On the influence of assumed drop size distribution form on radar-retrieved thunderstorm microphysics
On the influence of assumed drop size distribution form on radar-retrieved thunderstorm microphysics
复制标题
DOI：
10.1175/jam2335.1
复制
发表时间：
2006-02
影响因子：
3
通讯作者：
E. Brandes;Guifu Zhang;Juanzhen Sun
中科院分区：
文献类型：
--
作者：
E. Brandes;Guifu Zhang;Juanzhen Sun
本文利用偏振雷达资料反演了亚热带雷暴的雨滴谱分布。检索与单矩指数下降的大小模型的马歇尔和帕尔默驱动雷达反射率测量和两个参数的约束伽玛下降的大小模型，利用反射率和差分反射率。结果进行了比较与disdrometer观察。检索与约束伽玛DSD模型得到了更好的代表性的总液滴浓度，液态水含量，和下降的中值体积直径，更好地描述了它们的自然变异。马歇尔-帕尔默DSD模型，与一个固定的截距参数，往往低估了风暴核心的总滴浓度和高估显着的浓度在层状区域。强对流中的雨水含量被低估了2-3倍，在层状雨下降中位体积直径被低估了0.5毫米。为了确定可能的DSD模型对数值预报的影响，蒸发和吸积率使用凯斯勒型参数化计算。基于Marshall-Palmer DSD模式的降水率在强对流中比基于约束伽玛模式的降水率低2-3倍，在层状降水中比基于约束伽玛模式的降水率高2倍左右。这项研究表明，偏振雷达测量的潜力，以提高降水过程和数值预报模式中的微物理参数化的理解。
Polarimetric radar measurements are used to retrieve drop size distributions (DSD) in subtropical thunderstorms. Retrievals are made with the single-moment exponential drop size model of Marshall and Palmer driven by radar reflectivity measurements and with a two-parameter constrained-gamma drop size model that utilizes reflectivity and differential reflectivity. Results are compared with disdrometer observations. Retrievals with the constrained-gamma DSD model gave better representation of total drop concentration, liquid water content, and drop median volume diameter and better described their natural variability. The Marshall–Palmer DSD model, with a fixed intercept parameter, tended to underestimate the total drop concentration in storm cores and to overestimate significantly the concentration in stratiform regions. Rainwater contents in strong convection were underestimated by a factor of 2–3, and drop median volume diameters in stratiform rain were underestimated by 0.5 mm. To determine possible DSD model impacts on numerical forecasts, evaporation and accretion rates were computed using Kessler-type parameterizations. Rates based on the Marshall–Palmer DSD model were lower by a factor of 2–3 in strong convection and were higher by about a factor of 2 in stratiform rain than those based on the constrainedgamma model. The study demonstrates the potential of polarimetric radar measurements for improving the understanding of precipitation processes and microphysics parameterization in numerical forecast models.