Radiance simulator


Current version: v2.1, June 2018

The NWP SAF Radiance Simulator is a tool designed to support pre-launch scientific studies and pre-operational development work for new satellite instruments. It provides a straightforward means of generating simulated radiance datasets from NWP model analysis or background fields using the NWP SAF fast radiative transfer model RTTOV.


The radiance simulator performs the following functions:

  • Ingest of NWP model fields, provided in common data formats. This includes support for the following formats:
    • GRIB
    • Met Office fieldsfiles / PP files
    • NWP SAF 60L profile dataset from ECMWF analyses
    • NWP SAF 91L profile dataset from ECMWF analyses
    • NWP SAF 137L profile dataset from ECMWF analyses

    Model fields will consist of:

    • Level pressure
    • Temperature
    • Humidity
    • Cloud liquid water
    • Cloud ice water
    • Cloud fraction
    • Surface wind
    • Surface skin temperature
    • Surface air temperature
    • Surface humidity
    • Sea-ice fraction
    • Orography

    Some fields are optional depending on the chosen setup.

  • Ingest of observation files (optional). The user may provide observation metadata including observation locations and viewing geometry and other fields to allow simulations to be performed at those locations.
  • Interpolation of model fields to observation locations. This is optional, dependent on the above. If no observation data are provided, simulations are performed at model profile locations.
  • Prepare input to, and run, radiative transfer model. The model used in Radiance Simulator v2.0 is RTTOV v12. Depending on the availability of the required model fields, both infrared and microwave scattering simulations can be run.
  • Output simulated data to a file. Output fields include:
    • Brightness temperatures or radiances
    • Input observation data
    • Simulation meta-data
    • Optional output fields include:

    • Emissivities
    • Jacobians
    • Layer transmittances
    • Model profiles at obs (simulation) locations


Radiance-Simulator-related Publications