黑潮延伸体海温多尺度结构经向移动对中高纬气旋活动的影响

Mid-latitude cyclone is a large low pressure weather system that arises from baroclinic instability. Its activity significantly alters the atmospheric momentum, energy exchange and moisture transport, and increases the extreme event risk such as flood. Mid-latitude cyclone activity is strongly influenced by the underlying surface and ocean, the overlying stratosphere, and the tropical and polar atmosphere on either side. On the lower boundary ocean, the correspondent west boundary current and the multi-scale sea surface temperature (SST) structure comprised of the gradient, mesoscale and basin-scale SST on the vicinity of the current significantly drives mid-latitude cyclone, and it is important to for disaster mitigation to reveal the influence mechanism of meridional shift of this multi-scale SST structure on mid-latitude cyclone activity. The present program utilizes high-resolution SST data and numerical modeling and aims at northern hemisphere Kuroshio Extentension area, identify the influence pattern of SST multi-scale structure meridional shift on mid-latitude cyclone; reveal its mechanism through diagnosing energy budget, and quantify the contribution of basin-scale and mesoscale SST on mid-latitude cyclone. This research is essential to improve understanding of mid-latitude cyclone activity driving mechanism and disaster mitigation.

由于斜压不稳定而产生的大型低压涡旋系统—中高纬气旋，显著改变大气动量、能量交换与水汽输送，增加洪涝等极端灾害风险。中高纬气旋活动受到气旋下方海洋或陆地、上方平流层、以及侧面极地和热带区域天气气候条件的强烈影响，下边界海洋所对应的西边界流及其两侧锋面、涡旋与周边海盆尺度海温共同构成的海温多尺度结构驱动气旋活动。研究并揭示这种海温多尺度结构经向移动对气旋活动的影响机制对于减少灾害风险十分重要。本项目拟针对北半球西边界黑潮延伸体典型区，结合高分辨率海温数据与数值模拟试验，辨识海温多尺度结构经向移动对中高纬气旋活动的影响规律；结合能量收支分析研究并揭示其影响机制，定量区分海盆、锋面及涡旋尺度海温对气旋活动影响的相对贡献。该研究对于增加气旋活动驱动机制的理解及防灾减灾具有重要意义。

由于斜压不稳定而产生的大型低压涡旋系统—中高纬气旋可显著增加洪涝等极端灾害风险，其活动受到下边界海洋所对应的西边界流及其两侧锋面、涡旋与周边海盆尺度海温共同构成的海温多尺度结构的影响。研究并揭示这种海温多尺度结构经向移动对气旋活动的影响机制对于减少灾害风险十分重要。本项目针对北半球西边界黑潮延伸体典型区，结合高分辨率海温数据与数值模拟试验，辨识了黑潮延伸体海温多尺度结构偏北对应气旋偏强，偏南对应气旋减弱的影响规律，该关系与下游降水及水汽辐合辐散、感热潜热等变量的强弱变化相对应；结合能量收支分析研究并揭示黑潮延伸体通过影响海洋边界层上湍流热通量及近表层辐合强迫次级环流并加强气旋强度的影响机制；锋面、涡旋尺度海温对于气旋生成贡献约30%。该研究对于增加气旋活动驱动机制的理解及防灾减灾具有重要意义。