Analyzing cloud radiative variability with sea ice variability in the ERA-40 reanalysis and polar-WRF

Arctic cloud cover and cloud properties alter with variations in sea ice concentrations. The radiative effect of the cloud changes is less known. We examine the surface cloud radiative effect in the ERA-40 reanalysis with relation to changes in sea ice concentration from 1982 to 2001 over the entire Arctic domain. The most statistical significant relationships occur during the winter and spring months. During the winter months, the longwave spectrum dominates the relationship; decreased sea ice corresponds with increased longwave surface warming from clouds. There is an apparent increase in cloud cover with decreased sea ice concentrations in the spring season, but the surface cloud radiative effect nearly cancel the total cloud radiative effect because the shortwave and longwave effects counteract . Statistically insignificant correlations occur between cloud radiative changes associated with changes in sea ice occur in the summer and early autumn. Statistically significant relationships occur from October to May. Changes in surface cloud radiative forcing associated with differing sea ice concentrations are also examined in polar-WRF over the Laptev Sea during the transition from summer to autumn to better understand the ERA-40 results. During decreased sea ice extent years, increased low level cloud water is predicated during the summer and autumn, but clouds only significantly warm the surface after the removal of insolation.