太平洋年代际振荡的年代际预测方法

A possible approach for the decadal prediction of PDO

  • 摘要: 太平洋年代际振荡(PDO)是北太平洋海表温度年代际变率的主模态。由于太平洋年代际振荡对区域乃至全球气候的显著影响,其合理的预测结果可以带来多方面收益。然而,针对太平洋年代际振荡及其有关的海表温度的年代际预测,目前气候模式的预测水平还十分有限,因此,提出了一个新的增量方法。一系列的验证结果表明,增量方法可以有效预测太平洋年代际振荡,其中包括成功预测出其振荡的年代际转折。增量方法的预测过程主要包括3个步骤:(1)采用5 a滑动平均得到太平洋年代际振荡的年代际变率;(2)利用3 a增量形式的预测因子构建预测模型,预测3 a增量的太平洋年代际振荡(DI_PDO);(3)将预测得到的DI_PDO加上3 a前的观测PDO,得到最后预测的PDO。增量方法亦可以应用到气候系统年代际内部变率的其他模态(如:北大西洋年代际振荡)和其他气候变量的年代际预测(如:海表温度)。

     

    Abstract: The Pacific Decadal Oscillation (PDO) is a leading mode of decadal sea surface temperature variability in the North Pacific. Skillful PDO prediction can be beneficial in many aspects because of its global and regional impacts. However, current climate models cannot provide satisfying decadal prediction of PDO and related decadal variability of sea surface temperature. A new prediction approach was proposed, i.e., the increment method. A series of validations demonstrate that the increment method effectively improves the decadal prediction on PDO and can well capture the phase changes of PDO with high accuracy. The prediction processes include three steps: (1) A five year smoothing is performed; (2) effective preceding predictors for PDO are selected, with all predictors and predictands in the form of a three year decadal increment (DI); (3) the prediction model is set up for PDO three year decadal increment (DI_PDO), and the PDO prediction can then be obtained by adding the predicted DI_PDO to the observed PDO three years ago. This new method can also be applied for decadal climate prediction of other modes (e.g., Atlantic multidecadal oscillation) and predictands (e.g., sea surface temperature).

     

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