【作者】 刘炜桦；

【导师】 魏鸣；

【作者基本信息】 南京信息工程大学 ， 大气遥感科学与技术， 2011， 硕士

【摘要】 近年来随着数值天气预报技术的发展,目前中尺度数值预报模式在许多方面日臻成熟,同时现在的计算机能力已使过去难以想象的各种各样精细的中、小尺度天气学数值模拟研究得以实现,中尺度业务数值预报也在许多国家先后开展起来。目前探空站网点之间的距离为300公里或更多些,含有的信息主要代表了天气尺度及大尺度系统的特征。若仅用常规探空资料,则会较大程度地漏掉中小尺度系统,雷达资料的应用则可部分弥补这一缺陷,研究结果表明用雷达资料优化后的初始场能够更详细、客观的描述暴雨中尺度系统的特征,显著提高了模式对降水特别是甚短时降水的落区和量级的预报准确率。本文使用NCEP1°×1°逐6h分析资料、雷达观测资料对2009年6月14日飑线过程发生的大、中尺度背景进行了分析。使用NCEP fnl全球分析资料和新一代天气雷达资料,对该过程进行了数值模拟和间接同化雷达反射率因子试验,分析了飑线系统的演变过程及降水区域,结论如下：(1)雷达资料的预处理和质量控制(包括去除地物杂波和孤立点、退模糊速度、数据填补与平滑处理、稀疏化)可以去除噪声和减少资料间的相关性,有利于同化的实施。(2)在雷达反射率因子间接同化方面：雷达反射率因子的间接同化,湿度场的适应是非常明显的,湿度分析场的变化明显,引起的气压场变化也明显,雷达反射率因子的同化对中尺度强降水预报的改善是显著的。(3)在飑线降水的数值模拟方面,在控制试验中已经发现了降水的数值模拟结果比实际观测是雨量偏小的,同化雷达反射率因子资料以后,能够增加控制试验的模拟降水量,根据雷达基本反射率因子同化试验与控制试验的对比,可以发现,降水落点和降水量得到改善,降水量增加了10-30nmn。表明雷达基本反射率因子的同化对飑线降水预报是有相当大改善的。更多还原

【Abstract】 In recent years with the development of numerical weather prediction technology, mesoscale numerical prediction model more matureis in many ways, while computer capacity has made the past unimaginable variety of mesoscale, small-scale numerical simulation weather achieved,and mesoscale numerical prediction operations are carried out in many countries.Currently the distance between the sounding station network of 300 km or more, the main representative of the information contained in the synoptic scale and large scale system features. If only conventional sounding data, it will miss a large extent on small scale systems, and satellite images and radar echoes may be part of the application to compensate for this defect, the results show that radar data of the initial field can be optimized more detailed and objective description of the characteristics of rainfall in the scale system significantly improves the model even short-term precipitation, especially off the area and magnitude of precipitation in the forecast accuracy.Based on the radar echo and NCEP reanalysis data of 1°×1°with the 6h interval, a squall line event in the large scale and meso-scale weather background were analyzed comprehensively. In the analysis using the NCEP data and a new generation of radar data, to simulate the process and assimilate the radar reflectivity test, analysis of the evolution of squall line system and the precipitation area, the following conclusions:(1)Radar preprocessing and quality control which include removing anomalous propagation, ground clutter, isolated point, velocity dealiasing, data filling, data smoothing and thinng play an important role in the radar data assimilation.(2) Radar reflectivity factor in the direct assimilation:Radar reflectivity factor of the direct assimilation, the humidity field of adaptation to the thermal field is very obvious; assimilation the higher of radial resolution, the more the radar reflectivity data assimilation,the obvious moisture in changes, the more obvious changes in air pressure caused by the greater, so the wind farm also will be adjusted significantly; radar reflectivity factor of the direct assimilation of the mesoscale heavy rainfall forecast for the improvement is significant.(3) Precipitation in the squall line simulation, we have found in the control experiment the numerical simulation of precipitation are small than the actual rainfall observations, after the assimilation of radar reflectivity data can increase the control of precipitation, under the radar base reflectivity difference between assimilation and distribution of controlled trials can be found, precipitation improved placement and precipitation, precipitation increased 10-30 mm. Show that the radar base reflectivity assimilation of the squall line precipitation forecast is considerably improved.更多还原