In this project, the PI's will use the global XBT data set over the 10-year period, 1979-1988 to map the thermal structure over the globe and study seasonal and interannual variability. Of particular interest are the sea surface temperature and vertically averaged temperature over the upper 400 meters, the latter addressing variability of heat content and steric sea level. An expected result is the identification of global teleconnections in the interannual variability of both sea surface temperature and vertically averaged temperature associated with El Nino and Southern Oscillation. Cross correlation with seasonal atmospheric pressure fields will allow the study of coupled modes of global variability.