WORLD METEOROLOGICAL ORGANIZATION · Web viewEncourage more direct, two-way interactions between users, managers of observing systems and providers of forecasts, building on enhanced

Figure 6: Plate shows MJO activity during the “year”. Weak and short lived MJOs during the first part of the ‘year” gave way to two strong successive MJOs during the latter part. The red bands show the four transpose AMIP periods identified for Transpose AMIP (CMIP5) model evaluations involving eight climate models. [Plate, courtesy Matt Wheeler]

Future work

Identify support for the research phase of YOTC from funding agencies worldwide Continue communication of the YOTC project to the international community Convene the YOTC International Science Symposium, May 16-19, 2010, hosted by China

Meteorological Administration (CMA), Beijing, China jointly with the 8th Asian Monsoon Years (AMY) Workshop

2.7 Collaboration with GEOSS

The purpose of GEOSS as agreed at the 2005 Ministerial meeting is;

To achieve comprehensive, coordinated and sustained observations of the Earth system, in order to improve monitoring of the state of the Earth, increase understanding of Earth processes, and enhance prediction of the behaviour of the Earth system. GEOSS will meet the need for timely, quality long-term global information as a basis for sound decision making, and will enhance delivery of benefits to society.

CAS/THORPEX ICSC9/Doc.2.4.1.1, p. 2

The 2015 strategic targets respond to the call of the 2008 G8 Summit in Tokyo to accelerate GEOSS efforts to meet the growing demand for Earth observations. Also, they are a further step towards addressing the challenges articulated by the 2002 World Summit on Sustainable Development, including the achievement of the Millennium Development Goals.

The Strategic Weather Target is that before 2015, GEO aims to:

Close critical gaps in meteorological, ocean and related observations, enhance observational capabilities, and improve weather information, especially for high impact events and in the developing world.

This will be achieved through the programmes and activities of the World Meteorological Organization (WMO), and building on enhanced observational capabilities, which will:

Monitor the performance and impact of global meteorological and related ocean observing systems, and facilitate the closure of critical gaps in observations and capabilities, utilizing a mix of space-based and in-situ observing systems as appropriate;

Make progress towards implementing the Vision for the Global Observing System 2025; Encourage the design and implementation of optimal observational networks to better

meet the needs of users for observational data; Promote the improvement of data assimilation, modeling systems, and verification and

assessment techniques; Advance the use of observations in forecasting and warning services globally, advocate

for research and development in key areas and encourage the rapid transfer of related research outcomes into operational use, especially in developing countries;

Encourage more direct, two-way interactions between users, managers of observing systems and providers of forecasts, building on enhanced observational capabilities to improve the forecast process;

Provide integrated data collection and automated dissemination of observational data and products, as well as data discovery, access and retrieval services.

This will be demonstrated by:

Identification and addressing of critical gaps in observational networks that reflect, in particular, the needs of developing countries, the need for continuity in space-based and in-situ observations, and the potential benefits of an interactive observing system to support user needs

Improvements in the range and quality of services for high impact weather forecasting due to the design, future development, and operation of global observing, data assimilation, numerical modelling, and user application techniques

More accurate, reliable and relevant weather analyses, forecasts, advisories and warnings of severe and other high impact hydrometeorological events enabled by enhanced observational capabilities

2.7.1 WWRP-THORPEX activities within the GEO 2012-15 Work Plan

There are several Tasks within the new Work Plan to which WWRP-THORPEX contributes

WE-01 C1 “Global Multi-Model Prediction System for High-Impact Weather”

Task Leads - WMO (WWRP/THORPEX)

Priority Actions

Further develop TIGGE (THORPEX Interactive Global Grand Ensemble), a user-friendly database of global ensemble weather forecasts. Use web-enabled technology to foster


the generation and distribution of products. Develop a future archive strategy, product generation and service provision. Finalize and implement access arrangements

Implement the Global Interactive Forecast System (GIFS). As an initial step, produce user-driven probabilistic products (based on TIGGE forecasts) such as tropical cyclone tracks, heavy rainfall and strong wind distributions. Build upon the WMO Severe Weather Forecast Demonstration Project (SWFDP) to provide a framework for the evaluation of these prototype products, and to ensure that products address needs of operational forecasters and end-users.

Funding for TIGGE data bases in Europe - GEOWOW

A consortium of European institutions has submitted a proposal, GEOWOW (GEOSS Interoperability for Weather Ocean and Water), for funding through the European Union Framework Programme. GEOWOW proposes to:

i. Consolidate global data discovery and enable global access to, and use of, Earth Observation data and resources (computing, data handling tools, model etc.) through the GEOSS Common Infrastructure (GCI)

ii. Develop tools and protocols to promote the implementation of the GEOSS Data Sharing Principles, and the re-use and dissemination of Earth Observation data

iii. Develop operational capabilities of the GCI through applications in three areas:a. Weather, with a focus on unified access to Earth Observations and forecasting

systems for hazard and extreme meteorological eventsb. Water, with a focus on hydrological applications and run-off process using in-situ and

satellite datac. Ecosystem, with a focus on the implementation of GOOS by engineering and testing

access to Ocean data via the GCI.iv. Enhance multidisciplinary interoperabilityv. Analyse the benefits of GEOSS for Europe using models linking economy, environment,

and society

The GEOWOW proposal, which includes a TIGGE weather element, is led by the European Space Agency (ESA). The weather element of the proposal involves further development and integration of the THORPEX Interactive Grand Global Ensemble (TIGGE) global weather forecasts data products into the GCI which will be undertaken by the European Centre for Medium-Range Weather Forecasts, the UK Met Office and Météo-France – the requested funding for the TIGGE weather element is 1.2 M€.

WE-01 C2 “Easy Access to, and Use of, High-impact Weather Information”

Task Leads - Korea (KMA), Spain (AEMET), WMO (WWRP/THORPEX), ACMAD

Priority Actions

Support the implementation of THORPEX Africa in developing a common platform to collect, store and exchange data – not only observations and model outputs but also event documentation, particularly impacts on African society, economy and environment. This platform would also contain specific detailed case studies as well as archive ongoing High Impact Weather events across Africa with the intention of improving prediction through promoting collaboration between the research and operational communities.

Extend the concept of Virtual Centers for high-impact weather prevention to Central America, building upon the experience of the operational Centre for Eastern South


America. Deploy weather-watching networks (based on remote sensing) to better detect and forecast high- impact weather

Facilitate technical cooperative activities for the exchange of weather prediction hardware, software, technologies, and expertise

Develop training activities for the use of numerical weather prediction, meteorological satellite images and meteorological radar data, as a prerequisite to the implementation of early warning systems

Task WE-01 C2:

Will be implemented in connection with IN-01 (Earth Observing Systems), IN-03 (GEOSS Common Infrastructure), ID-02 (Institutional and Individual Capacity), ID-04 (Building a User-driven GEOSS), ID-05 (Catalysing Resources for GEOSS), SB-01 (Oceans and Society), DI-01 (Disaster Risk Reduction), CL-01 (Climate Information), WA-01 (Integrated Water Information) and AG-01 (Global Agricultural Monitoring)

And is related to 2009-2011 Work Plan Tasks (non exhaustive) WE-06-03: TIGGE and the Development of a Global Interactive Forecast System for Weather WE-09-01a) Infrastructure for Numerical Weather Prediction WE-09-01b) Socio-economic Benefits in Africa from Improved Predictions of High-Impact Weather

CL-01 C3 “Weather, Climate and Earth-System Prediction Systems”Task Leads - IGBP, WCRP, WMO (WWRP/THORPEX)

Priority Actions

Foster advances on seamless prediction, sub-seasonal to seasonal prediction, and polar prediction through the implementation of dedicated international research projects

Improve the representation of organized tropical convection in models and of its interaction with the global circulation. In particular, further support the Year of Tropical Convection (YOTC). Develop diagnostics/metrics for robust simulation of the Madden Julian Oscillation.

2.7.2 Concluding remarks

The contributions from the WWRP-THORPEX area of responsibility (and the WMO more generally) form very important elements of the new GEO Work Plan and GEOSS. This is a two way supportive relationship in which the GEO framework can help WWRP-THORPEX deliver its objectives in these areas by linking activities, providing visibility at ministerial level and identifying resource mobilisation opportunities.

3. Predictability and Dynamical Processes

THORPEX Predictability and Dynamical Process research has provided the framework for the academic dynamical meteorology community and the operational numerical weather prediction centres to carry out joint projects. The THORPEX Predictability and Dynamical Processes Working Group (PDP WG) has encouraged these communities to carry out dynamical process studies with the specific aim of improving the understanding of the relationship between particular processes and weather forecast accuracy. During the first phase of THORPEX, These studies have

i. Contributed to the preparation and evaluation of international field experimentsii. Raised the awareness in the PDP community of the research objectives of THORPEX

and the availability of THORPEX data sets (notably TIGGE, T-PARC, YOTC)iii. Supported the development of research projects dedicated to THORPEX PDP research


iv. Established a linkage to WGNE on the issue of model uncertainties

v. Promoted THORPEX through the organisation of summer schools, sessions at international conferences and dedicated workshops

vi. Identified key topics for future PDP research

Several key examples of these activities include

(i) Summer and winter T-PARC campaigns in 2008/2009 and the start of the preparation of a field experiment T-NAWDEX during the second phase of THORPEX

(ii) The setup of informal “Interest Groups” for discussing recent achievements and outstanding research questions during the first two years of THORPEX and the presentation of PDP overview talks at international conferences and workshops, highlighting in particular the newly available data sets from TIGGE, YOTC, and T-PARC

(iii) Several research initiatives (see the section on regional committees) profited from the overall THORPEX structure and the international exchange about research priorities and field experiments, leading to several PDP-oriented nationally funded research projects

(iv) Organization, with WGNE, of two workshops on Model Errors (ETH Zurich, 2010) and on Stochastic Processes (ECMWF 2011)

(v) The preparation of a first PDP summer school at the Banff International Research Station (BIRS) for Mathematical Innovation and Discovery, Canada, in July 2011 on Advanced Mathematical Methods to Study Atmospheric Dynamical Processes and Predictability, and the organization of numerous PDP sessions at conferences and workshops

(vi) An attempt to regularly review and critically discuss the development in key PDP research areas. The development in some of these areas during the first phase of THORPEX will be outlined briefly in the next sub-sections.

