Arctic Surface Clear-sky Flux Anomalies and Surface Cloud Radiative Effect Anomalies Associated with the Arctic Oscillation and Arctic Dipole

Atmospheric variability and Arctic surface energy budget variability are linked in part through surface longwave and shortwave radiative flux anomalies, generated by changes in the thermodynamic and cloud characteristics within the atmospheric column. Previous studies have shown that this link plays a crucial role the local and regional initialization and acceleration of Arctic sea ice melt. In the results presented, we quantify Arctic-average and regional clear sky and cloud radiative surface flux anomalies associated with the Arctic Oscillation (AO) and Arctic Dipole (AD), two prominent modes of atmospheric variability. We regress monthly AO and AD indices with monthly CERES-EBAF surface flux data. Both the AO and AD are associated with significant Arctic-mean clear-sky surface downwelling longwave radiative flux anomalies in late fall and winter. Significant positive surface longwave cloud radiative effect anomalies are also associated with AD in winter. Additionally we determine the tropospheric dynamical and thermodynamical mechanisms that bring about the associated flux anomalies, through regressions of monthly AO and AD indices with key dynamical and thermodynamical quantities in MERRA2 and ERA-Interim reanalysis data. The longwave clear-sky flux anomalies associated with AO and AD are a result of changes in temperature and water vapor content in the lower troposphere collocated with the surface flux anomalies. Increased cloud liquid water path in the atmospheric column plays a crucial role in generating the increased longwave cloud radiative effect in winter associated with AD.