Improving the horizontal transport in the lower troposphere with four dimensional data assimilation

► We examine the uncertainty of observed and modeled winds in the lower troposphere. ► Uncertainty of wind observations was found to be about 1.8 m s−1 and 20-25°. ► Assimilation of wind profile observations reduced modeled transport uncertainty. ► Nudging in the planetary boundary layer using surface wind may not be necessary. ► Our nudging method reduces modeled transport uncertainty to that of the observations.