3.1 T-PARC

The three related THORPEX experiments T-PARC, TCS08 and Winter T-PARC were aimed at increasing understanding of how and why (a) Typhoons form (or do not form) in the West-Pacific TCS-08) (b) Typhoons or ex-Typhoon vortices interact with mid-latitude jet streams (T-PARC) and (c) supplemental targeted observations reduce or fail-to-reduce forecast error (TCS08, T-PARC and Winter T-PARC). Major findings in the area of dynamical atmospheric processes and the ability of models to predict observed processes and associated recommendations include the following:

1. Despite the fact that the Easterly wave from which Typhoon Nuri formed could be tracked for 10 days preceding the TC formation, a suite of numerical forecast models failed to capture the formation until 48 hrs before the event (Lussier 2010). The inability of current weather forecast models to simulate the effect of moist processes on Easterly waves (Sean Milton, personal communication) is no doubt part of the reason for this failure. Such systematic errors will strongly limit our ability to predict high impact tropical vortex events. Further study of the effect of moist processes on equatorial waves such as Easterly waves is strongly recommended, as is the development of parameterizations of moist processes that improve the realism of simulated tropical waves while not degrading representations of moist processes in mid-latitudes.

2. Aircraft missions into pre-depression Hagupit revealed a developing cyclonic low-level circulation (LLC) four days prior to the issuance of a tropical cyclone formation alert (Bell and Montgomery 2010). Model analyses and satellite imagery suggested that the early circulation was part of a westward propagating disturbance at 18N latitude, well displaced from the ITCZ and any southwesterly monsoonal flow. Studies comparing the frequency,


persistency, size and location of cyclonic LLCs in numerical simulations of the tropics with those from analyses are strongly encouraged because both theory and observations confirm their importance in the development of intense tropical vortices.

3. The analyses of in situ data obtained during the formations of TY Nuri and TY Hagupit have been generalized to a broad set of convective episodes using satellite data to examine 16 ring-like mesoscale convective events (Elsberry and Chollet 2010). Comparison with 25 km resolution ECMWF analyses from the Year of the Tropical Convection (YOTC) archive has revealed the three-dimensional structure of the synoptic environment of the mesoscale convective events. Studies comparing the frequency, persistency, size and location of ring-like meso-scale convective events in high-resolution numerical simulations of the tropics with those from analyses are also encouraged. The YOTC data set may prove useful in providing initial and boundary conditions for high-resolution regional simulations.

4. The performance of the ECMWF, UKMO, GFS, and NOGAPS models in predicting tropical cyclone formation has been evaluated (Elsberry et al. 2009). When all four global model forecasts were in agreement as to position and evolution, high confidence can be given to the prediction scenario with few false alarms. Studies on how to optimally combine information from forecasts and ensembles from distinct NWP centres is strongly encouraged. Such multi-centre ensembles are now readily accessible to the wider research community via the TIGGE data base.

5. Adding stochastic forcing to the NOGAPS ensemble improved the rate of detection of genesis in the WPAC during the T-PARC period (Snyder et al., 2011). False alarm rates also went up, but false alarm rates went up less than the detection rate, indictating some promise for stochastic convection to help with this forecast problem. Further study of the representation of the stochastic nature of unresolved sub-grid scale processes and their representation in parameterization schemes and/or stochastic model forcing is strongly encouraged.

6. Data denial experiments from Typhoon part of the experiment showed that while 20-40% improvements in track could be attributed to targeted observations in the NCEP and WRF prediction systems, the benefit to the ECMWF and JMA systems was much less (Weissmann et al. 2011). In winter T-PARC, targeted observations were shown to impart a 10-15% improvement within the verification regions of the 1-3 day forecasts for which targeting was performed. These winter-T-PARC results are consistent with results from the winter storms reconnaissance (WSR) programme that has been operated by NCEP over the last 10 years. The extent to which the WSR and winter T-PARC results are inconsistent or consistent with those from the ECMWF based on the denial of satellite observations over the Pacific is unclear due to significant differences in the set-up of the targeting problem. Thus, the degree of sensitivity of the impact of targeted observations on forecasts to the forecasting and data assimilation system employed remains unclear. This is unfortunate as many currently planned field experiments are based on the notion that supplemental observations will significantly reduce analysis and forecast error. Theory predicts that the relative value of targeted observations is a strong function of the quality of the forecasting system – so a system dependent result for targeted observations is to be anticipated. Indeed, a theoretical basis for quantitatively predicting and evaluating the error variance reduction due to targeted observations was given in Majumdar et al. (2001). It would greatly assist the design and efficacy of future field programmes if the accuracy of such quantitative predictions of the reduction in forecast error due to targeted observations could be further improved. Due to the fact that targeting has now taken place for more than a decade over the tropical summertime Atlantic and the wintertime mid-latitude Pacific, large targeted observational data sets now exist and the time is ripe for a concerted investigation of the aforementioned issues. Further research is strongly encouraged on (a) the dependence of


the effect of targeted observations on the forecasting/assimilation system for mid-latitudes and the tropics (b) improving our ability to quantitatively predict the reduction in forecast error variance due to targeted observations.

3.2. New diagnostic techniques to understand the origin of model errors

During the first half of THORPEX it was realized that model error diagnosis is one area where universities and research institution can make substantial contributions to the further development of models (and hence forecast skill), thereby supporting the relatively small community of model developers. In order to bring together dynamical meteorologists, model developers and experts on model error diagnosis to discuss diagnostic techniques that could be used and should be developed to understand the origin of forecast errors and, therefore, aid model improvement, a workshop entitled “Diagnosis of Model Errors” was held at ETH, Zurich, from 7 to 9 July 2010. In the following the key conclusions of the workshop, which was jointly organized by THORPEX PDP and the Working Group on Numerical Experimentation (WGNE), will be summarized (see the THORPEX website for a detailed report).

Our understanding of the dynamical and physical processes relevant for forecasting depends on the time scale and the region considered. In Polar Regions, for example, short-range weather forecasts are mainly influenced by local boundary layer processes and microphysics; on longer time scales, however, processes in remote regions (for example, mid-latitudes and tropics) become increasingly important. In general, it was found that there are a number of well-known forecast relevant processes such as condensation in warm conveyor belts of extra-tropical cyclones and deep convection in the tropics. However, it has been argued that we do not have a complete list of such processes and generally there is a lack of quantitative understanding of the relative importance of the different processes. In fact, this lack of knowledge is appreciated by the wider community as highlighted by the first results from the Community-wide Consultation on Model Evaluation and Improvement.

Currently there is a wide range of techniques available to diagnose model errors. A technique can be considered to have diagnostic value if it can help understand the origin of the problem in the model at the process level. In the last few years it has be realized that the development of diagnostic techniques is equally important for enhancing our understanding of the atmosphere/climate system (for example in extra-tropical cyclones and mountain torques) and for improving the models (e.g., Rodwell and Jung, 2008, Jung et al. 2010a).

One of the most promising ways forward is to employ a seamless diagnostic approach, that is, by studying how errors evolve throughout the forecast. Focusing on the first few time steps (initial and analysis increment techniques; Klinker and Sardeshmukh 1992, Rodwell and Palmer 2007) or short-range forecasts (Transpose-AMIP, Phillips et al. 2004) allows one to localize the problem and to directly compare the model with observational data; studying how errors further develop after the first few time steps helps to pinpoint the origin of errors (for example tropical versus extra-tropical) that develop later on in the forecast (e.g., Jung et al. 2010b). Interpreting results from the seamless diagnostic approach usually requires considerable insight into dynamical processes and their interaction with physical processes along with a deeper understanding of how numerical models work. In order to fully exploit the potential of the seamless diagnostic approach, it is important to improve collaboration between dynamicists and model developers in this area. From the results presented at the workshop it became clear that initial tendency techniques, which are nowadays routinely being used at ECMWF, JMA and the UK Met Office, have been very efficient in furthering our understanding of the impact of model changes (Rodwell and Jung, 2008) and pointing towards regions/processes where models are erroneous.


The involvement of universities and research institutions in model error diagnosis and hence model development requires the availability of special data sets. In this respect, substantial progress has been made during the first half of THORPEX as the following two examples will show. As part of the YOTC project, high-resolution analysis and forecast data from different NWP centres have been made available. For the ECMWF data set (1 May 2008 to 30 April 2010) it is also possible to download the tendencies from different physical processes which enable much more process-oriented research to be carried out. Furthermore, as part of the ECMWF reanalysis activities, 10-day hindcast have been carried out on a daily basis. These cover the periods 1959-2001 (ERA-40) and 1989-today (ERA-Interim). These forecasts provide valuable data sources to study flow-dependence of forecast error and to systematically identify source of particularly poor forecast (so-called forecast busts).

