News Archive
The news listed below have previously been shown in the "News" column of the ROM SAF Main page-
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[May 14, 2020]
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Release of an experimental reflection flag dataset
Since January 4, 2016, the ROM SAF data archive includes a list of RO events flagged with occurrence of reflected signals. The prototype product is provided for demonstration and research purposes.
The original set contains more than 4 million COSMIC RO events, since 2006 to the beginning of 2014, and some of 2015. A ROM SAF report has also been published in the ROM SAF website to facilitate the understanding of the flag, methodology used to determine the presence of reflected signals, and its validation. The report also presents some statistics of occurrence of reflected signals in RO, their geographic and seasonal behavior, an initial investigations about the potential nature of their occurrence (instruments, scattering surface and/or atmospheric conditions).
Data access (registered users*): Reflection flag data
Documentation: ROM SAF Report 23
(* New users can register here)
[February 9, 2016]
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Release of ROM SAF ROPP-7 software package
The ROM SAF is pleased to announce the seventh full release of the software deliverable 'ROPP', Version 7.0.
[October 21, 2013]
The main change from the previous release, v6.1, is the inclusion of a tool to diagnose tropopause heights from profiles of bending angle, refractivity, dry temperature or background temperature. The first two are derived from the covariance transform of the bending angle or refractivity profile; the last two from the lapse rate (and cold point) of the temperature profile. Quality control flags help the user to assign the appropriate level of confidence to the diagnosed tropopause heights.
All user documentation has been reviewed and updated. Details of all changes are available together with the updated software on the ROPP download website.
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Release of updated climate data based on the COSMIC satellites
The ROM SAF is now releasing an update of the climate data products based on data from the US-Taiwanese satellite mission FORMOSAT-3/COSMIC. The monthly mean time series now covers the period from September 2006 to December 2012.
[August 26, 2013]
This ROM SAF climate data set (products GRM-17 to 21) consists of zonal monthly means of bending angle, refractivity, temperature, humidity, and geopotential height, on a 5 degree by 200 meter latitude-height grid. The monthly data are delivered as CF compliant netCDF files that also incorporates related data: data numbers, error estimates, and comparisons to the ECMWF operational model fields.
The data can also be viewed on the ROM SAF Climate Monitoring pages , which includes time series plots for the full length of the climate data set, as well as various quality indicators.
User documentation and access to the climate products are available at the Product Archive.
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ROM SAF Visiting Scientist position
The ROM SAF is seeking a Visiting Scientist to perform the tasks described in this PDF file. The duration is estimated to be three months to be carried out in the period from September/October to December 2013. The successful candidate should spend three weeks at the Danish Meteorological Institute (DMI) in the beginning of this activity and the remaining time at the home institute.
[July 5, 2013]
The payment for this Visiting Scientist Activity (VSA) will consist of half a salary compensation for ten weeks to be paid to the home institute. In addition, the ROM SAF will pay the trip and per diem for the three weeks stay at DMI.
If you are interested in this Visiting Scientist activity, please email a brief application and short CV to the ROM SAF Helpdesk (email) before 24 July 2013.
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Release of climate data based on the COSMIC satellites
The ROM SAF is pleased to announce the release of a new set of climate data products, based on data from the US-Taiwanese satellite mission FORMOSAT-3/COSMIC. Launched in April 2006, the satellites still continues to make important contributions to the set of global RO climate data, even though their 5-year design life time ended in 2011.
[June 10, 2013]
This ROM SAF climate data set (products GRM-17 to 21) consists of zonal monthly means of bending angle, refractivity, temperature, humidity, and geopotential height, on a 5 degree by 200 meter latitude-height grid. The monthly data are delivered as CF compliant netCDF files that also incorporates related data: data numbers, error estimates, and comparisons to the ECMWF operational model fields.
The data can also be viewed on the ROM SAF Climate Monitoring pages , which includes time series plots for the full length of the climate data set, as well as various quality indicators.
