Oceanic thermal forcing of North Atlantic tropical cyclones

Abstract

The relationship between North Atlantic tropical cyclone (TC) peak intensity and subsurface ocean temperature is investigated in this study using atmospheric and ocean reanalysis data. It is found that the peak intensity of basin-wide strong TCs (Categories 4 and 5) is positively correlated with subsurface ocean temperature in the extratropical North Atlantic. A possible physical mechanism is that subsurface ocean temperature in the extratropical North Atlantic can affect local sea surface temperature (SST); on the other hand, the moisture generated by the warming SST in the extratropical North Atlantic is transported to the main region of TC development in the tropics by a near-surface anticyclonic atmospheric circulation over the tropical North Atlantic, affecting TC peak intensity. Moreover, coastal upwelling off Northwest Africa and southern Europe can affect subsurface ocean temperature in the extratropical North Atlantic. Therefore, the peak intensity of strong TCs is also found to be directly correlated with the water temperature in these two upwelling regions on an interdecadal timescale.摘要利用大气与海洋再分析数据等相关资料, 本项研究发现, 北大西洋强台风 (Saffir–Simpson分类中的第4和第5类) 的最大强度与亚热带北大西洋的次表层海温呈正相关. 由于亚热带北大西洋的次表层海温会影响当地的海表温度, 该地区海面产生的水汽通过近地面的反气旋大气环流可被输送到位于热带的台风主要发展区域, 进而影响台风的最大强度. 与此同时, 位于西非北部和南欧的近岸涌升流会影响亚热带北大西洋的次表层海温. 因此, 强台风的最大强度也被发现与上述两个涌升流区域的海温具有相关性, 但是这种相关性主要体现在年代际时间尺度上.