Putting more emphasis on model error diagnosis during the second half of THORPEX is certainly a very promising way forward given that state-of-the-art models still suffer from substantial errors and that diagnostic work has the potential to inform model developers about model problems at the process level and therefore provide information necessary to guide model development. Despite substantial improvements in diagnostic techniques in recent years it is crucial to further support research to advance diagnostic techniques to the point where they become of direct use for model development. While considerable attention is being devoted to thermodynamic aspects future progress will hinge on a better understanding of physics-dynamics interactions–an area of research in which the PDP community has considerable expertise. Finally, it is clear that there is a lack of quantitative understanding how errors in the representation of different processes contribute to forecast failures. In order to be able to prioritize future model development it was recommended to carry out detailed research to obtain a better quantitative understanding of this issue.

3.3 Ensemble-based Prediction (initial conditions, assimilation and stochastic parameterizations)

More than a dozen meteorological services now run operational ensemble prediction systems, both global and regional. These systems provide a priori, situation dependent estimates of the uncertainty of the forecast, an information that a purely deterministic system, whatever its intrinsic quality, cannot provide. Thanks to the TIGGE database (see below), a large fraction of those ensemble predictions is made available to the scientific community, for study and comparison, within a short delay.

Among recent developments, one can mention that ECMWF has introduced a system of Ensemble Variational Assimilation which complements the singular vectors already used for the definition of the initial ensembles.

Active research is being pursued in numerous places on the definition of initial ensembles, as well as on the evaluation of ensemble predictions. Concerning the definition of initial ensembles, several methods are used at present: singular (linear) modes, bred modes, Ensemble Transform Kalman Filter (ETKF), Ensemble Kalman Filter (EnKF) and Ensemble Variational Assimilation. All these methods (except singular modes, which are partially or totally defined in several services over the early period of the forecast), use only past information and are meant to sample the present uncertainty on the state of the atmosphere, or at least to identify components of the flow where recent instabilities have taken place. Ensemble Kalman Filter and Ensemble Variational Assimilation are full-fledged assimilation algorithms. One point of view is that the best initial ensembles are those that sample best the present uncertainty on the state of the flow. That point of view, which is supported by idealized experiments, is not as strongly supported by real life comparisons. Further research is required on that aspect.


Regional ensemble prediction requires the definition of appropriate lateral boundary conditions. The problem is in essence similar to the problem of the definition of initial conditions, but research is still on that aspect in its infancy.

A number of statistical scores are used for objectively assessing the quality of ensemble predictions (Brier score and its various generalizations, measures of ‘spread-skill’ relationship ….). Those various scores evaluate different aspects of ensemble prediction, and full understanding of their exact significance requires further work. A particularly important point, in view of the fact that verification requires large validation samples, is clear identification of the limits of what ensemble prediction can achieve. Results suggest that scores saturate for ensemble dimension on the order of a few tens of units. The implications of that fact, if it is confirmed (see below 5.4), can be of great importance.

While significant progress has been made with developing the theoretical basis of accounting for the effects of initial condition uncertainties in ensemble forecasting, a similar theory of accounting for the effect of model errors is yet to be developed. In particular, while the uncertainty in sub-grid scale parameterization schemes is generally viewed as one of the prime sources of forecast uncertainty, the exact mechanism through which parameterization schemes contribute to the degradation of forecast accuracy is little understood. The PDP WG expects the development of techniques to account for the effect of uncertainty in the parameterization schemes to be one of the most important areas of ensemble research in the coming years. Motivated by this expectation the PDP WG was the first to discuss and endorse the plans to organize a joint ECMWF/WGNE/THORPEX/WCRP Workshop on Representing Model Uncertainty and Error in Numerical Weather and Climate Prediction Models. This meeting will be held at ECMWF, Reading, UK from 20 to 24 June 2011. The website of the workshop is available athttp://www.ecmwf.int/newsevents/meetings/workshops/2011/Model_uncertainty/.Istvan Szunyogh represents the PDP WG on the organizing committee of the workshop.

Generating ensembles by perturbing the model parameters is an approach that is particularly popular among scientist developing limited area ensemble systems. This approach is also used in the global setting at Environment Canada. While the PDP WG recognizes the motivation, rooted in the Monte-Carlo approach view of ensemble forecasting, to account for the uncertainties by perturbing all potential sources of uncertainty, it also finds, that the current approach of making largely ad hoc perturbations of the parameters is not firmly based on scientific arguments. The PDP WG views the development of stochastic parameterization schemes (see discussion under 5.2) as the scientifically justifiable approach to account for the uncertainties in the parameters of the parameterization schemes.

3.4 T-NAWDEX - Atmospheric dynamics and diabatic processes in the extratropics

The study of the role of diabatic processes for the genesis and evolution of extratropical weather systems has become an important theme of PDP-related research. Progress in this field requires a combination of improved theoretical understanding, detailed process studies based upon numerical model simulations, and the application of novel observational facilities in field experiments dedicated to the analysis of dynamical and physical processes in developing high-impact weather systems. To this end, the THORPEX - North Atlantic Waveguide and Downstream Impact Experiment (T-NAWDEX) has been proposed by the PDP working group as a key element of the European THORPEX Science Plan. Its overarching scientific goal is to investigate in detail the link between skill in forecasts on the 1-7 days range, systematic model errors and the representation of physical processes that contribute most to model error. The focus will be on the diabatic modification of air masses, the influence this has on the development of Rossby waves as they propagate across the North Atlantic and the subsequent

http://www.ecmwf.int/newsevents/meetings/workshops/2011/Model_uncertainty/


effects on high impact weather forecasts for Europe. Although regional in experimental focus, the results and conclusions will be pertinent to the extra-tropics world-wide.

A key motivation is to tackle the attribution of forecast model error to process head-on; acknowledging that the non-local nature of large-scale wave propagation and balance makes this a challenging task. Recent research activities have shown that some of the worst forecasts for Central Europe are associated with a common sequence of events, tracing Rossby wave activity along the jet at tropopause level back to a large-amplitude trough-ridge system oriented along the East coast of North America (e.g., Dirren et al. 2003). The rationale for stopping the chain of events there is that the associated PV anomalies are substantially modified by non-conservative processes and it is this aspect which is not well represented in the models. Extra-tropical transition of cyclones also takes place over the western Atlantic, is uncertain in models but has an important influence on waves along the jet and downstream development (Riemer et al. 2008; Cordeira and Bosart 2010; Riemer and Jones 2010). Latent heat release has also been established as a key player in intense Mediterranean cyclones (McTaggart-Cowan et al. 2010) and in violent windstorms hitting Western Europe, such as Lothar and Martin in 1999. Such events are smaller scale, feature rapid low-level development and typically occur crossing the exit of strong westerly jets (Moore et al. 2008; Riviere 2010; deVries et al. 2010; Boettcher and Wernli 2011). In contrast, subtropical cyclones evolve in regions with weak low-level baroclinicity and are associated with intense deep convection (Davis 2010). The recently proposed three-fold classification of extratropical cyclones introduces a novel type C category for which latent heat release is crucial to development (Deveson et al. 2002). Cyclones of this category are frequent both in the North Atlantic (Dacre and Gray 2009) and in the southern Norwegian Sea (Bracegirdle and Gray 2008). Composites of potential vorticity profiles in mature extratropical cyclones statistically corroborate the importance of cloud condensational effects for their intensification (Campa and Wernli 2011).

The role of diabatic processes (primarily associated with cloud radiative effects) has also been highlighted for the development of coherent cyclonic tropopause-level vortices (Cavallo and Hakim 2009, 2010; Kew et al. 2010), for the formation of prominent upper-level cut-off lows over Northern Africa (Knippertz and Martin 2007), and for the inception of atmospheric blocking (Croci-Maspoli and Davies 2009). Prominent examples of recently studied mesoscale dynamical features where diabatic processes are of key importance include mesoscale convective vortices (Davis and Trier 2007; Davis and Galarneau 2009), snowbands in extratropical cyclones (Novak et al. 2009), and so-called low-level “sting jets” within intense cyclonic storms (Martinez-Alvarado et al. 2010). The field experiment T-NAWDEX also aims at providing novel observations for studying the dynamics and predictability of these mesoscale features, which will provide an important linkage between the larger-scale atmospheric flow and adverse and potentially high-impact near-surface weather conditions.

T-NAWDEX update

The plans for T-NAWDEX were predicated on the availability of the new DLR Halo aircraft. Unfortunately, to date, it has not been possible to get the appropriate certifications for the instruments that were called for in this plan.

Despite this set-back, the plans for the international field campaign T-NAWDEX (the North Atlantic Waveguide and Downstream impact Experiment) are evolving. The Institute of Atmospheric Physics (IPA) has arranged to keep the DLR FALCON research aircraft for the next few years and this opens the possibility to conduct field campaigns with a THORPEX focus in collaboration with DIAMET (see below) and/or HYMEX in 2012: "T-NAWDEX-Falcon". The scientific focus would be put on water vapour transport, cloud processes within weather systems involving condensation and latent heat release and fluxes in the atmospheric boundary layer


T-NAWDEX, DIAMET and HyMeX synergies

The DIAMET field campaign is part of the UK NERC “Storm Mitigation Programme”. The main objectives of DIAMET are:

i. Characterising the generation of mesoscale potential vorticity anomalies in cyclonic storms, and their implication for the larger-scale development of the storm and for the effects (e.g. high winds, heavy rain)

ii. Physical processes and improving model parameterisations Physical processes and improving model parameterisations

iii. Predictability

The field campaigns will involve flights of the FAAM Bae146 research aircraft into extratropical cyclones and associated frontal systems as they approach the UK and cross the high density ground-based network (Doppler radar, radiosondes, wind profilers and surface stations). Three pilot flights were conducted in November 2009. These sampled some very active systems: a tropopause fold over-running the low-level warm sector with vigorous convection beneath, a developing frontal cyclone and a mature cold front with a WCB (warm conveyor belt).

