京津冀地区与海风锋相互作用的对流系统的发展预判分析

Analysis of the development prognosis of the convective systems interacting with sea breeze front in the Beijing-Tianjin-Hebei region

运用WRF模式,对京津冀地形触发对流系统与海风锋相互作用的两个个例开展了数值模拟,通过对两个个例模拟的广义湿位涡异常和雷达回波分布的对比分析,对广义湿位涡异常预判该类天气过程中对流系统发展的潜力进行了检验。分析结果显示,广义湿位涡异常较雷达回波提前0.5至1 h示踪到山地背风坡和海风锋处的对流系统的发展。斜压与水汽梯度相互作用和非绝热加热对广义湿位涡异常提前示踪山地背风坡和海风锋处对流系统发展有重要的贡献。过山气流的显著扰动和午后相对于陆地大气较为冷湿的海风辐合上升是分别造成山地背风坡和海风锋出现明显的斜压与水汽梯度相互作用的主要原因。

In this study,the generalized moist potential vorticity （GMPV）anomaly and radar echoes were compared to verify the potential application of the GMPV anomaly in the development prognosis of the convective systems that are triggered by ter-rain and interact with sea breeze front in the Beijing-Tianjin-Hebei region.Simulations of two cases with the WRF （Weather Research and Forecasting）model were carried out for the analysis.The results showed that GMPV anomaly emerged about 0.5 to 1 hour earlier than radar echoes for the tracing of the development of convective systems triggered at the mountain leeside and around sea breeze front.The interaction between baroclinity and water vapor gradient （IBWVG）as well as diabatic heating made important contributions to the earlier appearance of GMPV anomaly.Notable perturbation of over-mountain flow and the convergence ascending of relatively moister and colder （compared to atmosphere near the land surface）sea breeze in the after-noon were the causes of the significant productions of IBWVG at mountain leesid and sea breeze front,respectively.