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COST actions in general

COST actions in general. COST is a framework for international co-operation 32 member countries, over 400 COST actions Funding for general co-ordination and secretarial services, management committee meetings, experts' travelling expenses and the organisation of events

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COST actions in general

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  1. COST actions in general • COST is a framework for international co-operation • 32 member countries, over 400 COST actions • Funding for general co-ordination and secretarial services, management committee meetings, experts' travelling expenses and the organisation of events • It is not a source of funding for international research projects • A COST action is relatively easy to start: at least five COST members must sign • A management committee implements and co-ordinates the Action

  2. Objectives of COST-716 Exploitation of Ground-Based GPS for Climate and Numerical Weather Prediction Applications Primary Objective • Assessment of operational potential on an international scale to provide near real time observations Secondary Objectives • Development and demonstration of a prototype • Validation and performance verification • Exploitation for numerical weather prediction (NWP) and climate applications • Requirements for operational implementation

  3. Status of COST-716 • Memorandum of Understanding approved Dec. 97 • 15 countries have now signed the MoU: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Hungary, Italy, Netherlands, Norway, Spain, Sweden, Switzerland and UK. • Action in force September 1998 (duration 5 years). • Chairperson Gunnar Elgered (vice chair H-P. Plag) • Secretary: Zoltan Dunkel (COST bureau) • Management committee meets twice per year • 1st Workshop 10-12 July, 2000, Oslo, Norway • 2nd Workshop planned for 28-29 Jan 2002 hosted by GFZ, Potsdam

  4. COST-716 Projects • State of the art and production requirement: workshop & review • Demonstration: near real time network demonstration and trial report • Applications: Assimilation & data utilisation for NWP and Climate; impact assessment & recommendations • Planning for the operational phase: cost/benefit analysis, recommendations for international operational work Each project is handled by a working group

  5. WG1 - State of the art and production... Deliverables • Review of the state of the art • Equipment specification • Recommended software and data format • Preliminary user specification Status • Final report presented at the Oslo Workshop (2000) • Joined with WG2 Chairperson: Peter Pesec

  6. WG2 - Demonstration Deliverables • Near real time network demonstration (March 2001 …) • Benchmark dataset • Verification of hardware and software codes • Assessment of sensitivity to site variables • Quality control and validation scheme (site specific) Status • Started September 1999, first meeting March, 2000 • NRT demonstration started, benchmark finished Chairperson: Hans van der Marel

  7. WG3 - Assimilation and data utilisation ... Deliverables • Impact assessment for numerical weather prediction and climate research • Recommendations for data exploitation, quality control and performance monitoring and data archiving • Revised user requirements and system specifications Status • Started September 1999 • Requirements ready, assimilation trials started Chairperson: Sylvia Barlag

  8. WG4 - Planning for the operational phase Deliverables • Review of implementation options • Assessment of optimal density and impact on current observing system • Cost/benefit analysis • Recommendations for international operational work Status • Started December 2000 • Working group is being formed Chairperson: John Nash

  9. Ground-based GPS for Meteorology Proof of concept has already been given by several (inter)national studies and projects. Two types of applications: • operational meteorology (NWP models); need Total Zenith Delays (TZD) or Slant delays • climate research and monitoring; need integrated water vapour (IWV) IWV is not necessary for NWP, although very useful for synoptic use and comparisons

  10. User Requirements - GPS Meteorology In order to be useful for meteorology in Europe: 1) The data expected from the GPS network(s) should cover (at least) Europe and the Northern Atlantic as much as possible (island stations). 2) Two data qualities are necessary: a) As needed for near-real-time data assimilation (operational meteorology) b) For climate use (i.e. post-processed) 3) The WAVEFRONT processing recommendations should be followed, and the CLIMAP formats, possibly amended, should be used for the distribution of data. (Source: Working Group 3)

  11. User Requirements - NWP applications Adapted from general User Requirement Statement for Meteorological Data, drafted by WMO: 3D- and 4D-VAR Numerical Weather Prediction (NWP) models can directly assimilate Total Zenith Delay (TZD). The requirements for mesoscale NWP models are similar, except that horizontal resolution better than 50km and timeliness better than 1 hour are preferred.

  12. User Requirements - Climate No direct interest in zenith delays; use time- and spaced-averaged water vapour columns, or 3D analysed fields from NWP models Similar to NWP, except • long-term means are taken • stable, and low biases are demanded !!

  13. Demonstration project - Deliverables ‘Modified’ deliverables (July 2000) • Near real time network demonstration • Post-processed network for Climate applications • Production of a Benchmark dataset • Quality control and validation scheme (site specific) • Assessment of equipment and expertise, needed to run the processing at meteorological institutes • Verification of hardware and software codes • Assessment of sensitivity to site variables

  14. Benchmark dataset - Goals • To test and validate the algorithms, dataflow, formats and assimilation into NWP models for the near real-time demonstration project • To have a campaign that can serve as a benchmark against which to test various processing environments • To show the potential use of GPS-TZD for NWP In contrast to the actual demonstration, where analysis centers will process different GPS sub-networks, all analysis centers processed a (more or less) common network of 44 stations.