For DIAMET, there will be three flight periods:

i. 14-30 September 2011 – based from Cranfield (North of London)ii. 23 November – 15 December 2011 – based from Exeteriii. July/August 2012 – based from Cranfield

The main area of operation will be to the southwest of England (between France and Ireland). Flights will be conducted in a combination of three modes:

1. In situ cloud microphysics flying through regions of active convection and cloud associated with fronts and large-scale ascent

2. Dropsonde sections across fronts with particular emphasis on warm conveyor belts (WCBs). Back to back flights: the first aiming to cross WCB dropping sondes as far upstream as possible and the second at low levels further upstream (in a quasi-Lagrangian sense)

3. Box patterns along and across fronts within the BL over ocean, measuring turbulent fluxes, including temperature, moisture and momentum. Emphasis on fluxes under high wind conditions in which models have poorer performance

Originally the DIAMET experiment was conceived as the UK contribution to the planned T-NAWDEX experiment. However, the emphasis for the Storm Risk Mitigation programme funding the project is on shorter lead times (less than 2 days) than T-NAWDEX, concentrating effort on precipitation and high wind forecasts using convection-permitting models (Met Office UKV) and the influence on mesoscale structures on the skill. The data assimilation effort is on model error in convection-permitting ensembles and the nature of balance (covariances) between variables in high resolution forecasts. The field campaign and associated modelling focussing on the upscale impact of diabatic processses on the mesoscale structure within storms and subsequent evolution.

It is still possible to coordinate with the DLR falcon and its LIDAR measurements of water vapour transports if it were to fly in August 2012. This would open the possibility of a two-aircraft Lagrangian experiment as envisaged for T-NAWDEX.


Unfortunately the FAAM aircraft is now not available for the beginning of HyMeX (September 2012) since it will be in Brazil. Also, it was thought that the objectives of DIAMET, given its emphasis on high resolution forecasts for the UK, would not overlap sufficiently with HyMeX in the absence of a go-between aircraft (the role of the HALO aircraft in the T-NAWDEX plan).

On the longer term, consideration is being given to a newly designed T-NAWDEX (2014) involving European and US partners.

4. GIFS Developments

The THORPEX implementation plan envisages the development of a Global Interactive Forecast System (GIFS) which would be an internationally coordinated system for high-impact weather forecasting benefitting all WMO partners with a special emphasis on developing nations. Beginning in 2007, the GIFS-TIGGE Working Group started to prepare plans for the development of a prototype for GIFS – the sixth of the original TIGGE objectives. This work will contribute towards the development of a proposed future WMO Forecast System which would supersede the current WMO Global Data Processing and Forecasting System (Hayes, 2008).

An initial concept plan included the development of a second phase for TIGGE with an archive distributed across the providing centres, from which multi-model products could be readily generated. However, there was growing realisation that this approach would not be feasible due to cost and technical issues. At the fifth GIFS-TIGGE working group meeting, in Pretoria in March 2008, a sub-group was set up to formulate plans for the development of GIFS. It was agreed that a first step towards the development of GIFS would be the exchange of tropical cyclone forecasts using an XML-based data format.

The sixth working group meeting was held in conjunction with other THORPEX working groups in Geneva in September 2008. The GIFS-TIGGE working group agreed the basic strategy proposed by the GIFS planning sub-group and adopted a step-by-step approach to the development of GIFS, with the first step being focused on tropical cyclone prediction, as one of the highest priority application areas, to be followed by heavy rainfall products.

The initial development of products for tropical cyclone forecasting is based on the exchange of ensemble tropical cyclone forecasts using a specific data format called “Cyclone XML” (or CXML). CXML was developed by the GIFS-TIGGE WG for the rapid exchange of tropical cyclone related information from global ensemble forecast systems. The CXML data from seven providers was first made available in real time during the THORPEX Pacific-Asian Regional Campaign (T-PARC) for use during the field phase. The data continues to be available since the end of T-PARC and several interested centres are assessing its value. Figure T4 shows an example, taken from an experimental tropical cyclone products website developed by MRI/JMA, illustrating the use of ensemble forecasts to estimate strike probabilities. A case study to illustrate use of probabilistic products to improve tropical cyclone forecasts was reported in a recent issue of the WMO Bulletin (McCaslin et al, 2010) and a GEO publication (GEO, 2010). Probabilistic products for precipitation and near surface wind will be considered in the next phases of GIFS development.

The GIFS plans call for probabilistic forecast products specifically designed for and tested in a few selected regions, where the transfer of new technology can have the greatest benefit. GIFS will be based on (1) real time access to ensemble forecast data; (2) statistical post-processing and combination of such data from several ensemble providers; and (3) generation of products and services for WMO nations in particular in developing regions. . This regional approach should benefit of the contribution from higher resolution LAM EPS, where available.


Figure T4 – Example of tropical cyclone strike probability forecasts for typhoon Megi, from 0 UTC 17th October 2010, based on ensemble forecasts from several TIGGE data providers (above) and by combining all available forecasts (below). Colour shading indicates strike probability while the black line shows the observed track.

It is envisaged that products will be generated and distributed using a global to regional to national cascade, as illustrated in Fig. T5. The use of this cascading approach has been demonstrated very successfully by the WMO/CBS Severe Weather Forecast Demonstration Project (SWFDP), notably in a regional demonstration project for Southern Africa. Thus, the GIFS-TIGGE Working Group has adopted the concept of distributed production rather than the single “TIGGE production centre” envisaged in the original TIGGE objectives.


Figure T5 – A global to regional to national cascade for generating and distributing GIFS products – based on the approach successfully used by SWFDP

In order to better coordinate GIFS developments with the SWFDP, the eighth meeting of the GIFS-TIGGE working group was held in conjunction with SWFDP steering group, at Geneva in February 2010. It became clear during the meeting that the best way forward for GIFS was to work with the SWFDP and other WMO regional projects, rather than to set up a separate GIFS Forecast Demonstration Project. Formal links were established between the SWFDP and GIFS-TIGGE, focused on the development of prototype GIFS products for the SWFDP regional subprojects. It was agreed that GIFS products, mainly based on combined ensembles, would be used to supplement products already available through the SWFDP, and evaluated in conjunction with the SWFDP.

On a similar basis, the GIFS-TIGGE working group will also work closely with other WMO Research & Development Projects and Forecasting Demonstration Projects to evaluate prototype GIFS products in other regional environments.

As the TIGGE archive and plans for GIFS have been developed by the broader community, the Meteorological Service of Canada (MSC), the US National Weather Service, and the Meteorological Service of Mexico developed the first operational multi-centre ensemble forecast system called North American Ensemble Forecast System (NAEFS, Toth et al 20XX – thorpex symposium presentations). NAEFS includes the basic elements of GIFS: (a) real time exchange of ensemble data from two centres (MSC and US NWS); (b) statistical bias correction, downscaling, and combination of information from the multiple centres; and (c) generation of probabilistic and other ensemble-based products. NAEFS was operationally implemented in 2006 at MSC and the US NWS. It led to significant improvements in probabilistic medium- and extended range forecast skill and is now widely used as numerical guidance for high impact weather forecasting in Canada, Mexico, and the US. NAEFS also serves as an example of how GIFS can be further developed in a broader international collaboration.

EPS1 EPS2 EPS3

Generate Products

Regional Centre

users

National Centre

National Centre

National Centre

users usersusers


4.1 Future Directions

Collaborative approach

The operational NWP centres that act as TIGGE data providers are continually improving the scientific basis and resolution of their ensemble prediction systems. Scientific research based on TIGGE helps inform these on-going developments. The ensemble prediction systems contributing to TIGGE and GIFS will also benefit from model developments fostered by the WCRP/WWRP Working Group on Numerical Experimentation (WGNE). In addition to implementation of these on-going improvements, the GIFS TIGGE working group will be focusing increasingly on the development and evaluation of products to support the forecasting of high-impact weather events. The evaluation of those products will be guided by advice from the Joint Working Group on Forecast Verification Research (JWGFVR).

It is clear that both TIGGE and GIFS development efforts will require close collaboration with many WWRP, WCRP and CBS groups. In particular stronger links will be established with the Working Groups on Mesoscale Weather Forecasting Research (WGMWFR) and on Socio-Economic Research and Applications (WGSERA). Finally, there is an increasing emphasis on developing seamless aspects of weather forecasting, with the possible establishment of a WMO project focused on sub-seasonal to seasonal forecasting; the GIFS-TIGGE WG will collaborate with this new project on research topics of common interest.

TIGGE

The three archive and ten providing centres remain committed to the continued support of TIGGE in the forthcoming years. Discussions about further developments are also on-going, though additional improvements are subject to funding. The initial implementation of the TIGGE archive systems was based on archiving systems already in place at the TIGGE data centres. While this entailed significant investment from the three archive centres, further developments require additional funding. A new validation data portal is being designed and will be coupled to the TIGGE access portal at NCAR, making both the forecast fields and observations available from the same interface. Further developments will include improved treatment of time-series data and provision of TIGGE data in formats other than GRIB2. Additional developments to the NCAR portal are in hand, and a funding proposal (GEO-WOW) has been submitted to the EU which would support enhancements to the ECMWF portal.

