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The THORPEX Interactive Grand Global Ensemble (TIGGE) Richard Swinbank, Zoltan Toth and Philippe Bougeault, with thanks to the GIFS-TIGGE working group.

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Presentation on theme: "The THORPEX Interactive Grand Global Ensemble (TIGGE) Richard Swinbank, Zoltan Toth and Philippe Bougeault, with thanks to the GIFS-TIGGE working group."— Presentation transcript:

1 The THORPEX Interactive Grand Global Ensemble (TIGGE) Richard Swinbank, Zoltan Toth and Philippe Bougeault, with thanks to the GIFS-TIGGE working group and other colleagues

2 TIGGE overview  Introduction to TIGGE  Objectives  The TIGGE archive  TIGGE-LAM  Early results based on TIGGE data  Intercomparison of ensemble forecasts  Use of multi-model ensembles  Towards the Global Interactive Forecast System  Implementing THORPEX science  The TIGGE User Workshop  What users can learn about TIGGE this week

3 TIGGE A key component of THORPEX: a World Weather Research Programme to accelerate the improvements in the accuracy of 1- day to 2-week high-impact weather forecasts for the benefit of humanity The TIGGE project has developed a database of global ensemble forecasts collected in near real-time. Objectives:  Enhance collaboration on ensemble prediction, both internationally and between operational centres & universities.  Facilitate research on ensemble prediction methods, especially methods to combine ensembles and to correct systematic errors  Enable evolution towards a prototype operational system, the “Global Interactive Forecast System” For more about TIGGE, see

4 TIGGE infrastructure  Data collected in near- real time (via internet) at central TIGGE data archives  Could be implemented at relatively little cost  Can handle current data volumes (approaching 300 GB/day) within available network and storage capabilities  More information in Baudouin Raoult’s presentation tomorrow NCAR EPS 1EPS 2EPS n academicNHMSusers Predictability science Applications ECMWFCMA

5 Summary of TIGGE database Centre Ensemble members Output data resolution Forecast length Forecasts per day Fields (out of 73) Start date BOM331.50º x 1.50º10 day2553 Sep 07 CMA150.56º x 0.56º10 day26015 May 07 CMC211.00º x 1.00º16 day2563 Oct 07 CPTEC151.00º x 1.00º15 day2551 Feb 08 ECMWF51 N200 (Reduced Gaussian) N128 after day day2701 Oct 06 JMA511.25º x 1.25º9 day1611 Oct 06 KMA171.00º x 1.00º10 day24628 Dec 07 Météo-France111.50º x 1.50º2.5 day16225 Oct 07 NCEP211.00º x 1.00º16 day4695 Mar 07 UKMO241.25º x 0.83º15 day2701 Oct 06

6 TIGGE-LAM: TIGGE for limited-area models The TIGGE-LAM panel, chaired by Tiziana Paccagnella (ARPA- SIM), supports the development of the Limited Area Model Ensemble Prediction System component of TIGGE. This Panel works in close coordination with the GIFS-TIGGE WG, in liaison with pre-existing LAM EPS initiatives and in coordination with the THORPEX regional committees. Aims:  encourage a coordinated approach to LAM EPS for the mutual benefit of WMO members;  facilitate the interoperability of the different modelling systems contributing to TIGGE;  coordinate the archiving of limited-area ensemble forecasts – the three TIGGE archive centres have agreed to host a sub-set of high priority data;  contribute to the definition of scientific issues related to LAM EPS and particularly to TIGGE-LAM and propose specific initiatives to address these issues to advance LAM EPS.

7 Early Results from TIGGE Ensemble forecasts Z500 Spaghetti Diagram Courtesy Mio Matsueda

8 Comparison of RPSS N. hem Z500 DJF07 (90c) JJA07 (84c) ECMWF UKMO NCEP MSC JMA CMA BMRC KMA ON07 (45c) AM07 (62c) from Park et al, 2008

9 Comparison of extra-tropical cyclone tracks Courtesy Lizzie Froude Ensemble mean error: Position (verified against ECMWF analyses) Ensemble mean error – Propagation speed Propagation speed bias

10 Comparison of multi-model ensemble with ECMWF Courtesy Mio Matsueda MGCE51 10 members from each of 5 centres MCGE168 All 12Z forecasts MCGE327 All forecasts for each day

11 Multi model M2 (ECMWF+UKMO): effect of bias correction (nbc vs bc) EC(nbc) UK(nbc) M2(EU,nbc) M2(EU,bc) RMSE RPSS M2(EU,nbc) M2(EU,bc) M2(EU,nbc) from Park et al, 2008 Z500 NHT850 Tropics

12 Multi-model combination: MSLP & T2m Brier skill-scores of multi-model combination of bias-corrected ECMWF, Met Office and NCEP forecasts. Mean Sea Level Pressure and 500 hPa (not shown) show only small benefits from combining different models 2m temperature shows more benefit (1-5 days improvement in lead time) More sophisticated weighting led to only small additional skill Courtesy Christine Johnson T2m > mean MSLP > mean T2m > 90 %

13 Similarity of ensembles D has small values (high similarity, blue) if the between model variance is small compared to the mean-square- error of the multi-model mean. mslptemp D+2 D+10 D+2 D+10

14 Applications: flood prediction Predictions with a 5-day lead-time for a flood event on River Jiu in Romania from Pappenberger et al, 2008

15 Towards the Global Interactive Forecast System (GIFS)  The objective of the GIFS is to realise the benefits of THORPEX research by improving the delivery of improved forecasts of high- impact weather.  As a first step, the GIFS-TIGGE working group set up a pilot project for the exchange of real-time tropical cyclone predictions using “Cyclone XML” format.  Further plans for the development of GIFS will be presented by Zoltan Toth, and discussed later in the workshop.

16 The TIGGE User Workshop  Overview of the TIGGE project  The TIGGE archive and how to access it:  Presentation during TIGGE-B session, Tuesday afternoon  Hands-on user demonstrations in coffee/poster breaks  Opportunity for you to tell us what you need  Presentations of early results from TIGGE  In TIGGE-A/B/C/D sessions and throughout the symposium.  Plans for GIFS  Presentation during TIGGE-C, Thursday afternoon  Opportunity to get involved in developing improvements to operational forecasting of high-impact weather: focus group discussion during Thursday coffee/poster break.

17 Conclusions  Since October 2006, the TIGGE archive has been accumulating regular ensemble forecasts from leading global NWP centres.  The archive is a tremendous resource for the research community at large, and in particular the science working groups of THORPEX.  TIGGE provides the basis for research and development projects targeted at specific applications of severe weather forecasts (health, energy, flood warning, wind storms, fire weather, etc…).  Products to enhance the prediction of high-impact weather will form the basis of the development of the Global Interactive Forecast System. TIGGE website:


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