中高纬度印度洋海温与西北太平洋夏季台风生成数的相关性

从独立性、显著性和滞后性角度分析西北太平洋夏季台风生成数(WNPTYF)与前期中高纬度印度洋海表温度(SST)的关系, 结果表明:前期中高纬度印度洋SST与WNPTYF相关显著, 且独立于热带东太平洋SST(或ENSO)对WNPTYF影响;中高纬度印度洋SST年际变化对WNPTYF年际变化的指示能力相当或超过热 带东太平洋, 综合两者的影响预测夏季西北太平洋台风生成数的变化有非常重要的现实意义。进一步的分析表明, 中高纬度印度洋SST对WNPTYF影响有明显的滞后性, 前期相关显著而同期相关不显著。这种滞后性意味着其前期中高纬度印度洋SST对WNPTYF的影响并不是通过SST的持续性, 而很可能是通过南半球大气活动的持续性及异常信号在大气中的传播而影响到夏季的环流, 最终影响WNPTYF异常。这种影响机制有待进一步研究。

Relationship between Sea Surface Temperature of Middle-High Latitude Indian Ocean and Summer Typhoon Frequencies over the Western North Pacific

Previous analyses have focused on the relationship between sea surface temperatures (SSTs) over tropical oceans and summer typhoons over the western North Pacific (WNPTYF); however, few studies have been conducted on other oceans. To determine the relationship between the WNPTYF and SSTs over the middle-high latitude Indian Ocean (MHIO), their independence, significance, and hysteretic characteristics are examined in this study. The results show that SSTs over MHIO can influence WNPTYF independently when the effect of El Ni?o-Southern Oscillation (ENSO) is not considered. The annual change in SST over MHIO can indicate WNPTYF’s yearly change, in addition to that over the tropical East Pacific, with greater accuracy. Synthesis of the SST anomalies over the two areas is useful when the WNPTYF forecast is abnormal. Results also show that SSTs over MHIO influence WNPTYF in hysteresis, with significant correlation in the previous stage, from January to April, and week correlation at the same time, from June to September. The lagged influence of SSTs over MHIO to WNPTYF indicates that the former affects the latter through continuity of the abnormal atmospheric action over the Southern Hemisphere rather than by SST steadiness. However, for better understanding of this mechanism, further research is required.