DOI: 10.1007/s00382-012-1340-1
Scopus记录号: 2-s2.0-84874315322
论文题名: Spring asymmetric mode in the tropical Indian Ocean: Role of El Niño and IOD
作者: Chakravorty S. ; Chowdary J.S. ; Gnanaseelan C.
刊名: Climate Dynamics
ISSN: 9307575
出版年: 2013
卷: 40, 期: 2017-05-06 起始页码: 1467
结束页码: 1481
语种: 英语
英文关键词: ENSO
; IOD
; Northwest Pacific anticyclone
; Spring asymmetric mode
; Tropical Indian Ocean
英文摘要: The spring asymmetric mode over the Tropical Indian Ocean (TIO) is characterized by contrasting patterns of rainfall and surface wind anomalies north and south of Equator. The asymmetric pattern in rainfall has evolved as a leading mode of variability in the TIO and is strongly correlated with El Niño-Southern Oscillation (ENSO) and positive Indian Ocean Dipole (IOD). The evolution of the asymmetric pattern in rainfall and surface wind during pure El Niño/IOD and co-occurrence years are examined in the twentieth century reanalysis for the period of 1871-2008 and atmospheric general circulation model (AGCM) simulations. The study revealed that spring asymmetric mode is well developed when El Niño co-occurred with IOD (positive) and is driven by the associated meridional gradients in sea surface temperature (SST) and sea level pressure (SLP). The pure El Niño composites are characterized by homogeneous (spatially) SST anomalies (positive) and weaker SLP gradients and convection, leading to weak asymmetric mode. The asymmetric mode is absent in the pure IOD (positive) composites due to the persistence of east west SST gradient for a longer duration than the co-occurrence years. The meridional gradient in SST anomalies over the TIO associated with the ENSO-IOD forcing is therefore crucial in developing/strengthening the spring asymmetric mode. The northwest Pacific anticyclonic circulation further strengthen the asymmetric mode in surface winds by inducing northeasterlies in the north Indian Ocean during pure El Niño and co-occurrence years. The simulations based on AGCM, forced by observed SSTs during the period of 1871-2000 supported the findings. The analysis of available station and ship track data further strengthens our results. © 2012 Springer-Verlag. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/55074
Appears in Collections: 过去全球变化的重建
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作者单位: Indian Institute of Tropical Meteorology, Pune, 411008, India
Recommended Citation:
Chakravorty S.,Chowdary J.S.,Gnanaseelan C.. Spring asymmetric mode in the tropical Indian Ocean: Role of El Niño and IOD[J]. Climate Dynamics,2013-01-01,40(2017-05-06)