Impact of Satellite Temperature Sounding Data on Weather Forecasts

The concept of radiometric sounding of atmospheric temperature profiles from satellites was first demonstrated with data gathered by infrared spectrometers on the Nimbus-3 satellite in 1969. Operational satellite sounding over oceanic areas was introduced by the VTPR (Vertical Temperature Profile Radiometer) instrument on the NOAA 2 satellite in 1972. Early evaluations of these new observational data centered on their accuracy compared to data obtained from the conventional radiosonde system. More recent evaluations have focused on the impact of the satellite temperature soundings on numerical weather forecasts. In this paper, we review the results of such impact tests in several countries. On the average, the inclusion of satellite sounding data leads to a small improvement in the numerical forecasts.