Abstract:

Using sea ice surface roughness measurements made by a helicopter-borne altimeter in the northwestern Weddell Sea, the formulas to derive ice–air drag coefficient Cdn(10) at a reference height of 10 m under neutral and stable conditions and form drag on ridge sails were improved. Morphological parameters and distributions of ridge sails were incorporated. Variations of Cdn(10) and contribution of form drag on ridge sails to total drag with increasing ridging intensity and roughness length were discussed. Results revealed that Cdn(10) increases with increasing ridging intensity. When ridging intensity is low, Cdn(10) increases with roughness length whereas it decreases with roughness length when ridging intensity is high. The contribution of form drag on ridge sails to total drag increases with ridging intensity and decreases with increasing roughness length, because form drag on ridge sails dominates over skin drag over rough ice surface when ridging intensity becomes extremely large.

Key words: Antarctica, ice–air drag coefficient, form drag, parameterization