Computation of Surface Fluxes from Climatological and Synoptic Data

Abstract

The effect of using climatological and synoptic atmospheric data commonly available at oceanic locations on the computations of surface fluxes was examined. The data used in this study are a 10-year time series of surface meteorological measurements from Ocean Weather Station P (50°N, 145°W). Examination of the cumulative covariances of the quantities used in bulk transfer calculations of fluxes show that to estimate the stress and sensible heat flux requires measurements at intervals of 2 days or less but that long- term averages or less frequent samples may be used to estimate the latent heat flux. A comparison of the values of monthly wind stress and latent beat flux as calculated from the data organized into the format of the Marine Climatic Atlas with the directly calculated values show good agreement between the two methods. The sensible heat flux deviates more seriously, particularity in months of small fluxes. The effect on computing surface fluxes from surface weather chart data was examined by computing these fluxes from vector averaged wind data. The use of this data format results in substantial reductions to the wind stress (magnitude reduced to less than one-half of the directly calculated value for an averaging period of one month). The latent heat flux is reduced to about 0.5 of the directly calculated value and the sensible heat flux to about 0.6 of the directly calculated value for a monthly averaging period.