【作者】 燕成玉；

【导师】 闵锦忠；

【作者基本信息】 南京信息工程大学 ， 气象学， 2011， 硕士

【摘要】 秦皇岛市短历时强降水频发,因其东临渤海、北依燕山,地形复杂,所以其强降水具有独特性。本文采用Micaps实时资料、NCAR/NCEP再分析资料、多普勒雷达资料、自动站风场及降水资料,利用WRF模式、雷达回波分析方法、EVAD方法、四维变分方法对秦皇岛市2009年7月6日出现的一次短历时强降水过程进行了细致分析,主要结论如下：(1)采用WRF模式对本次强降水进行了数值模拟,结果表明：模拟的降水分布与实况较接近,但是模拟的秦皇岛降水偏弱；WRF模式能模拟出低槽在东移过程中在海风加强时段得到加深,其模拟的地面辐合线和水汽辐合中心对强降水具有明显的指示意义,但其对有关物理量的模拟偏弱。WRF模式模拟的降水和有关物理量偏弱,可能是由于初始场资料密度较小,模式在作格点插值时,较小的天气系统有可能被平滑掉。因此,采用常规资料时,WRF模式对中小尺度系统的模拟还有局限性。(2)对本次强降水过程的多普勒雷达反射率因子特征、垂直风廓线特征及径向速度场特征分析得到：垂直风廓线产品能反映雷达上空大气水汽含量的变化;当中层有干冷空气入侵时,降水强度增大；多普勒雷达径向速度场对强降水的指示作用要早于反射率因子。(3)运用EVAD方法计算平均大气散度,变分法计算平均大气垂直速度,对此次降水过程动力条件进行分析,通过与降水强弱变化的对比分析,结果表明：该方法能够反映出此次降水过程的动力学特征,当中低层辐合较强,出现强上升运动时,将会引发短历时强降水天气的产生。(4)通过四维变分方法(每次输入相邻的两个体扫资料)进行风场的反演,对本次短历时强降水进行中小尺度天气系统分析,得到较为真实的中小尺度天气系统状况,强降水发生在“人”字型切变线的暖切变线的前侧,当暖切变线附近出现中-γ闭合气旋性环流时,降水进一步增强。更多还原

【Abstract】 Short heavy rainfall happens frequently in Qinhuangdao because that it locates in the west of Bohai bay and the north of Yanshan Mountain and has complex terrain. Severe precipitations in the short time have its unique properties. In this paper, utilizing Micaps information, NCAR/ NCEP reanalysis data, Doppler radar, automatic weather station wind and precipitation data, using WRF model, the radar echo analysis, EVAD method, four-dimensional variation method, analyzing a short duration heavy rain occurred in 6 July 2009 in Qinhuangdao City, the main conclusions are as follows:(1)Using the WRF model simulate the heavy precipitation, the results shows that the simulated distribution of precipitation is close to the observation, but the rainfall in Qinhuangdao simulates weak. WRF model can simulate the trough moving eastward deepening with the strengthening the sea breeze, the simulated surface convergence line and moisture convergence center has obvious implications for heavy rainfall, but relevant physical quantities simulates a little weak. The reasons may be that the initial field data is density, when the model is interpolating, the smaller the weather system may be smoothed out. Therefore, using conventional data simulate small-scale systems in WRF model also has some limitations.(2)Analyzing the characteristics of Doppler radar reflectivity, vertical wind profile and radial velocity field in the heavy rainfall, the results show that the vertical wind profile radar products can reflect the atmospheric water vapor content changes in higher level; when the dry cold air in middle layer invades, the rainfall intensity increases; the instructions of Doppler radar’s radial velocity field on heavy rainfall is earlier than the reflectivity.(3)Using EVAD method calculate the average atmospheric divergence, using the variation method calculate the average atmospheric vertical velocity, analyzing the dynamic process of the precipitation, the results show that the method can reflect the dynamic characteristics of the precipitation process, the severe convective weather would be brought out when there was strong convergence of low-mid level Jet Stream and with the severe ascending motion.(4)By four-Dimensional Variation Method (the data of two adjacent volume scan were input once in so-called 4DVM), to run the wind field interpretation, depending on the analysis for the severe precipitation of micro-and meso scale systems in the short time, the situation of micro-and meso-scale weather system can be reflected truly. The heavy rainfall occurred in the "people"(Chinese character) shaped shear line before the warm the shear line side, when the middle-y cyclonic circulation appears near the warn shear line, the precipitation will enhanced further more.更多还原