OBJECTIVE ANALYSIS OF ATMOSPHERIC FRONTS AND ESTIMATION OF ITS EFFICIENCY

N. P. Shakina, E. N. Skriptunova, and A. R. Ivanova

An approach is proposed for estimating the efficiency of objective frontal analysis based on direct comparison of the analysis results against precipitation totals measured at the stations. This approach and the 1998/99 winter data are used to estimate efficiencies of the two objective analysis methods proposed earlier. In one method, the frontal parameter is a characteristic of baroclinicity of the 850—500-hPa layer. In the other method, a number of characteristics of baroclinicity in the lower troposphere and of cyclonicity of the pressure field at the surface and in the lower troposphere are used to calculate the frontal parameter. The latter method is shown to be more efficient, but a linear combination of both frontal parameters is found to be preferable. The combined frontal parameter, a quantitative measure of grid-scale dynamic forcing, is proven to be a statistically significant predictor of precipitation, especially of heavy and very heavy precipitation.