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徐桂荣, 张文刚, 万霞, 王斌, 冷亮, 周伶俐, 万蓉. 2019: 地基微波辐射计反演的青藏高原东侧甘孜大气温湿廓线分析. 暴雨灾害, 38(3): 238-248. DOI: 10.3969/j.issn.1004-9045.2019.03.006
引用本文: 徐桂荣, 张文刚, 万霞, 王斌, 冷亮, 周伶俐, 万蓉. 2019: 地基微波辐射计反演的青藏高原东侧甘孜大气温湿廓线分析. 暴雨灾害, 38(3): 238-248. DOI: 10.3969/j.issn.1004-9045.2019.03.006
XU Guirong, ZHANG Wengang, WAN Xia, WANG Bin, LENG Liang, ZHOU Lingli, WAN Rong. 2019: Analysis on atmospheric profiles retrieved from microwave radiometer observation at Ganzi in the eastern Qinghai-Tibet Plateau. Torrential Rain and Disasters, 38(3): 238-248. DOI: 10.3969/j.issn.1004-9045.2019.03.006
Citation: XU Guirong, ZHANG Wengang, WAN Xia, WANG Bin, LENG Liang, ZHOU Lingli, WAN Rong. 2019: Analysis on atmospheric profiles retrieved from microwave radiometer observation at Ganzi in the eastern Qinghai-Tibet Plateau. Torrential Rain and Disasters, 38(3): 238-248. DOI: 10.3969/j.issn.1004-9045.2019.03.006

地基微波辐射计反演的青藏高原东侧甘孜大气温湿廓线分析

Analysis on atmospheric profiles retrieved from microwave radiometer observation at Ganzi in the eastern Qinghai-Tibet Plateau

  • 摘要: 微波辐射计能够获取分钟级别的大气温湿廓线,可以弥补气象探空在时间分辨率上的不足。本文利用青藏高原东侧甘孜站2017年8-10月并址观测的微波辐射计和探空资料,对微波辐射计反演大气廓线的精度进行分析,并利用这些廓线探讨甘孜大气热力和云水变化特征。分析结果显示,总体上微波辐射计反演参量与探空观测之间具有高相关系数,微波辐射计反演的温度、相对湿度和水汽密度与探空观测的偏差分别为1.3℃、-2%和0.71 g·m-3,相应的均方差分别为2.9℃、20%和1.08 g·m-3,非强降水对微波辐射计观测质量的影响较小。微波辐射计与探空的温度偏差在多数高度层上小于2℃,能够达到气象业务的偏差要求。非雨天时微波辐射计与探空的相对湿度偏差在多数高度层上约为10%,雨天时相对湿度偏差在3.5 km以下小于5%。基于甘孜微波辐射计资料的统计分析发现,甘孜大气具有白天干热、夜间湿冷的日变化特征,云液态水含量白天较小、夜间较大,而且白天低层云发展较弱、云底较高,夜间低层云发展较强、云底较低。云液态水含量在云天和雨天具有相似的垂直结构,云液态水含量随高度增加先快速增大,然后在一定高度内波动变化,之后又快速变小,能够较好地指示入云和出云的特征。此外,云天低层云的云体主要处在0.1-2.5 km高度,而雨天低层云的云体分布高度范围更大为0-3.5 km高度。这些分析结果表明,微波辐射计反演大气廓线在甘孜具有可用性,能为定量研究云特征提供科学数据。

     

    Abstract: Microwave radiometer (MWR) can retrieve atmospheric profiles with a temporal resolution of several minutes, which compensates for the low temporal resolution of the meteorological radiosonde data. In this study, we use the data of MWR and radiosonde observed from August to October in 2017 at Ganzi, a station on the eastern side of the Qinghai-Tibet Plateau (QTP), to analyze the accuracy of atmospheric profiles retrieved from the MWR observation and investigate the properties of atmospheric thermal profiles and cloud liquid water content profiles over Ganzi. The results show that the correlation coefficient between the MWR and radiosonde observations is high. The general deviations of MWR-retrieved temperature, relative humidity and vapour density against the data of radiosonde were 1.3℃, -2%, and 0.71 g/m3, with the corresponding root mean square errors of 2.9℃, 20%, and 1.08 g·m-3, respectively. The impact of precipitation weather on the accuracy of observed data by the MWR was weak except for heavy rainfall weather conditions. The deviation of temperature profile between the MWR and radiosonde was less than 2℃ in most height layers, which can meet the deviation requirement of meteorological operations. The relative humidity deviation between the MWR and radiosonde under non-precipitation condition was about 10% in most height layers, while it was less than 5% below 3.5 km under precipitation conditions. Based on the statistical analysis of the MWR data in Ganzi, it was found that the atmosphere was dry and hot in daytime while wet and cold at nighttime during the observation period. At the same time, the cloud liquid water content was lower in daytime and larger at nighttime, and the development of low-level clouds was weaker during the daytime with higher cloud base heights and stronger during the nighttime with lower cloud base heights. Moreover, the cloud liquid water content showed a similar vertical structure under cloudy and rainy conditions, in which the cloud liquid water content rapidly increased with height and significantly decreased after a fluctuation within a certain height. This variation well indicated the characteristics of entering and leaving clouds. In addition, the cloud body of low-level clouds under cloudy conditions mainly located at the height of 0.1-2.5 km, while the cloud body of low-level clouds under rainy condition widely spread from the surface to 3.5 km. These analysis results showed that the atmospheric profiles retrieved from the MWR observation were credible at the Ganzi station, and the MWR can provide actual data for quantitative study of cloud characteristics.

     

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