In this study, an approach is proposed to improve the numerical weather prediction (NWP) of convective event forecasts by combining very short-term extrapolated reflectivity (0−1h) with a numerical model. After direct assimilation of real radar observations, the pseudo-water vapor estimated from future extrapolated reflectivity is assimilated using a cycled three-dimensional variational assimilation (3DVAR) system. To filter extrapolated reflectivity values with large errors and extract reliable and useful convection information, a proposed regional filtering procedure is performed on the extrapolated reflectivity. In addition, regional filters of different scales and the reflectivity of different extrapolation times are examined. The assimilation results for two convection events with different characteristics show that assimilation of the pseudo-water vapor estimated from extrapolated reflectivity can improve the reflectivity and accumulated precipitation forecasting. The improvement effect is more significant in case 1, which is a well-organized squall line event, and less effective in case 2, which is a faster developing and evolving local convection event. In both cases, the regional filtering method can limit the wet bias in the analysis field and suppress spurious forecasts of reflectivity and precipitation caused by assimilating the pseudo-water vapor estimated from extrapolated reflectivity without regional filters. Additionally, the assimilation of a shorter (30 min) time window may prevent the introduction of more error into the analysis field, but the improvement of the forecasting skill may be limited.

在这项研究中，提出了一种方法，通过结合非常短期的外推反射率（0-1 h) 与数值模型。在直接同化实际雷达观测后，使用循环三维变分同化 (3DVAR) 系统同化从未来外推反射率估计的伪水汽。为了过滤具有大误差的外推反射率值并提取可靠和有用的对流信息，对外推反射率执行建议的区域过滤程序。此外，研究了不同尺度的区域滤波器和不同外推时间的反射率。对具有不同特征的两次对流事件的同化结果表明，将外推反射率估计的拟水汽同化可以提高反射率和累积降水预报。案例1的改善效果更显着，这是一个组织良好的飑线事件，在案例 2 中效果较差，这是一个发展和演变更快的局部对流事件。在这两种情况下，区域过滤方法都可以限制分析场中的湿偏差，并抑制由于同化从没有区域过滤器的外推反射率估计的伪水汽而导致的反射率和降水的虚假预测。此外，较短（30 分钟）时间窗口的同化可能会防止将更多错误引入分析领域，但预测技能的提高可能会受到限制。区域滤波方法可以限制分析场中的湿偏差，抑制在没有区域滤波的情况下同化由外推反射率估计的拟水汽引起的反射率和降水的虚假预报。此外，较短（30 分钟）时间窗口的同化可能会防止将更多错误引入分析领域，但预测技能的提高可能会受到限制。区域滤波方法可以限制分析场中的湿偏差，抑制在没有区域滤波的情况下同化由外推反射率估计的拟水汽引起的反射率和降水的虚假预报。此外，较短（30 分钟）时间窗口的同化可能会防止将更多错误引入分析领域，但预测技能的提高可能会受到限制。