Starting on June 10, 2013, the ROM SAF climate data set includes monthly data from January 2008 to June 2012. During the following weeks, the data set will be extended back to August 2006 and forward into 2013. After that, the climate data set will be continuously updated, lagging the stream of new observational data with less than 6 months.
User documentation and access to the climate products are available at the Product Archive.
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Software Release
The ROM SAF is pleased to announce an update to the sixth full release for the software deliverable 'ROPP', Version 6.1.
The main changes from the previous release, v6.0, are as follows.- (1) A tool to read background profiles of RO data from gridded datasets in GRIB format. The resulting background profiles can be converted to a form suitable for use with the ROPP 1D-Var retrieval module ropp_1dvar.
- (2) A tool to read "grouped" EUMETSAT-style RO data in netcdf-4 format, and to output in standard ROPP or BUFR format.
- (3) The automatic calculation of dry temperature by tools in the ROPP pre-processing package ropp_pp, and its full incorporation within the standard ROprof structure.
All user documentation has been reviewed and updated. Details of all changes are available together with the updated software on the ROPP download website.
[April 9, 2013]
There are few other changes, so unless users wish to take advantage of these new features there is no need to update their applications to use this latest ROPP distribution.
Details of all changes are available together with the updated software on the ROPP download website.
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Refractivity data from the Metop-B satellite, Resumed
Today the ROM SAF resumes the demonstration dissemination of the Metop-B refractivity products.
[April 8, 2013]
The products will be level 2 BUFR files with a similar content as the current BUFR files from GRAS on Metop-A, i.e. they will contain the retrieved refractivities and a copy of the thinned bending angle that is disseminated by EUMETSAT CAF.
More information is given in this UNS-message (requires login). Please do not hesitate to contact the ROM SAF team if you have any questions related to this.
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NRT monitoring of Metop-B data
The ROM SAF is pleased to announce that our NRT monitoring page now includes GRAS RO data from the Metop-B satellite ("GRAS-B").
Mozilla Firefox users may have to do CTRL+SHIFT+R to refresh javascripts before viewing the data. Note that the matched occultations (RO-RO and RO-sonde) are not yet linked but this will happen as soon as possible.
[December 19, 2012]
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Refractivity data from the Metop-B satellite
The EUMETSAT Central Application Facilities (CAF) started the dissemination of GRAS level 1b bending angle data from the Metop-B satellite on November 15.
[December 10, 2012]
The subsequent ROM SAF processing into level 2a refractivities has been running since October and these products have now undergone validation. Today the ROM SAF starts a demonstration dissemination of these products.
The products will be level 2 BUFR files with a similar content as the current BUFR files from GRAS on Metop-A, i.e. they will contain the retrieved refractivities and a copy of the thinned bending angle that is disseminated by EUMETSAT CAF.
More information is given in this UNS-message (requires login). Please do not hesitate to contact the ROM SAF team if you have any questions related to this.
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ROM SAF on Twitter
The ROM SAF recently created a twitter account: https://twitter.com/rom_saf.
[December 10, 2012]
Follow @rom_saf
We intend to use Twitter for brief information about our UNS information and other news.
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Metop-B succesfully launched
EUMETSATs newest polar-orbiting weather satellite Metop-B was successfully launched from Baikonur in Kazakhstan on a Soyuz rocket on September 17.
Metop-B's role is to ensure continuity of observations from polar orbit which are vital to Numerical Weather Prediction as well as climate and environmental monitoring. This service is currently provided by the first satellite in the series, Metop-A (launched October 19, 2006), which has exceeded its nominal lifetime. The value of Metop data for weather forecasting is illustrated by recent studies of the impact of various data sources (in situ, airborne and space-based) on the performance of 24-hour forecasts, in which Metop-A accounts for the highest level of contribution at 25%. Focusing on the contribution of data from individual satellites, Metop-A's contribution is nearly 40%, which is more than double the contribution of a polar orbiting satellite of the previous generation.
Like Metop-A, Metop-B is carrying a GRAS instrument (Global navigation satellite system Receiver for Atmospheric Sounding), which will supply radio occultation data to the ROM SAF. The first test occultation from the instrument is expected on September 24, and commissioning and cal/val-activities will last until February 2013, whereafter the first ROM SAF GRAS products from Metop-B are expected to be declared operational and become publicly available. In parallel, ROM SAF GRAS products from Metop-A will continue to be produced, as long as this satellite is operational.
