This projects will combine a suite of data on atmospheric humidity from diverse sources to refine the moisture correction for GEOSAT altimetry. The altimetric signal is refracted by moisture in the atmosphere, and since there is no spaceborne sensor on GEOSAT, humidity must be obtained from other methods. This work will use the TIROS Operational Vertical Sounder (TOVS), and SSMI data, if available. The project will provide global maps of both water vapor and altimeter corrections on an appropriate time and space scale. Appropriate scales will be determined from analysis of the atmospheric variability.