David B. Parsons School of Meteorology University of Oklahoma 1

Based on a paper in preparation for submission to the Bulletin of the American Meteorological Society by Parsons, Shapiro and many others The article proposal has been accepted and a first draft with holes should be completed in ~2 weeks. 2

Background The 10-year THORPEX era is coming to a close (e.g., “initiated” by the WMO in 2003 and “implemented” in 2005) The Executive Committee of the THORPEX International Core Steering Committee (ICSC) has asked me to lead an effort to formally document the scientific and operational outcomes of the program, including the challenges faced through an article in the refereed literature A plan for an article to be submitted to the Bulletin of the American Meteorological Society (BAMS) was approved by the THORPEX ICSC followed by a proposal submitted to and approved by the BAMS editorial staff Numerous scientists involved in THORPEX are contributing text and more will contribute by reviewing the document for accuracy. 3

Background Numerous scientists involved in THORPEX are contributing text and more will contribute by reviewing the document for accuracy. Note on authors and strategies……… Lead authors selected for various sections --- Selection of lead authors depends heavily on discussions at ICSC (and current WG co-chair roles) --- Lead authors suggest others that made important contributions and should to be included ---- Other researchers critical to THORPEX effort will be included and asked to review the document ---- We will be inclusionary 4

Outline 1. Introduction – History, goals, objectives and organization – Mel Shapiro 2. Research to advance the components of numerical weather prediction systems 3. Global-to-regional aspects of high impact weather: regional campaigns 4. THORPEX from the poles to the equator 5. Broader impacts (collaborations, training, meetings, etc) 6. A legacy of improvements to operational prediction and forecasting 7. Lessons Learned and Challenges Faced 8. Conclusions and the THORPEX legacy projects 5

1. Introduction – Shapiro lead – possible content a) History – Sequence of events that led to the founding of THORPEX b) Overarching goal – “accelerate improvements in the accuracy of 1-day to 2-week forecasts of high impact weather” c) Establishment of four research priorities and core objectives --- pgs. 8 and 9 of science plan d) Organization of the Scientific and Technical Teams e) Governance of project and implementations– WMO Research Dept, WWRP, Trust fund and IPO 6

2. Research to advance the components of numerical weather prediction systems a) Insight into the global observing system – Mujumdar, Langland and Hamill--- An evaluation of adaptive measurement strategies b) Advancing data assimilation – Saunders, and Rabier Furthering ensemble-based assimilation techniques and promoting new techniques for data impact studies c) Ensemble prediction – Swinbank and Bougeault Creating the TIGGE data base, subsequent research and regional examples (TIGGE-LAM, NAEFS and S. American efforts) 7

2. Research to advance the components of numerical weather prediction systems a) Insight into the global observing system – The basis of this section is the WMO report produced by Majumdar et al. 2011) summarizing a decade of Observation System Experiments and forecast sensitivity studies associated with THORPEX were: i. The value of extra-tropical targeted data was positive, but small on average; ii. Adaptive observations sampled around tropical cyclones improved track forecasts; iii. Observations taken in sensitive areas had more value than those deployed randomly; iv. The value of adaptive observations depended on the modeling and assimilation; v. Adaptive processing and selection of satellite data, particularly on larger spatial and temporal scales than are achievable by aircraft, can be a cost-effective solution. Recent evaluation of the impact of targeted observations during NOAA’s 2011 Winter Storm Reconnaissance program found neutral impact (Hamill et al. 2013). The average marginal impact of an individual observing system is decreasing, and therefore an ongoing assessment of the cost-effectiveness of targeted (and routine) observations is necessary. 8

3. Global-to-regional aspects of high impact weather: regional campaigns a) High impact weather in the Mediterrean (HYMEX) -- Ducrocq Knowledge of atmospheric and hydrological influences that lead to flash floods, development of improved coupled modeling systems and data assimilation strategies on convection permitting-scales b) West African Monsoon (AMMA) – Redelsperger and Thorncroft Advancing observational strategies (rawinsonde and satellite) over West Africa and knowledge of data impacts, dynamics of African Easterly waves, tropical-- extratropical interacts -- NASA collaboration, THORPEX role limited to WG2 c) Tropical cyclones and extra-tropical transitions (T-PARC and related tropical cyclone experiments) – Harr, Jones, and Nakazawa with ONR in a major way Knowledge of tropical cyclone targeting in the N. Pacific basin, understanding and advances in prediction of tropical cyclone genesis, and ET dynamics and forecast failures 9

4. THORPEX from the poles to the tropics a) Weather and climate in polar regions (including THORPEX-IPY cluster) – Brunet and Rabier --- probably THORPEX’s largest effort b) Middle latitude dynamics --- Davies, Wernli and Szunyogh c) Year of Tropical Convection (YOTC) – Moncrieff and Waliser 10

4. THORPEX from the poles to the tropics Weather and climate in polar regions (including THORPEX-IPY cluster) Concordiasi Antarctic project--- Rabier et al. (2010) – use of driftsonde and long duration ballooning, cold bias in all satellite data with inversions under estimated, identification of errors in model physics, ensemble data assimilation for AMPS, etc THORPEX Arctic Weather and Environmental Prediction Initiative (TAWEPI) -- improvement/implementation/evaluation of detailed dynamical-thermodynamic sea- ice coupled with ocean currents and snow models over the Arctic basin has been peformed (Chung et al., 2010, 2011), evaluate regional weather prediction model (e.g. Deacu et al., 2011) and the use of satellite observations (Garand et al., 2011) in the Arctic Greenland Flow Distortion Experiment – Renfrew et al. (2008) see special issue of QJRMS for scientific results The Storm Studies of the Arctic (STAR) included enhanced observations in the eastern Canadian Artic, gap flow, air-sea interactions, orographic precipitation, interaction of cyclones with topography (Hanesiak et al., 2010). 11

5. Broader impacts a) WCRP, GEO collaborations, training, workshops, symposiums etc) – Caughey and Nakazawa b) Enhancement in university and operational collaboration – Parsons and Jones c) PANDOWAE: a national example --- Jones d) Socio-economic research and applications – Mills and Rogers 12

6. Examples of legacy impacts on operational prediction a) North American Ensemble Forecast System - Toth et al b) Hybrid data assimilation system in the US (NOAA THORPEX) – Wang et al. c) TIGGE as a bench mark for improving individual systems – Martin (?) d) Legacy of high resolution polar prediction models (Env Canada and CONCORDIASI AMPS in the US) -- Gilbert and Charron for Env Canada and Parsons and Cavallo for AMPS e) Tropical cyclone predictions, real-time ensemble products – Nakazawa et al f) THORPEX Africa and the forecasters handbook -- Parker and Diongue et al. 13

7. Challenges and lessons learned a) Difficulty in making a difference in the developing world (should have tried to bring in sponsors early --- USAID, European Commission, WHO, NGOs, etc??) b) Changes in program managers (loss of Jay Fein and David Rogers) and varying commitment of science leads) contributing to a small grant pool? -- need long-term commitment higher in the agencies?? c) Funding agencies do not seem to be designed to handle such a cross-cutting project (easy to obtain field project funding, hard to get funding for focused scientific objectives, stove piping in agencies – all needs to be fixed for next time) d) Interagency coordination is better than now, but could have been better and may have slowly unraveled with time? e) Difficulties integrating social science research into THORPEX f) Certain communities (e.g., large-scale dynamics) tend not to work together on large projects) Has that has changed – T-NAWDEX-- Downstream, wx ready nation? g) Conflicts among scientists and scientific camps did occur, but perhaps less than expected 14