我国汛期季度降水预报得分和预报技巧

Score and Skill of Seasonal Forecasts of Summer Precipitation in China

利用1951—2008年我国160站夏季降水资料分析了季度降水预报的气候得分,又用1978年以来我国历年汛期业务降水预报结果检验了其预报能力和技巧。多年来,我国业务汛期降水季度预报有一定的预报技巧,但也有些年份预报能力较低。预报能力高或有技巧的年份是江淮地区降水少的年份,但对长江中下游降水多的年份,预报能力较低。我国汛期降水预报能力要建立在区域年代际信号和年际早期信号叠加的基础上。年代际信号是在划定我国为不同区域的基础上,把握区域年代际降水变化的规律。年际早期信号实际上是要跟踪降水年际振荡与大气下垫面强迫季节早期信号的关系。

Seasonal operational forecast dataset of summer precipitation（1978—2008）was used to investigate the forecast ability and forecast skill.Compared with 160 stations＇ observations（1951—2008）,the high forecast skill years and the low forecast skill years were distinguished.The highest forecast skill appeared in the years when dry domain controls the Yangtze-Huaihe River Basin;however,the lowest score appeared in the years when the mid-low Yangtze River Basin was wet.Two signals from inter-decadal and inter-annual timescales should be utilized in the operational forecast.For the inter-decadal timescale,the monsoon region in East China should be divided into several sub-regions first,and then actual inter-decadal signals at individual sub-region can be used in the operational forecast.Inter-annual precursory signals could be the biennial oscillation and seasonal forcing such as the sea temperature,snow cover and soil moisture anomalies.