The Real-Time Mesoscale Analysis (RTMA) is an operational objective surface analysis developed by the National Center for Environmental Prediction. The RTMA is an objective analysis incorporating surface observations from various networks such as standard land synoptic, METAR, various mesonets, and satellite based winds, using a 2D version of NCEP's Gridpoint Statistical Interpolation (GSI) software. The goal of this study is to test the sensitivity of the analyses to the specification of the anisotropic error covariances of the background field.