毫米波雷达与无线电探空对云垂直结构探测的一致性分析

Consistency analysis for cloud vertical structure derived from millimeter cloud radar and radiosonde profiles

  • 摘要: 在众多种针对云垂直结构的探测中,毫米波雷达可获取云底、云顶、云厚等完整的云垂直结构信息,并可以连续监测云的垂直剖面变化,是有力的探测手段之一。而无线电探空因其直接的测量优势,能直观、确切地描述大气湿度垂直结构,可将其进一步处理生成云垂直结构信息,并作为一种数据源用于与毫米波雷达云垂直结构探测结果进行比对,以评估毫米波雷达针对云宏观垂直结构的探测性能,为毫米波雷达更好地应用于云探测提供参考。通过获取位于北京南郊观象台的毫米波雷达2014年10月28日至2015年2月17日长达113天连续观测的反射率因子以及探空温、压、湿数据,设计或选取合适的方法对二者进行云边界的计算,并进行云高(包括云底高和云顶高)以及云层数的一致性比对分析。结果认为,除对于高层云的云顶高度毫米波雷达由于探测限制不能探测到10 km以上的云顶,某些时刻与探空产生较大差异外,在云底高度以及中低云的云顶高度上可以与探空观测取得很好的匹配效果,对于云的垂直分层上二者也有较强的一致性。该毫米波雷达具有较为准确并连续刻画10 km以下云垂直结构的能力。

     

    Abstract: Millimeter cloud radar is one of the powerful instruments for cloud vertical structure observation. It can continuously monitor cloud changes and obtain complete information of cloud vertical structure including the cloud base height, cloud top height, and cloud thickness etc. Meanwhile, radiosonde observations can directly and accurately describe the vertical structure of atmospheric humidity due to its in situ measurement advantages. Observations of radiosonde can be further processed to generate cloud vertical structure information, which can then be used as a data source to validate the cloud vertical structure observed by millimeter cloud radar and assess the performance of millimeter cloud radar for cloud vertical structure observations. In this study, based on the millimeter cloud radar reflectivity data and sounding data collected at Beijing Observatory from 28 October 2014 to 17 February 2015, appropriate methods for calculations of cloud boundary height from the millimeter cloud radar and radiosonde observations are designed or selected, and their consistency is analyzed. The results show that the cloud vertical structures derived from cloud radar and radiosonde observations have a good consistency regarding to the cloud base height, cloud top height in low or middle level, and its vertical stratification. Due to the limitation of the detection capability of the millimeter cloud radar, it can not detect cloud tops above 10 km height. Thereby large differences are found in high-level cloud top height between millimeter cloud radar and radiosonde observations.

     

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