What’s New

To comment or to suggest future enhancements to RTTOV, please contact the helpdesk.

RTTOV v12.1

RTTOV v12.1 was released in February 2017 by the NWP SAF. The main new features of RTTOV v12 compared to v11.3 are:

  • Visible/IR scattering updates:
    • Discrete Ordinates Method multiple-scattering solver for clouds and aerosols: there are independent options available for the treatment of scattering for thermal emission and solar radiation.
    • Ice optical properties from the SSEC database replace the old Hexagonal/Aggregate ice shapes.
    • Baran2014 ice parameterisation extended to visible/near-IR wavelengths.
    • New option to supply cloud and aerosol inputs as mass mixing ratios (kg/kg).
  • Surface emissivity and BRDF updates:
    • New MW sea surface emissivity model, TESSEM2, intended for use with ICI.
    • New IR sea surface emissivity model including wind speed and Tskin dependency.
    • Improved treatment of sea surface reflectance for solar radiation.
    • Updated TELSEM MW land surface and sea-ice emissivity atlas (TELSEM2).
    • Updated CNRM MW land surface emissivity atlas.
    • New IR land surface emissivity atlas (CAMEL).
    • More flexible interface to land surface emissivity and BRDF atlases allowing data from multiple atlases, for multiple months and/or instruments to be initialised and used concurrently.
  • Other scientific updates:
    • New visible/IR coefficients based on updated training profiles applicable to whole satellite era (1970-202x) with contemporary reference (background) profiles for CO2, N2O and CH4. Coefficients supporting variable ozone and CO2 are available for all visible/IR sensors.
    • New coefficients available allowing SO2 as an optional trace gas.
    • Updated non-LTE bias correction.
    • New PC-RTTOV coefficients including non-LTE bias correction.
    • New option to call HT-FRTC PC RT model (available separately through the NWP SAF website) through RTTOV interface.
  • Technical updates:
    • Python/C++ wrapper now supports all visible/IR/MW clear-sky and scattering simulation types (direct and K models) and use of BRDF and emissivity atlases.
    • RTTOV GUI has been updated to support new RTTOV capabilities.
    • Improved consistency in subroutine interfaces and derived type naming.
    • Optimisation of gas optical depth calculation in particular for v9 predictors with all trace gases.

RTTOV v11.3

RTTOV v11.3 was released in September 2015 by the NWP SAF. A list of the main new features of RTTOV v11.3 compared to RTTOV v11.2 is given below:

  • Technical changes
    • New Python and C++ interface to RTTOV: allows much RTTOV functionality to be called directly from Python or C++.
    • Updates to the RTTOV GUI including new 1DVar functionality.
    • New option to specify input units for gas profiles (ppmv over moist air, ppmv over dry air, kg/kg over moist air).
    • PC-RTTOV can now be run for all surface types (requires new PC coefficient files available on the website).
    • IR emissivity and BRDF atlases now also available in HDF5 format with much reduced file size due to compression, and avoids the need for compiling against the netCDF library.
    • Example programs simplified and new examples added for IR cloudy simulations and RTTOV-SCATT.
    • Four new subroutines which can be used to allocate any or all input/output arrays and structures for the RTTOV direct, TL, AD and K models simplifying code which calls RTTOV.
    • New interactive script to make compiling RTTOV easier.
    • New interactive script to download coefficients from website.
    • RTTOV libraries no longer have minor version numbers in their names.
  • Scientific Changes
    • Option to treat surfaces as Lambertian reflectors for the downwelling surface-reflected emission can now be applied to IR as well as MW sensors.
    • Option to supply ocean surface foam coverage fraction to FASTEM instead of using the internal foam parameterisation.
    • Improved treatment of snow in land surface BRDF atlas (requires a new eigenvector data file to be downloaded from the website).
    • IR emissivity atlas has new option to include a correction for zenith angle (requires new additional atlas data files available on the website)

RTTOV v11.2

RTTOV v11.2 was released in June 2014 by the NWP SAF. A list of the main new features of RTTOV v11.2 compared to v11.1 is given below:

  • Technical changes
    • RTTOV v11.2 reproduces RTTOV v11.1 radiances for identically configured simulations (bug fixes notwithstanding).
    • Code rewritten in places to improve readability and maintenance.
    • Test suite profile sets are now based on the six US76 standard atmospheres.
    • Code has undergone optimisation for scalar architectures, particularly the solar sea surface reflectance calculation, IR scattering code, and PC-RTTOV.
    • Coefficient I/O in HDF5 format now allows channel selection.
    • RTTOV GUI is supplied with the RTTOV package: this allows users to run the direct and K models and visualise the results.
  • Scientific changes
    • New interpolation options are available which eliminate the jaggedness observed in temperature Jacobians under certain circumstances.
    • New option for profile extrapolation at top of atmosphere based on regression limits.
    • New FASTEM-6 option which has improved treatment of azimuthal dependence.
    • Updated Baran ice optical property parameterisation for cloudy IR simulations.

RTTOV v11.1

RTTOV v11.1 was released in May 2013 by the NWP SAF. A brief overview of the main new features of RTTOV v11 is given here.

  • Technical changes
    • RTTOV v11 reproduces RTTOV v10 radiances for identically configured simulations.
    • Code rewritten in places to improve readability and maintenance.
    • Test suite has been extended to allow all aspects of RTTOV to be configured via input files or via the commandline.
    • Code has undergone optimisation for scalar architectures, particularly the direct and K models and the IR emissivity atlas.
    • Capability to read and write coefficients in HDF5 format.
    • Capability to convert mietables to binary format.
  • Scientific changes
    • Coefficients based on a new set of 54 levels.
    • Capability to simulate visible/near-IR channels.
    • New land surface bi-directional reflectance function (BRDF) atlas.
    • Capability to correct for non-local thermodynamic equilibrium effects.
    • PC-RTTOV may now be run for clear-sky and cloudy profiles over sea.
    • Option to specify scattering parameters explicitly for aerosol and cloudy IR simulations.
    • New ice particle parameterisation for cloudy IR simulations.
    • Two new aerosol particle types: a new volcanic ash type derived from measurements of the Icelandic eruption in 2010, and an Asian dust type.
    • New option to treat the surface as a Lambertian reflector for the reflected down-welling radiance calculation.
    • Capability to account for variable cell pressure in SSU sensors.
    • Improvements to MW scattering code including capability to supply hydrometeor profiles in units of kg/kg.