西北太平洋上层海洋对台风响应的个例研究

基于数字台风网、欧洲中心ERA-Interim、美国国家海洋与大气局以及中国Argo实时资料中心的资料研究了西北太平洋上层海洋对台风"奥鹿"的响应。研究结果表明,当"奥鹿"移动速度在2 m/s以下时,强风应力产生的Ekman泵是上层海洋响应的主要机制,移动速度越慢,Ekman抽吸速率(EPV)越大,海表温度(SST)降温持续时间短,冷尾迹出现在台风中心位置处。当"奥鹿"移动速度达到6 m/s以上时,持续风应力驱动的惯性泵是主导机制,SST降温持续时间长,冷尾迹出现在台风路径的右侧。惯性泵比Ekman泵持续的时间长,但Ekman泵影响深度比惯性泵大得多。在"奥鹿"经过西北太平洋时,混合层深度(MLD)变浅并伴随着"冷抽吸"作用的出现。上层海洋中"冷抽吸"现象较"热泵"现象影响深度深,持续时间长,在"奥鹿"过境后可持续20天以上。

A case study of the response of northwest Pacific upper ocean to typhoon

The upper-ocean response to typhoon NORU is investigated based on data from Digital Typhoon,European Center ERA-Interim, USA National Oceanic and Atmospheric Administration and China Argo Real-time Data Center. The results show that when the moving speed of NORU is below 2 m/s, the Ekman pumping generated by strong wind stress is the main mechanism for the upper ocean response. Compared to inertial pumping,the slower the moving speed of NORU, the greater the Ekman pumping rate, resulting a shorter duration of Sea Surface Temperature cooling and the cold point appearing near the center of typhoon track. When the moving speed of NORU is above 6 m/s, the inertial pump driven by continuous wind stress is the dominant mechanism, resulting a long time SST cooling and cold point appearing on the right side of the typhoon track. Inertial pumping can last longer than Ekman pumping, however with much less influence than that of Ekman pumping. The shallower mixed layer depth (MLD)accompanied with "cold pumping" appear when NORU passing Northwest Pacific. After the crossing of NORU, "cold pumping" phenomenon in the upper ocean canlast for more than 20 days and affect deeper than the "heat pumping" , which can last only for a short time.