中国旱涝极端事件前兆信号及可预测性研究

Analysis of precursors and predictability of PDSI extremes in China

基于百分位,研究了Lorenz系统极端事件的前兆信号分布特征及可预测性;利用前兆信号及接收器算子特征曲线(receiver operator characteristiccurve,ROC曲线)对中国旱涝极端事件可预测性进行研究,得到了极端事件的可预测效果与序列的自相关性、极端事件的极端程度之间的关系.研究表明,无论是Lorenz系统分量序列还是Palmer干旱指数序列(Palmer drought severity index,PDSI),存在极端事件的可预测性随极端程度增强而增加的现象.同时对各区域极端旱涝事件前兆信号及可预测性进行分析,为中国旱涝极端事件的预测提供一定科学依据.

We investigate precursors and predictability of extreme events of Lorenz system with different percentile. The precursors and predictability of Palmer Drought Severity Index （PDSI） extremes in China are analyzed,and obtained how the quality of the prediction depends on the size of the extreme events and on the correlation strength. Results indicate that for extreme events of Lorenz system and PDSI series,the stronger the extreme,the higher the predictablility. Moreover, we analyzed precursors and predictability of eight regions in China and provide some due scientific basis for flood and drought predictions.