Channels sensitive to the terrestrial surface have not been widely used in Numerical Weather Prediction (NWP) due to the inherent complexities of the land surface. Thus, the present paper tested the tridimensional variational data assimilation framework implemented in the Global Model (G3DVAR) at the Center for Weather Forecast and Climate Studies (CPTEC) from the National Institute for Space Research (INPE) with near surface radiances from the NOAA-15 satellite. Since the operational version of the G3DVAR uses only NOAA-15, other experiments including the NOAA-18 and NOAA-19 satellites were performed. An assessment of the simulated brightness temperature for the near surface channels was made (i) through a comparison against observations and (ii) through a validation of the radiative transfer equation for the three satellites. The results indicate that the radiative transfer model overestimate, on average, the brightness temperature from the channels sensitive to the earth surface for all the considered satellites over South America during the austral summer. Furthermore, the number of observations accepted by the assimilation system increased substantially when NOAA-18 and NOAA-19 satellites were included, suggesting that incorporating these two new satellites should bring a positive impact to the G3DVAR operational system at CPTEC/INPE.
data assimilation; radiance; observation; simulation; AMSU-A; NOAA
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