Minimize Auxiliary Data Files

Besides instrumental data (Level-1 SRAL and Level-1 MWR products), auxiliary data are required as input to Level-2 processing aimed at building Level-2 products:

  • Orbit position/velocity vectors to update location, satellite altitude and orbital altitude rate.
  • SRAL and MWR instrumental characterisation data to account for the instrumental features in the processing.
  • Platform data used to reference altimeter ranges to the platform COG and to provide mispointing angle in the products.
  • Meteorological data such as surface pressure, mean sea level pressure, specific humidity, temperature and orography.
  • MOG2D data: the files are generated by SALP and are used for supporting the generation of the STC and NTC products. The MOG2D file allows IGDR and GDR products to integrate both corrections of both the high frequency part of the ocean variability and the low frequency part of the inverse barometer effect. The barotropic corrections are on a regular Cartesian grid 0.25º x 0.25º.
  • Pole location data: the data files are generated by SALP. Each file contains the instantaneous pole location and it is used for polar tide computation in the Level 2 processing.
  • Along track ionospheric data: the GIM ionospheric correction files are generated by SALP and are used for supporting the generation of the NRT and STC/NTC products. Each file contains the nadir ionospheric correction to be applied to the altimeter measurement on Ku band. They are used for polar tide computation in the Level 2 processing.
  • Configuration data: tuning parameters used in the processing by the "scientific" and the "data management" algorithms.
  • Modelled instrumental corrections: range, significant waveheight, backscatter coefficient and square of the mispointing.
  • Product attributes such as netCDF convention used, name of the data producer, software version, name of the altimeter sensor, name of the source and institution for sea-state bias.
  • Universal constants: includes all the physical constants necessary for the IPF processors. It is used by the SRAL and GNSS Instrument Processing Facilities.
  • Coefficients map for the diurnal and semi diurnal elastic ocean tide calculation: the files contain the values of the harmonic coefficients for the principal tide waves. The model used for the processing is GOT4.8 for solution 1 and FES2004 for solution 2. They are used for supporting the L2 processing.
  • Coefficients map for the tidal loading effect calculation: the files contain the values of the harmonic coefficients for the principal tide waves. The model used for the processing is GOT4.8 for solution 1 and FES2004 for solution 2. They are used for supporting the L2 processing.
  • Land/sea mask file: classifies points on the earth surface as Land/Sea or Coastline, land ice or lakes. It is used for supporting the generation of the L1 and L2 products.
  • Coefficients map for long period ocean tide calculation: the file contains the values of the harmonic coefficients to the four dynamical waves of the FES2004 model. They are used for supporting the L2 processing.
  • Mean Sea Surface height map. Solution 1: the file contains the values of the mean sea surface heights of the CNES-CLS-11 model and the associated error values. Solution 2: the file contains the values of the mean sea surface heights of the DTU-10 model.
  • Geoid height map: the file contains the values of the geoid heights of the EGM2008 model.
  • Bathymetry/topography map: the model used is the Gobal Digital Elevation Model ACE2, with a 30 arcseconds resolution.
  • Wind table: the tables contain wind speed values that correspond to Abdala, 2007. The format is identical for LRM and SAR modes.
  • Expected Ku-band sigma0 Tables: the format is identical for LRM and SAR modes.
  • Cartwright and Edden tide potential amplitudes for the solid earth tide and equilibrium long period ocean tide height calculation: the solid earth tide and the equilibrium long period ocean tide height calculation are built from Carthwright and Edden tide potential amplitudes.
  • Surface slopes models: the surface slopes models file contains the slope of the surface computed in the X and Y directions respectively.
  • Map of the slopes of the MSS/geoid with respect to the ellipsoid: the Doppler/MSS file contains the map of the MSS/geoid with respect to the ellipsoid.
  • Climatological pressure grids: the climatological pressure grids (4 files) contain the climatological pressure referenced to the sea on a Cartesian grid, for each of the twelve months of the year.
  • S1 and S2 tide grids of monthly means of global amplitude: the S1 and S2 tide grids of monthly means of global amplitude consist of two binary files, one file for the S1 wave and the other for the S2 wave.
  • S1 and S2 tide grids of monthly means of global phase: consist of two binary files, one for the S1 wave and the other for the S2 wave.
  • The Mean Dynamic Topography (MDT) file contains MDT and variance values. The model used for the processing is CNES/CLS 09.
  • The theoretical distance to shore is provided on a grid. The distance to shore file is a netCDF file with a 1/16º resolution.
  • SSB correction tables: one table for SAR mode is one for LRM mode, contain values of the Sea State Bias for the Ku and C band. The format is identical for both modes.
  • Snow depth climatology: the snow depth data is available from the National Snow and Ice Data Centre (NSIDC). This data has been further processed by UCL, from the period Jan 1994 to Dec 2002, to create 12 files containing gridded snow depth: one for each calendar month of the year.
  • Sea-ice concentration climatology: the Sea Ice concentration file is derived from SSM/I daily brightness temperaturs and there is one file per month. For every month from Jan 1994 to Dec 2002, a file of the median ice concentration for that month was calculated.
  • Sea surface temperature seasonal tables: the SST tables correspond to seasonal grids covering -60º to 60º range in latitude and 0º to 358º range in longitude, with 2º of resolution.
  • Lapse rate climatology table: the lapse rate climatology table covers the -60º to 60º range in latitude and 0º to 360º range in longitude, with 1º of resolution. The Gama parameter (unit is K/km) is computed through a linear fit of the temperature decrease rate with altitude (between surface and 800 mb level) from 3D ECMWF fields.
  • Seasonal freezing level table: the seasonal freezing level table covers the -70º to 70º range in latitude, with 2.5º of resolution and 0º to 360º range in longitude, with 5º of resolution. The freezing level parameter (unit is Km) is computed from monthly tables provided by IFREMER (Tournadre).
  • Freezing level table: the freezing level table has a dependency on both brightness temperatures: it covers the 140 K to 280 K range in 23.8 GHz brightness temperature and the 130 K to 280 K range in 36.5 GHz brightness temperature with a step of 1 K in both cases. The freezing level parameter is provided by IFREMER (Tournadre).
  • Rain rate correction table: the rain rate correction table is a function of the rain rate. The rain rate correction parameter is provided by IFREMER (Tournadre).
  • Coastal configuration type: the coastal configuration type file, in netCDF, provides information about the geographical situation of givel point, taking into account the surrounding area.
  • Surface classification mask: the surface classification mask is a combination of GlobCover and MODIS data and classifies points on the Earth Surface using a 7-states flag.