利用衛星測高偵測颱風所引起的中尺度氣旋渦

Detecting Cyclonic Eddies Induced by Global Super Typhoons by Using Satellite Altimetry

鄭宜婷(Yi-Ting Cheng) ； 曾若玄(Ruo-Shan Tseng) ； 張育嘉(Yu-Chia Chang) ； 陳昭銘(Jau-Ming Chen)

《航測及遙測學刊》 23卷1期 (2018/03) Pp. 15-24

https://doi.org/10.6574/JPRS.201803_23(1).0002

摘要

當颱風的行進速度小於該海域的第一斜壓模之相位速度時，定義為緩慢移動，本研究探討颱風在緩慢移動狀態下所造成的表層流場特性，在1993-2015期間全球一共有22個緩慢移動的超級颱風，分析其衛星海面測高資料、衛星追蹤表面漂流浮球與實測海洋水溫剖面數據，發現其中有7個超級颱風促使(或加強)中尺度氣旋渦的產生。這些氣旋渦的特徵比起一般大洋的渦漩更為明顯，其中又以西北太平洋與南太平洋的超級颱風渦漩最強，流速可達2 m/s，渦漩動能達到4800 cm^2/s^2，存活時間多達8個月。水溫資料顯示，當颱風消失後，氣旋渦結構持續增強且形成湧升流。此外，渦漩動能與颱風行進速度亦呈現負相關性。

關鍵字

超級颱風 ； 中尺度氣旋渦 ； 衛星高度儀 ； 表面漂流浮球 ； 絕對動力地形

並列摘要

This study analyzed data from satellite altimeter measurements, satellite-tracked surface drifters and global typhoons from 1993 to 2015 to investigate mesoscale cyclonic eddies induced by slow-moving super typhoons, defined as that the translation speed of typhoon is less than the phase speed of first baroclinic mode in that ocean. Our results show that among 22 slow-moving super typhoons found globally in this period, only seven typhoons produced or strengthened cyclonic eddies (3 in Northern Hemisphere, and 4 in Southern Hemisphere). Comparing to the averaged characteristics of eddies in open oceans, these typhoon-induced eddies had stronger intensity and longer lifespan, especially for the Northwestern Pacific and South Pacific Oceans. Take TC-Nida-eddy for instance, maximum current speeds of over 2 m/s, lifespan of 8 month, temperature drop of 4.5 ˚C and formation of upwelling were observed. A negative correlation is also found between eddy’s EKE and TC's translation speed.

並列關鍵字

Super Typhoon ； Mesoscale Cyclonic Eddy ； Satellite Altimetry ； Surface Drifter ； Absolute Dynamic Topography

參考文獻

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