Changes in Seasonal and Extreme Arctic Cyclone Events in the CMIP5 Climate Models

Abstract:

Cyclone activities are governed by many boundary conditions, such as the underlying SST or sea ice, the relative heating between the continent and the ocean, and their relative location against the jet stream to name a few. All these factors and their seasonal march is prone to change under the future global warming condition. Especially in the Arctic, the timing of sea ice melting and freezing, seasonal change in snow cover, and the location of upper level jets all contribute towards a change in cyclone seasonal distribution and extreme events. Here, we use a Langrangean method of detecting cyclones and their activity under the historical and rcp 4.5 scenario of 8 CMIP5 climate models to assess the change in Arctic cyclone activities. We find that while the models show weaker cyclone activities than observation and inter-model difference is large in some cases, they simulate the seasonal cycle and extreme events reasonably well. In the winter season under the global warming scenario, many models exhibits a northeastward shift in mid-latitude storm track resulting in mode cyclones entering the Arctic from the mid-latitudes. There is also a marked increase in the number of cyclones in the Barents/Kara Sea where correlation with sea ice is suspected. During the summer season, a large change in the Arctic cyclone activity located near the North Pole is evident in many models. This change in Arctic cyclone is due to contribution of more cyclogenesis within the Arctic circle. In this presentation, we also look at other seasons and the seasonal march of the cyclone activity within the Arctic and its interaction with the mid-latitudes. We also document the change in extreme events under the climate models.