The launch of the Ocean Surface Topography Mission (OSTM) builds on 15 years of continuous high quality altimeter measurements from TOPEX/POSEIDON and Jason-1. As with all altimetry missions, the challenge continues to be improving the quality of the observations while advancing their use in studies of ocean circulation. This work deals with both aspects of this challenge by using all altimeter data and other in situ and space-based oceanic observations, ocean models either in barotropic or baroclinic configurations, and estimation techniques that efficiently synthesize the information in the observations and models. Altimeter comparisons using tandem mission data and separate analysis of various noise terms (radar noise, environmental corrections, etc.) are intended to derive spatial and temporal characteristics of the errors for OSTM and other missions. Modeling and data assimilation methodologies will be applied to estimate atmospherically-driven high frequency sea level variability, which is poorly sampled by the altimeters, with the goal of providing improved de-aliasing procedures for altimeter data processing. More generally, data and model analyses are planned to address the characteristics and dynamics of the large-scale sea level variability. Topics we explore include the dynamics of ocean loading by surface pressure, freshwater flux and long-period tides, the relation between coastal sea level and the large-scale (deep ocean) signals at seasonal and longer timescales, the relative contributions of surface heat and moisture fluxes, density advection, and mixing to regional sea level variability, the possibility of nonlinear interactions between strong rapid signals driven by synoptic atmospheric systems and the slow (climate) timescales, and the causes of interannual fluctuations in mean sea level. This work addresses NASA strategic objectives of advancing scientific understanding of planet Earth by using space-based observations, particularly regarding sea level variability and its impact on human societies around the globe.
Studies Of The Large-Scale Ocean Variability Using Satellite Altimetry