[1] We present estimates of whitecap coverage on a global scale from satellite-measured brightness temperature of the ocean surface. This is a first step in a larger framework aiming at more realistic modeling of the high variability of whitecap coverage as a function of wind speed and a suite of additional environmental and meteorological factors. The involvement of oceanic whitecaps in various physical and chemical processes important for climate studies such as production of sea-salt aerosols, enhancement of airsea gas exchange, and influence on retrievals of ocean surface wind and ocean color motivates this effort. A critical review of the physical variables causing the high variability of whitecap coverage and existing approaches modeling this variability establishes the need for a database of whitecap coverage and concomitant measurements of additional factors. The necessity to build such an extensive database justifies the quest for a method estimating whitecap coverage from satellite data. We describe the physical concept, a possible implementation, error analysis, results, and evaluation of a method for estimating whitecap coverage from routine satellite measurements. The advantages of the concept and the drawbacks and necessary improvements of the implementation are discussed.

Water science finds itself at an interesting and critical crossroads. Sophisticated atmospheric modeling, remote sensing, and Internet‐based exchange of data enable exciting new synergies to develop among scientists, policy‐makers, and the private sector. Paradoxically we find it evermore difficult to validate products from these high‐technology tools and to exploit their full potential due to a severe and sustained decline in available hydrologic data sets.

Inertial‐period oscillations have been observed by numerous investigators at deep‐sea locations ranging from subtropical to polar latitudes. Although observational techniques have favored surface‐layer measurement, there is evidence for the existence of inertial motions at all depths. There is, however, no strong evidence that the amplitude of inertial motions is strongest near the surface. The character of inertial motions has been described more fully by recent observations with moored current meters. Inertial motions have a transient nature, with generation and decay times of a few days. An analysis of the data from a single simple experiment shows that the inertial motions are coherent horizontally over much greater scales than they are coherent vertically. Thus the picture that emerges is one of transient phenomena, of thin vertical extent, and of apparent possible occurrence anywhere in the oceans.

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Calculations have been made, using surface velocity observations, of the horizontal transfer of kinetic energy from meanders to mean flow at two separate localities in the Gulf Stream System. In both cases, it was found that there was a surface flow of kinetic energy from the meanders to the mean flow, exactly opposite to what would be expected if the meanders were frictionally driven. The observations suggest that the meanders derive cnergy from sources other than the kinetic energy of the mean flow. The role of the meanders in relation to the mean Gulf Stream appears analogous to that of large-scale eddies in relation to the general circulation of the atmosphere.

Further observations are reported, in which the action of eddies in the Florida Current produces a surface flux of momentum towards higher mean velocities. The results are thus in contrast to what would be expected if the eddies acted as a frictional dissipation mechanism. Furthermore, associated with the momentum flux is a surface transfer of kinetic energy from the eddies to the mean flow.The results from four locations along the length of the Florida Current are compared.The kinetic energy transfer between fluctuations and mean flow is found to be similar in magnitude at all locations and is restricted primarily to the zone of cyclonic shear of the mean surface velocity field. The flow of kinetic energy to the mean flow is sufficient to maintain the current against the dissipative actions of lateral eddy processes. Both the techniques used to measure surface velocities and the sampling method are examined. Neither appears to introduce any biases which might account for the observed momentum fluxes.

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