The REAPER (REprocessing of Altimeter Products for ERS) project covers both the ERS-1 and the ERS-2 altimetry missions.
Major improvements with respect to the previous ESA RA products format (OPR - Ocean Product - and WAP - Waveform product) have been implemented (e.g. the four Envisat RA-2 retrackers, RA calibration improvement, new reprocessed Precise Orbit Solution, ECMWF ERA-interim model, NICO09 ionospheric correction until 1998, GIM ionospheric correction up to 2003, new SSB, etc.). The assessment of the REAPER data quality versus the ERS OPR and WAP data shows a clear improvement in terms of accuracy over the tandem periods between ERS-1, ERS-2 and Envisat missions (currently assessed periods). However, the REAPER dataset presents some limitations (such as the use of poor MWR Wet tropospheric correction, out of range PTR corrections, etc.) that are fully described in the Product Handbook.
Intercalibration between ERS-1, ERS-2 and Envisat, between all three radar altimeters and all three microwave radiometers, has led to several improvements, including the incorporation of inter-mission bias corrections. Envisat style retrackers are used in the REAPER processing, allowing easier comparison. REAPER ERS-2 data is cross-calibrated to the released Envisat v2.1 product and the REAPER ERS-1 data to REAPER ERS-2.
This project is part of ESA's (Multi-)Sensor Timeseries activities. To facilitate the various end-user and science applications, there is a need for the agency to support and maintain the quality aspects across missions with similar sensors. The Sensor Performance, Products and Algorithms (SPPA) team's multi-sensor activities focus primarily on the sensor Fundamental Data Records (FDR), i.e. the level 1 data, on the instrument's core products, as outlined in the Mission Requirements Documents (MRD) of each mission, and on some select additional geophysical parameters that facilitate the improvements of the sensor FDR.
If you have any questions about this project, contact:
Dr. Philippe Goryl