Proposed Predictability, Dynamics & Ensemble Forecasting Expert Team

1. Proposed Predictability, Dynamics & Ensemble Forecasting Expert Team Richard Swinbank Masayuki Kyouda GIFS-TIGGE WG, Exeter, June 2013

2. Contents • Post-THORPEX plans • Evolution of GIFS-TIGGE • Proposed expert team • Discussion…

3. WWRP structure 3 3

4. Legacy THORPEX PCPI MJO TF WGSIP WGDAOS WGPDP Subseasonal to Seasonal Prediction Project JWGFVR WGNR /MFR Polar Prediction Project High Impact Weather Project WGNE SWFDP WGSERA WGTMR 4 4

5. WWRP structure and links to WCRP 5 5

6. TIGGE – Research focus The TIGGE project (& GIFS-TIGGE working group) was originally focused on the technical work enabling the establishment of the TIGGE archive dataset. The main scientific aspects of THORPEX were covered by Predictability & Dynamical Processes WG, and also Data Assimilation & Observing Systems WG(s). Following the successful establishment of the TIGGE dataset, the focus of the GIFS-TIGGE working group has shifted towards research on ensemble forecasting. Particular topics of interest include: a posteriori calibration of ensemble forecasts; combination of ensembles produced by multiple models; research on and development of probabilistic forecast products. More recently, we have broadened our range of interest to cover improvement of EPSs, including: representing uncertainties in initial conditions stochastic physics & other techniques to account for model error

7. Ensemble Forecasts Evaluate, Diagnose Develop, Improve Virtuous Circle To improve EPSs we need to develop a virtuous circle – best with a single group with focus on ensemble prediction

8. TIGGE development Calibration, combination, products EPS improvement Time Evolution of TIGGE & GIFS • GIFS-TIGGE should also be a forum to focus on R&D directed at improving our EPS systems, to help us develop a “virtuous circle”. • We introduced a section of the WG meeting for discussing ensemble initial conditions, stochastic physics & other aspects of improving our EPSs. • We also need to maintain an interest in ensemble verification & links with convective-scale EPS and the new sub-seasonal to seasonal group.

9. Looking forward -A proposed new working group • The logical evolution of an increased focus on research would be the creation of a Predictability Dynamics & Ensemble Forecasting working group, combining much of the current GIFS-TIGGE and PDP groups. • This new group would provide a centre of scientific expertise on dynamics, predictability and ensemble forecasting that is currently lacking in the core WWRP programme.

10. Scope • A centre of scientific expertise on dynamics, predictability and ensemble forecasting • Bridge between academic & operational communities • Promote use of TIGGE and TIGGE-LAM • Scientific issues include • Growth & evolution of errors • Stochastic representation of unresolved processes • Short- to medium-range forecast timescales (potentially longer)

11. Relationship with other teams / groups • Clear linkages with WGNE and other WWRP expert teams • Numerical modelling, ensembles, data assimilation, stochastic parameterization & evaluation all closely linked on weather forecast & climate timescales. • Too big for a single expert team – need a set of more specialised teams. • Providing expert support to WWRP projects (S2S, PPP, HIW, RDPs & FDPs)

12. Other issues • Development of severe weather products • Would fit well into scope of proposed HIW project • Technical management of data archives • Ongoing management could be done by a liaison group of archive centres & some or all data providers. • Could report to PDEF team (or HIW project)? Representative of technical group on ET. • Transition arrangements • Work towards merger of GIFS-TIGGE and PDP groups at end of 2014 • New members of both groups chosen for role in new team.

13. Next Steps • Discuss here and at joint THORPEX/ICSC and WWRP/JSC meeting. • What is the process for approving the new group?