Arctic summer sea ice has decreased dramatically over the last few; decades, with a substantial part of this decline attributed to internal; variability. However, models show large differences in their simulated; internal variability, increasing projection uncertainty and; complications with model-observation comparisons. Here we will present; results that aim to quantify the contribution of internal variability in; different models which provide large ensemble simulations, and compare; them with estimates from observations. In particular, we are comparing; five models from the CLIVAR multi-model large ensemble (CanESM2, CESM1,; CSIRO MK36, GFDL ESM2M, and MPI ESM1) with observations. So far, we have; found a large range in simulated pan-Arctic sea ice area standard; deviation from 0.35 million km2 (CSIRO MK36) to 0.74 million km2 (CESM1); for mean September areas between 4.00-4.25 million km2. Spatially, the; detrended standard deviation in the central Arctic is consistently; over-represented in models compared to observations. Conversely, the; marginal seas are simulated to have slightly below to several times; below observed detrended standard deviation. Further analysis on a more; regional scale will be done over the coming months to further; characterize the realism of simulated internal variability in Arctic sea; ice.
