Ensemble-based estimation of sea-ice volume variations in the Baffin Bay

Abstract

Abstract. Sea ice in the Baffin Bay plays an important role in deep water\nformation in the Labrador Sea and contributes to the variation of the\nAtlantic meridional overturning circulation (AMOC) on larger scales. Sea-ice\ndata from locally merged satellite observations (Sat-merged SIT) in the\neastern Canadian Arctic and three state-of-the-art sea ice–ocean models are\nused to quantify sea-ice volume variations from 2011 to 2016. Ensemble-based\nsea-ice volume (SIV) fluxes and the related standard deviations in the\nBaffin Bay are generated from four different estimates of SIV fluxes that\nwere derived from Sat-merged SIT, three modeled SITs and satellite-based\nice-drift data. Results show that the net increase in the SIV in Baffin Bay\noccurs from October to early April with the largest SIV increase in December\n(113\u2009 ± \u200917\u2009km 3 \u2009month −1 ) followed by a reduction from May to\nSeptember with the largest SIV decline in July ( − 160\u2009 ± \u200932\u2009km 3 \u2009month −1 ). The maximum SIV inflow occurs in winter with the amount of\n236\u2009( ± 38)\u2009km 3 while ice outflow reaches the maximum in spring\nwith a mean value of 168\u2009( ± 46)\u2009km 3 . The ensemble mean SIV inflow\nreaches its maximum (294\u2009 ± \u200959\u2009km 3 ) in winter 2013 caused by high\nice velocity along the north gate while the largest SIV outflow (229\u2009 ± \u200967\u2009km 3 ) occurs in spring of 2014 due to the high ice velocity and thick\nice along the south gate. The long-term annual mean ice volume inflow and\noutflow are 411\u2009( ± 74)\u2009km 3 \u2009yr −1 and 312\u2009( ± 80)\u2009km 3 \u2009yr −1 , respectively. Our analysis also reveals that, on average, sea\nice in the Baffin Bay melts from May to September with a net reduction of\n335\u2009km 3 in volume while it freezes from October to April with a net\nincrease of 218\u2009km 3 . In the melting season, there is about 268\u2009km 3 \nfreshwater produced by local melting of sea ice in the Baffin Bay. In the\nannual mean, the mean freshwater converted from SIV outflow that enters the\nLabrador Sea is about 250\u2009km 3 \u2009yr −1 (i.e., 8\u2009mSv), while it is\nonly about 9\u2009% of the net liquid freshwater flux through the Davis Strait.\nThe maximum freshwater flux derived from SIV outflow peaks in March is 65\u2009km 3 (i.e., 25\u2009mSv).