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Altimetry production degraded between 21 and 23 May 2011

From ESA Earthnet Online (13th June 2011) -

"The ENVISAT Altimetry production was degraded between 21 May 2011 at 00:58 (starting from orbit #48220) and 23 May 2011 at 15:11 UTC (up to orbit #48257) due to the unavailability of the DORIS and the MWR (Microwave Radiometer) instruments throughout this period.

The impact is a degradation in the FDGDR, IGDR, GDR and meteo Altimetry data products as follows:
1) Orbital parameters:

  • FDGDR orbital data are generated from an orbit propagator algorithm, starting from the state vector defined in the level 0 Main Product Header. There is the potential for significant errors in these predicted orbital parameters
  • IGDR orbital data (MOE Orbit) will be based on laser ranging data and the accuracy will be impacted
  • GDR orbital data (POE Orbit) will also be based on laser ranging data but the impact on the data quality is expected to be less

The actual reduction in the quality of the orbital data is not yet known.
2) Because the MWR instrument was unavailable during this period, the FDGDR, IGDR and GDR products will be processed without MWR data. Consequently, the following MWR parameters will be set to the default value corresponding to 32767:

MWR wet tropospheric correction

MWR liquid water content

MWR water vapour content

Interpolated brightness temperatures at 23.8 and 36.5 GHz and their standard deviations

Users are advised to not consider these parameters for further processing."