Conductive Heat Flux Over Arctic Sea Ice From 1979 to 2022

Abstract

The conductive heat flux (CHF) from the ocean to the snow/sea ice-atmosphere interface through sea ice is a crucial component of the surface energy budget over the sea ice-covered Arctic Ocean. The CHF is influenced by surface skin temperature, sea ice thickness, and depth of snow on sea ice. This study uses monthly mean surface skin temperature from ERA5 reanalysis, and sea ice thickness and snow depth from the Pan-Arctic Ice-Ocean Modeling and Assimilation System to derive the means and changes of CHF over the Arctic Ocean from 1979 to 2022. The findings reveal that CHFs are generally positive (from flux to the surface from below) from November to March and negative from June to August. CHFs are large in peripheral seas with thin sea ice and low snow depth, and small over pack ice with thick sea ice and snow. The thinning of sea ice and snow on sea ice contributes to increasing CHF, while rising surface skin temperatures lead to decreasing CHF. Overall, CHF increases from 1979 to 2022, primarily driven by the thinning of sea ice. The magnitude of CHF changes during this period is comparable to or higher than those in sensible heat flux, latent heat flux, and net longwave/thermal radiation flux at the surface from November to March over the peripheral seas. A better representation of sea ice thickness and snow depth over sea ice in the reanalysis would possibly improve the depiction of CHF and surface temperature changes.