1.Wuhan Regional Climate Center;2.Laboratory for Climate Studies,National Climate Center,CMA
The real-time forecast accuracy of summer precipitation in Northeast China (NEC) is significantly low from 1978～2018. In the last second years, when the prediction of the overall distribution of summer precipitation anomaly for the whole country is relatively accurate, the prediction of summer precipitation anomaly in NEC is contrary to the actual situation. Therefore, it is necessary to analyze the reasons for the low forecasting accuracy. In this paper, the forecasting ability of dynamic models and cognitive defect on forecasting summer rainfall in NEC are discussed. Also, by systematically reviewing the climatic characteristics, influencing factors and prediction methods of summer drought and flood in NEC, and the test of the real-time forecasting, the reasons are as follows: (1) the precipitation in early summer in NEC is mainly affected by the cold eddy activity in NEC, and in midsummer it is mainly affected by the subtropical high in the West Pacific, the southerly wind in the Northeast and the circulation pattern in the middle and high latitudes. However, the main dynamic climate models commonly used at home and abroad can’t accurately reflect the key circulation systems associated with precipitation in early summer and midsummer in NEC. (2) the relationship between the summer rainfall in NEC and global sea surface temperature (SST) is weak and unstable. Especially, the influence of ENSO on summer precipitation in NEC is complicated, the relationship between them varies from decadal to decadal; (3) the summer rainfall in NEC has obvious multi-time scale variability (inter-seasonal, inter-annual and inter-decadal time-scale) influenced by different circulation systems, which makes it more difficult to accurately predict summer precipitation in NEC. Finally, some scientific problems and possible solutions are further discussed for summer rainfall forecasting in NEC, which may be helpful for the future summer rainfall prediction in this area.