DOI: 10.1175/JCLI-D-15-0838.1
Scopus记录号: 2-s2.0-84993969542
论文题名: February drying in Southeastern Brazil and the Australian Monsoon: Global mechanism for a regional rainfall feature
作者: Kelly P. ; Mapes B.
刊名: Journal of Climate
ISSN: 8948755
出版年: 2016
卷: 29, 期: 20 起始页码: 7529
结束页码: 7546
语种: 英语
Scopus关键词: Atmospheric pressure
; Atmospheric thermodynamics
; Budget control
; Climatology
; Momentum
; Tropics
; Anticyclones
; Atmospheric circulation
; Barotropic flows
; Monsoons
; South atlantic convergence zones
; Subtropics
; Rain
; anticyclone
; atmospheric circulation
; barotropic motion
; monsoon
; rainfall
; subtropical convergence
; Australia
; Brazil
英文摘要: A dry February rainfall signal in southeastern Brazil is shown to be a robust, repeatable feature of climatology. This February depression or minimum in climatological rain curves has an amplitude of about 30% of the seasonal mean and coincides with a poleward excursion of tropical barotropic easterlies to about 25°S in austral midsummer. Momentum budget decomposition indicates that stationary eddy momentum flux [u*υ*] near 150 hPa in Australian longitudes is a main sink in that latitude belt's zonal momentum budget. A physical linkage among these phenomena is suggested by statistically significant interannual correlations among February anomalies of southeastern Brazil rainfall, zonal-mean zonal wind, and indices of the Australian monsoon. To test a causality hypothesis that the sharply peaked Australian region monsoon drives the sharp climatological dry signal over Brazil, an observation-inspired tropospheric heating signal near Australia is added to the temperature equation of the full-physics Community Atmosphere Model. Results indicate the near linearity of the global subtropical responses for the modest (roughly 1 and 2 K day-1) magnitudes and scales of imposed heating. Consistent with the hypothesis, this imposed heating robustly causes easterly changes to subtropical, barotropic, zonal-mean momentum, a westward displacement of the mean synoptic-scale pattern in the western Atlantic (the western edge of the subtropical high), and reduced rainfall in southeastern Brazil. These results are closely analogous to the previous findings on a related boreal summer subtropical signal. © 2016 American Meteorological Society. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/50241
Appears in Collections: 气候变化事实与影响
There are no files associated with this item.
作者单位: Department of Atmospheric Science, University of Miami, Miami, FL, United States; Pacific Northwest National Laboratory, Richland, WA, United States
Recommended Citation:
Kelly P.,Mapes B.. February drying in Southeastern Brazil and the Australian Monsoon: Global mechanism for a regional rainfall feature[J]. Journal of Climate,2016-01-01,29(20)