Predictability of Rossby wave packets: Climatology and dynamical characteristics

罗斯贝波包的可预测性：气候学和动力学特征

• 批准号: 389709309
• 负责人: Privatdozent Dr. Michael Riemer
• 金额: --
• 依托单位: Institut für Physik der Atmosphäre
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/389709309?language=en
• 关键词: Predictability; Rossby; wave; packets; Climatology

Rossby waves are of fundamental importance for the dynamics of the Earth's atmosphere, and midlatitude weather systems are often embedded in distinct Rossby wave packets (RWPs). The significance of these wave packets for weather forecasting has long been recognized and special attention has been given to the role of RWPs as precursors to high-impact weather events. In general, it may be expected that RWPs, as large-scale flow features obeying balanced dynamics, exhibit a large degree of predictability, which may then be inherited by embedded, smaller-scale weather features. On the other hand, a number of recent studies have demonstrated that forecast errors and forecast uncertainty propagate and amplify within RWPs, severely affecting predictability. The important question therefore arises: Under which conditions do RWPs exhibit high predictability and under which conditions low predictability? The work proposed herein will significantly contribute to answer this question. We propose to investigate RWP predictability from a climatological perspective using a 30-year ensemble reforecast dataset. Our approach considers RWPs as distinct, physically meaningful entities that can be described by specific characteristics: amplitude, size, shape, and position, Predictability of these characteristics will be assessed from the ensemble data. Variations of predictability with season, geographical region, duration, and the phase of the life cycle of the RWP will be investigated. This phenomenological investigation will be complemented by a process-based investigation of the RWP dynamics. The goal is to contrast the dynamics of RWPs with high and low predictability, respectively, and thus to better understand significant variations in RWP predictability.

罗斯比波对地球大气动力学具有重要的基础意义，而中纬度天气系统通常嵌入不同的罗斯比波包（RWPs）中。这些波包对天气预报的重要性早已被认识到，并特别注意到rwp作为高影响天气事件前兆的作用。一般来说，可以预期rwp作为服从平衡动力学的大尺度流动特征，表现出很大程度的可预测性，然后可以由嵌入的较小尺度天气特征继承。另一方面，最近的一些研究表明，预测误差和预测不确定性在rwp内传播和放大，严重影响可预测性。因此，重要的问题出现了：在哪些条件下，rwp表现出高可预测性，在哪些条件下表现出低可预测性？本文提出的工作将显著有助于回答这个问题。我们建议从气候学的角度利用一个30年的集合预报数据集来研究RWP的可预测性。我们的方法将rwp视为独特的、物理上有意义的实体，可以通过特定的特征来描述：振幅、大小、形状和位置，这些特征的可预测性将从集合数据中进行评估。将调查可预见性随季节、地理区域、持续时间和RWP生命周期阶段的变化。这种现象学调查将辅以基于过程的RWP动态调查。目标是分别对比可预测性高和低的RWP动态，从而更好地理解RWP可预测性的重大变化。