[September 21, 2012]
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2012 EUMETSAT conference
The ROM SAF participated in the EUMETSAT Meteorological Satellite Conference held in Sopot, Poland, September 3-7, 2012.
[September 21, 2012]
The contribution consisted of one presentation:
ROM SAF and Radio Occultation Products
and two posters:
Improvement Metrics for Water Vapour and Temperature Profiles Retrieved from GPS RO Profiles through 1D-Var
ROM SAF Global Climate Data Based on GNSS-RO Measurements.
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GRAS SAF becomes ROM SAF
From March 1, 2012, the GRAS SAF has a new name: ROM SAF (Radio Occultation Meteorology SAF). The new name reflects the fact that the products and services are not limited to RO data from the GRAS instrument. The change of name also marks the beginning of the 2nd Continuous Development and Operations Phase (CDOP-2) for the SAF.
[March 1, 2012]
The new domain name is: http://www.romsaf.org
Although www.grassaf.org will redirect to the new domain for some time, we encourage users to update their bookmarks, web links, etc. accordingly.
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Software Release
The GRAS SAF is pleased to announce the sixth full release for the software deliverable 'ROPP', Version 6.0.
[February 27, 2012]
The principal changes from the previous release, v5.0, are a consolidation of the ropp_pp module and a better thinning of occultations near the pole. Numerous bug-fixes and minor enhancements, particularly with regard to the building and testing of ROPP, have also been included. All user documentation has been reviewed and updated. Details of all changes are available together with the updated software on the ROPP download website.
Users are recommended to update their applications to use this latest ROPP distribution.
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Software Release
The GRAS SAF is pleased to announce the fifth full release for the software deliverable 'ROPP', Version 5.0.
[July 11, 2011]
The principal changes from the previous release, v4.1, are the inclusion of non-ideal gas effects (compressibility factors) in the forward model and 1D-Var modules, and support for the ECMWF BUFR library. Numerous bug-fixes and minor enhancements, particularly in the ropp_pp module, have also been included. All user documentation has been reviewed and updated. Details of all changes are available together with the updated software on the ROPP download website.
Users are recommended to update their applications to use this latest ROPP distribution.
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NRT Monitoring of SAC-C and C/NOFS Data
The GRAS SAF is pleased to announce that our NRT monitoring page now includes RO data from two more satellites: The Argentinian satellite SAC-C and the US satellite C/NOFS.
[May 30, 2011]
The data are processed and disseminated by UCAR and are now on the GTS, though data since February 2011 are provided.
Firefox users may have to do CTRL+SHIFT+R to refresh javascripts before viewing the data. Note that the matched occultations (RO-RO and RO-sonde) are not yet linked but this will happen soon.
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1D-Var Products Declared Operational
The GRAS SAF is pleased to announce, that the following 1D-Var products have been officially declared operational: GRM-02 (NRT temperature profile), GRM-05 (NRT surface pressure), and GRM-07 (Error covariance matrix for NRT products). The following 1D-Var products have been officially declared pre-operational: GRM-03 (NRT specific humidity profile) and GRM-04 (NRT pressure profile).
[May 3, 2011]
The products are expected to become available to users through dissemination and download in Q4 2011.
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NRT Monitoring of TerraSAR-X Data
The GRAS SAF is pleased to announce that our NRT monitoring page now includes RO data from the German TerraSAR-X satellite.
[October 26, 2010]
The data, processed and disseminated by the GFZ, have an improved stratospheric bias from October 21 onwards. Corresponding ECMWF statistics are available.
Firefox users may have to do ctrl+shift+R to refresh javascripts before viewing the data.
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Successful GRAS SAF Climate Workshop
On September 6-11, 2010, the GRAS SAF co-organized OPAC2010 (International Occultations for Probing Atmosphere and Climate Workshop) together with the University of Graz. OPAC2010 comprised the Joint OPAC-4, GRAS SAF Climate, and IROWG-1 workshops, and was held in Graz, Austria.
