Modeling of the drag and thermal conductivity coefficients in tropical cyclones taking into account foam cover

A formal averaging procedure over the air-sea interface is developed for both momentum and enthalpy surface-transfer coefficients, C_D C_K and  in hurricane conditions. This leads to
splitting of both the transfer coefficients across the total area of the sea surface, C_D,K into the sums of their partial values over the foam-free, C_D,K,W, and foam-covered, C_D,K,F fractions weighted with foam- and water-coverage coefficients αf and 1-αf . The transfer coefficients, C_Dk and C_Dkw, are estimated by measurements in open-sea and in laboratory conditions, respectively, while the transfer coefficients across the foam-covered fraction, ܥ ,௙௄,஽ which cannot be measured directly, are estimated from the splitting relations. Applying the Monin Obukhov similarity theory at the neutral stability atmospheric conditions to the transfer coefficients, separately to the foam-free, the foam-covered, and the total sea surfaces, yields the roughness lengths, Z,_DKW. The study is aimed at explaining an anomalous behavior of the momentum and enthalpy transfer coefficients, C_D and C_K with wind speed U10 under hurricane conditions, by the effect of the foam slipping layer sandwiched between the atmosphere and the ocean.