The three layers of vertically integrated precipitable water content, temperature, outgoing long-wave radiation (OLR) from NOAA series of polar orbiting satellites are being routinely derived at Chennai in real time. An attempt is made in this study to compare and evaluate the impact of OLR and total precipitable water content (TPWC) data in global data assimilation and forecast system (GDAFS). Since India is surrounded by large data sparse oceanic regions, the remotely sensed data from satellites are the only source of meteorological information currently available for use in numerical weather forecasting. The OLR and TPWC values from NOAA satellite are comparable with other sources. The impact of OLR and TPWC in GDAFS are encouraging
