Impact of Local Atmospheric Intraseasonal Variability on Mean Sea Ice State in the Arctic Ocean

The Arctic atmosphere shows significant variability on intraseasonal time scales of 10-90 days. The intraseasonal variability in the Arctic sea ice is clearly related to that in the Arctic atmosphere. It is well known that the Arctic mean sea ice state is governed by the local mean atmospheric state. However, the response of the Arctic mean sea ice state to the local atmospheric intraseasonal variability is unclear. The Arctic atmospheric intraseasonal variability exists in both the thermodynamical and dynamical variables. Based on a sea ice-ocean coupled simulation with a quantitative sea ice budget analysis, this study finds that 1) the intraseasonal atmospheric thermodynamical variability tends to reduce sea ice melting through changing the downward heat flux on the open water area in the marginal sea ice zone, and the intraseasonal atmospheric dynamical variability tends to increase sea ice melting by a combination of modified air-ocean heat fluxes, ice-ocean heat fluxes, and sea ice deformation; 2) the intraseasonal atmospheric dynamical variability increases summertime sea ice concentration in the Beaufort Sea and the Greenland Sea but decreases summertime sea ice concentration along the Eurasian continent in the East Siberia-Laptev-Kara Seas, resulting from the joint effects of the modified air-ocean heat fluxes, ice-ocean heat fluxes, and the sea ice deformation, as well as the mean sea ice advection due to the changes of sea ice drift. The large spread in sea ice in the CMIP models may be partly attributed to the different model performances in representing the observed atmospheric intraseasonal variability. Reliable modeling of atmospheric intraseasonal variability is an essential condition in correctly projecting future sea ice evolution.