1D-Var

1D-Var Overview

Current version: v1.0, August 2014
The NWPSAF 1D-Var package is a stand-alone system for doing 1D-Var retrievals with user-provided files of observation and background error covariances. The package is configured to support ATOVS, AIRS, IASI, ATMS, CrIS and SSMIS sensors, and is capable of supporting any nadir-sounding sensor for which a suitable radiative transfer model is available. The code is written in Fortran-90, using many of the intrinsic features. It is tailored to be flexible for research purposes and for portability rather than being streamlined for operational running within an NWP model. Users who require the code to run efficiently within their NWP system should expect to do some optimisation of the code for their platform.

Version 1.0 contains the merged capabilities of the previously developed Met Office, ECMWF and SSMIS 1D-Var schemes. To become a licensed user of the NWPSAF 1D-Var code v1.0, please register with the NWP SAF site and access the downloads via your user area.

Please note that the radiative transfer model RTTOV is required for most applications of the NWPSAF 1D-Var. RTTOV is available from the NWP SAF, also free of charge, under a separate licence.