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	Multi-scale forcing and the formation of subtropical desert and monsoon
	Wu, G. X.1; Liu, Y.1; Zhu, X.1,2; Li, W.3; Ren, R.1; Duan, A.1; Liang, X.3
刊名	Annales geophysicae
	2009
卷号	27期号:9页码:3631-3644
关键词	Meteorology and atmospheric dynamics Climatology General circulation Precipitation
ISSN号	0992-7689
通讯作者	Liu, y.(lym@lasg.iap.ac.cn)
英文摘要	This study investigates three types of atmospheric forcing across the summertime subtropics that are shown to contribute in various ways to the occurrence of dry and wet climates in the subtropics. to explain the formation of desert over the western parts of continents and monsoon over the eastern parts, we propose a new mechanism of positive feedback between diabatic heating and vorticity generation that occurs via meridional advection of planetary vorticity and temperature. monsoon and desert are demonstrated to coexist as twin features of multi-scale forcing, as follows. first, continent-scale heating over land and cooling over ocean induce the ascent of air over the eastern parts of continents and western parts of oceans, and descent over eastern parts of oceans and western parts of continents. second, local-scale sea-breeze forcing along coastal regions enhances air descent over eastern parts of oceans and ascent over eastern parts of continents. this leads to the formation of the well-defined summertime subtropical losecod quadruplet-heating pattern across each continent and adjacent oceans, with long-wave radiative cooling (lo) over eastern parts of oceans, sensible heating (se) over western parts of continents, condensation heating (co) over eastern parts of continents, and double dominant heating (d: lo+co) over western parts of oceans. such a quadruplet heating pattern corresponds to a dry climate over the western parts of continents and a wet climate over eastern parts. third, regional-scale orographic-uplift-heating generates poleward ascending flow to the east of orography and equatorward descending flow to the west. the tibetan plateau (tp) is located over the eastern eurasian continent. the tp-forced circulation pattern is in phase with that produced by continental-scale forcing, and the strongest monsoon and largest deserts are formed over the afro-eurasian continent. in contrast, the rockies and the andes are located over the western parts of their respective continents, and orography-induced ascent is separated from ascent due to continental-scale forcing. accordingly, the deserts and monsoon climate over these continents are not as strongly developed as those over the eurasian continent. a new mechanism of positive feedback between diabatic heating and vorticity generation, which occurs via meridional transfer of heat and planetary vorticity, is proposed as a means of explaining the formation of subtropical desert and monsoon. strong low-level long wave radiative cooling over eastern parts of oceans and strong surface sensible heating on western parts of continents generate negative vorticity that is balanced by positive planetary vorticity advection from high latitudes. the equatorward flow generated over eastern parts of oceans produces cold sea-surface temperature and stable stratification, leading in turn to the formation of low stratus clouds and the maintenance of strong in situ longwave radiative cooling. the equatorward flow over western parts of continents carries cold, dry air, thereby enhancing local sensible heating as well as moisture release from the underlying soil. these factors result in a dry desert climate. over the eastern parts of continents, condensation heating generates positive vorticity in the lower troposphere, which is balanced by negative planetary vorticity advection of the meridional flow from low latitudes. the flow brings warm and moist air, thereby enhancing local convective instability and condensation heating associated with rainfall. these factors produce a wet monsoonal climate. overall, our results demonstrate that subtropical desert and monsoon coexist as a consequence of multi-scale forcing along the subtropics.
WOS关键词	PACIFIC WARM POOL ; TIBETAN PLATEAU ; SUMMER ; CIRCULATION ; MODEL ; ANTICYCLONES ; REANALYSES ; DYNAMICS ; CLIMATE ; ECMWF
WOS研究方向	Astronomy & Astrophysics ; Geology ; Meteorology & Atmospheric Sciences
WOS类目	Astronomy & Astrophysics ; Geosciences, Multidisciplinary ; Meteorology & Atmospheric Sciences
语种	英语
出版者	COPERNICUS PUBLICATIONS
WOS记录号	WOS:000270321600024
内容类型	期刊论文
URI标识	http://www.corc.org.cn/handle/1471x/2402581
专题	中国科学院大学
通讯作者	Liu, Y.
作者单位	1.Chinese Acad Sci, State Key Lab Numer Modeling Atmospher Sci & Geop, Inst Atmospher Phys, Beijing 100029, Peoples R China 2.Chinese Acad Sci, Grad Univ, Beijing 100029, Peoples R China 3.China Meteorol Adm, Natl Climate Ctr, Beijing 100081, Peoples R China
推荐引用方式 GB/T 7714	Wu, G. X.,Liu, Y.,Zhu, X.,et al. Multi-scale forcing and the formation of subtropical desert and monsoon[J]. Annales geophysicae,2009,27(9):3631-3644.
APA	Wu, G. X..,Liu, Y..,Zhu, X..,Li, W..,Ren, R..,...&Liang, X..(2009).Multi-scale forcing and the formation of subtropical desert and monsoon.Annales geophysicae,27(9),3631-3644.
MLA	Wu, G. X.,et al."Multi-scale forcing and the formation of subtropical desert and monsoon".Annales geophysicae 27.9(2009):3631-3644.

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