GIFS

The fourth of the original TIGGE objectives focused on the development of a more interactive forecast system. The further development of GIFS will require significant investments from both the academic community (ensemble and probabilistic forecasting related basic and applied research) and the operational centres (global NWP centres providing ensemble forecasts, and in addition regional and national centres statistically post-processing the data and deriving, supporting, and disseminating to users probabilistic products and services for high impact events). Subject to positive scientific results from the GIFS development project, additional investments to support GIFS may include telecommunication upgrades, and international agreements on data exchange policy and the use of products. The concept of re-locatable LAM EPS systems will also be considered as a possible future adaptive component of GIFS. Depending on further scientific developments and tests, a future GIFS may also consider the adaptive use of the observing systems to further reduce uncertainty associated with high impact weather events. The GIFS system will follow CBS guidelines on operational systems and requirements, using the WIS infrastructure and would undergo thorough pre-implementation testing and evaluation period. Subject to sufficient progress, a prototype of GIFS offering high


impact advanced warning for tropical cyclones, precipitation, winds and temperature could be field tested in a THORPEX campaign possibly organized near the end of its lifecycle. Should the system become operational, arrangements will need to be made for sustainable production and distribution of products.

5. Data Assimilation and Observing Systems

5.1 Overview

At the start of THORPEX two working groups were created: the Observing Systems Working Group (OSWG) and the Data Assimilation and Observing Strategies (DAOS-WG) groups. They met separately although representatives from each group participated in the other group meetings. After three years the two groups were combined to form the current Data Assimilation and Observing Systems Group (DAOS-WG). This brief summary of achievements in the domain of observing systems and data assimilation is a combination of the achievements from both these groups and recently the current unified DAOS group. For convenience highlights are separated out to those concerning observations and those for data assimilation.

5.2 Development of Observing Systems

The objectives of the original OSWG were to help ensure that THORPEX develops a scientifically well-founded strategy for the design of the next generation of the WMO Global Observing System, as an integral element of GEOSS, required to support NWP primarily from 1-14 days. The OSWG acted as a focal point across the spectrum of THORPEX activities for observations and to offer advice on field campaigns. It was important to maintain a close link with the CBS-OPAG IOS which is the main group for coordinating the global observing system. The OSWG met at three working group meetings: the first in Reading (March 2006), the second in Boulder (May 2007) and the final meeting in Geneva (2008) when it was combined with the DAOS-WG.

After five years the major achievements have been:

i. Enhancement of the current radiosonde network by supporting the provision of sondes to the former Soviet Union and for the AMMA campaign over Saharan Africa

ii. Promotion of the establishment of the following new observing systems that will lead to the development of a robust global observing system: Bi-directional radiosondes and more frequent reporting of measurements during

ascent New aircraft observing systems for example TAMDAR which is progressively being

introduced on more routes to improve coverage Ground-based GPS wet delay which is now operational in several NWP centres GPS radio occultation systems some of which are now routinely used at NWP

centres Doppler wind radars on satellites Demonstrating benefits with satellite rapid scan atmospheric motion winds in regional

NWP models and tropical cyclone forecasts Using more satellite data over land for example clear sky radiances Extending the use of satellite radiances over cloudy regions Polar Communications and Weather Mission in a Molniya orbit for improved

coverage of the northern polar latitudes Raman lidar which shows vertical profiles of water vapour at very high time and

vertical resolution and can be available 24 hrs a day for high resolution mesoscale models


iii. Ensure the space based and terrestrial systems evolve to form an optimised integrated overall system by taking into account the characteristics of all observations in the network design

iv. Input to the observing strategy for several Thorpex field campaigns was given including E-TREC, T-PARC, IPY–GFDeX, IPY-ConcordIASI, HyMex and T-NAWDEX with particular emphasis on the strategy for adaptive observations

v. The status of the space based observing system was periodically reviewed and where appropriate recommendations were passed to the WMO OPAG-IOS group and the CBS

vi. Promoting the use of a universal format for weather radar data to allow exploitation of these data easily

vii. Links with the Thorpex regional committees were established to ascertain their needs for observations and what was in place and planned

viii. A review of terrestrial sounding and profiling systems that might be applicable for use in remote oceanic and continental regions was produced as part of the 2nd OSWG report

ix. A report was prepared on the potential strategies for enhancing the surface based observing system in western China and provided to CMA. This was an annex to the 2 nd

OSWG report

5.3 Evaluation of the impact of observations and linkage with the CBS OPAG-IOS

The DAOS-WG co-ordinates the use of OSEs for the evaluation of data impacts, targeting studies for longer-range forecasts but in this regard notes that issues for targeting at shorter range remain and should be addressed before considering longer range forecasts. To link with the CBS activities on the assessment of the value of the global observing system, several members of the DAOS participated in the Data Impact Workshop, which took place in May 2008 in Geneva. It contributed to the discussion on the following points:

i. Impact of observations : the DAOS promoted an intercomparison experiment to evaluate the robustness of new tools to measure the impact of observations. The results indicated that these new approaches provide more detailed information on the impact of observations which is found extremely valuable in the evaluation of the global observing systems. It was also shown that these tools are complementary to OSEs and permit the evaluation of the influence of other observations on the impact of a particular observation type. Since then, a paper has been submitted to Monthly Weather Review which presents the results from this intercomparison in which three centres took part (Gelaro et al.,2010).

ii. THORPEX-IPY : because of the lack of profile-type observations in the polar latitudes, every effort should be made to maintain the existing radiosonde sites, and/or find new systems to observe the vertical structure of the atmosphere (wind, temperature, humidity) in the polar areas. The IPY year has been an opportunity to have new systems deployed (e.g. drifting balloons and unmanned aerial vehicles). The extension of some of these systems beyond the IPY should be considered.

iii. AMMA : remote radiosonde stations are still of exceptional value (as shown with isolated islands, ASAP observations and AMMA radiosonde observations). They are essential and should not be closed although they are the most expensive. We have not yet reached the point with satellite data assimilation that makes it possible to close down such stations. Experiments have shown that it is important to have observations over un-observed regions but also that models can suffer in the same regions with different sources of bias that extra observations cannot reduce. It has been shown (Agusti et al 2010) that a sparse radiosonde network covering only the west and central Africa can degrade the forecast in East Africa (again due to model bias). Studies on better usage of AMVs over Africa (offering a homogeneous data coverage) have shown a potential


benefit and more work for a more suitable and efficient assimilation of AMVs has been encouraged.

iv. Longer range forecasts : more attention should be given to the forecasts at ranges 7 to 14 days, in some future impact studies. In this context, some studies should address the requirements for surface variables such as soil moisture, SST and sea-ice and also the observation requirements in the stratosphere. Ensemble prediction systems could be a helpful tool for these future studies.

Specific recommendations for observation campaigns Winter T-PARC, AMMA and IPY

At the second DAOS working group meeting in 2008, the following recommendations and comments for Winter T-PARC were developed and were subsequently conveyed to the Principal Investigators.

i. Can observations be deployed to test the hypothesis that “the source of forecast errors could be due a lack of amplitude in the forecasts of upper-tropospheric ridging in the cyclonic warm sector”?

ii. Investigate the use of additional observations to evaluate bias corrections of satellite radiances and their use in cloudy regions.

iii. Carry out tests, using operational systems, to evaluate the impact of the additional Russian radiosondes that will be deployed – this may help to generate support to continue making these observations routinely.

iv. Since the rapid-scan facility on MTSAT-2 is not likely to be available the use of GOES rapid-scanning should be explored prior to the field phase

v. Explore the use of BoM and CIMSS Atmospheric Motion Vectors (AMVs)

AMMA studies have shown a large impact from additional radiosonde data (properly calibrated) and these data have improved analyses, precipitation forecasts and have provided valuable insights into model error and deficiencies in data assimilation procedures. Since these data are now used operationally it is recommended that:

i. The new in situ data sites continue to operateii. Operational centres continue to carry out data impact studies in support of the

THORPEX African Regional Plans

A few of the projects in the THORPEX IPY cluster are focused on improving the use of satellite data over polar regions and these should continue to be supported.

5.4 Data Assimilation

The objectives of the original Data Assimilation and Observing Strategies WG were to ensure that THORPEX contributes to the international efforts to optimise the use of the current WMO Global Observing System (GOS) and to the development of well-founded strategies for the evolution of the GOS to support Numerical Weather Prediction primarily for 1 to 14 day weather forecasting.

To achieve its mission, it should act, in collaboration with the CBS OPAG-IOS, to

Address data assimilation issues including the development of improved understanding of the sources and growth of errors in analyses and forecasts,

Promote research activities that lead to a better use of observations and the understanding of their value, and


Provide input and guidance for THORPEX regional campaigns for the deployment of observations to achieve scientific objectives.

The working group met on several occasions at three working group meetings: the first in Reading, UK (March 2006), the second in Geneva (September 2008) during the THORPEX workshop of all working groups and the third (now combined with the OSWG) was held recently in Montréal, Canada (July 2010). Other meetings in which the working was involved were:

i. Open informal meeting of the working group (December 2006 during the THORPEX Symposium held in Landshut, Germany)

ii. Fourth Workshop on the Impact of Various Observing Systems on Numerical Weather Prediction which was attended by almost all members of the working group (Geneva, May 2008 - organized by the CBS OPAG IOS with financial support from THORPEX)

iii. Side meeting during the Third THORPEX International Science Symposium in September 2009, in Monterey, California, USA

Results and reports from work carried out, or promoted by the working group, was a major contribution to the report from the Fourth Workshop on the Impact of Various Observing Systems on Numerical Weather Prediction – item (ii) above.

