THE IMPACT OF NOAA SATELLITE SOUNDING DATA ON THE SYSTEMATIC FORECAST ERROR OF B-MODEL

This paper is to examine the impact of satellite data on the systematic error of operational B-model in China.Emphasis is put on the study of the impact of satellite sounding data on forecasts of the sea level pressure field and 500 hPa height.The major findings are as follows.(1) The B-model usually underforecasts the strength of features in the sea level pressure(SLP) field,i.e.pressures are too low near high pressure systems and too high near low pressure systems.(2) The nature of the systematic errors found in the 500 hPa height forecasts is not as clear cut as that of the SLP forecasts,but most often the same type of pattern is seen,i.e.,the heights in troughs are not low enough and those in ridges are not high enough.(3) The use of satellite data in the B-model analysis/forecast system is found to have an impact upon the model's forecast of SLP and 500 hPa height.Systematic errors in the vicinity of surface lows/500 hPa troughs over the oceans are usually found to be significantly reduced.A less conclusive mix of positive and negative impacts was found for all other types of features.