[September 20, 2010]
OPAC2010 was a successful forum for everybody interested in atmospheric remote sensing by occultation methods and/or the use of occultation data in atmospheric physics, chemistry, and meteorology, this time with special focus on climate applications.
For program, abstracts, and presentations, please visit the OPAC2010 web page.
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Software Update
The GRAS SAF is pleased to announce an update to the fourth full release for the software deliverable 'ROPP', Version 4.1.
[July 20, 2010]
The principle change from the previous release, Version 4.0, is an update to the radio occultation pre-processing module to provide more robust processing of open loop data. Additional functionality to process GRAS occultation phase and amplitude data has also been included. The 1DVar module has also been updated to provide improved support in defining observation and background error structures, and to output additional diagnostic information. All user documentation has been reviewed and updated. Details of all changes are available together with the updated software on the ROPP download website.
Users are recommended to update their applications to use this latest ROPP distribution.
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Climate Workshop
The GRAS SAF is co-organizing OPAC2010 (International Occultations for Probing Atmosphere and Climate Workshop) together with the University of Graz. OPAC2010 will comprise the Joint OPAC-4, GRAS SAF Climate, and IROWG-1 workshops, and will be held on September 6-11, 2010 in Graz, Austria.
[April 23, 2010]
OPAC2010 will be an attractive forum for everybody interested in atmospheric remote sensing by occultation methods and/or the use of occultation data in atmospheric physics, chemistry, and meteorology, this time with special focus on climate applications.
For more information please visit the OPAC2010 web page.
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NRT refractivity product operational
The GRAS SAF is pleased to announce that the GRAS SAF level 2 NRT refractivity product (GRM-01) has been declared operational. This is happening in connection with an upgrade of the GRAS SAF operational processing software, which will significantly reduce the current bias in GRM-01 above about 30 km. The standard deviation above 40 km will in general be a little larger than before. The influence on the data below 30 km should be insignificant.
[February 1, 2010]
The details of the change are described in the associated Validation Report (available at the Product Archive). The main thing is a shift from statistical optimization based on a 1-parameter background fit to a 2-parameter fit in combination with a global search in a library of climatological profiles. The statistical optimization used is known as optimal linear combination (OLC).
Due to the change of approach in processing the data at high altitudes, some profiles are dismissed as outliers above 40 km, and they are not further processed. As a consequence the number of refractivity profiles after the upgrade will on average be less than before (a reduction of about 5%).
Other minor changes:
NetCDF variables:
- time_offset [Time offset for georeferencing (since start of occ.)] is currently incorrect and will therefore be set to missing value.
- azimuth [GNSS->LEO line of sight angle (from True North) for the reference coordinate] will now be provided in 'atm' files.
BUFR variables:
Local Earth parameters:
- Time increment [data field 29; descriptor 0 04 016] is currently incorrect and will therefore be set to missing value.
- Bearing or azimuth [data field 36; descriptor 0 05 021] will now be provided.
Until today the GRAS SAF refractivity product had the status of pre-operational (version 1.2). After the upgrade the refractivity product is now declared operational (version 1.3).
The upgraded refractivity product is disseminated over the GTS and EUMETCast systems in BUFR format in NRT. It is also being archived at our website in both NetCDF and BUFR files for offline access.
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Software Update
The GRAS SAF is pleased to announce the fourth full release for the software deliverable 'ROPP', Version 4.0.
[January 11, 2010]
The principle change from the previous release, v3.0, is the addition of a new two-dimensional bending angle observation operator, together with the corresponding two-dimensional tangent linear and adjoint codes and I/O support. Additional functionality has been provided in the pre-processing of excess phase data to ionospheric corrected bending angle and refractivity profiles, including use of external navigation bit data (this algorithm has experimental status and is suitable for research use only), revised filtering algorithms and additional options for initialising the Abel transform. Output diagnostic and error information from any ROPP routine may now be controlled by the user. Dependence on the third-party udunits library has been removed. All user documentation has been reviewed and updated. Details of all changes are available together with the updated software on the ROPP download website.
