Contribution of Antarctic coastal polynyi to total ice production: comparison of satellite- and model-derived estimates

Continuous, i.e. daily, measurements of coastal polynyi in the Weddell Sea have been carried out for the period July through November 1987 with a special method applied to passive microwave data of the SSM/I. Using the derived areas along with surface air temperature and wind field data, freezing rates and the amount of ice produced in the polynyi has been estimated. The results are compared with ice concentration analyses and a large-scale dynamic-thermodynamic sea ice model. The comparison shows that daily changes in near-coast freezing rates, predominantly caused by changes in polynya area, are reflected in changes in the freezing rate for the entire Weddell Sea. Additionally a polynya area of only 0.3% of the Weddell Sea ice extent can be responsible for a change in ice extent of 5.5%. Although in general the model results for areas adjacent to the coast agree with the passive microwave results, some areas show significant differences freezing rate