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

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

WWRP structure 3 3

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

WWRP structure and links to WCRP 5 5

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

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

Evolution of TIGGE & GIFS TIGGE development Calibration, combination, products EPS improvement Time 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.

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.

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)

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)

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.

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