Momentum and heat transfer across the foam-covered air-sea interface in hurricanes

Abstract

Procedures of formal averaging over the air-sea interface are applied to both momentum and enthalpy surface-transfer coefficients, CD and CK, in hurricane conditions. The transfer coefficients across the total area of the sea surface and water-covered portions of the sea surface, CD, CK, and CDw, CKw, are estimated by measurements in the open-sea and laboratory (foam-free) conditions, respectively, while the transfer coefficients across the foam-covered portion of the sea surface, CDf, Kf, which cannot be measured directly, are estimated using the splitting relations. Applying the Monin-Obukhov similarity theory at the neutral stability atmospheric conditions to the transfer coefficients (separately for the foam-free, foam-covered, and total sea surfaces) yields the roughness lengths ZDw, ZKw, ZDf, ZKf, and ZD, ZK. The study is aimed at the description of an anomalous, as compared with laboratory conditions, behavior of the momentum and enthalpy transfer coefficients in hurricane conditions with wind speed U10 by the effect of the foam slipping layer sandwiched between the atmosphere and the ocean.