Several members were also involved in the WMO WWRP-THORPEX Workshop on 4D-Var and Ensemble Kalman Filter Intercomparisons held in Buenos Aires, Argentina (10-13 November 2008) and in the 5th WMO Symposium on data assimilation in meteorology and oceanography held in Melbourne in 2009.

The use of adaptive observations

During the first half of THORPEX the emphasis has been on the evaluation of the impact of observations, including targeted observations, based on results from field experiments (ATReC, AMMA, IPY), OSEs and OSSEs. In addition, the group has contributed significantly to the preparations for T-PARC. The working group activities have been presented at a number of conferences and a report on the activities of the group has been published in Rabier et al. (2008). The main outcomes from these impact studies may be summarised as follows:

i. The value of extra-tropical targeted data has been found to be positive but small on average Observations taken in sensitive areas have more value than observations deployed

randomly Past experiments do not provide evidence of a major impact obtained from just a few

observations (when averaged over a large sample of cases) There are limitations due to the current assimilation methodologies (spatial structure

functions which control the use of observations in data assimilation are not yet fully flow-dependent)

The methods employed to characterize sensitive areas do not appear to be a major problem

Additional observations for tropical cyclones have proven to be usefulii. These studies also suggest that additional benefit may be obtained from:

Optimization of existing operational resources Regional (vs highly localized) and systematic targeting during low predictability flow

regimes on a continuous basis (periods of days to weeks) Adaptive processing and data selection of satellite data (e.g. Bormann and Bauer,

2010)


Based on the above it is recommended that:

Observation campaigns should be based on science plans that take into consideration assimilation issues

Expensive observation campaigns should not be justified based on current targeting strategies alone

Decisions to undertake observational field campaigns would benefit from pre-campaign evaluation of expected value (e.g., using OSSEs or OSEs)

iii. In order to facilitate the inter-comparison of the results of the impact of targeted observations planned for Winter T-PARC, it would be useful to have results from the 2001-2008 Winter Storm Reconnaissance campaigns summarized as a review paper using the same metrics adopted for other studies. This will be discussed in the review paper on adaptive observations currently in preparation

The objective of the Third DAOS-WG workshop, held in Montréal, Canada in July 2010, was to review the use of adaptive observations in view of recent results and to agree on a redaction team to write a review paper on the value of adaptive observations. Sharan Majumdar accepted to take the lead on this and a paper to be submitted to BAMS is currently in preparation. A first draft is expected by January 2011 and will be presented at the next ICSC meeting in February 2011.

Higher resolution data assimilation

Of the studies reviewed by the group it is clear that global data assimilation, to provide lateral boundary conditions and background fields for example, is an essential ingredient of any regional forecasting scheme. Indeed, currently downscaled 4D-Var analyses provide better results than meso-scale data assimilation systems employing 3D-Var and it is clear that more work needs to be carried out to assess what is really required for meso-scale data assimilation. However, there are potential benefits:

iv. Higher resolution gives better picture of high-impact weatherv. Higher resolution allows better assimilation and forecast of observed detailvi. Affordable timely forecasts can be made with regional systems with the most recent

observationsvii. Regional systems provide a basis for tailored numerical weather prediction

Future Directions

At the mid-term point of THORPEX the role of the working groups within the broader WMO structures needs to be assessed. At the moment, the DAOS is clearly leading a valuable research effort aiming at making better use of observations to improve weather forecasts. This is linked to the CBS OPAG-IOS and effort should be made to insure a good linkage between these two central activities for WMO. The recent participation of the DAOS to the Observation Impact Workshop is an example of its contribution to structuring the research that could be done to progress on data assimilation issues that need to be addressed.

The work and progress of the DAOS working group has been reported at the WGNE annual meetings. WGNE benefited from the fact that some of its members are or have been part of the DAOS-WG (P. Gauthier, T. Hamill, A. Lorenc, F. Rabier) and could bring up data assimilation issues to the attention of WGNE. The structure of WGNE now includes ex-officio members to represents working groups such as SPARC, GEWEX, GLASS, GABLS and GCSS, to name of few. It was acknowledged that it would be beneficial to WGNE to link with a working group who could represent the data assimilation community. It was recognized that the DAOS could act as


the link to the data assimilation community. This could be achieved by having a representative of the DAOS as an ex officio member on WGNE.

There are a number of other issues that are not part of the DAOS mandate but are covered within other programmes. SPARC has an interest in data assimilation and so has the GLASS working group who has an interesting project, PILDAS, on surface data assimilation. Mesoscale data assimilation is also a concern and will raise a number of scientific challenges as well. These should not be included in the mandate of the DAOS but linkages should be made so that the data assimilation issues can have a forum. The WMO Symposium on Data Assimilation Symposium is occurring every four years or so, to bring together different areas where data assimilation is applied. It would be valuable to think about ways through which the coordination of these distinct efforts in data assimilation could be achieved.

6. Future research and development

In the framework of increasingly powerful high end computing and the expected increasing resolution and sophistication of numerical models the WWRP-THORPEX programme will remain focussed on making significant improvements in the short-period prediction of high-impact weather worldwide, extending markedly the range of useful forecasts and encouraging a globally integrated approach through the careful evaluation and scientific assessment of the potential benefits of the introduction of the GIFS.

A most important issue remains understanding and addressing the societal and economic imperatives for improved forecasts including aspects related to health, agriculture, energy etc., and ensuring that user relevant verification of forecasts is employed throughout. This approach requires strong cross-community collaboration between scientists, social scientists and economists.

Major THORPEX scientific priorities that need to continue to be addressed include:

i. Basic issues of predictability and key dynamical processesii. The required initial conditions and implied observational coverageiii. Strategies for observations for the requirement and use of targeted observationsiv. Tackling the problem issues in data assimilation especially at high resolutionv. Handling of the tropics particularly organised convection, TCs, and ET and tropical-

extra-tropical interactions

and new projects for the

vi. Improvement of weather and environmental prediction in Polar Regionsvii. Sub-seasonal to seasonal prediction

6.1 Improvement of weather and environmental prediction in Polar Regions

The International Polar Year (IPY) was a great leap forward which contributed to the enhancement of the observational network, a better understanding of physical processes, and improvements in the use of observations, modelling, and prediction in Polar Regions.

The positive impact of Numerical Weather Prediction (NWP) and Environmental Prediction (EP) on health, safety, and economic competitiveness is recognized worldwide. The benefit of NWP/EP applications in Polar Regions has been somewhat delayed due to the higher priority of forecasting in the more densely populated mid-latitude and tropical regions. Concerns about an amplification of anthropogenic climate change at higher latitudes combined with an increasing interest of many governments throughout the Polar Regions requires a better understanding of


weather and environmental processes in Polar Regions in order to improve our ability to make reliable, quantitative predictions up to a season ahead.

Consequently, at its 15th session (November 2009), the WMO Commission of Atmospheric Sciences (CAS) recommended, as a legacy of the International Polar Year (IPY), the establishment of a THORPEX Polar Research project to improve understanding of the impact of polar processes on polar weather, the assimilation of data in Polar Regions, and the prediction of high impact weather over Polar Regions.

In developing this recommendation the CAS acknowledged that important steps forward in the polar analysis and prediction had resulted from

the success of the THORPEX IPY Cluster Project the success of the JCOM IPY Ice Logistics Portal the European GMES Marine Core service and its polar prediction and sea-ice

information provision services the scientific and operational advances in satellite data assimilation

The CAS recognized that the research outcomes of these efforts would provide valuable input to the programme of work for such a legacy project.

During its deliberations, the CAS noted that the Executive Council Panel of Experts on Polar Observations, Research, and Services (EC-PORS) decided that the design and development of polar prediction systems is an important task that will require effective collaboration across the relevant WMO Technical Commissions along with other partners as appropriate and recommended that efforts be made to further polar prediction for weather and climate and to extend efforts to snow, ice, carbon, and ecosystem modelling and analysis. This would also require the involvement of the World Weather Research Programme (WWRP), including THORPEX, the Global Atmospheric Watch (GAW), and the World Climate Research Programme (WCRP) and support from WMO Members.

Finally, the CAS concurred with the EC-PORS on the requirement for effective collaboration and therefore recommended that any efforts to develop a future prediction system include outcomes from the IPY-THORPEX cluster of projects and from the planned THORPEX legacy project. The first step to develop such a legacy project was the organisation of a Workshop on “Improvement of Weather and Environmental Prediction in Polar Regions” (Met No Oslo, 6 to 8 October 2010) and the report from this Workshop is available at (http://www.wmo.int/pages/prog/arep/wwrp/new/documents/recommendations_final.pdf ).

The outcome of this workshop was the establishment of a basis for an IPY legacy project which is intended to provide a framework for cooperative international research and development efforts to improve high impact weather, climate, and environmental prediction capabilities for the Polar Regions.

Three forecast prediction ranges are of interest:

short-term regional forecasts (one hour to 48 hours) medium-range forecasts (one day to two weeks) sub-seasonal to one season forecasts

However, it was clear from the workshop discussions on “gaps” that many of the problems are common to all prediction systems whatever the range – notably, problems with the parameterization of atmospheric, oceanic, and land-surface physical processes.

http://www.wmo.int/pages/prog/arep/wwrp/new/documents/recommendations_final.pdf


Such a legacy project would aid the coordination of current and future polar prediction activities and increase awareness of the need for new resources for polar prediction research and it should be based on a few NWP internationally coordinated polar initiatives (new or existing). Joint field campaigns and more long term activities for verification (e.g. weather and ice forecasts, monitoring super-sites) and optimal utilization of satellite-based and in situ observations that involve nations operating NWP systems for the Polar Regions are examples.

