1.Department of Marine Meteorology,College of Oceanic and Atmospheric Science,Ocean University of China;2.Hunan Meteorological Observatory/Key Open Laboratory of High Impact Weather of China Meteorological Administration;3.Huangdao Meteorological Bureau
The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan)
本文基于多源卫星遥感数据、Argo浮标数据和HYCOM (Hybrid Coordinate Ocean Model)再分析数据，分析了上层海洋对2020年第8号北上强台风“巴威”的温盐响应特征，结果表明：台风中心附近Ekman抽吸引起上升流，表层以下海水辐合高盐冷水上翻，Ekman输运方向由台风路径指向路径两侧沿岸，海水在黄海两侧沿岸堆积引起下降流。由此导致台风路径附近SST(Sea Surface Temperature，海表面温度)与SSH(Sea Surface Height，海表面高度)下降，SSS(Sea Surface Salinity，海表面盐度)上升，路径两侧沿岸SSH上升，次表层海水温度增加和盐度降低。此外，由于台风前进方向右侧的风速更大，右侧Ekman输运强度比左侧大。由于台风更靠近右侧陆地，地形阻挡导致风速减小，在济州岛西南侧的海域上空10 m风呈现反气旋旋转，出现负EPV(Ekman Pumping Velocity，Ekman抽吸速率)，为下降流，所以在台风和济州岛之间的海域存在着由强烈上升流到下降流的转变。这会让原本台风前进方向右侧强的夹卷和垂直混合进一步加强。这就导致了SST下降和SSS上升在台风前进方向右侧更为显著。除了夹卷和垂直混合，台风前进方向右侧SSS的增加还和表层海水由南向北的水平流动有关。
In this study, the upper ocean temperature and salinity responses to typhoon Bavi (2008) were investigated using multiple remote sensing data, Argo data and HYCOM (Hybrid Coordinated Ocean Model) reanalysis data. The results show that: Ekman pumping near the typhoon center causes Upwelling, the seawater below the surface converges with high salinity cold water and turns upward, the Ekman transport direction points from the typhoon path to the coasts on both sides of the path, and the seawater accumulates on both sides of the Yellow Sea and causes downwelling. This leads to a decrease in SST (Sea Surface Temperature) and SSH (Sea Surface Height) near the typhoon path, an increase in SSS (Sea Surface Salinity), an increase in SSH along both sides of the path, and an increase in subsurface seawater temperature and salinity. In addition, due to the higher wind speed on the right side of the typhoon's heading direction, the intensity of Ekman transport on the right side is greater than on the left side. As the typhoon is closer to the land on the right side, the terrain blocks the wind speed, and the 10 m wind above the sea area on the southwest side of Jeju Island shows an Anticyclone rotation, with a negative EPV (Ekman Pumping Velocity), which is a downwelling. Therefore, there is a transition from strong Upwelling to downwelling in the sea area between the typhoon and Jeju Island. This will further strengthen the strong entrainment and vertical mixing on the right side of the typhoon's heading direction. This leads to a more significant decrease in SST and an increase in SSS on the right side of the typhoon's heading direction. In addition to entrainment and vertical mixing, the increase in SSS on the right side of the typhoon's forward direction is also related to the horizontal flow of surface seawater from south to north.