2024年2月初,受持续性冷空气影响,湖南邵阳地区出现了较为罕见的持续性低温雨雪冰冻天气,邵阳市区和邵东48 h最低气温降幅达7.5℃以上,2月2日至7日全市平均气温0.9℃,较历年同期(6.5℃)偏低5.9℃。对EC模式预报产品检验分析发现,最新起...2024年2月初,受持续性冷空气影响,湖南邵阳地区出现了较为罕见的持续性低温雨雪冰冻天气,邵阳市区和邵东48 h最低气温降幅达7.5℃以上,2月2日至7日全市平均气温0.9℃,较历年同期(6.5℃)偏低5.9℃。对EC模式预报产品检验分析发现,最新起报时次的各层温度0线、逐3小时和逐6小时降雪量,对预报雨雪相态转换以及降雪落区具有很好的指示作用。在本轮过程中700 hPa 0℃线南压至邵阳是降水相态转为雪的重要经验指标,降水相态为冻雨时的850 hPa温度和地面温度低于雨夹雪。双偏振雷达CC、ZDR与KDP产品在本次低温雨雪过程中对降水相态的判定有较为明显的指示作用。In early February 2024, due to the continuous cold air, Shaoyang area in Hunan Province experienced a rare sustained low-temperature rain, snow, and freezing weather. The minimum temperature in Shaoyang city and Shaodong decreased by more than 7.5˚C in 48 hours. From February 2nd to 7th, the city’s average temperature was 0.9˚C, which was 5.9˚C lower than the same period in previous years (6.5˚C). The inspection and analysis of EC model forecast products found that the zero temperature line at each layer and the snowfall amount every 3 hours and 6 hours at the latest evening are good forecast indexes for forecasting the phase of rain and snow and the transformation of snowfall regions. In this round, the southward pressure of the 700 hPa 0˚C line to Shaoyang is an important empirical indicator for the transition of precipitation phase to snow. When the precipitation phase is freezing rain, the 850 hPa temperature and ground temperature are lower than those of sleet. The products of dual-polarization radar CC, ZDR and KDP have obvious indication function on the judgment of precipitation phase in the process of low temperature rain and snow weather.展开更多
本文介绍了车载双偏振雷达参数ZDR的处理方法,首先分析了信噪比SNR对ZDR参数的影响,得出信噪比SNR至少要>18 d B,ZDR数据才可信;其次分析了雷达附近的不同类型遮挡物对ZDR参数的影响,结果表明,尖状的遮挡物容易造成ZDR正的偏差,房屋...本文介绍了车载双偏振雷达参数ZDR的处理方法,首先分析了信噪比SNR对ZDR参数的影响,得出信噪比SNR至少要>18 d B,ZDR数据才可信;其次分析了雷达附近的不同类型遮挡物对ZDR参数的影响,结果表明,尖状的遮挡物容易造成ZDR正的偏差,房屋等遮挡物容易造成负偏差,而对树林等遮挡物,偏差的正负变化很大。随着遮挡程度的减小,ZDR的变化幅度变小;针对ZDR的系统误差,使用反射率因子结合ΦDP增量可以很好的进行计算,ZDR系统误差在短时间内变化不大,但是,随时间变化而逐渐变化,需要进行实时订正;最后,使用FIR滤波方法进行KDP参数计算并用于ZDR衰减订正,取得了不错的效果。针对业务应用,给出了实时处理ZDR参数的业务流程图。展开更多
文摘2024年2月初,受持续性冷空气影响,湖南邵阳地区出现了较为罕见的持续性低温雨雪冰冻天气,邵阳市区和邵东48 h最低气温降幅达7.5℃以上,2月2日至7日全市平均气温0.9℃,较历年同期(6.5℃)偏低5.9℃。对EC模式预报产品检验分析发现,最新起报时次的各层温度0线、逐3小时和逐6小时降雪量,对预报雨雪相态转换以及降雪落区具有很好的指示作用。在本轮过程中700 hPa 0℃线南压至邵阳是降水相态转为雪的重要经验指标,降水相态为冻雨时的850 hPa温度和地面温度低于雨夹雪。双偏振雷达CC、ZDR与KDP产品在本次低温雨雪过程中对降水相态的判定有较为明显的指示作用。In early February 2024, due to the continuous cold air, Shaoyang area in Hunan Province experienced a rare sustained low-temperature rain, snow, and freezing weather. The minimum temperature in Shaoyang city and Shaodong decreased by more than 7.5˚C in 48 hours. From February 2nd to 7th, the city’s average temperature was 0.9˚C, which was 5.9˚C lower than the same period in previous years (6.5˚C). The inspection and analysis of EC model forecast products found that the zero temperature line at each layer and the snowfall amount every 3 hours and 6 hours at the latest evening are good forecast indexes for forecasting the phase of rain and snow and the transformation of snowfall regions. In this round, the southward pressure of the 700 hPa 0˚C line to Shaoyang is an important empirical indicator for the transition of precipitation phase to snow. When the precipitation phase is freezing rain, the 850 hPa temperature and ground temperature are lower than those of sleet. The products of dual-polarization radar CC, ZDR and KDP have obvious indication function on the judgment of precipitation phase in the process of low temperature rain and snow weather.
文摘本文介绍了车载双偏振雷达参数ZDR的处理方法,首先分析了信噪比SNR对ZDR参数的影响,得出信噪比SNR至少要>18 d B,ZDR数据才可信;其次分析了雷达附近的不同类型遮挡物对ZDR参数的影响,结果表明,尖状的遮挡物容易造成ZDR正的偏差,房屋等遮挡物容易造成负偏差,而对树林等遮挡物,偏差的正负变化很大。随着遮挡程度的减小,ZDR的变化幅度变小;针对ZDR的系统误差,使用反射率因子结合ΦDP增量可以很好的进行计算,ZDR系统误差在短时间内变化不大,但是,随时间变化而逐渐变化,需要进行实时订正;最后,使用FIR滤波方法进行KDP参数计算并用于ZDR衰减订正,取得了不错的效果。针对业务应用,给出了实时处理ZDR参数的业务流程图。