Based on the outcome of the Oslo workshop, the feedback from EC-PORS (and potential partners) and the support from Cg-XVI, a Joint Polar Prediction Project, similar to the Year of Tropical Convection (YOTC) project, supported by WWRP, WCRP, and THORPEX will be established.

This project will require a Steering Group (consisting of members with scientific and operational expertise and representatives of the user community). The first task for the Steering Group will be the preparation of an Implementation Plan which includes estimates of resources and a strategy for the coordination of polar prediction research.

A first draft of an Implementation Plan should be available for the next meetings of the WWRP/JSC (late winter 2011/12) and the WCRP/JSC (spring 2012) and it should also be presented to EC-PORS.

6.2 Sub-seasonal to seasonal prediction

At its 15th session (November 2009), the WMO Commission of Atmospheric Sciences (CAS) requested the Joint Scientific Committees of the World Weather Research Programme (WWRP) and the World Climate Research Programme (WCRP) and also the THORPEX international Core Steering Committee (ICSC) to set up an appropriate collaborative structure to carry out an international research initiative on sub-seasonal to seasonal forecasting. It recommended that such a research initiative is closely coordinated with the present existing WMO Commission on Basic Systems (CBS) infrastructure for long-range forecasting (with centres producing long-range forecasts and regional climate centres) and with the future developments in WMO climate service delivery and the Global Framework for Climate Services called for in the High-Level Declaration of the World Climate Conference 3 (WCC-3).

The initial response to this request was to convene a joint WWRP/THORPEX/WCRP Workshop which was held at the UK Met Office (1 to 3 December 2010). The Report from the Workshop on “Sub-seasonal to Seasonal Prediction” (Met Office, Exeter 1 to 3 December 2010) has been published to the web(http://www.wmo.int/pages/prog/arep/wwrp/new/documents/recommendations_final.pdf ).

The major Workshop recommendation was that a Panel and Project for Sub-seasonal prediction research should be established. Panel members should include representatives from WWRP-THORPEX, WCRP, CBS and CCl and their relevant programme bodies. The first task for the Panel should be the preparation of an Implementation Plan which is consistent with the contents of the Workshop Report and Recommendations.

As recommended by Workshop, the Implementation Plan should give high priority to:

Sponsorship of a few international research activities The establishment of collaboration and co-ordination between operational centres

undertaking sub-seasonal prediction to: ensure, where possible, consistency between operational approaches to enable

the production of data bases of operational sub-seasonal predictions to support

http://www.wmo.int/pages/prog/arep/wwrp/new/documents/recommendations_final.pdf


the application of standard verification procedures and a wide-ranging programme of research

Facilitating the wide-spread research use of the data collected for the CHFP (and its associate projects), TIGGE and YOTC for research

The establishment of a series of regular Workshops on sub-seasonal prediction

In a separate plan, or as part of the Implementation Plan, the WWRP/SERA Working Group and the WCRP should outline plans for a number of regional projects.

The next step will be to establish a small Planning Group to prepare an Implementation Plan for a “Sub-seasonal Prediction Research Project”. A first draft of this plan should be available for the next meetings of the WWRP/JSC (late winter 2011/12) and the WCRP/JSC (spring 2012).


Appendix 1 - References

Sub-section 2.1 “The THORPEX Interactive Grand Global Ensemble (TIGGE)

………

Sub-section 2.2 “The Atlantic THORPEX Regional Campaign (A-TRec)”

D. Mansfield, D. Richardson and B. Truscott. An Overview of the Atlantic THORPEX Regional campaign.S. Stringer and B. Truscott. Atlantic THORPEX Regional Campaign : Operations Plan, EUCOS Studies Programme Paper, February 2004. N. Fourrié, D. Marchal, F. Rabier, B. Chapnik and G. Desroziers. Impact study of the 2003 North Atlantic THORPEX Regional Campaign. Q.J.R. Meteorol. Soc. (2005) pp 1-20.G. Desroziers, G. Hello and J.-N Thépaut. A 4D-Var Reanalysis of FASTEX. Q.J,R. Meteorol. Soc. (2003)A. Doerenbecher, M. Leutbecher and D.S.Richardson. Comparison of observation targeting predictions during the A-TReC. Proceedings of the first International THORPEX Science Symposium, 6-10 Dec. 2003, Montreal, Canada.A. Doerenbecher. Comparison of targeting techniques used in the A-TReC 2003. In preparation.R. Langland. Observation impact during the North Atlantic TreC-2003. MWR, 133, 2297-2309.

Sub-section 2.6 “The Year of Tropical Convection (YOTC)”

Moncrieff, M.W., M. Shapiro, J. Slingo, and F. Molteni, 2007: Collaborative research at the intersection of weather and climate. WMO Bulletin, 56, 204-211.

Moncrieff, M.W., 2009: The multiscale organization of moist convection and the intersection of weather and climate. AGU Geophys. Monog, 189, Why does Climate Vary? Ed. D. Sun and F. Bryan, 3-26.

Moncrieff, M.W., D.E. Waliser, M.A. Shapiro, G.R. Asrar, and J. Caughey, 2010: Year of Tropical Convection (YOTC): The scientific basis. Bull. Amer. Meteorol. Soc., submitted.

Waliser, D. E., and M. Moncrieff, 2007: Year of Tropical Convection - Joint WCRP-THORPEX activity to address the challenge of tropical convection. GEWEX News, 17, No. 2, page 8.

Waliser, D.E., M.W. Moncrieff, 2008: Year of Tropical Convection (YOTC) Science Plan,WMO/TD-No. 1452, WCRP -130, WWRP/THORPEX- No 9, 26 pp.

Waliser, D. E., M. Moncrieff, D. Burrridge, A. Fink, D Gochis, B. N. Goswami, B Guan, P Harr, J Heming, H.-H. Hsu, C Jakob, M. Janiga, R. Johnson, S Jones, P. Knippertz, J Marengo, H Nguyen, M Pope, Y Serra, C Thorncroft, M Wheeler, R. Wood, and S. Yuter, 2010: The "Year" of Tropical Convection (May 2008 to April 2010): Climate Variability and Weather Highlights. Bull. Amer. Meteorol. Soc., submitted.

Sub-section 3.1 “T-PARC”


Bell, M. M., and M. T. Montgomery, 2010: Development of pre-depression Hagupit observed during TCS-08. 29th Conference on Hurricanes and Tropical Meteorology, American Meteorological Society, Boston, MA.

Berger, H., C. S. Velden, R. Landland, and C. A. Reynolds, 2010: Special satellite data analysis and NWP impact studies during T-PARC. 29th Conference on Hurricanes and Tropical Meteorology, American Meteorological Society, Boston, MA.

Chen, S.-G., S. J. Majumdar, and C. C. Wu, 2010: Properties of the ensemble transform Kalman filter adaptive sampling strategy for tropical cyclones. 29th Conference on Hurricanes and Tropical Meteorology, American Meteorological Society, Boston, MA.

Cisneros, J., C. Lopez-Carrillo, and D. J. Raymond, 2010: High resolution analysis of the structure of a convective system in developing Typhoon Nuri. 29th Conference on Hurricanes and Tropical Meteorology, American Meteorological Society, Boston, MA.

Elsberry, R. L., and A. Chollet, 2010: Role of mesoscale convective rings and mesoscale convective blowouts in tropical cyclone formations during the TCS-08 experiment. 29th

Conference on Hurricanes and Tropical Meteorology, American Meteorological Society, Boston, MA.

Grams, C. M., 2010: The interaction between the outflow of Typhoon Jangmi (2008) and the midlatitude jet during T-PARC. 29th Conference on Hurricanes and Tropical Meteorology, American Meteorological Society, Boston, MA.

Harnisch, F., and M. Weissmann, 2010: Sensitivty of typhoon forecasts to different subsets of targeted dropsonde observations. Mon. Wea. Rev., 138, 2664-2680.

Harr, P. A., E. R. Sanabia, and A. B. Penny, 2010: Typhoon Sinlaku during T-PARC: Sensitivity of the re-intensification and downstream development to the track following recurvature. 29th Conference on Hurricanes and Tropical Meteorology, American Meteorological Society, Boston, MA.

Lussier, L. L., 2010: The genesis of Typhoon Nuri as observed during the tropical cyclone structure 2008 (TCS-08) field experiment. 29th Conference on Hurricanes and Tropical Meteorology, American Meteorological Society, Boston, MA.

Raymond, D., and C. Lopez-Carillo, 2010: Vorticity budget in developing typhoon Nuri. 29th

Conference on Hurricanes and Tropical Meteorology, American Meteorological Society, Boston, MA.

Reynolds, C. A., J. D. Doyle, R. M. Hodur, and H. Jin, 2010: Naval Research Laboratory Multi-scale Targeting Guidance for T-PARC and TCS-08. Wea. Forecasting, 25, 546-564.

Sanabia, E. R., and P. A. Harr, 2010: Scale interactions during the re-intensification of Typhoon Sinlaku prior to extratropical transition. 29th Conference on Hurricanes and Tropical Meteorology, American Meteorological Society, Boston, MA.

Snyder, A., Z. Pu and C. A. Reynolds, 2011: Impact of stochastic convection on ensemble forecasts of tropical cyclone development. Mon. Wea. Rev., in press.

