P2002 hypothesized (see Figure 2) that in winter, the wind (a dynamic factor) drives the ice and ocean in a clockwise (anticyclonic) sense so that the BG accumulates fresh water mechanically through a deformation of the salinity field (Ekman convergence and subsequent downwelling). In summer, winds (Figure 2) are weaker (and may even reverse to be counterclockwise) and the summer resultant anomaly in Ekman convergence releases fresh water, thereby relaxing salinity gradients and reducing BG Fresh Water Content (FWC). P2002 tested this mechanical hypothesis for fresh water accumulation and release by employing a relatively simple model (Figure 2, bottom panels) where wind was the major driving force (the influences of sea ice and ocean thermodynamics were neglected). At the same time, P2002 pointed out that thermodynamic processes may also be important – in winter, ice growth and subsequent salt release reduce the FWC of the BG, and in summer ice melt increases the FWC. The interplay between dynamic and thermodynamic forcing is no doubt complicated. These mechanisms of the seasonal fresh water transformations was investigated by Proshutinsky et al  and are provided in section FWC seasonal transformations.
Aagaard, K., and E. Carmack (1989), The Role of Sea Ice and Other Fresh Water in the Arctic Circulation, J. Geophys. Res., 94, 14,485– 14,498.
Proshutinsky, A., R. H. Bourke, and F. A. McLaughlin (2002), The role of the Beaufort Gyre in Arctic climate variability: Seasonal to decadal climate scales, Geophys. Res. Lett., 29(23), 2100, doi:10.1029/2002GL015847.