利用毫米波云雷达数据反演层云微物理参数和云内湍流耗散率的研究
投稿时间:2018-02-03  修订日期:2018-05-14  点此下载全文
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作者单位E-mail
黄兴友 南京信息工程大学 气象灾害预报预警与评估协同创新中心 hxyradar@126.com 
陆琳 南京信息工程大学 气象灾害预报预警与评估协同创新中心  
基金项目:国家自然科学基金资助项目(41475034;41475035)
中文摘要:云是影响天气和降水的关键因子,对云的微物理参数(有效半径、数量浓度等)和宏观参数(云高、云厚)进行探测是深入研究云物理过程和云辐射效应的基础。论文主要利用地基毫米波雷达进行云参数及云内湍流特性的探测和反演。根据云雷达回波的功率谱数据,反演出大气垂直运动速度和云微物理参数,得到云内湍流耗散率的大小和分布情况,并进一步研究和分析了云内空气垂直运动与云微物理参数、反射率因子、多普勒速度、速度谱宽变化的关系,更好地了解云的演变情况。对2016年8月8日四川稻城的一次层状云过程的探测和反演表明:(1)粒子有效半径随着上升气流的增强而增大,由于碰并聚合的作用,粒子数浓度也呈现相应减小的趋势。(2)云内湍流耗散率 在云底、云顶较大,云内较小,量级在10-8-10-2m2s-3,多普勒速度能谱验证了假设雷达探测湍涡的尺度在惯性副区的合理性。(3)随着上升气流的增强,云粒子的下沉运动相应减小,速度谱宽相应增大。
中文关键词:毫米波雷达 湍流耗散率 空气垂直运动 云微物理参数 反演
 
A case study on the retrieval of microphysical parameters and in-cloud stratus turbulent dissipation rate by millimeter-wave cloud radar measurement
Abstract:Clouds have an important influence on the weather and precipitation. The detection of cloud microphysical parameters (particle effective radius, drop number concentration, etc.) and macro-physical parameters (cloud height, cloud thickness) is essential to study cloud physical process and cloud radiation effects. This paper aims to the detection and retrieval of cloud parameters and in-cloud turbulence characteristics with a ground-based millimeter cloud radar. With the Doppler spectrum data, ambient vertical air velocity and cloud microphysical parameters are solved, and turbulent dissipation rate and its distribution is thereby obtained, and the relationships of vertical air motion to cloud microphysical parameters, to radar reflectivity factor, to Doppler velocity, to Doppler spectrum width, are completely studied and analyzed for understanding the cloud evolution. Cloud radar measurements and retrievals of a Stratiform cloud process case at Daocheng, Sichuan on August 8, 2016 shows that (1) cloud particle effective radius increases as the updraft increase, and cloud drop number concentration decreases accordingly due to the collision-coalescence process; (2) The turbulent dissipation rates is strong near cloud base and cloud top, and weak in middle layer, and ranges from 10-8 to 10-2 m2s-3. The Doppler spectrum validates the hypotheses that the turbulent scale captured by cloud radar is in inertial subrange; (3) With the air updraft gets stronger, the cloud particles deposition speed gets weaker, and the Doppler spectrum width gets stronger.
keywords:millimeter-wave cloud radar  turbulent dissipation rate  vertical air motions  cloud microphysical parameters  retrieval
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