RELATIONSHIP OF TOPEX POSEIDON ALTIMETRIC HEIGHT TO STERIC HEIGHT ANDCIRCULATION IN THE NORTH PACIFIC/

TOPEX/Poseidon altimetric height is compared with 20 transpacific eddy -resolving realizations of steric height. The latter are calculated fr om temperature (expendable bathythermograph (XBT)) and salinity (expen dable conductivity and temperature profiler (XCTD)) profiles along a p recisely repeating ship track over a period of 5 years. The overall di fference between steric height and altimetric height is 5.2 cm RMS. On long wavelengths (lambda < 500 km), the 3.5 cm RMS difference is due mainly to altimetric measurement errors but also has a component from steric variability deeper than the 800 m limit of the XBT. The data se ts are very coherent in the long wavelength band, with coherence ampli tude of 0.89. This band contains 65% of the total variance in steric h eight. On short wavelengths (lambda > 500 km), containing 17% of the s teric height variance, the 3.0 cm RMS difference and lowered coherence are due to the sparse distribution of altimeter ground tracks along t he XBT section. The 2.4 cm RMS difference in the basin-wide spatial me an appears to be due to fluctuations in bottom pressure. Differences b etween steric height and altimetric height increase near the western b oundary, but data variance increases even more, and so the signal-to-n oise ratio is highest in the western quarter of the transect. Basin-wi de integrals of surface geostrophic transport from steric height and a ltimetric height are in reasonable agreement. The 1.9 x 10(4) m(2) s(- 1) RMS difference is mainly because the interpolated altimetric height lacks spatial resolution across the narrow western boundary current. A linear regression is used to demonstrate the estimation of subsurfac e temperature from altimetric data. Errors diminish from 0.8 degrees C at 200 m to 0.3 degrees C at 400 m. Geostrophic volume transport, 0-8 00 m, shows agreement that is similar to surface transport, with 4.8 S verdrup (Sv) (10(6) m(3) s(-1)) RMS difference. The combination of alt imetric height with subsurface temperature and salinity profiling is a powerful tool for observing variability in circulation and transport of the upper ocean. The continuing need for appropriate subsurface dat a for verification and for statistical estimation is emphasized. This includes salinity measurements, which significantly reduce errors in s pecific volume and steric height.