1971-2020年我国月气候预测业务预报评估

Assessment of monthly climate prediction in China from 1971 to 2020

我国已开展短期气候预测工作近70 a,是世界上开展短期气候预测研究和业务最早的国家之一。自2021年3月开始,国家气候中心通过官网正式公开发布未来15~30 d、自然月和季节的气候预测公报,短期气候预测越来越受到社会关注。2013年中国气象局预报与网络司在短期气候预测业务的基本状况和历史评估方法的基础上,发布了短期气候业务预测效果评估方法,本文使用该方法对国家气候中心1971—2020年全国月气候趋势预测产品进行了评估。结果表明:无论是月平均气温距平还是月降水量距平百分率预测,夏半年的预测准确率均整体高于冬半年;近50 a全国月平均气温距平预测水平上升趋势明显,全年中除了12月外,其余月份平均气温距平预测与实况的距平相关系数在全国大部地区都呈正相关;近50 a全国月降水量距平百分率预测水平呈先降后升的趋势,尤其是近30 a呈现较为稳定的提升态势,月降水预测与实况的相关分布主要有3种形态,体现出降水预测比气温预测更为复杂的特性。

China has been engaged in short-term climate prediction for nearly 70 years and was one of the earliest countries in the world to carry out short-term climate prediction and relevant researches.Since March 2021,the National Climate Center(NCC)of China has released officially the climate prediction for the next 15-30 days,months and seasons through its website.Short term climate forecasts are receiving increasing attention from society.In 2013,based on the operational prediction of short-term climate and the pre⁃vious assessment methods,the Department of Forecasting and Networking of China Meteorological Administration issued a new method to assess operationally the short-term climate prediction.Using this new method,this paper analyzed the evaluation results for monthly climate prediction products during 1971-2020 released by the NCC.The results show that the prediction scores are lower in the winter half year than in the summer half year both for monthly temperature anomaly and precipitation anomaly percentage.The forecast skill of monthly temperature anomaly has been improved significantly in recent 50 years.The anomaly correlation coefficient between the fore⁃cast and observation of monthly temperature anomaly are positive in most parts of China throughout the year,except for December.The prediction level of monthly precipitation anomaly percentage in China in 50 years shows a trend of decreasing first and then increasing,especially in the past 30 years,it shows a relatively stable upward trend.The distribution of correlations between precipitation forecast and observation has three main patterns,which is much more complex than that of temperature,suggesting that the precipitation fore⁃cast is more challenging than temperature forecast.