Users are recommended to update their applications to use this latest ROPP distribution.
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New GRAS SAF user survey
The GRAS SAF is conducting a new user survey, the questionnaire can be found here. Initially, email invitations have been sent out to 574 recipients.
[December 15, 2009]
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GRAS SAF web site updated
The GRAS SAF web site has undergone a major update. Notable changes are a modified look, individual product pages, and merging of the two previously separated parts www.grassaf.org and garf.grassaf.org. Users, who previously logged in to access the garf.grassaf.org part, will notice that login is now only required to download product, software, and documents.
[November 17, 2009]
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New GRAS SAF Report (GSR 09)
A new GRAS SAF report addressing the issue of refractivity coefficients has been published. The report is written by Sean Healy, ECMWF, and has the name "Refractivity coefficients used in the assimilation of GPS radio occultation measurements"
[October 9, 2009]
Summary: The sensitivity of ECMWF numerical weather prediction analyses to the empirical refractivity coefficients and the introduction of non-ideal gas effects in the bending angle operator have been investigated. A review of the literature on the refractivity coefficients suggests that the uncertainty in the values is probably larger than has been recognised. The results reinforce the need for new measurements of the refractivity coefficients at radio frequencies.
The GSR 09 report can be viewed here.
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Software Release
The GRAS SAF is pleased to announce an update release for the software deliverable 'ROPP', Version 3.0.
[July 6, 2009]
The principle changes from the previous release, v2.0, is to provide functionality to process excess phase and amplitude time series to compute L1 and L2 channel bending angle profiles by geometric optics and wave optics methods. This complements existing functionality to compute ionospheric corrected bending angle and refractivity profiles from L1 and L2 channel bending angle data.
Users are recommended to update their applications to use this latest ROPP distribution.
Details of all the changes are available together with the updated software package on the ROPP download website.
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Feature on GRAS SAF
EUMETSATs web page has a feature on the GRAS SAF and our refractivity product this week.
[April 17, 2009]
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Data access on GARF
The GRAS SAF is pleased to announce that the product archive GARF is open for access to archived NRT data. Read more here.
[March 30, 2009]
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Refractivity (GRM-01) product via EUMETCast
The GRAS SAF is pleased to announce that the GRAS SAF level 2 NRT refractivity product (GRM-01) is being disseminated in trial mode via the EUMETCast at EUMETSAT. The dissemination started 30 March 2009, at about 11:00 UTC. For more information see EUMETSAT's announcement below:
- Subject: Trial Dissemination of the GRAS SAF NRT refractivity product (GRM-01)
Date: Friday, March 27, 2009 12:15 PM
Dear Members of the STG-OPS Working Group
We are pleased to announce on 30 March 2009, the inclusion of new GRAS SAF products on EUMETCast.
The GRAS SAF level 2 NRT refractivity product (GRM-01) is generated for every occultation in BUFR format. The product has "pre-operational" status.
For more information about the BUFR files please read the following document: BUFR Specification
EUMETCast requirements: Files will appear on the channel "SAF-Europe" (PID 500, multicast address 224.223.222.28:3011) The filenames start with "S-GRM_-GRAS_RO_L12" with full details in the Product User Manual, see: PUM
For further information, please consult the SAF web site via the link provided above.
Access to the above product will be automatically provided for Member/Cooperating State NMS and registered manufacturers. Following the successful trial, it is planned to make the products available to the wider EUMETCast User community.
With best regards
Sally Wannop
User Relations Manager
EUMETSAT User Service
- Subject: Trial Dissemination of the GRAS SAF NRT refractivity product (GRM-01)
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NRT refractivity product pre-operational
The GRAS SAF is pleased to announce that the GRAS SAF level 2 NRT refractivity product (GRM-01) has been declared pre-operational.
[March 25, 2009]
The product is disseminated in NRT via the GTS system and is in the final stages of being made available over the EUMETCast system; a separate announcement will be issued when this is ready. On Thursday this week we will open the GRAS SAF Archive and Retrieval Facility (GARF) where archived NRT data can be retrieved.
