Much has been established on the variation of wind-stress coefficient with wind velocity under neutral atmospheric conditions; conveniently applicable formulae have also been suggested [Garratt, 1977; Smith, 1980; Wu, 1980]. However, the air and sea generally have different temperatures to produce stable and unstable atmospheric conditions, modifying significantly the wind stress coefficient. Conventional procedures providing the correction factor in terms of the stability parameter Z/L are somewhat tedious. Consequently, empirical formulae were proposed earlier [Wu, 1986], and a table was introduced recently [Smith, 1988]. REFERENCES Garratt, J. R., Review of drag coefficients over oceans and continents, Mon. Weather Rev., 105,915-929, 1977. 1775 1776 Wu: COMMENTARY Kondo, J., Air-sea bulk transfer coefficients in diabatic conditions, Boundary Layer Meteorol., 9, 91-112, 1975. Smith, S. D., Wind stress and heat flux over the ocean in gale force winds, J. Phys. Oceanogr., 10, 709-726, 1980. Smith, S. D., Coefficients for sea surface wind stress, heat flux, and wind profiles as a function of wind speed and temperature, J. Geophys. Res., 93, 15,467-15,472, 1988. Wu, J., Wind-stress coefficients over sea surface near neutral conditions--A revisit, J. Phys. Oceanogr., 10, 727-740, 1980. Wu, J., On critical roughness Reynolds number of the atmospheric surface layer, J. Geophys. Res., 86, 6661-6665, 1981. Wu, J., Stability parameters and wind-stress coefficients under various stability conditions, J. Atmos. Oceanic Technol., 3, 333-339, 1986.

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Abstract. Turbulent fluxes have been measured in the atmospheric surface layer from a boom extending upwind from the Dutch offshore research platform Meetpost Noordwijk (MPN) during HEXMAX (Humidity Exchange over the Sea Main Experiment) in October-November, 1986. We started out to study eddy flux of water vapour, but discrepancies among simultaneous measurements made with three different anemometers led us to develop methods to correct eddy correlation measurements of wind stress for flow distortion by nearby objects. We then found excellent agreement among the corrected wind stress data sets from the three anemometers on the MPN boom and with eddy correlation measurements from a mast on a tripod. Inertial-dissipation techniques gave reliable estimates of wind stress from turbulence spectra, both at MPN and at a nearby ship. The data cover a range of wave ages and the results yield new insights into the variation of sea surface wind stress with sea state; two alternative formulas are given for the nondimensional surface roughness as a function of wave age.

Polynyas and leads are openings in pack ice due to divergences in ice drift and to local melting. They are the vents and windows to the polar oceans. In winter they are a major source of brine during freezing and a locus for gas exchange. Large sensible heat fluxes, together with evaporation and longwave radiation from a very small percentage of open water and thin ice, dominate regional heat budgets. In summer, solar radiation is absorbed by open water but is reflected from snow‐covered pack ice. Experiments and models describing these processes are reviewed.