Specification of the Wind Distribution in the Marine Boundary Layer for Wave Forecasting

Abstract

PrefaceThis techrical report describes research by Dr. Cardone that began in 1 966 and has been sponsored by three different contracts as its scope increased and as the many applications that it will have become apparent.The first application of this work is to use available data more intelligently in the development of numerical wave hindcasting and forecasting procedures. In 1964, a wave climatology for the North Atlantic was produced that used ship reports to generate the wind fields for the wave hindcasts. It took one half an hour on a CDC 1604 to generate the wind fields for every six hours for a year. Although the hindcasts gave quite good results, it was clear that higher resolution wind fields and a better theory for the winds in the planetary boundary layer would improve the quality of wave predictions. This report more than adequately makes up for the nalvet of previous wind field models in the planetary boundary layer.A second goal for this study was to aid in the development of the software to be used should radar scatterometry and passive microwave data become available from a spacecraft.The definition of the winds over the ocean depends on many factors. Work is actively in progress to combine the results of this paper with simulated data such as might be obtained from remote .sensing techniques so that an optimum analysis of the planetary boundary layer can be made. This report makes it possible to develop ways to use the widely scattered ship reports over the ocean obtained on a synoptic basis in an intelligent way for the extrapolation and interpolation of spacecraft data into areas not observed by ships.A numerical model of the North Atlantic Ocean is presently under development for the Office of Naval Research. For this model, the wind stress at the sea surface and the sensible and latent heat fluxes at the air sea boundary are needed. The procedures described in this report define the wind stress at the sea surface, the atmospheric stability and the air sea temperature differences on an oceanic scale.

On aerosol production and enrichment by breaking wind waves

“…The wind dependence «*, of (5) agrees with the observations of several authors for bubble densities and as shown later it also agrees with the observations of Woodcock (1953) and Lovett (1978) for aerosol densities, it has been argued by Cardone (1969) and Wu (1979) that the wind effect that represents the work done by the atmosphere on the ocean is proportional to the areal extent of white-caps. Accordingly, if the total number of bubbles near the surface is proportional to the total area of bubbling, the bubble density in a given white-cap must be independent of the breaking wave's dimensions.…”

Trends in ship wind speeds adjusted for observation method and height

“…They identified anemometer heights for only about 8% of measured reports. Estimated winds, equivalent to 10-m measured winds by definition, tended to be lighter than measured VOS winds, which were from anemometers with average heights of 20 m. Estimated winds were adjusted using a revised Beaufort equivalent scale referenced to 20 m (Cardone, 1969). This reduced the positive trend to near zero in the analysed areas in the N. Pacific and Indian Oceans, while a positive trend remained in the South China Sea.…”

“…WMO1100-estimated winds are thought to contain systematic errors that vary non-linearly with wind speed, due to the statistical method and limited data used to derive the scale (Isemer and Hasse, 1991), causing an underestimation of climatological monthly means. Various authors developed alternative Beaufort equivalent scales, although none was adopted operationally (Cardone, 1969;WMO, 1970;Kaufeld, 1981;Isemer, 1992;da Silva et al, 1995;Lindau, 1995a). The WMO1100 scale corresponds to wind speed at 10-m, while ship anemometers tended to 748 B. R. THOMAS ET AL.…”

Spectral reflectance of whitecaps: Their contribution to water‐leaving radiance

“…These relationships remain noisy, despite attempts to fine tune particular data sets, because of the dynamic nature and interdependence of the many parameters involved in whitecap formation. Whitecap coverage is primarily dependent on wind speed but is also dependent on other factors such as fetch and duration [Cardone, 1969] [Garrett, 1967]. A slightly different approach by Wu [1988] relates whitecap coverage to the product of wind friction velocity and wind stress.…”