1. Page 1© Crown copyright 2005 The Radio Occultation Processing Package GRAS-SAF Team (Axel von Engeln), August 2005 GPSRO2, Lansdowne, Virginia

2. Page 2© Crown copyright 2005 Introduction

3. Page 3© Crown copyright 2005 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 3 rd party freeware support libraries required (e.g. netCDF, udunits, Lapack)

4. Page 4© Crown copyright 2005 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

5. Page 5© Crown copyright 2005 ROPP Context GRAS Level 1b (CGS) PFS netCDF pfs2ropp GRAS Level 2 (SAF) ropp2bufr BUFR ropp_1dvarropp_fm NWP VAR system NWP User netCDF ropp_preproc ropp_qc

6. Page 6© Crown copyright 2005 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.

7. Page 7© Crown copyright 2005 Modules

8. Page 8© Crown copyright 2005 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)

9. Page 9© Crown copyright 2005 ROPP Modules (2)  ropp_1dvar  1DVar Library (Minimiser, Q/C)  ropp_ug  User Guide

10. Page 10© Crown copyright 2005 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)

11. Page 11© Crown copyright 2005 ROPP Examples

12. Page 12© Crown copyright 2005 ROPP Examples: Information content Tropical profile, w/ and w/o inflated background errors above 5 hPa, for various uncorrelated bending angle noise levels

13. Page 13© Crown copyright 2005 ROPP Examples: 1K Altitude One order of magnitude in noise reduction ~ 15 km in altitude.

14. Page 14© Crown copyright 2005 ROPP: Surface Pressure Retrieval Surface pressure retrieval increments. Small inconsistency in altitude reference (top) and modified (bottom).

15. Page 15© Crown copyright 2005 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

16. Page 16© Crown copyright 2005 Questions & Answers