach for SGS ice clouds could lead to an overestimation of the effect of ice condensation for the turbulent mixing and model biases in simulations with both cloud resolving models and general circulation models. The present result underlines the critical nature of the treatment of SGS ice clouds in turbulence schemes which reflects a realistic ice condensation time scale not only for a better representation of high clouds in the current climate but for an improved projection of changes of high clouds due to global warming.

著者

太城 康良 和田 正法 野田 明 Tashiro Yasura Wada Masanori Noda Akira

出版者

三重大学地域人材教育開発機構

雑誌

三重大学高等教育研究 = Mie University Journal of Studies on Higher Education (ISSN:24325244)

巻号頁・発行日

vol.26, pp.81-84, 2020-03

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リーディング・ライティング教育を行う「教養ワークショップ」では,新書に対する書評を成果物としている.本研究の目的は,学生による評価を成績に加味することの妥当性を検証することである.相関解析の結果,教員による評価と学生による評価は,ある程度高い正の相関を示した.学生による評価では,単純な評価票を用い,評価法を指示し,匿名性を持たせることで,教員による評価と同様の傾向を持つようになる.条件を整えることで,学生による評価も成績に加味することの妥当性が示された.