Evaluating Snow Depth on Arctic Sea Ice in CCSM Objective To compare CCSM snow-on-sea-ice simulations with observed data, document biases and investigate sensitivity of sea ice/snow conductive fluxes to perturbations of snow characteristics. • Approach • Compare CCSM output with data from a climatology based on Russian drifting station observations • Identify seasonal biases • Perturb snow thermal conductivity • Seasonal snow depth biases of 40-150% lead to negative sea ice volume biases (too little ice) • nonlinear feedback mechanisms, including clouds and ocean temperatures, modify these biases CCSM Arctic Ocean snow depths for the period 1954-1993 validated against Russian drift station measurements. Vertical bars indicate one standard deviation for both in situ and model snow depths. Impact Snow conductivity can not be used as a simple tuning parameter in sea ice models. Instead, complex snow processes need to be modeled. Blazey, B. A., Holland, M. M., and Hunke, E. C.: Arctic Ocean sea ice snow depth evaluation and bias sensitivity in CCSM, The Cryosphere, 7, 1887-1900, doi:10.5194/tc-7-1887-2013, 2013.