DOI: 10.1007/s00382-016-3093-8
Scopus记录号: 2-s2.0-84964556311
论文题名: A new perspective of the climatological features of upper-level cut-off lows in the Southern Hemisphere
作者: Pinheiro H.R. ; Hodges K.I. ; Gan M.A. ; Ferreira N.J.
刊名: Climate Dynamics
ISSN: 9307575
出版年: 2017
卷: 48, 期: 2017-01-02 起始页码: 541
结束页码: 559
语种: 英语
英文关键词: Climatology
; Cut-off lows
; Southern hemisphere
; Variability
英文摘要: This study presents a detailed view of the seasonal variability of upper-level cut-off lows (COLs) in the Southern Hemisphere. The COLs are identified and tracked using data from a 36-year period of the European Centre for Medium Range Weather Forecast reanalysis (ERA-Interim). The objective identification of the COLs uses a new approach, which is based on 300 hPa relative vorticity minima, and three restrictive criteria of the presence of a cold-core, stratospheric potential vorticity intrusion, and cut-off cyclonic circulation. The highest COL activity is in agreement with previous studies, located near three main continental areas (Australia, South America, and Africa), with maximum frequencies usually observed in the austral autumn. The COL mean intensity values show a marked seasonal and spatial variation, with maximum (minimum) values during the austral winter (summer), a unique feature that has not been observed previously in studies based on the geopotential. The link between intensity and lysis is examined, and finds that weaker systems are more susceptible to lysis in the vicinity of the Andes Cordillera, associated with the topographic Rossby wave. Lysis and genesis regions are close to each other, confirming that COLs are quasi-stationary systems. Also, COLs tend to move eastward and are faster over the higher latitudes. The mean growth/decay rates coincide with the major genesis and lysis density regions, such as the significant decay values across the Andes all year. As a consequence of using vorticity for the tracking method a longer lifetime of COLs is detected than in other studies, but this does not affect the total frequency of occurrence. Comparisons with other studies suggest that the differences in seasonality are due to uncertainties in the reanalyses and the methods used to identify COLs. © 2016, The Author(s). Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/53405
Appears in Collections: 过去全球变化的重建
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作者单位: Center for Weather Forecast and Climate Studies, National Institute for Space Research, Sao Jose dos Campos, SP, Brazil; Department of Meteorology, The University of Reading, Reading, United Kingdom
Recommended Citation:
Pinheiro H.R.,Hodges K.I.,Gan M.A.,et al. A new perspective of the climatological features of upper-level cut-off lows in the Southern Hemisphere[J]. Climate Dynamics,2017-01-01,48(2017-01-02)