1. L. L. Fu A. Cazenave Eds . Altimetry and Earth Science A Handbook of Techniques and Applications vol. 69 of International Geophysics Series (Academic Press London 2001).
2. We analyzed Topex-Poseidon altimetry data (merged Geophysical Data Records available from the AVISO/Altimetry data center Centre National d'Etudes Spatiales Toulouse France) from January 1993 through December 2000. Geophysical and instrumental corrections applied to the data are the most recent version provided by AVISO. In addition to the onboard oscillator drift the 1 mm/year radiometer drift is taken into account up to December 1996. A 7-mm bias is applied to the data beyond February 1999 to account for the vertical offset after the switch to the redundant Topex altimeter (18). Otherwise the data processing is identical to that used in (6) and (19). For sea level trends computations two different processing were applied depending on the required representation (global mean sea level trend or geographical distribution of the regional trends). For the former we averaged the along-track sea level data over each 10-day orbital cycle applying an equi-area weighting. Only data between 60°S and 60°N are considered because of noisy data at higher latitudes. The mean trend is based on a simple least squares fit to the sea level time series. The associated uncertainty is the formal error based on the scatter of the fit. To estimate regional sea level trends we interpolated along-track sea level data onto regular 1° by 1° grids. Finally we low-pass filtered the raw time series at each grid point to remove short-period (≤1 year) signal and fitted a linear trend to the filtered time series through a least squares inversion.
3. S. Levitus C. Stephens J. I. Antonov T. P. Boyer NOAA Atlas NESDIS 40 (U.S. Government Printing Office Washington DC 2000).
4. To compute gridded time series of the thermosteric (i.e. due to temperature change) sea level we first converted the gridded temperature anomalies in terms of density anomalies at each standard level using the classical expression for the equation of state of the ocean (20). Then we vertically integrated the density anomalies to compute the thermosteric sea level anomaly. Regional trends were computed through a least squares fit of the thermosteric sea level time series at each grid mesh.
5. Using Topex/Poseidon data over the years 1993 through 1998 Nerem and Mitchum (21) found a rate of sea level rise of 2.5 ± 1.3 mm/year. Their rate uncertainty is based not only on the formal error but also on instrumental drift errors.