The Naval Research Laboratory and Naval Oceanographic Office at Stennis Space Center use the Modular Ocean Data Assimilation System (MODAS) [Carnes et al., 1996] to produce, as one of several products, global, daily, 1/8 ° resolution maps of sea-surface steric height anomalies relative to 1000 m. Steric height anomaly is the difference in the height of a given water column and the height of an ideal 0° C , 35 salinity column, where the heights are integrated between specified pressure surfaces. MODAS daily global estimates of steric height anomaly begin with optimal interpolation (OI) of TOPEX and ERS2 altimetry. The OI uses a mesoscale-tuned estimate of the error covariance [Jacobs and Barron, submitted] to develop a field of height deviation from the altimetric mean. The final steric height anomaly is produced by adding the deviation field to two others, a MODAS climatological mean steric height anomaly and a correction for the difference between the altimetric and climatological means. The climatological steric height anomaly is computed by integrating from the climatological pressure at 1000 m to the surface (for more details, see http://www7300.nrlssc.navy.mil/altimetry) . The steric height anomaly is a true height and will be referred to as SSH.