Geophysical model functions for the sea state bias in satellite altimetry

摘要

The sea state bias in altimeter measurements of sea surface height have been investigated by many authors, resulting in several proposed algorithms of the form SSB=/spl epsi/H where H is the significant wave height (SWH) and /spl epsi/ is a non-dimensional function of wind and wave parameters. All known algorithms are presently rated. The most popular, linear model of the form /spl epsi/=a/sub 0/+a/sub 1/U is shown to yield an improvement over the simplest algorithm with a constant /spl epsi/. A three-parameter form /spl epsi/=a/sub 0/+a/sub 1/U+a/sub 2/H produces even better results. However, the accuracy of the polynomial models is below that obtained with a two-parameter, physically-based model relating /spl epsi/ to the pseudo-wave-age /spl xi/: /spl epsi/=M/spl xisup -m/. The /spl xi/ is estimated using altimeter wind U and SWH: /spl xispl ap/A(gH/U)/sup V/ where A and v are constants. By analyzing the performance of different models we conclude that further progress can hardly be achieved by raising the degree of the polynomial for /spl epsi/(U,H). Physically-based approaches employing a small number of adjustable parameters and theoretically justified non-dimensional combinations of external wind and wave factors appear to be more promising.