海表面盛行风背景下大气对黑潮海洋锋的响应特征

Atmospheric response to the sea surface temperature front of Kuroshio over the East China Sea under different prevailing surface winds in spring

采用一系列高分辨率的卫星资料,应用高通滤波等方法,研究了春季不同海表面盛行风背景下,东海黑潮海洋锋区附近的海气关系。观测分析表明:在东海,春季3种不同海表面盛行风条件下海表面温度与海表面风速之间都存在明显的正相关关系,表现为海洋对大气的强迫作用。大气对海洋锋的响应在3种不同盛行风条件下也存在明显的差异。在西北盛行风和东南盛行风背景下,即当风向垂直于海洋锋由冷侧(暖侧)吹向暖侧(冷侧)时,海表面风的辐散(辐合)出现在海洋锋上空。同时,海洋锋对海平面气压(SLP)、降水和对流活动的影响较弱,表明大气对海洋锋的响应主要局限在大气边界层内。在东北盛行风背景下,即当风平行于海洋锋时,在海洋锋的暖(冷)水侧上空为海表面风的辐合(辐散),并与SLP的异常低(高)值相对应,主要雨带出现在黑潮暖舌上空。无论从总降水还是层云、对流降水频次的空间分布来看,盛行东北风时,海表面温度对其上雨带的影响最为明显。分析结果还表明,在不同盛行风背景下,海洋锋附近的海气关系由不同的物理机制在起主导作用。当盛行平行于海洋锋的东北风时,主要由SLP调整机制起作用;而盛行垂直于海洋锋的西北风时则主要由垂直混合机制起作用。

A series of high-resolution satellite data is used to investigate the sea-air interaction around the Kuroshio sea surface temperature （SST） front area over the East China Sea under different prevailing surface winds in spring.Results show that a significant positive correlation exists between the SST and the sea surface wind speed under three different kinds of prevailing surface wind,which presents the sea-air forcing.The responses of atmosphere to the SST front over the East China Sea under three different kinds of prevailing surface wind are obviously different.Under the northwest and southeast prevailing surface winds,the wind perpendicular to the SST front moves from the colder （warmer） flank to the warmer （colder） one,sea surface wind diverges （converges） over the SST front.Meanwhile,the weak influence of the SST front on the sea level pressure （SLP）,precipitation and convection indicates that the atmospheric responses to the SST front are mainly confined in the atmospheric boundary layer.Under the northeast prevailing surface wind,the sea surface wind parallel to the SST front converges （diverges） over the warmer （colder） flank of the front,corresponding to the low （high） value of SLP anomalies.An obvious rainband extends along the Kuroshio current over the East China Sea.Whether in terms of the total precipitation,or the distribution of stratiform and convective precipitation frequency,SST has the most obvious effects on the occurrence of its above rainband under the northeast prevailing sea surface wind.It is also found that different physical mechanisms are responsible for the air-sea interaction over the SST front under different prevailing surface winds.The SLP adjustment mechanism works when the northeast surface wind parallel to the SST front was prevailing,while the vertical mixing mechanism became the key factor when the northwest surface wind vertical to the SST front was prevailing.