Richard Swinbank, with thanks to the GIFS-TIGGE working group, THORPEX IPO and other colleagues

1. The THORPEX Interactive Grand Global Ensemble (TIGGE) and plans for a Global Interactive Forecast System (GIFS) - an introduction Richard Swinbank, with thanks to the GIFS-TIGGE working group, THORPEX IPO and other colleagues

2. TIGGETHORPEX Interactive Grand Global Ensemble • A major 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 • GEO task WE-06-03 – “TIGGE and the Development of a Global Interactive Forecast System for Weather” 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”

3. TIGGE data • Ten of the leading global forecast centres are providing regular ensemble predictions to support research on predictability, dynamical processes and development of probabilistic forecasting methods. • TIGGE data is made available for research after a 48-hour delay. Near real-time access may be granted for specific projects through the THORPEX International Project Office.

4. TIGGE infrastructure Predictability science Applications • 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 400 GB/day) within available network and storage capabilities academic NHMS users NCAR ECMWF CMA EPS 1 EPS 2 EPS n

5. Summary of TIGGE database

6. Some nice features of TIGGE that demanded a lot of effort All data are archived at native resolution (on native grid when possible) Data are interpolated on any limited-area lat-lon grid defined by the user just before download Field names, definitions, units, accumulation times, etc… are fully standardized Data gaps are continuously monitored and every effort is made to repair them quickly Data can be obtained either in GRIB2 or NETCDF format (only from NCAR at the moment) More functionalities will be installed (e.g. access to single point data, automatic requests, local calculation and plot generation, etc…) depending on user numbers, requests and funding 6

7. 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.

8. Comparison of RMS errors Courtesy Mio Matsueda

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

10. Multi-model combination: MSLP & T2m MSLP > mean 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 T2m > 90 %

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

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

13. MJO forecast comparison Mio Matsueda

14. Towards the Global Interactive Forecast System (GIFS) • Many weather forecast situations are low probability but high risk – unlikely but catastrophic. Probabilistic forecasting is a powerful tool to improve early warning of high-impact events. • The objective of the GIFS is to realise the benefits of THORPEX research by developing and evaluating probabilistic products to deliver 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.

15. GIFS concept • GIFS is planned to use global-regional-national cascade pioneered by the WMO Severe Weather Forecast Demonstration Project (SWFDP) • Further development and evaluation of products will be done in conjunction with SWFDP and other regional pilot projects.

16. GIFS development • GIFS-TIGGE WG has initiated a GIFS development project • Develop products, based on TIGGE ensembles, focused on forecasts of • Tropical cyclones • Heavy precipitation • Strong winds • Collaborate with WMO Severe Weather Forecast Demonstration Project (SWFDP) and other FDPs and RDPs to provide an environment for the evaluation of prototype products • Need to engage with users to ensure products address needs of operational forecasters and end users.

17. GIFS development project interactions

18. Tropical cyclone productsfrom MRI/JMA http://tparc.mri-jma.go.jp/cyclone/

19. New tropical cyclone product:Strike probability time-series at a city (available afternext major update) Courtesy Tetsuo Nakazawa

20. Forecasting TC genesis strike probability 5-7 days ahead Courtesy David Richardson / ECMWF

21. Summary • 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. • Products to enhance the prediction of high-impact weather, starting with tropical cyclones, will form the basis of the development of the Global Interactive Forecast System. • GIFS products will be developed & evaluated in conjunction with SWFDP and other regional projects. TIGGE website: http://tigge.ecmwf.int