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

Min, Chao; Yang, Qinghua; Mu, Longjiang; Kauker, Frank; Ricker, Robert

Sea ice in the Baffin Bay plays an important role in deep water formation in the Labrador Sea and contributes to the variation of the Atlantic meridional overturning circulation (AMOC) on larger scales. Sea-ice data from locally merged satellite observations (Sat-merged SIT) in the eastern Canadian Arctic and three state-of-the-art sea ice–ocean models are used to quantify sea-ice volume variations from 2011 to 2016. Ensemble-based sea-ice volume (SIV) fluxes and the related standard deviations in the Baffin Bay are generated from four different estimates of SIV fluxes that were derived from Sat-merged SIT, three modeled SITs and satellite-based ice-drift data. Results show that the net increase in the SIV in Baffin Bay occurs from October to early April with the largest SIV increase in December (113 inline-formula± 17 kminline-formula3 monthinline-formula−1) followed by a reduction from May to September with the largest SIV decline in July (inline-formula−160 inline-formula± 32 kminline-formula3 monthinline-formula−1). The maximum SIV inflow occurs in winter with the amount of 236 (inline-formula±38) kminline-formula3 while ice outflow reaches the maximum in spring with a mean value of 168 (inline-formula±46) kminline-formula3. The ensemble mean SIV inflow reaches its maximum (294 inline-formula± 59 kminline-formula3) in winter 2013 caused by high ice velocity along the north gate while the largest SIV outflow (229 inline-formula± 67 kminline-formula3) occurs in spring of 2014 due to the high ice velocity and thick ice along the south gate. The long-term annual mean ice volume inflow and outflow are 411 (inline-formula±74) kminline-formula3 yrinline-formula−1 and 312 (inline-formula±80) kminline-formula3 yrinline-formula−1, respectively. Our analysis also reveals that, on average, sea ice in the Baffin Bay melts from May to September with a net reduction of 335 kminline-formula3 in volume while it freezes from October to April with a net increase of 218 kminline-formula3. In the melting season, there is about 268 kminline-formula3 freshwater produced by local melting of sea ice in the Baffin Bay. In the annual mean, the mean freshwater converted from SIV outflow that enters the Labrador Sea is about 250 kminline-formula3 yrinline-formula−1 (i.e., 8 mSv), while it is only about 9 % of the net liquid freshwater flux through the Davis Strait. The maximum freshwater flux derived from SIV outflow peaks in March is 65 kminline-formula3 (i.e., 25 mSv).

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Min, Chao / Yang, Qinghua / Mu, Longjiang / et al: Ensemble-based estimation of sea-ice volume variations in the Baffin Bay. 2021. Copernicus Publications.

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