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Abstract:
Atmospheric circulation is one of the major drivers of Arctic sea ice and so, one of the key elements for its predictability. Most studies devoted to the atmosphere-sea ice coupling have so far only considered the effects of the troposphere. However, the low predictability of the polar tropospheric weather beyond two weeks hampers longer predictions of the sea ice. Further, changes in the stratosphere, such as sudden stratospheric warmings, have been found to affect surface conditions for up to several weeks, being the polar region one of the most affected areas. Thus, the consideration of the occurrence of these events may remarkably improve the predictability of the Arctic area.
In this study, we aim to evaluate the predictive capacity of SSWs at sub-seasonal scale on Arctic sea ice concentration (SIC). To do so, we have used hindcast simulations of the sub-seasonal prediction model of the European Centre for Medium-Range Weather Forecasts (ECMWF) during the 20-year period of 1999-2018. Our results show that the model can reproduce the downward propagation of the stratospheric signal expected after an SSW event. It also simulates significant SIC anomalies after the occurrence of the downward-propagating SSWs. Finally, our results indicate an improvement in the prediction of Arctic sea ice after downward propagating SSWs compared to years without SSWs.
