定量降水预报技术进展

Advances in Techniques of Quantitative Precipitation Forecast

对21世纪以来定量降水预报技术流程中的数值模式预报、统计后处理、检验评估和预报员作用4个方面的研究工作进行了归纳,主要进展包括:业务全球模式对于降水的预报能力持续提升,而发展高分辨率模式(尤其是对流尺度模式)和集合预报是提高定量降水预报精准化水平的主要途径,且将两者相结合以促进短期降水预报是发展趋势;统计后处理技术已发展到应用数据挖掘方法对海量预报数据中有效信息进行提取和集成,而再预报资料的出现将进一步促进统计后处理技术的发展;为解决评估精细化定量降水预报面临的新问题,多种新的检验技术得到发展和应用,如极端降水检验评分、空间检验技术及概率检验方法等;预报员在模式和后处理方法上能够提供的附加值越来越有限,但在预报流程中仍将处于核心地位,其角色将逐渐向帮助用户进行决策方向转变。文章指出,定量降水预报技术的发展所面临的挑战包括大气水汽观测及同化技术改进、暖区和复杂地形下暴雨预报等科学问题的解决。

The quantitative precipitation forecast（QPF） is a core operation of weather forecast.Modern technological processes of the QPF include numerical weather forecast,verification and evaluation,objective calibration and integration,forecaster＇s subjective modification and gridding post-processing.Domestic and international research work covering these five aspects are investigated and summarized,to provide reference for development of the quantitative precipitation forecast.In the aspect of numerical weather forecast,the forecast skill of the operational global model for precipitation has been improving continuously（a gain of about 1 forecast day per decade）,and developments of the high resolution model（especially the convection-permitting model） contribute to describing characteristics of the convective precipitation,while the ensemble models provide uncertainty information and the most possible outcome of the forecast.These two techniques are the main way to improve the fine level and accuracy of QPF,and improvement of short-term precipitation forecast by developing operational high-resolution model ensembles is the international tendency.Objective calibration and integration as well as gridding post-processing make up the statistical post-processing technique of the QPF,which now reach a level that applies multiple approaches of data mining to extract and integrate more useful information from massive data,and the emergence of reforecast dataset will further promote the development of statistical postprocessing.In terms of verification and evaluation,to solve new problems in assessing the fine level and accuracy of the QPF,a variety of new verification approaches are developed and applied,such as the new score for verifying the precipitation forecast of different climate backgrounds,extremes and multiple types,spatial verification methods for avoiding dual punishments of traditional methods,as well as the probability verification methods for verifying the stability,sharpness,and resolution of the probability forecast.In the aspect of forecaster＇s subjective modification,although the value added to model and post-processing methods become more and more limited,forecasters still play a core role,gradually changing to help users make decision.The development of QPF techniques still face challenges of solving scientific problems such as the observation of atmosphere moisture and data assimilation methods,as well as heavy rain forecast in warm section and complex topography.