REPORT OF THE IPO (submitted by WMO Secretariat)

WORLD METEOROLOGICAL ORGANIZATION COMMISSION FOR ATMOSPHERIC SCIENCES INTERNATIONAL CORE STEERING COMMITTEE FOR THORPEX Tenth Session WMO, Geneva(3-5 October 2012) CAS/ICSC-10/DOC2.4.1 (26. IX. 2012) Original: English REPORT OF THE IPO (submitted by WMO Secretariat) This document provides a progress report on the development of THORPEX and highlights in particular: 1. Introduction THORPEX, an element of the WMO World Weather Research Programme, is a major contribution to the WMO Natural Disaster Reduction and Mitigation Programme and a key goal of WWRP/THORPEX is to accelerate improvements in the accuracy of 1-day to 2-week high-impact weather forecasts. The THORPEX International Science Plan was published in November 2003 and this was followed by a THORPEX International Research Implementation Plan in December 2004 (both plans are available on www.wmo.int/thorpex/plans.html). The international THORPEX activities are supported and coordinated by the THORPEX International Programme Office (IPO) which in tern is supported through, voluntary contributions of the governments of the WMO Members participating in THORPEX, including donations to the THORPEX Trust Fund established by WMO. The manager of THORPEX IPO, and the THORPEX Working Groups and Regional Committees, report to a THORPEX International Core Steering Committee (ICSC). The ninth meeting of the THORPEX (ICSC-9) took place in Geneva (21-22 September 2011) and the report from ICSC-9 is available on http://www.wmo.int/pages/prog/arep/wwrp/new/documents/final_thorpex_16_icsc9.pdf. 2. Activities of THORPEX Executive Committee Since ICSC-9, the EC met at UKMO (8 March 2012). During this meeting, the EC discussed the THORPEX legacy and possible follow-on programme and prepared the document with three options (A, B and C). Option C is to establish a new 10-year programme (Environmental Prediction Initiative) with the WCRP with a focus on improving the predictability of high impact weather from hours to a season (seamless prediction) and within the framework of a changing climate. The EC preferred option was Option C. 3. Outcome of WWRP/JSC5 (11-13 April 2012) highlights The 5 th session of the WWRP/JSC (JSC5) was held in Geneva, 11-13 April 2012. The following is the extraction from the JSC5 on THORPEX related topics. 3.1 Progress Review of THORPEX The title of the document, originally called as Mid-term review, should be THORPEX Progress Report (TPR), as suggested by the JSC. The JSC members were requested to provide review statements to the Chair of the JSC. The Chair of the JSC was asked to present the main findings of the review to the ICSC-10.

CAS/ICSC10/DOC2.4.1, p. 2 3.2 DAOS Working Group The IASI instrument on Metop-A now makes a major contribution to the short-range forecast skill. ConcordIASI was very successful and many additional observations were obtained over Antarctica from dropsondes. The JSC endorsed the view that the DAOS WG is the leading data assimilation group within the WMO and must be maintained beyond the end of the THORPEX programme. The DAOS WG is encouraged to extend its area of interest to include regional scales whilst maintaining a focus on the global scale. 3.3 PDP Working Group The PDP WG had strong representation at a number of recent meetings e.g. the European Regional Committee meeting in Karlsruhe, the sub-seasonal workshop at ECMWF and the summer school held at Banff Canada (on Advanced mathematical methods to study atmospheric dynamics and predictability ). The main PDP projects were then outlined. These included DIAMET, PANDOWAE (2 nd phase 2011-2014), T-NAWDEX, T-PARC and HyMEX. The PDP WG is invited to consider representation from S. America. The PDP WG should ensure that consideration is given to its position post- THORPEX at the next PDP WG meeting in Reading in June 2012. The PDP WG is invited to consider how to link with work in the US concerning atmospheric rivers by possibly inviting a representative to a future WG meeting. 3.4 GIFS-TIGGE Working Group Since 2006 TIGGE has been collecting EPS data from the centres. These data are made available with a 48h delay and are used for research on probabilistic forecasting methods and predictability studies. The archive is expanding at the rate of about 10TB /month. TIGGE data is proving invaluable for a wide range of research activities e.g. research on dynamical processes and predictability studies. More than 50 articles have appeared in the literature. The active users now number about 100. The research emphasis of the WG is now shifting to consider the calibration of ensemble forecasts, combination of ensembles and specific probabilistic forecast products. Towards GIFS, the focus is on high impact weather events, with TCs and heavy rainfall being considered initially. A second phase will look at gridded data and aspects such as ensemble spread and TC strike probability. A prototype homepage is available to show the risk of heavy precipitation out to about 2 weeks ahead. Other products include strong winds, heavy precipitation and extreme temperatures. These will eventually be made available to the SWFDPs but with a 3 day delay. This delay will need to be reduced. It is intended that the SWFDPs will provide feedback on the new products. The SWFPDs should also be able to bring selected products into operational (real time) use based on their existing data agreements with the NWP centres. 3.5 THORPEX Legacy Discussion In discussion it was suggested that there is an Option D i.e. much as Option C but without the integration into a single large project. It is not clear what this integration is going to achieve. Thus, a set of large projects could be run each with their own Trust Fund and support.

