IMPORTANT information for users of ERS-1 altimetry data regarding:
There are two corrections to the ERS-1 and ERS-2 ranges that were applied to the online Greenland and Antarctica data. The first of these is a correction for a drift in the Ultra-Stable Oscillator(USO). The second is the Scanning Point Target Response(SPTR) correction. The characterization of these two corrections can be found on the ESA Earth Observation web site
The European Space Agency's (ESA) ERS-1 radar altimeter satellite was launched in July of 1991 and provided data from August 1991 to July 1996 in an orbit that extended coverage over the ice sheets to +/- 81.5 degrees. ERS-2 was launched in April of 1995 and will give similar coverage. The waveform analysis product produced by the UK-PAF, required to process ice sheet elevations has had numerous problems and large delays in release. As of February 1998, we have what we believe to be the complete data set for the ERS-1 data which includes a 168 day repeat cycle, 1 year of 35-day repeats, and several months of 3-day repeats.