Abstract
Since a few years, satellite altimetry has demonstrated its capability in measuring temporal change of the global mean sea level with a precision on the order of 1 mm/yr or better. Here we present results on the global mean sea level variations based on four and a half years (January 1993–July 1997) of reprocessed Topex-Poseidon altimetry data, with the most recently updated environmental and geophysical corrections applied. We focus the analysis on the interannual variations. If we adjust a purely linear trend to the mean sea level time series after removing a small seasonal signal, we find an apparent sea level rise of 1.4 ± 0.2 mm/yr. As noticed earlier by other investigators, the mean sea level curve is highly correlated with sea surface temperature (SST) from intraseasonal to interannual time scales. Moreover, we observe step-like discontinuities both in sea level and SST by mid-1994 and early 1997 clearly related to the 1994 and 1997 ENSO events. We also present global mean sea level results based on ERS-1 data from April 1992 through May 1996. Most of the ERS-1 geophysical corrections have been upgraded for this purpose, in particular the orbit. The ERS-1-derived global mean sea level curve shows little evidence of sea level rise (a trend of 0.3 ± 0.3 mm/yr for the period April 1992-May 1996 is reported). Over their time span of overlap ERS-1 and T P give the same rate of sea level change (∼ 0.5 mm/yr).
Published Version
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