湿热力平流参数在一次华北暴雨模拟诊断中的应用研究

对2011年7月24~25日发生在华北地区的一次暴雨过程进行了分析,并以NCEP资料为初值场对此次暴雨过程进行了数值模拟,结合实况对模拟结果进行对比分析。分析表明:模式对本次华北暴雨的模拟比较成功,基本反映出了本次暴雨过程的降水分布特点。利用湿热力平流参数对本次华北地区的降水落区进行了诊断分析。分析指出,湿热力平流参数纬向平均的垂直剖面图上,湿热力平流参数的高值区及大值中心与地面的强降水雨区对应得较好,其梯度大小及向上延伸高度均可以定性地指示降水的强弱;垂直积分的湿热力平流参数与地面6 h强降水落区具有较好的对应关系,而在示踪弱降水区时效果并不是很好,其大值中心并不与强降水中心完全重叠,而是其梯度大值区与降水中心相对应;垂直积分的湿热力平流参数与6 h累积地面降水的空间分布特征和时间演变趋势比较相似,并且其变化趋势能反映降水的发展和消弱。

Study and Application of Moist Thermodynamic Advection Parameter to Numerical Simulation and Diagnostic Analysis of a Rainstorm in North China

A rainstorm process that occurred during 24-25 Jul 2011 is analyzed by numerical simulation performed with NCEP data used for the initial field. The numerical simulation accurately simulates this rainfall process and essentially reflects the rainfall distribution characteristics. The moist thermodynamic advection parameter is chosen to perform diagnostic analysis for the rainfall region. Results show that in the meridional-vertical cross section of the zonal mean of the moist thermodynamic advection parameter, the high-value areas, and the centers of the moist thermodynamic advection parameter coincide well with the heavy rainfall region and that the gradient and the upward height can qualitatively indicate the intensity. The vertical integral of the moist thermodynamic advection parameter can trace the heavy rainfall region more accurately than the light rainfall region. The centers of the moist thermodynamic advection parameter do not completely overlap the heavy rain centers; instead, the high-value areas of the gradient correspond to the centers. Moreover, the moist thermodynamic advection parameter has a spatial distribution and time evolution trend similar to those of the simulated 6 h accumulated precipitation, and its change trend can reflect the increase and decrease of precipitation.