  15. Benchmark dataset (1) • 15 days of GPS data for the period of June 9-23, 2000 • 44 stations were selected to be processed by all analysis centers (but individual centers were allowed to process more stations) • Of the 44 common stations, about 25 were centred around the North-Sea, of which 15 in the UK, thus forming a dense sub-network. • GPS data were processed off-line, but to near-real time quality • For comparison purposes also solutions with post-processed quality were produced.

  16. Benchmark dataset (2) • The area and time were selected because the early part of the period was characterised by fine weather associated with a high pressure system over the UK, but which rapidly broke down, giving heavy rain with little warning in the NWP forecasts. • It is expected that under these conditions GPS will contribute significantly to improving NWP forecasts of precipitation. • The other stations were selected close to sites where radio-sonde are launched or sites equipped with radiometers for validation purposes.

  17. Main network of 44 benchmark stations

  18. Benchmark analysis centers The benchmark dataset was processed by 7 GPS analysis centers: ASI_ Agenzia Spaziale Italiana, Matera, Italy CNRS CNRS Geosciences Azur, Valbonne, France GOP_ Geodetic Observatory, Pecny, Czech Republic GFZ_ GeoForschungsZentrum, Potsdam, Germany IEEC IEEC, Barcelona, Spain LPT_ Federal Office of Topography, Wabern, Switzerland NKG_ Onsala Space Observatory, Sweden Many of the selected 44 stations were processed by all analysis centers, while several analysis centers added other stations to their solutions. Different processing strategies and software were used.

  19. Benchmark - Combined solutions • The individual solutions are compared with combined solutions of NRT and Post-processed quality • The combined solutions have been computed using the IGS combination procedure (G. Gendt) • NRT combination (7 centers, total 102 sites) • 44 sites used by 3 or more centers • 2 sites used by 2 centers • 56 sites used by 1 center • Post-processed combination (4 centers, 69 sites) • 43 sites used by 3 or more centers • 1 site used by 2 centers • 25 sites used by 1 center

  20. Benchmark – Results (4) Comparison of the individual NRT solutions

  21. Benchmark Results (5) Comparison of the individual Post Processed solutions

  22. NRT Post-proc.

  23. Benchmark dataset - Summary • So far, the results of the different processing strategies and analysis centers were compared • The overall consistency between the solutions is about 5-6 mm for the Zenith Delay (<1 kg/m^2 in Integrated Water Vapour). • The biases will be a problem for assimilation • A comparison with radio-sondes is underway. • The GPS Total Zenith Delays are assimilated into Numerical Weather Prediction model of the UK Met Office, SMHI, DWD, DMI, … in order to study the effect on the weather forecast. First results can be expected very soon.

  24. NRT demonstration trial • GPS data collection and processing are handled by the processing centers Timely available GPS data is required on a continental or global scale (NRT reference network), and on a local scale: • there are still (large) gaps in the hourly data network, • reliability and latency are poor More reliable hourly data for more stations is needed! • ZTD is sent within1h45m to UKMO in the COST format • The ZTD are used for (parallel) NWP assimilation trials • The ZTD is converted to IWV using • Measured pressure and temperature at GPS site • Pressure and temperature interpolated from nearby synoptic sites • Data from NWP models Has already resulted in a first application of the data at KNMI

  25. Example of NRT trial data (1)

  26. Example of NRT data (2)

  27. Post-processing network for climate ... • The requirements for climate research and climatology are basically the same as for the NRT network, but • more precise, smaller biases and long term stability • less strict on timeliness • Post-processing using final IGS orbits • Starting point is the existing EUREF network • enhanced by a few stations collocated with a radiosondes • adding post-processed results of the “NRT-networks” • Combined solution (as is done in IGS) by the EUREF troposphere coordinator • TZD parameter per station every 2 hours (EUREF) • Conversion to IWV should be arranged

  28. COST format for Total Zenith/Slant Delay • The proposed exchange format is the COST v1.0 format (based on CLIMAP) or BUFR format • The COST v1.0 is an ascii format that can be converted into BUFR • BUFR is the standard format used on the GTS network • COST format has recently been adapted to include slant delays, processing statistics, q/c information • Includes also surface meteo data and IWV • COST files can contain data for more than one station (virtual files)

  29. Conclusion • COST-716 is well underway • Requirements are clear • Demonstration based on several NRT-networks • Benchmark dataset and first test of NRT-network • Start of NRT processing in March 2001 • Not possible w/o IGS orbit products or IGS, EUREF and other hourly data!!!! • But, more reliable hourly data for more stations needed • Post-processing for climate applications • Seen first demonstrations of the use of GPS data in assimilation for NWP

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