The Effect of VISSR Atmospheric Sounder Data on Some LFM Analyses and Forecasts

Abstract

The impact of VMR Atmospheric Sounder (VAS) temperature profiles upon the Limited-Area Finemesh Model used operationally at the National Meteorological Center (NMC) is investigated for a set of six cases during the winter or 1981/82. Pairs of analyses are prepared for each case, one using both VAS and conventional data (VAS analyses) and one using only conventional data (control analyses). VISSR Atmospheric Sounder data, inserted over the northeast Pacific Ocean, generally effected moderate changes in the 30–60 range, upon 500 mb height analyses. A comparison of one of the VAS analyses with a concurrent LFM analysis prepared using NOAA-7 data shows that the two observing systems compare favorably, implying that the VAS data for that case were at least as accurate as the NOAA-7 data in depicting the features of a complex man field. Six sets of VAS and control forecasts were prepared using the analyses described herein as initial data for the LFM. Four of the six forecasts made using VAS data improved in comparison with their control counterparts.