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气象:2019,45(1):73-87
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同化雷达反射率资料对一次飑线过程的模拟研究
郑淋淋,邱学兴,钱磊
(安徽省气象台,合肥 230031)
Simulation Study of a Squall Line Case Based on Assimilation Radar Reflectivity Data
ZHENG Linlin,QIU Xuexing,QIAN Lei
(Anhui Meteorological Observatory, Hefei 230031)
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投稿时间:2017-10-26    修订日期:2018-01-08
中文摘要: 在用集合卡曼滤波方法(EnKF)同化雷达径向风、雷达反演风和GPS水汽资料的基础上,对2014年7月30日发生在安徽中东部的一次飑线过程采用雷达反射率资料对初始水汽场进行调整。该方法相对EnKF的模拟结果,在飑线强度、位置、持续时间、产生降水和地面风场方面均有改进。改进湿度场后飑线前部的地面辐合区模拟效果较好,这可能是飑线强度和位置模拟效果改进的原因之一。没有调整湿度场时飑线维持时间较短,且强度较弱,这是由于飑线后部的中层干冷空气夹卷较弱,且冷池很快远离飑线,不利飑线维持。调整湿度场后,飑线后部干冷空气夹卷较强,且在对流区下沉形成冷池,冷池位于飑线后部,有利飑线维持。夹卷加强的可能原因是:采用雷达反射率资料调整湿度场增加了中低层(600~900 hPa)湿度,大气不稳定性增加,对流发展造成低值系统增强,其南部的偏西风增强,导致飑线后部的干冷空气夹卷增强。该试验揭示了湿度调整、大气不稳定度改变造成的动力场调整对对流发展和组织的重要作用。
Abstract:Based on the assimilation of radar radial wind, radar retrieval wind and GPS water vapor data with the ensemble Kalman filtering (EnKF) method, the initial water vapor field of a squall line that occurred on 30 July 2014 in east central Anhui was adjusted according to radar reflectivity data. Compared with the simulation results of EnKF, this method has improved the simulation of intensity, location, duration, precipitation and surface wind of the squall line. Simulation performance of ground convergence zone in the front of the squall line was improved after adjusting humidity field, leading to better simulation results of the intensity and location of the squall line. In addition, the squall line maintained for a shorter time without humidity adjustment and the intensity was weak. This can be explained by the fact that mid level dry air entrainment was weak in the rear of the squall line, and the cold pool moved quickly away from the squall line, which was unfavorable for the maintenance of squall line. In contrast, after the humidity field was adjusted, dry air entrainment in the rear of the squall line was strong, and the resultant downdraft generated the cold pool, which was located in the rear of the squall line, favorable for the maintenance of squall line. The possible reason for dry air entrainment strengthening tends to be that atmospheric instability was increased with the moisturizing of mid low level (600-900 hPa) after the humidity field adjustment, and the development of convection results in the enhancement of low value system. The westerly in the south of low value system intensifies, strengthening the dry cold air entrainment in the rear of the squall line. This experiment reveals that the adjustment of the humidity leads to the adjustment of the dynamic field, which plays an important role in the development and organization of the convection system.
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基金项目:国家自然科学基金青年基金项目(41705029)资助
引用文本:
郑淋淋,邱学兴,钱磊,2019.同化雷达反射率资料对一次飑线过程的模拟研究[J].气象,45(1):73-87.
ZHENG Linlin,QIU Xuexing,QIAN Lei,2019.Simulation Study of a Squall Line Case Based on Assimilation Radar Reflectivity Data[J].Meteor Mon,45(1):73-87.