气候变化领域集成服务门户(CCPortal): Four-dimensional structure and sub-seasonal regulation of the Indian summer monsoon multi-decadal mode

CCPortal

DOI	10.1007/s00382-020-05407-y
	Four-dimensional structure and sub-seasonal regulation of the Indian summer monsoon multi-decadal mode
	Rajesh P.V.; Goswami B.N.
发表日期	2020
ISSN	0930-7575
起始页码	2645
结束页码	2666
卷号	55
英文摘要	A better understanding of the drivers and teleconnection mechanisms responsible for the multi decadal mode (MDM) of variability of the Indian summer monsoon rainfall (ISMR) with major socio-economic impacts in the region through clustering of large-scale floods or droughts is key to improving the poor simulation of ISMR MDM by most climate models. Here, using the longest instrumental record of ISMR available (1813–2006) and longest atmospheric and oceanic re-analyses, the global four dimensional (space–time) structures of atmospheric and oceanic fields of the multi-decadal mode of ISMR and sub-seasonal evolution of the teleconnection mechanism are brought out, essential for understanding underlying drivers but lacking so far. The relationships between the spatial structure of winds, Sea Surface Temperature (SST) and thermocline depth with the ISMR MDM indicate that the tropical ocean over the Indo-Pacific domain is passive responding primarily to the surface winds associated with the mode. A close association between the Atlantic Meridional Overturning Circulation (AMOC), north Atlantic (NA) SST, NA sea surface salinity (SSS) and the ISMR MDM indicate a slow oceanic pathway linking NA SST and the ISMR. In addition to strong correlation (~ 0.9) between global spatial patterns of JJAS SST associated with the MDMs of ISMR, NA SST and AMOC, strong temporal coherence (correlations ~ 0.9) between them is suggestive of regulation of the ISMR MDM (T ~ 65-years) by the NA SST associated with the Atlantic Multidecadal Oscillation (AMO) through a ‘fast’ atmospheric bridge. On a seasonal time scale, the atmospheric bridge manifests in the form of a stationary Rossby wave train generated by an anticyclonic (cyclonic) barotropic vorticity located above positive (negative) SST anomaly over NA in two phases of the AMO. That the AMO SST is the driver of the ISMR MDM is further supported when we unravel the sub-seasonal face of the teleconnection between the two. We show that phase locking of active (break) spells with annual cycle during positive (negative) phases of the ISMR MDM are forced by a similar phase locking of barotropic anticyclonic (cyclonic) vorticity over the NA SST with the annual cycle through the generation of a quasi-stationary Rossby wave train with an anticyclonic (cyclonic) vorticity at upper level over the Indian region with the NA columnar vorticity leading Indian monsoon rainfall by about a week. Our findings provide a basis for enhanced predictability of tropical climate through slow modulation by extra-tropical SST. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.
英文关键词	Atmospheric bridge; Four-dimensional structure; Monsoon multi-decadal mode; Sub-seasonal evolution
语种	英语
scopus关键词	air-sea interaction; climate modeling; correlation; decadal variation; four-dimensional modeling; monsoon; overturn; rainfall; Rossby wave; sea surface temperature; spatial variation; teleconnection; Atlantic Ocean; Atlantic Ocean (North); Indian Ocean; Pacific Ocean
来源期刊	Climate Dynamics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/145290
作者单位	Department of Physics, Cotton University, Guwahati, Assam 781001, India
推荐引用方式 GB/T 7714	Rajesh P.V.,Goswami B.N.. Four-dimensional structure and sub-seasonal regulation of the Indian summer monsoon multi-decadal mode[J],2020,55.
APA	Rajesh P.V.,&Goswami B.N..(2020).Four-dimensional structure and sub-seasonal regulation of the Indian summer monsoon multi-decadal mode.Climate Dynamics,55.
MLA	Rajesh P.V.,et al."Four-dimensional structure and sub-seasonal regulation of the Indian summer monsoon multi-decadal mode".Climate Dynamics 55(2020).