DOI: 10.1175/JCLI-D-16-0294.1
Scopus记录号: 2-s2.0-85014030304
论文题名: Impact of atmospheric blocking on south america in austral summer
作者: Rodrigues R.R. ; Woollings T.
刊名: Journal of Climate
ISSN: 8948755
出版年: 2017
卷: 30, 期: 5 起始页码: 1789
结束页码: 1806
语种: 英语
Scopus关键词: Atmospheric temperature
; Mechanical waves
; Atmospheric blocking
; Large amplitude
; Long-term variability
; Madden-Julian oscillation
; Refraction patterns
; South atlantic convergence zones
; Southeast Brazil
; Surface temperatures
; Climatology
; air temperature
; amplitude
; atmospheric blocking
; drought
; Madden-Julian oscillation
; precipitation (climatology)
; Rossby wave
; summer
; surface temperature
; tropopause
; wave propagation
; Brazil
; Indian Ocean
英文摘要: This study investigates atmospheric blocking over eastern South America in austral summer for the period of 1979-2014. The results show that blocking over this area is a consequence of propagating Rossby waves that grow to large amplitudes and eventually break anticyclonically over subtropical South America (SSA). The SSA blocking can prevent the establishment of the South Atlantic convergence zone (SACZ). As such, years with more blocking days coincide with years with fewer SACZ days and reduced precipitation. Convection mainly over the Indian Ocean associated with Madden-Julian oscillation (MJO) phases 1 and 2 can trigger the wave train that leads to SSA blocking whereas convection over the western/central Pacific associated with phases 6 and 7 is more likely to lead to SACZ events. It is found that the MJO is a key source of long-term variability in SSA blocking frequency. The wave packets associated with SSA blocking and SACZ episodes differ not only in their origin but also in their phase and refraction pattern. The tropopause-based methodology used here is proven to reliably identify events that lead to extremes of surface temperature and precipitation over SSA. Up to 80% of warm surface air temperature extremes occur simultaneously with SSA blocking events. The frequency of SSA blocking days is highly anticorrelated with the rainfall over southeast Brazil. The worst droughts in this area, during the summers of 1984, 2001, and 2014, are linked to record high numbers of SSA blocking days. The persistence of these events is also important in generating the extreme impacts. © 2017 American Meteorological Society. 资助项目: CNPq, Conselho Nacional de Desenvolvimento Científico e Tecnológico
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/49811
Appears in Collections: 气候变化事实与影响
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作者单位: Department of Geosciences, Federal University of Santa Catarina, Florianópolis, Brazil; Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Oxford, United Kingdom
Recommended Citation:
Rodrigues R.R.,Woollings T.. Impact of atmospheric blocking on south america in austral summer[J]. Journal of Climate,2017-01-01,30(5)