Data and Data Treatment

Abstract

Individual ship reports from the Comprehensive Ocean-Atmosphere Data Set (COADS) of the Atlantic Ocean from 1940 to 1979 are used for this climatological study. Maps of monthly mean distribution are calculated not only for the basic ship observations as wind speed or air pressure but also for the indirectly derived climate variables such as evaporation or wind stress, which are obtained by parameterisations. For the derived variables the individual method is used that conserves the effects of cross-correlations. The classical climatological method, that uses averaged values of the meteorological parameters, cannot account for these contributions. For the North East Atlantic JOSEY & al. (1995) showed that the latent heat flux is overestimated by the crude climatological method. The negative correlation between wind speed and sea-air humidity difference causes an overestimation from 1–2 Wm⁻² in winter to 7 Wm⁻² in summer.