新论文介绍:The Relationship between the Aleutian Low and the Australian Summer Monsoon at Interannual Time Scales

[发布日期: 2014-12-30 浏览量 667]

The relationship between the boreal winter (December, January, February) Aleutian Low (AL) and the simultaneous Australian summer monsoon (ASM) is explored in this study. A significant correlation is found between the North Pacific index (NPI) and ASM index, the bulk of which is attributed to the significant correlation after late 1970s. Significant differences in precipitation and outgoing long-wave radiation between typical negative and positive NPI years appear over the ASM area. A regression analysis of the circulation pattern against the NPI during the three months is performed separately. We propose that the NPI is related with the ASM circulation possibly through the changes in the upper level westerly jet. In a typical negative NPI (strong Aleutian Low) year, the jet is greatly reinforced and the anomalous anticyclonic circulation to the south is thus excited, from which the easterly wind anomalies °owing into the ASM region emanate. Further, strong sinking motion over the northern entrance region of the jet is enhanced, and the local Hadley circulation anomaly between the ASM region and the coast of East Asia is strengthened. In this way, anomalous upward motion over the ASM area can thus be strengthened, and the convective activity intensified. Then the monsoon rainfall over ASM area is increased. An \asymmetric" connection between AL and the monsoon is found in this study.