CAS/ICSC10/DOC2.4.1, p. 3 The structure of the WWRP was then discussed and it was suggested that it should comprise WGs and projects. The former would be long term fundamental topics such as data assimilation, ensemble prediction (including predictability), verification, etc., funded from the WWRP core budget. These WGs would complement the individual projects (which have a finite lifetime and carry their own funding) in a matrix structure. Some things should not be lost THORPEX facilitated interaction between the academic community and operational centres this should not be lost. It was noted that many exciting science questions remain and it important that the WWRP is now organised in the most efficient way possible to address them as well as attract outside funding. The OSC would be a good venue to launch the new look WWRP and post-thorpex structures. 4. Developing country support, workshops and reports 4.1 Africa The THORPEX Africa Regional Committee meeting was held in Geneva, 8-10 May 2012. The goal of this meeting was to explore how best to put an operational twist on the THORPEX activities and at the same time get better cooperation between research and operational communities at the national level to move the case studies forward. An additional aim was to explore how best the larger THORPEX community could contribute to the activities of THORPEX Africa. At the meeting the case studies of high impact weather events across the African continent have been identified. The case study project has 3 phases (event description, forecast assessment and modeling studies) and consists of 4 selected events (each with a defined lead person): - North African case study: flooding in northern Marocco (29-30 November 2010) associated with very strong advection of moist air from the tropics. - South African case study: flooding in South Africa (11-12 November 2008) - West African case study: heavy rainfall in Burkina Faso (late August/early September 2009) during a very active African easterly wave period. - East African case study: flood over East and Central Africa in October 1997 The focus is now on completing the case studies with the intention of publishing these by the time the THORPEX programme ends. The approach is to have the THORPEX WGs offer good support to the RC and the Case study leads. The wider THORPEX PDP, TIGGE and DAOS working groups are therefore welcomed to get involved to help ensure that these case studies can be completed by 2014 and leave a THORPEX legacy in place. 4.2 International Workshop on high-impact events The international Workshop on Dynamics and Predictability of high-impact weather and climate events was held in Kunming, 6-9 August 2012. There was a panel discussion for THORPEX Legacy at the workshop. The panellists were, Alan Thorpe, Richard Swinbank, Istvan Szunyogh, Pat Harr and Hisashi Nakamura. Alan Thorpe said that one of the aims of the THORPEX is to bring both operational centres and universities communities together to work with weather science and forecasting and also to bring in societal impacts to make weather research more interdisciplinary. Richard Swinbank showed the TIGGE accomplishments, includes big achievement to open up NWP data to research community in consistent GRIB2 format, invaluable resource for predictability and dynamic research. Istvan Szunyogh mentioned how the Predictability and Dynamic Processes Working Group (PDP WG) contributed to the THORPEX programme. It helped to develop the TIGGE database, to organize several symposiums and summer schools and to provide interpretation of the targeting observation. Pat Harr, as a member of PDP WG, talked about the T-PARC, which was a very successful field programme for tropical cyclone with 10-nation participation.

CAS/ICSC10/DOC2.4.1, p. 4 Hisashi Nakamura talked about collaboration between weather and climate during the discussion session. He said that CLIVAR was really concerned about the future projection of extreme weather/climate events in much finer/smaller scale, such as ocean fronts, which were not in traditional large-scale climate focus. 5. THORPEX Working Groups 5.1 DAOS Working Group The DAOS Working Group meeting was held in Madison, USA, 19-20 September 2012. The future role of the DAOS-WG was discussed in the post-thorpex era. All the proposed options in the THORPEX legacy document suggest that the DAOS-WG becomes an expert group within the WWRP structure, assuming this can be funded within the WMO budget. WGNE have acknowledged the role of the DAOS-WG as the leading expert group for atmospheric data assimilation research in WMO. There is a desire for the group to include convective-scale DA, and discussions are underway with the MWFR group to ensure any activities are complementary. The main focus should remain on improving assimilation to support NWP forecasting from 1 to 20 days. One of the DAOS-WG proposed activities is to organize the next WMO Data Assimilation Workshop which is due in 2013. The WG members were asked to investigate whether they could host such an event in late 2013. The next DAOS-WG meeting is planned to be in late 2013 or early 2014 with possible venues in Europe proposed. See more detailed report, Doc2.4.3, from the WG in this ICSC-10 meeting. 5.2 PDP Working Group The PDP Working Group meeting (WG) was held in Reading, 18-20 June 2012. The WG invited two scientists, David Lavers and Ryan Spackman, as experts for Atmospheric Rivers. Atmospheric rivers are narrow bands of high values of integrated water vapour, which appear to originate from the tropics (but moisture budget along the flow is complicated, as there is rainout, ocean evaporation and moisture flux convergence). Landfalling atmospheric rivers lead to high impact precipitiation events (e.g., US west coast storm on 4-5 Jan 2008). In the NW Pacific, about 40% of annual precipitation falls in association with atmospheric river episodes. There are also links between atmospheric rivers and UK winter flood events (e.g., November 2009 Cumbrian flood in NW England). Atmospheric rivers are considered as parts of warm conveyor belts in extratropical cyclones warm sectors, i.e., the core region of horizontal moisture transport. The top 10 floods in Northern England have similar water vapor transport patterns as the Cumbrian flood, which are fairly stationary over several days. For the prediction of these events, the representation of local topography is thought to be crucial. The THORPEX WGs have their own issues and merits. The PDP WG consists of a variety of independent academic research groups. The THORPEX data sets, in particular TIGGE, YOTC and T-PARC, are clearly a main achievement of THORPEX, and will be of great benefit for PDP research during the coming years. It will become very important that the Polar and Subseasonal Projects try to strongly include the dynamics and predictability communities. These projects and their science and implementation plans can be essential for getting funding for research projects at academic institutions (e.g., PANDOWAE, DIAMET). A very positive aspect of PDP activities has been educational work (e.g. the Banff summer school). The education aspect could also become key component of post THORPEX activities. It will be useful to suggest specific future activities on short and medium-range forecasting of high-impact weather events. The PDP WG agreed that it should develop a view on PDP research within the WWRP in the post THORPEX era as part of the paper being developed for ICSC 10 on post THORPEX arrangements.

