Smoothing Error Variance of the 500 mb Height Analyses for the FGGE Year

Abstract

The smoothing of 500 mb geopotential analyses has been studied by comparing the variances of the EOF components. As an indicator of the total analysis error, the sums of the smoothing variances and random error variances have been studied. In most cases, no essential differences between the total analysis error variances of different centers are found. The smoothing efficiency in the FGGE analysts (level IIIb, analyzed at ECMWF) seems to be close to that of the operational analyses. However, the total error variance of the FGGE analyses is smaller because of the small random error variance. In operational analysts the variances of the first EOF are larger than in the FOGGE analyses. An explanation for this can be given by biases in the climates of the operational models used in data assimilation.