JpGU-AGU Joint Meeting 2017

講演情報

[EE]Eveningポスター発表

セッション記号 A (大気水圏科学) » A-AS 大気科学・気象学・大気環境

[A-AS02] [EE] Cloud-Resolving Model Simulations for Cloud-Related Processes in Climate and Weather Studies

2017年5月22日(月) 17:15 〜 18:30 ポスター会場 (国際展示場 7ホール)

[AAS02-P04] Comparison between bulk and bin cloud microphysical schemes for warm rain

*久芳 奈遠美1鈴木 健太郎1Roh Woosub1清木 達也2佐藤 正樹1,2 (1.東京大学 大気海洋研究所、2.海洋研究開発機構)

キーワード:Cloud microphysical scheme, satellite simulator, two-moment bin scheme, two-moment bulk scheme

Two-moment bin and two-moment bulk cloud microphysical schemes were compared using a two-dimensional kinematic driver model and a forward simulator of satellite measurements. The conversion process from cloud droplets to raindrops was focused. From numerical experiments, the following results were found. The bulk and bin schemes studied in this paper show the effect of cloud droplet number on precipitation sufficiently, and the difference in rainfall amount between these schemes was small in contrast to previous studies. The vertical distributions of mass of rain water and number of raindrops in these schemes are quite different. It can be caused by overestimation of falling velocity of rainwater and underestimation of self-collection process (or overestimation of collisional breakup process) of raindrops in the bulk scheme. Time evolutions and patterns of the relationships between horizontally averaged reflectivity and optical depth from cloud top were similar between these schemes. The slope factor of this relationships (changing rate of horizontally averaged reflectivity for optical depth from cloud top) near the cloud top in a later stage of cloud lifetime is smaller in bulk scheme than bin scheme. Previous studies showed that the slope factor relates to bulk collection efficiency. However, it was shown that bulk collection efficiency assumed in this bulk scheme is almost same as that estimated in the bin scheme, and that overestimated falling velocity of raindrops leads to the smaller slope factor in this bulk scheme.