西北太平洋热带气旋生成与路径的次季节预报方法及其性能评估

Sub-seasonal prediction method and its performance evaluation for the Northwest Pacific tropical cyclone genesis and track

  • 摘要: 基于世界气象组织次季节至季节尺度预测计划数据集中11个动力模式回算预报试验中的热带气旋(Tropical Cyclone, TC)资料,对西北太平洋海域使用正则逻辑回归方程构建了TC生成与路径的统计预报模型,并评估了模型在次季节尺度上TC生成和路径的预报技巧,分析了动力模式在气候、年际和次季节尺度上对TC活动的预报能力及其对预报技巧的影响。结果表明:(1)西北太平洋TC活动本身的气候态预报能力对动力模式预报技巧具有关键影响,若动力模式能很好地再现气候和年际尺度上的TC活动、提高大气季节内振荡对TC活动调控作用的预报能力,可较好地改进TC生成和路径的次季节预报技巧。(2)在次季节尺度上,动力模式TC路径预报技巧普遍高于TC生成,较低的TC生成预报技巧反映了动力模式对TC强度预报能力的不足,制约了TC路径预报技巧的改进。提高动力模式在气候和年际尺度上对TC生成的预报能力有助于路径预报技巧的改进。

     

    Abstract: Using tropical cyclone (TC) data of reforecast experiments by 11 dynamical models from the World Climate Research Program and World Weather Research Program sub-seasonal to seasonal prediction project, this study evaluates skills of the 11 dynamical models for predicting TC genesis and track on sub-seasonal time scale over the Westernnorth Pacific, and compares with a statistical model that was developed by regularized logistic regression. The performances of these dynamical models on predicting TC activities at the climatic, interannual and sub-seasonal time scales are analyzed in this study. Results are as follows. (1) The performance of dynamical models on predicting climatic seasonal cycle of TC activities over the Western North Pacific has a critical impact on sub-seasonal forecast skills. If a dynamical model can well reproduce TC activities at the climatic and interannual time scales, there is an expected skill improvement of TC genesis and track forecast on sub-seasonal time scale by improving the model ability for forecasting intra-seasonal oscillation modulation on TC activities. (2) Most of the dynamical models have a better skill for TC track prediction than that for cyclogenesis prediction at sub-seasonal time scale, implying a lower skill for TC intensity prediction in the models. The lower skill for cyclogenesis prediction hampers the improvement of TC track prediction. Improving predictions of climatic and interannual cyclogenesis could enhance tropical cyclone track forecasts by dynamic models.

     

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