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Presentation of the Products

LEO Sea Surface Temperature

The Low Earth Orbiter SST products are currently derived from MetOp and Noaa-19.

Delivered products

The delivered products are :
  • MGR SST : full resolution SST (1 km) in satellite projection, corresponding to each granule of AVHRR data disseminated through EUMETCast
  • GLB SST, 12 hourly synthesis on a 0.05° global grid
  • NAR SST, a 2 km stereopolar product over North Atlantic and European Seas
    • Note: The old version of NAR SST product over 7 sub-areas has been replaced by the new product on one unique area. The new Operational NAR SST product is based on MetOp-A and NOAA-19.
    Link to: NARSST OLD VERSION -presentation-


    For further details consult the Low Earth Orbiter Sea Surface Temperature Product User Manual

    Physical definition

    Subskin SST : Comparable to in situ (buoy) measurements at night.

  • Relation to bulk SST : equivalent to bulk SST by night. By day, a bias of several Kelvin may be found under favorable diurnal heating conditions.
  • Relation to skin SST : by day and by night the subskin SST is convertible to skin temperature by subtracting 0.2K.

    • Figure 1 : Example of 0.05° resolution global SST product showing the contributing metagranules superimposed
    Figure 2 : example of 2 km resolution NAR SST product

    Formats and access

    Access to the Low Earth Orbiter SST products in Near real time is indicated in the following table :
    Name of the product Format Access
    MGR SST L2P NetCDF IFREMER FTP server
    NAR SST L3P NetCDF IFREMER FTP server
    NAR SST GRIB2 EUMETCAST
    GLB SST L3P NetCDF IFREMER FTP server
    GLB SST GRIB2 EUMETCAST


    L2P or L3P are the NetCDF format recommended by the GODAE High Resolution Sea Surface Temperature Pilot Project (GHRSST-PP), see Donlon, 2005. L2P and L3P are identical, “2” refer to products in satellite projection and “3” to gridded products.

    Unit

    °Kelvin. (generally displayed in ° Celsius in quicklooks)

    Processing scheme

    The SST products are derived from the MetOp/AVHRR data acquired and processed at the CMS. The processing chain includes the following main steps :

    Algorithms

    Based on previous experiences with GOES-East (Brisson et al., 2002) and SEVIRI (Le Borgne et al., 2006), the following algorithms have been applied :
    NL : SST = a T11 + (b TCLI + c Sθ)(T11 - T12) + d + eSθ + corr, for daytime
    T37_1 : SST = (a + b Sθ) T37 + (c + d Sθ) (T11 - T12) + e + fSθ + corr, for nightime

    T37, T11, T12 are the brightness temperatures at 3.7, 11 and 12 microns, respectively; corr is the correction term resulting from preliminary adjustment on the MDB; Sθ= sec(θ) –1, θ is the satellite zenith angle and TCLI is the mean climatological value.

    In twilight conditions, SST is calculated through a weighted mean of daytime and nightime algorithms.