Abstract: The impact of NOAA 9/10 satellite sounding data(at December 1987) has been assessed by both changes in S1 skill score and root mean square(RMS) errors for 24 and 48 hour forecasts of sea level pressure(SLP) and 500hpa height. A positive impact on RMS errors of up to 11.5% was observed over land for SLP and 8% over ocean for 500 hpa height for forecast period of 48 hour. The verification statistics(for both S1 skill score and RMS error) shows that there is more impact for forecast period of 48 hours than for 24 hours.

Key words: impact, S1 RMS, satellite sounding, B-model