The intraseasonal process of poleward moisture flux and sea-ice melting in Arctic winter.
Wednesday, 17 December 2014
Northern winter is the season when planetary-scale waves and blockings are most energetic. Here, by utilizing global reanalysis and satellite datasets, we show that northward moisture flux into the Arctic during the winter, followed by an enhancement in downward IR, can warm the surface by 20-40 Wm-2, hence cause reduction of sea-ice volume. It is proposed that the recurrence of strong downward IR events within a single winter season is able to reduce the sea-ice volume over wide area of Arctic Ocean. While downward IR is less effective than surface winds in changing sea-ice cover on intraseasonal time scales, the cumulative effect throughout the season can be larger. Further analysis indicates that the downward IR events are preceded several days by enhanced convection over the tropical Indian-western Pacific Ocean. This finding verifies that tropical SST pattern and the associated Rossby wave propagation can have a critical impact on the Arctic sea-ice conditions.