VISOP (VISible and near_infrared OPerator)

Simulated device: SEVIRI on MSG (other instruments would be possible): Visible and Near-Infrared Satellite Reflectances

Contact: Leonhard Scheck (leonhard.scheck@lmu.de)

Output parameter

Reflectance (dimensionless)

Technical specification

Column or 3D? 3D or column based
Operation on model time step? yes
Required libraries NetCDF, and if grib files should be read or written grib_api
Programming language Python + Fortran
If online, is it modular? The part of the code required in an online version will be a Fortran module. We would prefer to use Python for the additional routines required for an offline version.
Ground-based or space-borne? space-borne


Minimum set of physical quantities:

  • 3D: pressure, temperature, specific humidity, cloud water, cloud ice, cloud snow content, cloud cover
  • 2D: base and top height of shallow convection
  • The bare minimum required to compute reflectances would be pressure, temperature, specific humidity, and liquid water content. The ice / water particle radii are obtained from parametrizations.
  • External: reflectance look-up table has to be read in once (~100MB).

Need for a special grid?

  • Column based version: No.
  • 3D version: For each pixel the data in a ray directed  towards the satellite (and in future versions a second ray directed towards the sun) is required. At the moment implemented only for rectangular grids

Are parameters given via namelist or have to be coded?

  •  There is a standard command line interface. For the online version there will be a namelist.

Are there special requirements to the input quantities?

  •  no

Documentation: no

Models for application: COSMO (+ preliminary tests with UCLA-LES, ICON-LES)

Suitable for MESSy?: Column-based: should become available in the next months

Format of input data: NetCDF or grib

Format of output data: NetCDF

Computational costs:  The pure computing time is less than a CPU minute for a COSMO-DE scene using the look-up table based version with parallax correction. Future version will take further 3D effects into account (e.g. cloud shadows) and will presumably be several times slower.

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