南京地区冰云个例微物理参数的地基毫米波云雷达观测反演分析

Retrieval and analysis of case ice-cloud microphysical parameters over Nanjing with the measurement of a ground-based millimeter-wavelength cloud radar

中文关键词:  毫米波雷达，多普勒谱，冰云，微物理参数

英文关键词:Millimeter-wavelength cloud radar,Doppler spectra,Ice cloud,Microphysical parameter

中文摘要:

      冰云微物理参数在气候变化和降水过程中起到了重要的作用，本文选取南京2022年4月2日和4月25日两次冰云个例的Ka波段地基云雷达的观测数据，利用经验公式和多普勒谱数据进行了云参数的反演和分析，研究南京地区冰云的微物理特征。结果表明：（1）利用Z-IWC和Z-IWC-T经验关系，反演的冰水含量（IWC）有一些差异，但Z-IWC-T的反演结果更合理。（2）冰云中冰晶的数浓度介于104～107个/m3，有效直径变化范围是40～100μm，冰水含量在10-4～10-1g/m3之间，都比降雨云的对应参数小。此外，还结合谱偏度和谱峰度数据，分析冰晶云在下落过程中转化为水滴云的变化情况、融化和碰并过程对降水的微物理参数以及雷达回波数据有显著的影响。

英文摘要:

      Ice cloud microphysical parameters play an important role in climate change and precipitation process. In this paper, the observation data from a Ka-band ground-based cloud radar of two ice clouds cases on 2 April 2022 and 25 April 2022 over Nanjing are selected for study. Based on empirical relations and Doppler spectra, the microphysical parameters of ice-cloud and rainfall-cloud are retrieved and analyzed. The results show that (1) Ice water content（IWC）retrievals from empirical relations both Z-IWC and Z-IWC-T are acceptable. The Z-IWC-T retrieval is better though little difference is between the two retrievals. (2) The number concentration of ice crystals in ice clouds ranges from 104 to 107/m3, the effective diameter varies from 40 to 100 μm, and the ice-water content is between 10-4 and 10-1 g/m3, all of which are smaller than the corresponding parameters of rainfall-clouds. In addition, the ice-cloud microphysical parameter variation is analyzed by referring to the skewness and kurtosis of the Doppler spectra while the ice crystals melted to water droplets in the falling process. The melt and collide-coalescence in ice-cloud impacts greatly on the cloud microphyiscals and the radar measurements.