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This paper describes the procedure and methodology to formulate the convective weather potential (CWP) algorithm. The data used in the development of the algorithm are the radar echoes at 0.5° elevation from Guangzhou Doppler Radar Station, surface observations from automatic weather stations (AWS) and outputs of numeric weather prediction (NWP) models. The procedure to develop the CWP algorithm consists of two steps: (1) identification of thunderstorm cells in accordance with specified statistical criteria; and (2) development of the algorithm based on multiple linear regression. The thunderstorm cells were automatically identified by radar echoes with intensity greater than or equal to 50 dB(Z) and of an area over 64 square kilometers. These cells are generally related to severe convective weather occurrences such as thunderstorm wind gusts, hail and tornados. In the development of the CWP algorithm, both echo- and environment-based predictors are used. The predictand is the probability of a thunderstorm cell to generate severe convective weather events. The predictor-predictand relationship is established through a stepwise multiple linear regression approach. Verification with an independent dataset shows that the CWP algorithm is skillful in detecting thunderstorm-related severe convective weather occurrences in the Pearl River Delta (PRD) region of South China. An example of a nowcasting case for a thunderstorm process is illustrated. 相似文献
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北京大气边界层中风和温度廓线的观测研究 总被引:29,自引:4,他引:29
为了研究冬季北京城区大气边界层结构的特征,分别在城区和郊区4个观测点利用系留气艇在2001年1月5~13日和2月21~28日进行了大气廓线探测,并分析了温度和风廓线垂直变化的基本特征.初步结果显示城市热岛效应十分明显,热岛强度随高度增加而递减,近地层热岛强度在晴天最大可达到4℃左右.除了近地层郊区的风速大于城区外,城区和郊区风速的垂直分布特征有较大差异.在100~200m高度以下,城区和郊区风速和风向随高度分布都出现了明显的拐点,300 m以上高度风向和风速基本趋于一致,表明城区和郊区的风廓线均受到城市覆盖层的影响.随着北京市区的规模不断扩大,在今后探测中应考虑郊区测点的代表性. 相似文献
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