An Asymmetry in the IOD and ENSO Teleconnection Pathway and Its Impact on Australian Climate

被引:134
作者
Cai, Wenju [1 ,2 ]
van Rensch, Peter [1 ,2 ]
Cowan, Tim [1 ,2 ]
Hendon, Harry H. [3 ]
机构
[1] CSIRO Marine & Atmospher Res, CSIRO Wealth Oceans Natl Res Flagship, Aspendale, Vic 3195, Australia
[2] CSIRO Marine & Atmospher Res, CSIRO Water Healthy Country Flagship, Aspendale, Vic 3195, Australia
[3] Ctr Australian Weather & Climate Res, Bur Meteorol, Melbourne, Vic, Australia
关键词
INDIAN-OCEAN DIPOLE; EL-NINO; THERMODYNAMIC REGULATION; MODE EVENTS; LA-NINA; NONLINEARITY; REANALYSIS;
D O I
10.1175/JCLI-D-11-00501.1
中图分类号
P4 [大气科学(气象学)];
学科分类号
0706 ; 070601 ;
摘要
Recent research has shown that the climatic impact from El Nino-Southern Oscillation (ENSO) on middle latitudes west of the western Pacific (e.g., southeast Australia) during austral spring (September November) is conducted via the tropical Indian Ocean (TIO). However, it is not clear whether this impact pathway is symmetric about the positive and negative phases of ENSO and the Indian Ocean dipole (IOD). It is shown that a strong asymmetry does exist. For ENSO, only the impact from El Nino is conducted through the TIO pathway; the impact from La Nina is delivered through the Pacific South America pattern. For the IOD, a greater convection anomaly and wave train response occurs during positive IOD (pIOD) events than during negative IOD (nIOD) events. This "impact asymmetry" is consistent with the positive skewness of the IOD, principally due to a negative skewness of sea surface temperature (SST) anomalies in the east IOD (IODE) pole. In the IODE region, convection anomalies are more sensitive to a per unit change of cold SST anomalies than to the same unit change of warm SST anomalies. This study shows that the IOD skewness occurs despite the greater damping, rather than due to a breakdown of this damping as suggested by previous studies. This IOD impact asymmetry provides an explanation for much of the reduction in spring rainfall over southeast Australia during the 2000s. Key to this rainfall reduction is the increased occurrences of pIOD events, more so than the lack of nIOD events.
引用
收藏
页码:6318 / 6329
页数:12
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