doi:  10.3878/j.issn.1006-9895.1904.18218
北京一次短时局地大暴雨过程的特征及对云物理方案的敏感性数值模拟试验

Characteristics of a Short-Duration and Localized Severe Rainstorm Event in Beijing City and Sensitivity of Cloud Microphysical Schemes in Numerical Simulations
摘要点击 154  全文点击 94  投稿时间:2018-08-17  
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基金:  公益性行业 气象 GYHY201406001公益性行业(气象)科研专项GYHY201306047、GYHY201406001
中文关键词:  
英文关键词:  Cloud microphysics schemes  Localized heavy rainfall  Numerical simulation  Beijing
        
作者中文名作者英文名单位
陈赛男CHEN Sainan中国气象科学研究院灾害天气国家重点实验室,北京100081;湖北省气象局武汉中心气象台,武汉430074
郭学良GUO Xueliang中国气象科学研究院灾害天气国家重点实验室,北京100081;中国科学院大气物理研究所,北京100029;中国气象科学研究院云雾物理环境重点实验室,北京100081
付丹红FU Danhong中国科学院大气物理研究所,北京100029
引用:陈赛男,郭学良,付丹红.2019.北京一次短时局地大暴雨过程的特征及对云物理方案的敏感性数值模拟试验[J].大气科学,43(6):1344-1364,doi:10.3878/j.issn.1006-9895.1904.18218.
Citation:CHEN Sainan,GUO Xueliang,FU Danhong.2019.Characteristics of a Short-Duration and Localized Severe Rainstorm Event in Beijing City and Sensitivity of Cloud Microphysical Schemes in Numerical Simulations[J].Chinese Journal of Atmospheric Sciences (in Chinese),43(6):1344-1364,doi:10.3878/j.issn.1006-9895.1904.18218.
中文摘要:
      云物理过程是云和降水形成的重要环节。本文针对2011年6月23日发生在北京地区的一次大暴雨过程进行了云降水与天气特征分析,并开展了WRF模式中10种不同云微物理方案对此次暴雨强度、落区和发生时间的敏感性数值模拟试验。研究结果表明,此次大暴雨是由多单体组织、合并形成深厚的中尺度对流系统,并具有明显的短时局地特征和有利的高低空、高低纬度大中尺度天气环流形势及强烈的水汽输送条件。暴雨强度、落区和发生时间的数值模拟结果对云物理方案非常敏感。不同云物理方案对累积降水量≥50 mm和≥100 mm的暴雨模拟的ETS评分显示,只有Thompson方案对此暴雨量级的评分均为正,其他方案的ETS评分均不理想,特别是对累积降水量≥100 mm的大暴雨模拟。在小时暴雨强度和发生时间方面,Thompson方案模拟效果也较好,其次是Lin方案和WSM6方案;对区域累积最大降水量和落区的模拟方面,Thompson方案和Morrison方案模拟的最大累积降水量更接近观测值,但在落区方面,一些具有完整云物理过程的单参数方案(Lin方案、WSM6方案)模拟效果较好,但模拟的最大降水量偏小。针对暖雨的双参数方案WDM6对区域平均降水模拟较好,但对暴雨极端降水模拟较差。对造成差异的原因分析表明,不同云物理方案的差异主要体现在雪和霰的参数化方面,由于采用的粒子谱分布、密度和末速度不同,导致云中粒子间的碰并和形成过程不同,大部分云物理方案模拟的霰含量高,雪含量低。这种云微物理过程的差异会导致云动力过程的反馈作用出现明显不同,但这种反馈作用的差异主要体现在降水粒子对上升气流的拖曳作用不同。尽管云中相变潜热过程对云动力过程具有很重要的影响,但不同云物理方案在相变潜热过程和温度廓线分布方面造成的差异并不明显。因此,云物理方案中考虑合理的粒子谱分布、形态和密度变化,有利于提高暴雨的模拟效果。
Abstract:
      Cloud microphysics play a key role in clouds and precipitation. The authors investigated the characteristics of clouds and precipitation, and synoptic conditions of a severe rainstorm in Beijing. The authors conducted sensitivity experiments for ten cloud microphysics schemes with the WRF (Weather Research and Forecasting) model in simulating the intensity, location, and duration of the rainstorm. Results showed that the severe rainstorm had an apparent short-duration and localized properties, and was a deep convective system formed by a merging of multicellular clusters, with favorable conditions for a large, mesoscale weather system and water vapor. Simulated intensity, location, and duration of the rainstorm in the model were very sensitive to the cloud microphysics scheme. The ETS (Equitable Threat Score) of the 18-h accumulated rainfall ≥50 mm and ≥100 mm for the different microphysical schemes indicated that only the Thompson scheme had both positive skill while other schemes had very low or negative skill, particularly for rainfall ≥100 mm. The complicated microphysics schemes had much better performance in the high horizontal resolution condition. Hourly precipitation intensity and duration simulated by the Thompson scheme were closest to observations, followed by the Lin and WSM6 schemes. Maximum area-accumulated precipitation was well-simulated by the Thompson and Morrison schemes. The single moment schemes of Lin and WSM6 better simulated the location of the precipitation, and the simulated precipitation amounts were much smaller. WDM6 scheme could well-simulate the area-mean precipitation, but had worse performance in the simulation of extreme precipitation. The differences were due to the different treatments of snow and graupel processes. Since size distribution, density, and terminal velocity of hydrometeors are usually differently parameterized in different microphysics schemes, this would induce different collision and formation processes of cloud particles. Most schemes produced higher graupel content and less snow content except for the Thompson scheme. Moreover, these differences also induced different feedback of cloud dynamics, primarily for the dragging process of precipitation particles on updrafts rather than the change of temperature profile due to release of latent heat in the phase change process of hydrometeors. Therefore, microphysics schemes including an appropriate parameterization of size distribution, shape, density, and terminal velocity of hydrometers would be beneficial to the improvement of heavy rainfall simulation in a cloud microphysics scheme.
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