Relative contributions of local heat storage and ocean heat transport to cold-season Arctic Ocean surface energy fluxes in CMIP6 models

The Arctic near-surface air temperature increases most strongly during the cold season, and ocean heat storage has often been cited as a crucial component in linking the ice-albedo radiative feedback, which is active in summer, and near-surface air temperature increase in winter, when the lapse rate feedback contributes to Arctic warming. Here, we first estimate how much local heat storage and ocean heat transport contribute to net surface energy fluxes on a seasonal scale in CMIP6 models. We then compare contributions in a base state under weak anthropogenic forcing to a near-present-day state in which significant Arctic amplification is simulated. Our analysis indicates that, in a few regions, ocean heat transport plays a larger role for cold-season net surface energy fluxes compared with local heat storage. Analyzing differences between past and near-present-day conditions suggests that the lapse rate feedback, which mainly acts during the cold season in warm water inflow regions, may be more strongly influenced than previously thought by increased ocean heat transport from lower latitudes.