Climate model sensitivity to sea ice albedo parameterization |
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| Authors: | M P Morassutti |
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| Institution: | (1) Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, USA |
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| Abstract: | Summary Three one-year experimental simulations with the National Center for Atmospheric Research Community Climate Model (NCAR CCM) were performed with three sea ice albedo parameterizations and compared with control run results to examine their impact on polar surface temperature, planetary albedo and clouds. The first integration utilized sea ice albedos of the Arctic Basin for the spring and summer of 1977 derived from defence Meteorological Satellite Imagery (DMSP). The second simulation employed prescribed lead and melt pond fractions and an albedo weighting scheme. The third simulation involved the coupling of an interactive sea ice/snow albedo parameterization made a function of surface state.Results show that prescribed, and assumed  true satellite sea ice albedos produced higher planetary albedos than those calculated with the standard CCM sea ice albedo scheme in the control run. As a result, lower temperatures (up to 0.5 K) and increased cloudiness are generated for the Arctic region. The standard CCM sea ice albedo scheme is used as an adjustment to maintain normal temperatures for the polar oceans. The radiative impact of leads and melt ponds warmed sea ice regions only for short time periods. The third scheme generated markedly lower planetary albedos (reductions of 0.07 to 0.17) and higher surface temperatures (up to 2.0 K) than control values.The CCM simulates a gradual decrease in spring and summer Arctic cloud cover whereas observations show a sharp spring increase. Examination of the CCM code, particularly the cloud parameterization, is required to address this problem.With 12 Figures |
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