冬季稳定性降水相态预报研究进展

A Review on Stable Precipitation Type Forecast in Winter

冬季降水无论对地面的生产生活还是对高空飞机航行都可能造成严重灾害,降水相态预报的准确性决定了冬季降水预报的成功,该文系统回顾了近几十年降水相态预报取得的成果。降水相态预报方法大致分为3类:第1类是基于观测或数值天气预报建立的指标以及回归方程,其中某些方法高度依赖数值天气预报模式准确率;第2类是基于数值天气预报模式的微物理方案法和集合预报法;第3类是基于观测和数值预报产品的人工智能预报法。近年来降水相态模式预报产品准确率不断提高,成为降水相态预报中一个重要的产品支撑。但如何将降水相态形成机制的微物理研究成果用于改善数值预报模式降水相态预报的技巧,以及如何利用人工智能等技术提高降水相态预报的准确率等方面还需要不断努力。

The accurate identification of precipitation type at ground level is one of the greatest difficulties for forecasters during winter.Special types of precipitation can be a threat to public safety and human health and can disrupt transportation and commerce,causing seriously loss of the economy.Winter precipitation may also cause serious disasters to aircraft navigation.In those situations,the consequences can be catastrophic,with heavy and prolonged freezing precipitation,collapsed power lines causing prolonged power outages,transportation networks of many types completely paralyzed,and even major long-term damage to infrastructure and vegetation in the most severe cases.Therefore,the accuracy of precipitation type is crucial for winter precipitation forecast.Accurate predictions from weather forecast models of timing(onset and duration),intensity,spatial extent,and phase(i.e.,precipitation type)are crucial for decision-making and can help minimize the potential impacts.The research progress of precipitation type forecast in recent decades is investigated.The methods and techniques for predicting precipitation phases are reviewed systematically,which can be roughly divided into three categories.The index criterion methods are based on observations,numerical weather prediction weather predictions on thickness,area of warm atmosphere,significance level temperature,regression equation for vertical temperature profile,and model diagnosis.Some of those methods are highly dependent on the accuracy of the numerical model.The second type of methods are based on the microphysical processing scheme of numerical weather prediction model and ensemble prediction system.It includes microphysical scheme method and ensemble prediction method.The last type is the artificial intelligence prediction method including decision tree,artificial neural network,and deep learning etc.In recent years,sophisticated microphysical parameterizations schemes are widely used in high resolution regional forecast models,which help with precipitation-type prediction.The forecast accuracy of precipitation type model has been improved,which has become an important product support in precipitation type forecast.For instance,the precipitation type prediction product of ECMWF and the probabilistic prediction of precipitation type by ECMWF ensemble prediction.The probabilistic prediction has further improved the prediction skills compared with the deterministic model.However,even with such complex algorithms of NWP,correctly predicting what phase of precipitation ends up at the ground remains a challenging task.Besides this,many researches on the formation mechanism of microphysical processes are difficult to be applied to the precipitation type prediction,so it still needs continuous efforts to apply these achievements to improve the precipitation type prediction skill of numerical prediction model and increase the accuracy of precipitation type prediction by artificial intelligence and other technologies.