The current level 1b bending angle is obtained by GO and cannot be recommended for usage below about 8 km; this is also true for the refractivity. The quality of the refractivity product can be seen in the attached figure which shows the global O-B/B statistics compared to ECMWF. The figure shows the O-B/B mean and standard deviation and the product requirements accuracies: threshold (green) and target (red). We are currently improving on the standard deviation and the bias above 35 km and we expect to be able to provide an updated product within 1-2 months time.
On GARF we provide continuous NRT monitoring of the data quality and data flow. The monitoring does not only include MetOp/GRAS RO data from EUMETSAT and the GRAS SAF but also RO data from the following missions: FORMOSAT-3/COSMIC, CHAMP, and GRACE-A.
The BUFR file that is being disseminated via GTS contains in addition to the refractivity product a GRAS SAF produced thinnned version of EUMETSAT's NRT level 1b bending angle. The thinning is consistent with the thinning algorithm applied by EUMETSAT. In order to start receiving the GRAS SAF BUFR file please follow the normal procedures at your organization. The files are generated at DMI and carries the WMO bulletin headers: "IUT[A-L]14 EKMI". For more information about the BUFR files please read this document.
If you have questions please do not hesitate to ask us. Please address your questions directly to the GRAS SAF helpdesk by using this link: Helpdesk.
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Software Release
The GRAS SAF is pleased to announce an update release for the software deliverable 'ROPP', Version 2.0.
[December 1, 2008]
Details of the changes are available together with the updated software package on the ROPP download website.
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Software Release
The GRAS SAF is pleased to announce an update release for the software deliverable 'ROPP', Version 1.2.
[September 3, 2008]
The principle changes from the previous release, v1.1, is to increase flexibility to support other than the ECMWF NWP model levels, significantly decrease dependencies on 3rd party code and to fix some reported bugs relating to the processing of Level 1 GRAS data.
Details of the changes are available together with the updated software on the ROPP download website.
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User workshop
A joint ECMWF/GRAS SAF workshop on the assimilation of GPS radio occultation measurements was held at ECMWF in Reading, UK, from 16 to 18 June 2008. Read more here.
[June 16, 2008]
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NRT monitoring
The GRAS SAF is pleased to announce NRT monitoring of level 2 demonstration products based on pre-operational level 1b GRAS bending angle data from EUMETSAT.
[April 11, 2008]
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Software Release
The GRAS SAF is pleased to announce an update release for the software deliverable 'ROPP', Version 1.1. The principle change from the first release, v1.0 is to make the code in general much more robust to non- nominal data inputs and to support new forthcoming RO missions. The v1.1 code has also been successfully tested with a wider range of compilers, so portability is significantly enhanced.
[April 9, 2008]
Details of the changes are available together with the updated software on the ROPP download website.
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Software Release
The GRAS SAF is pleased to announce the first full release of the Radio Occultation Processing Package (ROPP-1 v1.0).
[April 11, 2007]
The package provides software to support GRAS (and other RO missions such as COSMIC and CHAMP) data to be assimilated into NWP models, RO data file interfaces plus various stand-alone tools such as 1D-Var retrieval and BUFR encoding/decoding. Full documentation is provided. There are no charges for this downloading or using this package.
The ROPP-1 software, test data, documentation and supporting items can be downloaded from the GRAS SAF Product Archive, from where ialso an overview document describing ROPP can be freely downloaded. In order to download the package components, you will first need to register as an ROPP user via this website. This is an automatic process and very simple and quick to obtain the access details. Users who have previously registered for the Beta release will need to re-register for the full release.
When you have your access details, you will be able to log in and navigate to the ROPP downloads page where - for the first login only - you will be required to agree to the terms of a Software Licence. Please first look at the Release Notes which contain a description of the available files, the current status of the packages components and a quick installation guide.
We thank you for your interest in ROPP and we look forward to hearing of your experiences in using the package. If you have any comments or questions about ROPP, please use the Helpdesk facilities.
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