Variability and extremes of poleward breaking Rossby waves over the North Atlantic - European Region (VARNAER)

在温带外地区，Rossby波在决定大气环流中起着重要作用，特别是在对流层上部/平流层下部。众所周知，冬季北大西洋-欧洲地区经常观测到极地破碎Rossby波的事件。在这个项目中，我们研究了观测到的对流层上层背景气流对极地Rossby波破裂事件的影响及其与恶劣天气的联系。我们将研究北大西洋-欧洲地区极地破碎Rossby波事件的季节内和年际变化，并基于ECMWF再分析(ERA-TERTER)和分析，诊断每个季节的波浪破碎事件的极端个例。通过使用不同的预报数据集，研究了此类事件的可预测性。此外，不同纬向变化的背景气流对极地Rossby波破裂的预期影响将在简化的全球ECHAM5模式模拟中进行考察，以提高对这一过程的理解。进一步的关键研究是对极地Rossby波破裂事件对对流层低层Grosswetterlage(大尺度气流)变化的影响的诊断和中尺度模拟(WRF)，以检验不同的作用机制，并了解影响和影响北欧恶劣天气的亚季节差异。

In the extratropics Rossby waves play an important role in determining the general circulation, especially in the upper troposphere / lower stratosphere region. It is known that events of poleward breaking Rossby waves are often observed over the North Atlantic-European region in wintertime. In this project we investigate the influence of the observed background flow in the upper troposphere on poleward Rossby wave breaking events and the link to severe weather. We will study the intra-seasonal and interannual variability of events of poleward breaking Rossby waves over the North Atlantic-European region and diagnose the extreme cases of the wave breaking events for each season, based on ECMWF Reanalysis (ERA-INTERIM) and analyses. The predictability of such events is investigated by using different forecasts data sets. Furthermore, the expected influence of the different zonally varying background flows on poleward Rossby wave breaking will be examined in simplified global ECHAM5 model simulations in order to improve the understanding of this process. A further key investigation is the diagnosis and mesoscale modelling (WRF) for implications of poleward Rossby wave breaking events on the change of the Grosswetterlage (large scale flow) in the lower troposphere, in order to examine different acting mechanisms, and to understand the sub-seasonal differences of the influence and of the impact on severe weather over Northern Europe.