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[1] Data from five recent field campaigns are selected for pure wind sea, deep water, and fully rough flow conditions. The combined data set includes a wide range of wave ages, with high variability in both friction velocity and wave phase speed. These data, which are expected to follow Monin-Obukhov similarity scaling, are used to investigate the influence of wave age on wind stress. The relationship between the dimensionless roughness and inverse wave age is found to be z o /s = 13.4 (u * /c p ) 3.4 , where z o is the surface roughness length, s is the standard deviation of the surface elevation, u * is the friction velocity, and c p is the wave phase speed at the peak of the spectrum. This relationship, which represents a significant dependence of roughness on wave age, was obtained using a procedure that minimizes the effects of spurious correlation in u * . It is also shown to be consistent with the wave age relationship derived using an alternate form of the dimensionless roughness, namely, the Charnock parameter z o g/u * 2 , where g is the gravitational constant.

Combining airborne remote, in situ, and expendable probe sensors with air-deployed ocean platforms provides a strategy for expanding knowledge of illusive high-wind air-sea fluxes in difficult-to-predict storms.

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An important outcome from the ONR-sponsored Coupled Boundary Layer Air-Sea Transfer (CBLAST) Hurricane Program is the first-ever direct measurements of momentum flux from within hurricane boundary layers. In 2003, a specially instrumented NOAA P3 aircraft obtained measurements suitable for computing surface wind stress and ultimately estimating drag coefficients in regions with surface wind between 18 and 30 m s Ϫ1 . Analyses of data are presented from 48 flux legs flown within 400 m of the surface in two storms. Results suggest a roll-off in the drag coefficient at higher wind speeds, in qualitative agreement with laboratory and modeling studies and inferences of drag coefficients using a log-profile method. However, the amount of roll-off and the wind speed at which the roll-off occurs remains uncertain, underscoring the need for additional measurements.

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Surface fluxes of momentum, freshwater, and energy across the air-sea interface determine oceanic circulation and its variability at all timescales. The goal of this paper is to estimate and examine some ocean surface flux variables using satellite measurements. The remotely sensed data come from the European Remote Sensing (ERS) satellite scatterometer on ERS-2, NASA scatterometer (NSCAT), and several Defense Meteorological Satellite Program (DMSP) radiometers [Special Sensor Microwave Imager (SSM/I)] on board the satellites F10-F14. The sea surface temperature comes from daily analysis calculated from Advanced Very High Resolution Radiometer (AVHRR) measurements. This study focuses on the 9-month period (October 1996-June 1997) of the NSCAT mission. To ensure high quality of the merged surface parameter fields, comparisons between different satellite estimates for the same variable have been performed, and bias corrections have been applied so that they are compatible with each other. The satellite flux fields are compared to in situ observations from buoys and ships globally and in different regions of the ocean. It is found that the root-mean-square (rms) difference with weekly averaged wind speeds is less than 2.5 m s Ϫ1 and the correlation coefficient is higher than 0.8. For weekly latent heat flux, the rms difference between satellite and buoys does not exceed 30 W m Ϫ2. The comparisons with weekly ship latent heat flux estimates gives an rms difference approaching 40 W m Ϫ2. Comparisons are also made between satellite fields and atmospheric analyses from the European Centre for Medium-Range Weather Forecasts (ECMWF) and reanalyses from the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR). The wind speeds and latent heat fluxes from these atmospheric analyses compare reasonably well with the satellite estimates. The main discrepancies are found in regions and seasons of large air-sea temperature difference and high wind speed, such as the Gulf Stream during the winter season.