摘要
The authors previous study reported the important role of extratropical intraseasonal oscillation(ISO)on the occurrence of a typical heatwave event over the Yangtze River Valley.Based on the ECMWF subseasonal reforecast database,this follow-up study evaluates the extended-range prediction skill of the heatwave event and further unravels the close link between the ISO and extended-range prediction of the event.With a two-week lead time,this heatwave event fails to occur in the reforecast because the predicted surface temperature is signi cantly underesti-mated.More detailed analysis demonstrates that the biases for both the intensity and the location of the warming region are primarily attributable to the inaccurate extratropical intrasea-sonal traveling signals.This work strongly indicates that accurately capturing the extratropical intraseasonal signal from the Eurasian continent is indispensable for extended-range prediction of East Asian extreme heatwave events.
江淮流域热浪事件的触发与大气季节内信号的传播密切相关。基于ECMWF次季节预测系统的回报数据,本研究在延伸期(10–30天)尺度上评估了一次典型江淮热浪事件的预测情况。评估采用气候态与季节内模态剥离的方法,揭示出大气季节内信号在江淮热浪延伸期预测中的必要作用。结果表明,相较于热带季节内信号,中纬度季节内信号在延伸期的预测偏差,是导致热浪超前2周预测失败的主要原因。本研究的重要启示是,提高中纬度地区大气季节内信号在延伸期尺度上的预测效果是提升东亚极端热浪事件预测水平的重要途径。
基金
supported by the National Key R&D Program of China(Grant No.2018YFC1505903)
the National Natural Science Foundation of China(Grant No.41775071)
the National Key R&D Program of China(Grant No.2016YFA0602401)
