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The Radio Occultation Processing Package. GRAS-SAF Team (Axel von Engeln), August 2005. GPSRO2, Lansdowne, Virginia. Introduction. ROPP Objectives.
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The Radio Occultation Processing Package GRAS-SAF Team (Axel von Engeln), August 2005 GPSRO2, Lansdowne, Virginia
ROPP Objectives To provide users with a comprehensive software package, containing all necessary functions to pre-process RO data from CGS Level 1b files or GRAS SAF Level 2 files, plus RO-specific components to assist with the assimilation of these data. Implemented as a set of pick’n’mix modules. Some 3rd party freeware support libraries required (e.g. netCDF, udunits, Lapack)
ROPP Background • Partly follows the AAPP idea (ATOVS and AVHRR Pre-processing Package / NWP-SAF) • Developed within the GRAS-SAF at the Met Office • Aims at Operational Meteorological Centers • Also allows stand alone processing
GRAS Level 1b (CGS) netCDF BUFR netCDF ropp_preproc PFS GRAS Level 2 (SAF) ropp2bufr ropp_1dvar ropp_fm ropp_qc ROPP Context NWP User pfs2ropp NWP VAR system
ROPP Facts • Portability built-in (tested with several Unix/Linux compilers) • Installation uses standard configure, make, make install sequence • Maintained under SVN version control • ROPP is NOT a black box, standalone, end-to-end processor but a modular system providing the required (possibly distributed) functions.
ROPP Modules (1) • ropp_tools • Utility Library (unit conversions, interfaces etc) • ropp_io • IO Library (bufr, netCDF, conversions) • ropp_fm • Forward Library, T/L & Adjoints for bending angles or refractivity (hybrid, pressure & height based)
ROPP Modules (2) • ropp_1dvar • 1DVar Library (Minimiser, Q/C) • ropp_ug • User Guide
ROPP Future Modules • ropp_preproc • Pre-processing Library from Level 1b to Level 2 (Version2: Abel transform, thinning, coordinate transforms, Version3: FSI) • ropp_qc • Quality control Libraries • ropp_fm • 2-D Bending Angle (hybrid, pressure & height based)
ROPP Examples: Information content Tropical profile, w/ and w/o inflated background errors above 5 hPa, for various uncorrelated bending angle noise levels
ROPP Examples: 1K Altitude One order of magnitude in noise reduction ~ 15 km in altitude.
ROPP: Surface Pressure Retrieval Surface pressure retrieval increments. Small inconsistency in altitude reference (top) and modified (bottom).
Acknowledgments / Contacts • Acknowledgments: • Met Office (Dave Offiler) • Met Office / EUMETSAT (Christian Marquardt) • Met Office / ECMWF (Sean Healy) • Contacts: • Email: grassaf@metoffice.gov.uk • Web:http://www.metoffice.gov.uk/research/interproj/grassaf/index.html