Mass and heat balance of sea ice during the thaw-freezing transition in the Pacific sector of Arctic Ocean derived from the buoy measurements in 2018
摘要
The thaw-freezing transition period is crucial to determine the initial sea ice status prior to the freezing season. The heat and mass balance at ice-ocean interface is the major driving process. In this study, we analyze heat fluxes profile through the ice from ice surface down to basal ice-ocean interface using the data measured by 11 thermistor string-based ice mass balance buoys (IMBs) between September and December 2018 in the Pacific sector of Arctic Ocean. The conductive heat fluxes gradually decreased from surface downward through the lower ice layers due to the thermal inertia and energy storage in the brine pockets. At the ice bottom, the oceanic heat flux decreased from (5.9 ± 1.3) W/m2 in mid-September to (1.8 ± 0.8) W/m2 by the end of December in response to the decreasing of available absorbed solar radiation regulated by the latitude and sea ice concentration. The initial ice thicknesses can explain the onset of ice basal growth by 44.8% (R2). From 15 September to the average onset of ice basal growth by 13 November, the accumulated heat fluxes released from the ice surface to the atmosphere, caused by the cooling of the ice layer, and from the ocean to the ice bottom were estimated as 25.73 MJ/m2, 6.49 MJ/m2, and 20.30 MJ/m2, respectively. The latter two components mainly play the roles in buffering the onset of ice basal growth.