CoAuthors

Fabien BLAREL (LEGOS-CNRS, France); Fernando Niño (LEGOS-IRD, France)

ERS2 and ENVISAT have been flying in tandem over the same orbit with
30min delay for about 1 year. We use the data from the 2 satellites
for this period. We have reprocessed the ERS2 data from waveform
altimeter product over all surfaces. We developed a number of
corrections to be used in conjunction and computed homogeneously for
the 2 satellites. We process the ERS2 data with the ICE2 retracking
with some algorithm improvement with regard to previous versions and
used the new Reaper combined orbit (Rudenko et al. 2012). We computed a new dry
troposphere correction with ERA-INTERIM fields valid over all surfaces
(Blarel and Legresy, 2013) and a new Doppler correction accounting for
the range rate (Blarel and Legresy, 2012) for both satellites. For
each waveform parameter (range, backscatter, leading edge width and
trailing edge slope) we computed empirical corrections so as to make
them comparable. We produce a dataset of high level to be used in
continuity between ERS2 and ENVISAT.
Here, we show the main validation and cross validation of the two
missions. We find some good general agreement and discuss the
differences. We also detect some anomalies like the 13degree north
anomaly on the waveform. We also find the need for the next ENVISAT
reprocessing to improve the trailing edge slope estimation. We find
this dataset and the associated corrections to be valid to be applied
on the entire ERS2 mission.