The Impact of Stored Solar Heat on Arctic Sea Ice Growth

High-resolution measurements of ocean temperature and salinity in the Arctic Ocean’s Canada Basin reveal the importance of the release of solar-derived stored ocean heat on sea ice growth. Locally absorbed summer solar heat is stored in a near-surface temperature maximum (NSTM) layer underlying the mixed layer. The heat content of the NSTM layer was anomalously large following summer 2007, which saw considerable sea ice losses and intense solar absorption into the exposed surface ocean. Measurements provide evidence for the entrainment of NSTM layer heat in fall/winter 2007–2008 by shear-driven mixing, and convective mixing by the release of dense, salty plumes during sea ice growth. While at least a portion of the NSTM layer was eroded, deeper warm ocean layers remained unaffected. It is shown that the release of solar heat stored following summer 2007 was sufficient to have reduced sea ice thickness at the end of the 2008 growth season by about 25%.