南极极涡位置变化与热带西太平洋对流活动的关系

Relationship between Position Variation of the Antarctica Polar Vortex and Tropical Western Pacific Convection

摘要: 利用1979~2019年NOAA月平均向外长波辐射(Outgoing Long-Wave Radiation, OLR)资料，NCEP/NCAR月平均再分析资料，采用统计学和动力机制分析的方法，探讨了南极极涡位置变化与热带西太平洋对流活动异常的关系。研究发现：热带西太平洋关键区域120˚E~140˚E，10˚S~0˚ (3~5月)和120˚E~140˚E，5˚S~5˚N (6~8月)内对流活动增强，会激发从澳大利亚东部经南太平洋向大西洋西南部传播的类太平洋–南美(Pacific-South American, PSA)遥相关波列，进而导致南极极涡偏向西半球。年代际尺度上，1999~2019年，3~5月热带西太平洋地区和6~8月南太平洋辐合带(South Pacific Convergence Zone, SPCZ)附近对流活动增强，激发的类PSA遥相关波列，是导致南极极涡偏向西半球的重要原因。

Abstract: Based on the monthly mean OLR (Outgoing Long-Wave Radiation) data provided by NOAA and NCEP/NCAR monthly mean reanalysis data from 1979 to 2019, the relationship between the position change of the Antarctic polar vortexes and anomalous tropical Pacific convection is investigated using statistical and dynamic mechanism analysis methods. It founds that increased convection in the tropical western Pacific key areas 120˚E~140˚E, 10˚S~0˚ (March-May) and 120˚E~140˚E, 5˚S~5˚N (June-August) can stimulate the Pacific-South American (PSA) teleconnection wave train. It travels from eastern Australia through the southern Pacific to the southwestern Atlantic, in turn, deflecting the Antarctic Polar Vortex towards the Western Hemisphere. On the interdecadal scale, from 1999 to 2019, the convection in the Tropical Western Pacific region from March to May and convection near the South Pacific Convergence Zone (SPCZ) from June to August are enhanced, which excites the PSA-like teleconnection wave train and results in the deflection of the Antarctic polar vortex towards the Western Hemisphere.