Ocean-bottom pressure measurements for radar altimetry calibration
Tilo Schoene(1) and Saskia Esselborn(1)
GFZ is operating several bottom-mounted pressure gauges and a wave tide recorder in the North Sea near the German coast. They are closely located to an intersection of ERS-2/ENVISAT, TOPEX/Poseidon, Jason-1 and a GFO sub-track, giving the unique possibility to directly compare tidal information with all active RA missions.
While the gauge measurements give only relative values, corrections for air pressure changes using a nearby surface platform give direct relative sea surface heights. With a sampling rate of 10 minutes resp. 30 minutes, the instantaneous sea surface height (iSSH) for each radar altimetry satellite track can be interpolated with high accuracy. Additionally the wave tide recorder gives information about the significant wave height.
In order to achieve a height-stable tidal record, the relative depth stability of each tide gauge sensor can be achieved by the intercomparison between the individual sensors. This allows monitoring the stability of the RA missions with a sufficient accuracy.
The results of the comparison between the RA measurements and the tide gauges will be shown.