CAS/ICSC10/DOC2.4.1, p. 5 Heini Wernli presented the idea of organizing a PDP winter school in 2013/2014 on Monte Verita in southern Switzerland, mainly on dynamical processes associated with high-impact weather events. The school would aim at providing a strong linkage between theoretical concepts, recent field experiments, and model diagnostics. It is agreed that Heini Wernli should move forward with preparing an application for submission in January 2013. WMO will probably be able to support travel costs for about 3-4 participants from developing countries. The relationship of the proposed PDP Summer School to that envisaged by the WWRP in the summer of 2013 was discussed. 5.3 GIFS-TIGGE Working Group The GIFS-TIGGE Working Group meeting was held in Boulder, 25-26 June 2012. Richard Swinbank outlined the aims of the meeting which included consolidating and completing the work so far and looking at future arrangements post THORPEX i.e. after 2014.There were two key aspects to the work the first was the TIGGE databases which were a real success. More needs to be done to expand the research use although this was now substantial. The second area was product development for demonstration and evaluation. The aim was to increase collaboration with the SWFDPs. It was hoped to add new products to the SWFDP website later in the year. Operational implementation will be, however, a matter for CBS. The multi-model ensemble approach shows increased skill over the single ensemble for surface temperature, precipitation and TC tracks. So, the main focus of GIFS product development is planned to be on the multi-model approach, but could also include innovative products based on single model ensembles. The next steps in the GIFS development process will include the generation of multi-model versions of ensemble TC track products and closer to real time versions of severe weather products. Priorities for further development should reflect the responses to the questionnaire sent to the SWFDP centres. There is also need to engage the verification WG in evaluation of products. It was recognised that ECMWF EPS data could be used by the Met Office to generate near real time multi-model products for the SWFDPs. The NCEP data could form a third component. If possible, JMA data should also be included, to allow a real-time product based on the same four ensembles as the prototype product developed by MRI. The WG recognised that the Met Office could and should take the lead and implement real time support to the SWFDPs within existing data policies. The vision in the US Hurricane Forecast Improvement Program is to organise the hurricane community to dramatically improve numerical forecast guidance to NHC in 5-10 years. Targets involve reducing track and intensity errors by 20% in 5 years and 50% in 10 years, extending useful predictions to 7 days and increasing the probability of detecting rapid deepening at day 1 to 90% and at day 5 to 50%. The WG discussed the THORPEX legacy and post possible THORPEX arrangements. A paper has been commissioned by the ICSC from the THORPEX EC for discussion at ICSC 10 in Oct. 2012. THORPEX WGs and ICSC members are invited to submit a one-page document setting out their view, which will be included as an annex to the ICSC paper. It is expected that the WWRP will be organised into a series a WGs addressing long term fundamental issues and a series of specific projects supported by Trust Funds. It is envisaged that the DAOS WG will become a WG of the WWRP. The consensus of the WG was that the PDP and TIGGE groups might merge to form another Predictability and Ensembles WG in the WWRP. The WG strongly supported the continuation of TIGGE beyond the end of THORPEX. The TIGGE data set is an invaluable resource for: scientific research on predictability and dynamics; EPS validation and verification; development of probabilistic forecast products; benefiting from enhancements and wider use resulting from

CAS/ICSC10/DOC2.4.1, p. 6 the GEOWOW project. It was recognised that the continuation of TIGGE will require support from at least one of the archive centres. The WG felt that the ongoing management of TIGGE could be accomplished with the minimum of effort.