热带气旋与海洋暖涡间的海-气相互作用

Air-Sea Interaction between Tropical Cyclone and Ocean Warm Core Ring

采用区域海-气耦合模式WRF-sbPOM,设计敏感性试验,通过控制海洋暖涡(WCR)的有无以及暖涡与热带气旋(TC)的相对位置,对理想性TC与WCR间的海-气相互作用进行模拟研究。结果表明,当TC经过WCR后,因为WCR区域较厚的暖水使海表温度在TC经过后并没有明显的降低,削弱了海–气间的负反馈机制,所以TC强度增大。但受作用时间、气旋强度以及WCR处较强流速的影响,TC强度增大的程度不同,移动速度较慢的TC有明显增强,移动速度较快的TC增强不明显。同时TC向海洋中输入大量的机械能,与WCR的反气旋式环流发生相互作用,WCR的形状由最初的圆形变为椭圆形,热容量损失约30%,动能损失约60%。

The air-sea interaction between a tropical cyclone （TC） and an ocean warm core ring （WCR） is studied using a regional air-sea coupled model WRF-sbPOM （Weather Research and Forecasting-Stony Brook Parallel Ocean Model）. A set of sensitivity experiments are carried out to examine the mutual response of the TC and the ocean without WCR and with a WCR placed on different locations alone the TC＇s track. Model results reveal that the TC intensifies when it passes a WCR due to the fact that the sea surface temperature （SST） does not cool sharply because thick thermoeline underneath the WCR suppresses the so-called negative feedback mechanism between the TC and the ocean. The degree of the TC intensification depends on the TC migration speed, TC strength, and the flow velocity of the WCR. The slow-moving TC intensifies sharply, while the fast-moving TC does not. Meanwhile, momentum is transferred from the TC to the ocean, interacting with WCR＇s anticyclonic flow. The shape of the WCR evolves from circular to ellipse, with ocean heat content loss by 30% and kinetic energy loss by 60%.