北極海ポリニヤ域における海氷生成量の衛星-モデル間比較

抄録

Winter sea ice production in the Arctic coastal polynyas was compared between a satellite microwave-based estimate and a pan-Arctic sea ice-ocean model. The Alaskan coast, Novaya Zemlya, and North Water were chosen as target regions in this study. The interannual model experiment showed high correlation of sea ice production with the SSM/I-based variability from 1993 to 2013 in the Alaskan coast and Novaya Zemlya regions. On the other hand, the modeled production was frequently smaller than the satellite values. The modeling analyses suggested that offshore-ward sea ice transport and upward ocean heat transport were intensified in the same years, in the Alaskan coast and North Water regions. The wind stress with specific direction caused both the processes. Since the satellite algorithm used in this study did not include the ocean heat flux under sea ice, on which the wind-driven upwelling and turbulent mixing work, the improvement using open water mask was expected. For surface heat budget calculation, the model and satellite algorithm utilized different atmospheric datasets. Whereas the air temperature obtained from two major reanalysis data showed the close values in the Alaskan coast and Novaya Zemlya regions, the obvious temperature bias would be one of factors for an error in sea ice production in the North Water region. For further model improvements, the formulation of sea ice internal stress should be verified to more precisely represent polynya expanding processes. To update satellite algorithm, snow and fine-scale open lead would be key issues.