There is a rainfall variability biennial relationship between Central America （CA） and equatorial South America （ESA） over the tropical western hemisphere, which is known to have arisen due to the combined effects...There is a rainfall variability biennial relationship between Central America （CA） and equatorial South America （ESA） over the tropical western hemisphere, which is known to have arisen due to the combined effects of ENSO and tropical North Atlantic （TNA） SST. Here, the authors report that this biennial rainfall relationship between CA and ESA has weakened remarkably since 2000, with weakening in both in-phase and out-of-phase rainfall transitions. The observed decadal changes in the biennial relationship between CA and ESA rainfall can be attributed to changes in the effects of ENSO and TNA SST since 2000, which may be associated with more frequent occurrences of the central Pacific or＇Modoki＇ type El Ni^o. The weakening of the association with ENSO for CA rainfall since 2000 might have given rise to the weakening of the in-phase rain transition from CA rainfall to the following ESA rainfall. The weakened linkage between boreal-winter ESA rainfall and the subsequent boreal-summer TNA SST since 2000 may have resulted in the weakening of the out- of-phase rainfall transition from boreal-winter ESA rainfall to the subsequent boreal-summer CA rainfall.展开更多
Recent studies suggest that the interannual variability in the tropical Pacific associated with the El Nino-Southern Oscillation has weakened since 2000. In this study, the authors report that the interannual variabil...Recent studies suggest that the interannual variability in the tropical Pacific associated with the El Nino-Southern Oscillation has weakened since 2000. In this study, the authors report that the interannual variability of the contrast in rainfall between the eastern equatorial Pacific and equatorial Atlantic has also weakened remarkably since 2000, attributable to the weakened interannual variability in the zonal sea surface temperature gradient between the eastern equatorial Pacific and equatorial Atlantic and in the associated equatorial low-level zonal wind across South America linking the two ocean basins. Diagnosis of a column-integrated moisture budget indicates that the weakening in the interannual variability of the contrast in rainfall is primarily attributable to the changes in moisture convergence associated with vertical motion. The results highlight the clear weakened interannual variability in the coupled equatorial Pacific-Atlantic climate system since 2000, including the Pacific El Nino, Atlantic Nino, equatorial zonal wind across South America, and rainfall over the eastern equatorial Pacific and equatorial Atlantic.展开更多
基金funded by the National Natural Science Foundation of China[grant number 41776031]the Guangdong Natural Science Foundation[grant number 2015A030313796]+3 种基金the National Program on Global Change and Air-Sea Interaction[grant number GASI-IPOVAI-04]the Strategic Priority Research Program of the Chinese Academy of Sciences[grant number XDA11010104]the program for scientific research start-upfunds of Guangdong Ocean Universitythe Foundation for Returned Scholars of the Ministry of Education of China
文摘There is a rainfall variability biennial relationship between Central America （CA） and equatorial South America （ESA） over the tropical western hemisphere, which is known to have arisen due to the combined effects of ENSO and tropical North Atlantic （TNA） SST. Here, the authors report that this biennial rainfall relationship between CA and ESA has weakened remarkably since 2000, with weakening in both in-phase and out-of-phase rainfall transitions. The observed decadal changes in the biennial relationship between CA and ESA rainfall can be attributed to changes in the effects of ENSO and TNA SST since 2000, which may be associated with more frequent occurrences of the central Pacific or＇Modoki＇ type El Ni^o. The weakening of the association with ENSO for CA rainfall since 2000 might have given rise to the weakening of the in-phase rain transition from CA rainfall to the following ESA rainfall. The weakened linkage between boreal-winter ESA rainfall and the subsequent boreal-summer TNA SST since 2000 may have resulted in the weakening of the out- of-phase rainfall transition from boreal-winter ESA rainfall to the subsequent boreal-summer CA rainfall.
基金funded by the Guangdong Natural Science Foundation[grant numbers 2015A0303137962016A030310015+7 种基金2016A030312004]the National Natural Science Foundation of China[grant numbers 412050264147601041676008]the Strategic Priority Research Program of the Chinese Academy of Sciences[grant number XDA11010104]the National Program on Global Change and Air–Sea Interaction[grant number GASI-IPOVAI-04]the Foundation for Returned Scholars of the Ministry of Education of Chinathe Foundation for Visiting Scholars from the China Scholarship Council[grant number20153012]
文摘Recent studies suggest that the interannual variability in the tropical Pacific associated with the El Nino-Southern Oscillation has weakened since 2000. In this study, the authors report that the interannual variability of the contrast in rainfall between the eastern equatorial Pacific and equatorial Atlantic has also weakened remarkably since 2000, attributable to the weakened interannual variability in the zonal sea surface temperature gradient between the eastern equatorial Pacific and equatorial Atlantic and in the associated equatorial low-level zonal wind across South America linking the two ocean basins. Diagnosis of a column-integrated moisture budget indicates that the weakening in the interannual variability of the contrast in rainfall is primarily attributable to the changes in moisture convergence associated with vertical motion. The results highlight the clear weakened interannual variability in the coupled equatorial Pacific-Atlantic climate system since 2000, including the Pacific El Nino, Atlantic Nino, equatorial zonal wind across South America, and rainfall over the eastern equatorial Pacific and equatorial Atlantic.
