首先, 采用高分辨率的卫星资料研究了春季我国东部海区海洋锋区附近的海温与风场之间的关系, 资料分析表明海温与海表面风速之间存在明显的正相关关系, 特别是在海洋锋强的年份, 这种正相关关系更明显。资料分析还表明春季是黄海、 东海海洋锋最强的季节, 海温与海表面风速的对应关系在春季尤为明显。然后, 采用一个高分辨率和先进物理方案的中尺度模式探讨了海洋影响大气的机制。控制试验再现了海洋锋区附近海温与海表面风速之间的正相关关系。模拟的边界层垂直结构说明海温能够明显改变锋区两侧边界层大气的稳定度和垂直混合的强弱, 证明了垂直混合机制的存在。而另一方面, 对控制试验和平滑海温试验的水平动量方程中各收支项的比较分析发现, 由于海洋锋的存在而产生的气压梯度力对穿越锋区的空气的加速也有相当重要的贡献。综合观测和模拟结果说明春季我国东部海区海洋温度锋区的海洋—大气相互作用过程中海洋对大气的影响非常明显, 在海洋影响大气的机理方面, 海平面气压调整机制和垂直混合机制都在起作用。
Air-sea interaction in the vicinity of an oceanic front in East China Sea during spring time is firstly investigated with high-resolution satellite measurements. The analyses reveal a significant positive correlation between sea surface temperature and surface wind speed. This positive correlation becomes even more significant when the SST front is intensified. The satellite measurements also indicate that in spring the oceanic front is strongest and the collocation of SST and wind speed anomalies is most significant. Then, a high-resolution mesoscale atmospheric model with state-of-the-art physical parameterizations is used to investigate the mechanisms by which the ocean can influence the atmosphere. The control run successfully reproduces the SST-wind positive correlation in the vicinity of the oceanic front. The simulated vertical structure of the Planetary Boundary Layer (PBL) indicates that the changes of SST can cause large differences in static stability and vertical mixing between cold and warm sides of the SST front and thus confirm the existence of vertical mixing mechanism. The analyses of the momentum budgets in the control and smoothed SST runs indicate that the pressure gradient force induced by the oceanic front is also important for the acceleration of cross-frontal winds. All in all, satellite observations and simulation results suggest that the ocean-to-atmosphere forcing plays a key role in air-sea interactions over the SST frontal area in East China Sea during spring time. Both the SLP (sea level pressure) mechanism and the vertical mixing mechanism are responsible for this ocean-to-atmospheric forcing.