Correlations between altimetric sea surface height and radiometric sea surface temperature in the South Atlantic (original) (raw)

1998, Journal of Geophysical Research

In the last decade, satellite altimetric measurements of sea surface height (SSH) and infrared radiometric measurements of sea surface temperature (SST) have provided a wealth of information about ocean circulation and atmosphere-ocean interactions. SSH is a depth-integrated quantity dependent upon the temperature and salinity structure of the water column and on the depth independent barotropic contribution. SST from infrared radiometers is a surface parameter representing the temperature of the top few microns of the ocean surface. Hence any relationship between SST and SSH provides dynamical information about the coupling between the ocean surface and subsurface. It also offers a promise of new techniques such as interpolating SSH data using SST and of improved calculations of eddy kinetic energy. We use SST data from the alongtrack scanning radiometer on ERS-1 and SSH data from the TOPEX/POSEIDON instrument to examine the relationship between SST and SSH anomalies within the South Atlantic region for 1993 and 1994. We find that positive (=0.2-0.6) spatial cross correlations between SST and SSH anomalies at zero lag are present throughout the region at large scales (wavelengths > 1000 km). Small-scale correlations, however, are high (=0.7) only in areas associated with fronts and mesoscale variability. These small-scale correlations are seasonal, being strongest in winter and weakest in summer. We discuss the application of these correlations to various techniques requiring the synergistic use of SSH and SST data. 1. Introduction Satellite remote sensing has established itself as an essential means of acquiring global information about our oceans. Satellites now measure sea surface temperature (SST), sea surface height (SSH), wind velocity, significant wave height, wave period, and ocean color. However, many of these parameters are traditionally still studied in isolation of the others. The future challenge must be to start combining multiinstrument satellite measurements to obtain extra insight on ocean dynamics and circulation. An initial attempt at combining two satellite-measured parameters, SST and SSH, is presented here. SST and SSH are arguably the remote-sensed parameters most fundamental to ocean circulation and climate. SST is used to identify ocean fronts and eddies [e.g., Olson et al., 1988] and is one parameter controlling the transfer of heat and moisture between the ocean and atmosphere. Furthermore, SST is a dominant factor controlling the genesis of hurricanes [Saunders and Harris, 1997] and is an indicator of climatic changes such as the E1 Nifio-Southern Oscillation and the North Atlantic Oscillation. SSH is dependent on the full depth density structure of the ocean, and knowledge of SSH relative