气候变化领域集成服务门户(CCPortal): Understanding Negative Subtropical Shallow Cumulus Cloud Feedbacks in a Near-Global Aquaplanet Model Using Limited Area Cloud-Resolving Simulations

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DOI	10.1029/2018MS001572
	Understanding Negative Subtropical Shallow Cumulus Cloud Feedbacks in a Near-Global Aquaplanet Model Using Limited Area Cloud-Resolving Simulations
	Narenpitak P.; Bretherton C.S.
发表日期	2019
ISSN	19422466
起始页码	1600
结束页码	1626
卷号	11 期号:6
英文摘要	Limited area cloud-resolving model (CRM) simulations called LASAM are used to reproduce and understand negative subtropical shallow cumulus cloud feedbacks in a near-global aquaplanet CRM (NGAqua) with 4-K sea surface temperature (SST) warming. NGAqua spans a large tropical channel domain, with 4-km horizontal resolution, zonally symmetric equatorially peaked SST, and no cumulus parameterization. Prior work showed that its coarsely resolved shallow cumulus increases with warming. It was suggested that with warmer SST, the moister boundary layer is destabilized by more clear-sky radiative cooling, driving more cumulus convection. A small doubly periodic version of the same CRM is configured to analyze this low cloud increase in a simpler context. It is driven by steady thermodynamic and advective forcing profiles averaged over the driest subtropical column humidity quartile of NGAqua. Sensitivity studies separate effects of radiative cooling and free tropospheric relative humidity changes from other aspects of NGAqua's warmer climate. Enhanced clear-sky radiative cooling explains most of the cloud increase due to SST warming, regardless of CRM model resolution and advection scheme. A boundary layer energy budget shows that the downward entrainment heat flux strengthens to balance enhanced radiative cooling, carried by a stronger updraft cloud mass flux from a larger cumulus cloud fraction. In deeper trade cumulus layers, the enhanced radiative cooling in a warming climate may be balanced by increased precipitation warming, leaving the cloud coverage area almost unchanged. With larger domain sizes, shallow cumulus self-aggregates, especially with higher SST, marginally increasing domain-mean cloud fraction, but this is a secondary contributor to the cloud feedback. ©2019. The Authors.
英文关键词	boundary layer radiative cooling; large eddy simulations; limited area cloud-resolving model; near-global aquaplanet cloud-resolving model; negative cloud feedbacks; subtropical shallow cumulus
语种	英语
scopus关键词	Advection; Boundary layers; Budget control; Clouds; Heat flux; Large eddy simulation; Oceanography; Radiative Cooling; Surface waters; Tropics; Cloud feedbacks; Cloud resolving model; Cloud resolving simulations; Cumulus parameterization; Relative humidity changes; Sea surface temperature (SST); Shallow cumulus; Shallow cumulus clouds; Precipitation (meteorology); advection; boundary layer; cooling; cumulus; energy budget; large eddy simulation; model validation; radiative forcing; relative humidity; sea surface temperature; updraft
来源期刊	Journal of Advances in Modeling Earth Systems
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/156902
作者单位	Department of Atmospheric Sciences, University of Washington, Seattle, WA, United States
推荐引用方式 GB/T 7714	Narenpitak P.,Bretherton C.S.. Understanding Negative Subtropical Shallow Cumulus Cloud Feedbacks in a Near-Global Aquaplanet Model Using Limited Area Cloud-Resolving Simulations[J],2019,11(6).
APA	Narenpitak P.,&Bretherton C.S..(2019).Understanding Negative Subtropical Shallow Cumulus Cloud Feedbacks in a Near-Global Aquaplanet Model Using Limited Area Cloud-Resolving Simulations.Journal of Advances in Modeling Earth Systems,11(6).
MLA	Narenpitak P.,et al."Understanding Negative Subtropical Shallow Cumulus Cloud Feedbacks in a Near-Global Aquaplanet Model Using Limited Area Cloud-Resolving Simulations".Journal of Advances in Modeling Earth Systems 11.6(2019).