AIRCRAFT TO AIRCRAFT INTERCOMPARISON DURING SEMAPHORE

During the Structure des Echanges Mer-Atmosphbre, Proprietes des Heter ogeneites Oceaniques: Recherche Experimentale (SEMAPHORE) experiment, performed in the Azores region in 1993, two French research aircraft w ere simultaneously used for in situ measurements in the atmospheric bo undary layer. We present the results obtained from one intercomparison flight between the two aircraft. The mean parameters generally agree well, although the temperature has to be slightly shifted in order to be in agreement for the two aircraft. A detailed comparison of the tur bulence parameters revealed no bias. The agreement is good for varianc es and is satisfactory for fluxes and skewness. A thorough study of th e errors involved in flux computation revealed that the greatest accur acy is obtained for latent heat flux. Errors in sensible heat flux are considerably greater, and the worst results are obtained for momentum flux. The latter parameter, however, is more accurate than expected f rom previous parameterizations.