Minimize Product Types introduction

The SLSTR product types are divided in six main products that are disseminated to the users, except the Level-2 WCT product.

  • One labelled as Level-1B product and output by SLSTR Level-1 processing. The Level-1 product provides radiances and brightness temperatures for each pixel in a regular image grid, each view and each SLSTR channel, plus annotations data associated with SLSTR pixels.
  • Five labelled as Level-2 products and output by SLSTR Level-2 processing:
    • Level-2 WCT product (not disseminated to users) providing the sea surface temperature for single and dual view, for two or three channels,
    • Level-2 WST product (disseminated to the users) providing L2P sea surface temperature, following the GHRSST specifications,
    • Level-2 LST products (disseminated to the users) providing land surface temperature,
    • Level-2 FRP products providing global (over land and water) fire radiative power (available to the user during the course of 2018),
    • Level-2 AOD products providing global (over land and water) aerosol optical depth (available to the user during the course of 2018),

For further information about SLSTR products, see the Technical Guide Level-1 products or Level-2 products.

There are different SLSTR data product types depending on delivery time to users and the available consolidated auxiliary or ancillary data:

  • The Near Real Time (NRT) timeliness implies a delivery in less than 3 hours after data acquisition. This timeliness is mainly used for marine meteorology and ocean-atmosphere gas transfer studies.
  • The Non-Time Critical (NTC) timeliness is typically defined for deliveries within 1 month after data acquisition. This additional delay allows consolidation of some auxiliary or ancillary data (e.g. precise orbit data) and the data are mainly used for geophysical studies and operational oceanography.

As consequences, SLSTR L1/L2 scenes can be found twice, processed in NRT and NTC conditions and including the following suffix "NR" or "NT" in their filename..

The differences between NRT and NTC products are due to auxiliary data (consolidated Orbit files used in NTC processing; Forecast ECMWF Meteorological dataset used in NRT processing instead of analysis ECMWF data in NTC processing; …) but also to some processing conditions and choices :

  • NRT and NTC have different orbit numbers.
  • The reference ANX can be different for NRT/NTC products. The ANX reference for NRT products are always the one preceding the granule, whereas the one associated with NTC products are the one preceding the start of the orbit. If the orbit are not defined ANX-to-ANX, these two references can be different. As the Y coordinates and scan re-indexation are based on this reference, possible shifts can be observed between NRT and NTC products. Similarly, as the regridding is based on Y coordinates, the resulting L1 image radiometric or L2 measurements data can present small deviation between both products.
  • The VIS/SWIR calibration is applied from the previous orbit for NRT, and the current orbit for NTC. In addition, Calibration is affected because a different start scan is used. Processor may also pick up a different VSC_AX file giving differences in VIS/SWIR calibration
  • Absolute geolocation will be the same, between both products.

As NTC should be in theory more consolidated than the NRT products, SLSTR ESLs' advice for the majority of non-operational users is to use NTC products.