基于毫米波雷达观测及探空反演的云垂直结构对比分析

Comparison of Cloud Vertical Structure Retrieved from Radiosonde and Millimeter Wave Cloud Radar

针对北京南郊观象台的Ka波段毫米波雷达以及L波段探空设备的观测原理和特点,提出了适用于各设备的云垂直结构判定方法,并基于二者2016年12月13日至2017年3月13日长达91 d的时空同步观测数据,结合激光云高仪、葵花8卫星、全天空成像仪等多源辅助数据,对探空与毫米波雷达观测结果(包括云底高、云顶高、云层数等)进行了对比,并对云高偏差的原因进行了分析,结论如下:毫米波雷达与探空判定的云垂直结构普遍具有较好的一致性,统计时段探空观测云顶高度比毫米波雷达平均高422 m,而云底高度则平均偏低350.7 m,导致二者观测云高差异主要包括二者观测原理不同、探空仪湿延迟、气球漂移引起的时空匹配偏差、探空判识云高算法的局限性、降雨时毫米波雷达的衰减等多方面。

Owing to the synchronizing continuous observation of Ka-band millimeter-wave cloud radar(MMCR),Lband radiosonde,ceilometer,Himawari-8 satellite,and Total Sky Imager(TSI)from 13 December 2016 to 13 March 2017,at Beijing Nanjiao Weather Observatory(BNWO),the cloud vertical structure(CVS,including cloud bottom height,cloud top height,cloud layers,etc.)derived from radiosonde and MMCR is compared,and the causes of observation deviation are analyzed.The results show that cloud top heights observed by MMCR are lower by 422.0 m on average,while cloud base heights are higher by 350.7 m.Generally,there is a good consistency between them.The difference of physical theory,balloon drifting,attenuation of MMCR during precipitation,and the limitations of algorithm for retrieving CVS,among others,are found to be the main causes of the deviation.