分析陕西不同区域雷暴大风形成环境差异,有助于更好地掌握此类过程的热力、动力和环流特征,为该类天气的预报预警提供参考。基于2017—2022年地面观测资料、闪电资料和欧洲中期天气预报中心(European Centre for Medium-Range Weather F...分析陕西不同区域雷暴大风形成环境差异,有助于更好地掌握此类过程的热力、动力和环流特征,为该类天气的预报预警提供参考。基于2017—2022年地面观测资料、闪电资料和欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)发布的第五代全球气候再分析资料(ERA5),分析陕西雷暴大风时空分布特征,并分区域对比分析暖型雷暴大风的环境参数和环流特征。结果表明:陕北和关中东部为雷暴大风高发区,暖型雷暴大风明显多于冷型;夏季远多于其他季节,6—8月暖型雷暴大风陕北明显多于关中和陕南。雷暴大风高发时段为15:00—21:00(北京时,下同),且14:00—18:00暖型雷暴大风发生频率陕北明显高于关中和陕南。不同区域暖型雷暴大风发生前热力、动力条件存在一定差异,陕北过程前能量和水汽条件相对较弱,动力条件相对较强;陕南能量和水汽条件相对更强,动力条件相对较弱。频率高于15%的环流型为陕北西风型和反气旋配合西风型、关中西风型和反气旋配合西风型、陕南气旋配合西风型和反气旋配合西风型。陕北西风型和反气旋配合西风型,陕北位于冷涡低槽底部或低槽底部与副热带高压之间,850 hPa和500 hPa温差较大,为对流天气发生提供了一定的不稳定条件,过程平均发生位置附近有切变存在,有利于对流天气触发;关中西风型,低层偏南气流较强,温度露点差较小;陕南气旋配合西风型,T-ln P图表现为近V型且能量条件较好;关中和陕南反气旋配合西风型,T-ln P图表现为近V型且水汽条件较好。展开更多
本文针对预报漏报的深圳机场2024年8月12日早间周边海域水龙卷过程,从雷达特征及触发条件开展分析发现,该水龙卷水平尺度较小,为百米级别,强度偏弱,需综合使用相控阵雷达对特定的钩状回波进行识别。此外,水龙卷由于垂直发展高度及云底...本文针对预报漏报的深圳机场2024年8月12日早间周边海域水龙卷过程,从雷达特征及触发条件开展分析发现,该水龙卷水平尺度较小,为百米级别,强度偏弱,需综合使用相控阵雷达对特定的钩状回波进行识别。此外,水龙卷由于垂直发展高度及云底高度较低,在雷达规划时需考虑土建海拔高度,并合理使用不同仰角扫描产品,避免龙卷特征出现在雷达高度以下。本次过程由弱暖区西南气流增长提供动力抬升,配合强烈能量释放形成强对流,同时叠加超过28 m/s的强低层风切变和底层涡旋触发出水龙卷。在短期预报中,低层垂直风切变、相对螺旋度等指标较难指示出水龙卷发生的可能性,但在临近预报中可重点关注上游风廓线雷达,可提供近1小时提前量,有利于及早开展短临预警。In this paper, for the water tornado process in the surrounding waters of Shenzhen Airport in the morning of August 12, 2024, which was not reported in the operational forecast, the radar characteristics and trigger conditions were detailed analyzed. It was found that the horizontal scale of the water tornado was small with the level of 100 meters, and the intensity was weak, so the special characteristic of hook echo in tornado should be recognized by the phased array radar. In addition, due to the low vertical development height and cloud base height of water tornado, it is necessary to consider the altitude for the radar design, and reasonably use different elevation scanning products to avoid the occurrence of tornado features below the radar altitude. This process is triggered by the growth of southwesterly in the weakly warm region, combined with the strong energy release to form strong convection. At the same time, the low-level vertical wind shear exceeding 28 m/s and the bottom vortex trigger the water tornado. In short-term forecasting, low-level vertical wind shear, relative helicity and other indicators are difficult to indicate the possibility of a water tornado, but in the near-term forecasting, we can focus on the upstream wind profile radar, which can provide nearly an hour in advance, and carry out the imminent early warning in time.展开更多
文摘分析陕西不同区域雷暴大风形成环境差异,有助于更好地掌握此类过程的热力、动力和环流特征,为该类天气的预报预警提供参考。基于2017—2022年地面观测资料、闪电资料和欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)发布的第五代全球气候再分析资料(ERA5),分析陕西雷暴大风时空分布特征,并分区域对比分析暖型雷暴大风的环境参数和环流特征。结果表明:陕北和关中东部为雷暴大风高发区,暖型雷暴大风明显多于冷型;夏季远多于其他季节,6—8月暖型雷暴大风陕北明显多于关中和陕南。雷暴大风高发时段为15:00—21:00(北京时,下同),且14:00—18:00暖型雷暴大风发生频率陕北明显高于关中和陕南。不同区域暖型雷暴大风发生前热力、动力条件存在一定差异,陕北过程前能量和水汽条件相对较弱,动力条件相对较强;陕南能量和水汽条件相对更强,动力条件相对较弱。频率高于15%的环流型为陕北西风型和反气旋配合西风型、关中西风型和反气旋配合西风型、陕南气旋配合西风型和反气旋配合西风型。陕北西风型和反气旋配合西风型,陕北位于冷涡低槽底部或低槽底部与副热带高压之间,850 hPa和500 hPa温差较大,为对流天气发生提供了一定的不稳定条件,过程平均发生位置附近有切变存在,有利于对流天气触发;关中西风型,低层偏南气流较强,温度露点差较小;陕南气旋配合西风型,T-ln P图表现为近V型且能量条件较好;关中和陕南反气旋配合西风型,T-ln P图表现为近V型且水汽条件较好。
文摘本文针对预报漏报的深圳机场2024年8月12日早间周边海域水龙卷过程,从雷达特征及触发条件开展分析发现,该水龙卷水平尺度较小,为百米级别,强度偏弱,需综合使用相控阵雷达对特定的钩状回波进行识别。此外,水龙卷由于垂直发展高度及云底高度较低,在雷达规划时需考虑土建海拔高度,并合理使用不同仰角扫描产品,避免龙卷特征出现在雷达高度以下。本次过程由弱暖区西南气流增长提供动力抬升,配合强烈能量释放形成强对流,同时叠加超过28 m/s的强低层风切变和底层涡旋触发出水龙卷。在短期预报中,低层垂直风切变、相对螺旋度等指标较难指示出水龙卷发生的可能性,但在临近预报中可重点关注上游风廓线雷达,可提供近1小时提前量,有利于及早开展短临预警。In this paper, for the water tornado process in the surrounding waters of Shenzhen Airport in the morning of August 12, 2024, which was not reported in the operational forecast, the radar characteristics and trigger conditions were detailed analyzed. It was found that the horizontal scale of the water tornado was small with the level of 100 meters, and the intensity was weak, so the special characteristic of hook echo in tornado should be recognized by the phased array radar. In addition, due to the low vertical development height and cloud base height of water tornado, it is necessary to consider the altitude for the radar design, and reasonably use different elevation scanning products to avoid the occurrence of tornado features below the radar altitude. This process is triggered by the growth of southwesterly in the weakly warm region, combined with the strong energy release to form strong convection. At the same time, the low-level vertical wind shear exceeding 28 m/s and the bottom vortex trigger the water tornado. In short-term forecasting, low-level vertical wind shear, relative helicity and other indicators are difficult to indicate the possibility of a water tornado, but in the near-term forecasting, we can focus on the upstream wind profile radar, which can provide nearly an hour in advance, and carry out the imminent early warning in time.
