基于地基遥感设备构建遥感探空廓线

利用天津地基遥感(风廓线雷达和微波辐射计)数据及地面自动气象站数据构建地基遥感探空廓线系统(简称遥感探空廓线), 旨在弥补常规探空层结信息时空密度不足, 对2020—2021年5—9月遥感探空廓线反演结果进行模式检验, 并从中选取10次强对流过程进行个例效果评估。结果表明:反演数据与欧洲中期天气预报中心再分析数据(ERA5)比湿的平均绝对偏差为1.06 g·kg-1, 对流有效位能相关系数为0.84(达到0.01显著性水平)。10次强对流过程中强对流发生前临近时次常规探空对流有效位能平均值为322 J·kg-1, 遥感探空廓线具有分钟级时间分辨率, 能高时效性地跟踪大气状态的演变趋势, 对流发生前8 h内对流有效位能平均峰值为1451.88 J·kg-1, 与常规探空相比具备明显对流指征。研究表明:遥感探空廓线能动态描述热动力参数的配置及对流潜势的发展与释放过程, 有利于提高短时临近预报的精细化水平。

Construction of Air-sounding-profile System Based on Foundation-remote-sensing Equipment

Radiosonde data are indispensable for severe convective weather forecast because they can not only reflect the temperature and humidity structure and dynamic characteristics of local atmosphere, but also indicate the favorable conditions of convection initiation and development. However, the conventional radiosonde cannot capture local environmental parameters instantly due to insufficient space layout and low detection frequency, and the drift of sounding balloon worsens the representativeness of data. Acquiring accurate high-resolution data of temperature, humidity and horizontal wind is in great need. Combining ground-based remote sensing data and automatic weather station (AWS) data, including data of wind profile radar and AWS at Xiqing Station and radiometer at Tieta Station, a Foundation-remote-sensing Air-sounding-profile System (FAS) is constructed based on the strength of specific humidity profile inversion method and WPR-HW method. The inversion results of FAS is verified using European Centre for Mudium-Range Weather Forecasts reanalysis (ERA5) through 10 severe convective weather cases.The comparison shows that the inversion data of specific humidity and convective available potential energy (CAPE) from FAS has good consistency with ERA5 data. The correlation coefficient is 0.93, the root mean square error is 1.4 g·kg-1, the mean absolute deviation is 1.06 g·kg-1, and the mean relative deviation is 11.22% for 130 groups of specific humidity between FAS and ERA5 data. The correlation coefficient is 0.84, and the mean relative deviation is 35% for CAPE in 65 groups. The comparison test verifies the credibility of FAS data (correlation coefficients of specific humidity and CAPE both passing the test of 0.01 level). The time resolution of FAS is much higher. The mean interval time between Beijing radiosonde's occurrence time and severe convection's occurrence time is 7 h 18 min, while FAS's time resolution is just a few minutes. As a result, the mean value of CAPE detected by Beijing radiosonde is 322 J·kg-1, which is too low to indicate local convective potential in the afternoon or evening, while the mean value by FAS is 1451.88 J·kg-1, which can describe the change of atmospheric state during severe convection. FAS has high practical value in short-term forecast, as it can be used to determine the presence of convective potential and distinguish severe convective weather types timely through the configuration of convective parameters. The FAS can also capture elaborate thermodynamic structure of meso-scale and micro-scale weather system before the occurrence of severe convection. The FAS can significantly improve the lead time and accuracy of forecast.