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Seminar talk: Non-Stationary Relationship between Autumn Arctic Sea Ice and the Winter NAO

Erik Kolstad, NORCE Climate will give a seminar talk on May 20. 

Erik Kolstad
Erik Kolstad

Short biography:

My main research interests are climate impacts, seasonal forecasting, and polar meteorology. Since August 2014, I've been a researcher at NORCE Climate. Between 2011 and 2014, I was a scientist at StormGeo in Bergen, working primarily with weather forecasting and forecast/hindcast products for the wind energy industry. Before that, starting in 2003, I worked for the Bjerknes Centre for Climate Research at the University of Bergen, where I also took my PhD in meteorology.



European winter weather is heavily influenced by the North Atlantic Oscillation (NAO). The so-called positive NAO brings mild and wet conditions to northern Europe in winter, and the negative NAO tends to be cold and dry. Scientists attempt to forecast the NAO in advance by one of two ways: using complex weather forecast models or using relatively simple statistical equations. Although statistical methods can outperform more complicated forecast models, they assume that predictor relationships do not change over time. This assumption is not always valid. In this study, we examined the relationship over time between autumn sea ice in the Barents-Kara Seas and the winter NAO. In recent decades, a strong relationship has been observed whereby especially reduced autumn sea ice often precedes negative NAO in the following winter. When we looked further back in time, however, we found that the ice-NAO relationship has been highly changeable and sometimes, the complete opposite to that seen recently. An analysis of hundreds of simulations from multiple climate models confirms that the ice-NAO relationship varies a lot, just due to natural climate variability. Our results suggest it is unwise to make predictions of the winter NAO based on autumn sea ice.


Arranged date for the seminar talk: May 20, 2019