Abstract

ERA-40 and NCEP-DOE global Reanalysis and the global tropospheric FNL analysis are compared with observations from the EPIC2001 experiment and data from TAO moorings along 95 degrees W, to assess how they represent the atmospheric conditions in the East Pacific. All analyses represent reasonably well the mean vertical wind profiles in the atmospheric boundary layer (ABL) and at all heights within the Intertropical Convergence Zone (ITCZ) at 95 degrees W. However, mean vertical zonal wind profiles show a poor agreement in the layer 850-600 hPa from the equator to 5 degrees N. This could cause differences in reproducing the surface meridional pressure gradient, as a result of geostrophic dynamics (Raymond, Bretherton, Molinari, 2006. Dynamics of the Intertropical Convergence Zone of the East Pacific. J. Atmos. Sci. 63, 582-597), that drives the meridional flow into the ITCZ. theta(e) vertical profiles, surface fluxes and near-surface temperature present appreciable differences with observations between the equator and 5 degrees N, suggesting that these global analyses must be used with caution in that region. Analyses seem to represent fairly well the time evolution of the surface meridional wind in the ITCZ and also the transitions of the zonal winds at 850 hPa, as a result of the easterly wave passages over the region. Westerly periods in the ITCZ are associated with strong surface southerly winds, which result in enhanced convection and indicate an increase in the relative circulation of the region. In addition, easterlies coincide with a decrease in relative circulation, which could be related to the decrease in the convective activity. The averaged wind field in the ITCZ is reasonably well reproduced by all datasets, supporting their use in dynamical studies in the region. Unfortunately, the same cannot be said for the relative circulation and detrained mass flux since they show large differences with observations. In general, all analyses could be used to study mean conditions over the study region, taking into account the described limitations. (C) 2008 Elsevier B.V. All rights reserved.