Weissmann, M., F. Harnisch, C. C. Wu, P. H. Lin, Y.Ohta, K. Yamashita, Y. H. Kim, E. H. Jeon, T. Nakazawa, and S. Aberson, 2011: The influence of assimilating dropsonde data on typhoon track and mid-latitude forecasts. Mon. Wea. Rev., in press.

Sub-section 3.2 “New diagnostic techniques to understand the origin of model errors”


Jung, T., M.J. Miller and T.N. Palmer, 2010a: Diagnosing the origin of extended-range forecast errors. Mon. Wea. Rev., 138, 2434-2446.

Jung, T., G. Balsamo, P. Bechtold, A.C.M. Beljaars, M. Köhler, M.J. Miller, J.-J. Morcrette, A. Orr, M.J. Rodwell and A.M. Tompkins, 2010b: The ECMWF model climate: recent progress through improved physical parametrizations. Quart. J. Roy. Meteor. Soc., 136, 1145-1160.

Klinker, E. and P.D. Sardeshmukh, 1992: The diagnosis of mechanical dissipation in the atmosphere from large-scale balance requirements. J. Atmos. Sci., 49, 608-627.

Phillips, T.J., G.L. Potter, D.L. Williamsom, R.T. Cederwall, J.S. Boyle, M. Fiorino, J.J. Hnilo, J.G. Olson, S. Xie and J.J. Yio. Bull. Amer. Meteor. Soc., 85, 1903-1915.

Rodwell, M.J. and T.N. Palmer, 2007: Using numerical weather prediction to assess climate models. Quart. J. Roy. Meteor. Soc., 133, 129-146.

Rodwell, M.J. and T. Jung, 2008: Understanding the local and global impacts of model physics changes: an aerosol example. Quart. J. Roy. Meteor. Soc., 134, 1479-1497.

Sub-section 3.4 “T-NAWDEX - Atmospheric dynamics and diabatic processes in the extratropics”

Boettcher, M., and H. Wernli, 2011: A case study of an explosively deepening diabatic Rossby-wave induced cyclone – dynamics and forecast performance. Mon. Wea. Rev., submitted

Bracegirdle TJ, Gray SL, 2008: An objective climatology of the dynamical forcing of polar lows in the Nordic seas. Int. J. Climatol., 28, 1903-1919.

Campa, J., and H. Wernli, 2011: A potential vorticity perspective on the vertical structure of mid-latitude cyclones. J. Atmos. Sci., submitted

Cavallo SM, Hakim GJ, 2009: Potential Vorticity Diagnosis of a Tropopause Polar Cyclone. Mon. Wea. Rev., 137, 1358-1371.

Cavallo SM, Hakim GJ, 2010: Composite Structure of Tropopause Polar Cyclones. Mon. Wea. Rev., 138, 3840-3857.

Chagnon JM, Gray SL, 2009: Horizontal potential vorticity dipoles on the convective storm scale. Q. J. Roy. Meteorol. Soc., 135, 1392-1408.

Cordeira JM, Bosart LF, 2010: The Antecedent Large-Scale Conditions of the "Perfect Storms'' of Late October and Early November 1991. Mon. Wea. Rev., 138, 2546-2569.

Croci-Maspoli M, Davies HC, 2009: Key Dynamical Features of the 2005/06 European Winter. Mon. Wea. Rev., 137, 664-678.

Dacre HF, Gray SL, 2009: The Spatial Distribution and Evolution Characteristics of North Atlantic Cyclones. Mon. Wea. Rev., 137, 99-115.

Davis CA, 2010: Simulations of Subtropical Cyclones in a Baroclinic Channel Model. J. Atmos. Sci., 67, 2871-2892.

Davis CA, Galarneau TJ, 2009: The Vertical Structure of Mesoscale Convective Vortices. J. Atmos. Sci., 66, 686-704.

http://apps.isiknowledge.com/full_record.do?product=UA&search_mode=GeneralSearch&qid=3&SID=N1G4@JoOPoDOFkhIIfE&page=1&doc=6&colname=WOS


Davis CA, Trier SB, 2007: Mesoscale convective vortices observed during BAMEX. Part I: Kinematic and thermodynamic structure. Mon. Wea. Rev., 135, 2029-2049.

Deveson, A. C. L., K. A. Browning, and T. D. Hewson, 2002: A classification of FASTEX cyclones using a height-attributable quasi-geostrophic vertical-motion diagnostic. Q. J. Roy. Meteorol. Soc., 128, 93-117.

de Vries H, Methven J, Frame THA, et al., 2010: Baroclinic Waves with Parameterized Effects of Moisture Interpreted Using Rossby Wave Components. J. Atmos. Sci., 67, 2766-2784.

Dirren S, Didone M, Davies HC, 2003: Diagnosis of “forecast-analysis” differences of a weather prediction system. Geophys. Res. Lett., 30, 2060.

Kew, S. F., M. Sprenger, and H. C. Davies, 2010: Potential vorticity anomalies of the lowermost stratosphere: A 10-yr winter climatology. Mon. Wea. Rev., 138, 1234-1249.

Knippertz P, Martin JE, 2007: The role of dynamic and diabatic processes in the generation of cut-off lows over Northwest Africa. Meteorol. Atmos. Phys., 96, 3-19.

Martinez-Alvarado O, Weidle F, Gray SL, 2010: Sting Jets in Simulations of a Real Cyclone by Two Mesoscale Models. Mon. Wea. Rev., 138, 4054-4075.

McTaggart-Cowan R, Galarneau TJ, Bosart LF, Milbrandt JA, 2010: Development and Tropical Transition of an Alpine Lee Cyclone. Part I: Case Analysis and Evaluation of Numerical Guidance. Mon. Wea. Rev., 138, 2281-2307.

Moore, RW; Montgomery, MT; Davies, HC, 2008: Title: The integral role of a diabatic Rossby vortex in a heavy snowfall event. Mon. Wea. Rev., 136, 1878-1897.

Novak DR, Colle BA, McTaggart-Cowan R, 2009: The Role of Moist Processes in the Formation and Evolution of Mesoscale Snowbands within the Comma Head of Northeast US Cyclones. Mon. Wea. Rev., 137, 2662-2686.

Riemer M, Jones SC, Davis CA, 2008: The impact of extratropical transition on the downstream flow: An idealized modelling study with a straight jet. Q. J. Roy. Meteorol. Soc., 134, 69-91.

Riemer M, Jones SC, 2010: The downstream impact of tropical cyclones on a developing baroclinic wave in idealized scenarios of extratropical transition. Q. J. Roy. Meteorol. Soc., 136, 617-637.

Riviere, G., P. Arbogast, K. Maynard, and A. Joly, 2010: The essential ingredients leading to the explosive growth stage of the European wind storm Lothar of Christmas 1999. Q. J. Roy. Meteorol. Soc., 136, 638-652.

Sub-section 2.1 “The THORPEX Interactive Grand Global Ensemble (TIGGE)” and section 4 “GIFS”

Bougeault, P., Z. Toth, C. Bishop, Barbara Brown, David Burridge, De Hui Chen, Beth Ebert, Manuel Fuentes, Tom Hamill, Ken Mylne, Jean Nicolau, Tiziana Paccagnella, Young-Youn Park, David Parsons, Baudouin Raoult, Doug Schuster, Pedro Silva Dias, Richard Swinbank, Yoshiaki Takeuchi, Warren Tennant, Laurie Wilson and Steve Worley, 2010: The THORPEX Interactive Grand Global Ensemble (TIGGE). Bull. Amer. Meteorol. Soc., 91, 1059–1072.






GEO, 2010: “Crafting geoinformation”, available from www.earthobservations.org/ documents/geo_vii/geo7_crafting_geoinformation.pdf Hagedorn, R. 2010: On the relative benefits of TIGGE multi-model forecasts and reforecast-calibrated EPS forecasts, ECMWF Newsletter 124, Summer 2010, available from www.ecmwf.int/publications/newsletters/Hayes, J., 2008: The World Weather Watch today, WMO Bulletin, 57 (1), 8-16Johnson, C. and R. Swinbank, 2009: Medium-range multi-model ensemble combination and calibration, Quart. J. R. Met. Soc., 135, 777-794.Matsueda, M., and H. Endo, 2011: C omparisons of MJO forecast performance using TIGGE data . to be submitted to GRL . McCaslin, P., T. Nakazawa, R. Swinbank and Z. Toth, 2010: Improving cyclone warning Case study: Philippines. WMO Bulletin, 59(2), 79-81.Richardson, D., R., Buizza and R. Hagedorn, 2005: Final report of the 1st Workshop on the THORPEX Interactive Grand Global Ensemble (TIGGE). WMO TD No. 1273, WWRP-THORPEX No. 5 Toth et al NAEFSWheeler, M.C. and H.H. Hendon, 2004: An All-Season Real-Time Multivariate MJO Index: Development of an Index for Monitoring and Prediction. Monthly Weather Review, 132, 1917-1932.Worley, S. Schuster, D., Raoult, B, Chen, D. and Gong, J., 2008: Improving High-impact weather forecasts EOS, 89, 36, 330-331.

Many additional scientific papers describing research using TIGGE data are listed at http://tigge.ecmwf.int/references.html

Section 5 “Data Assimilation and Observing Systems”

Agustí-Panareda, A., Beljaars, A., Ahlgrimm, M., Balsamo, G., Bock, O., Forbes, R., Ghelli, A., Guichard, F., Köhler, M., Meynadier, R. and Morcrette, J.-J. (2010), The ECMWF re-analysis for the AMMA observational campaign. Quarterly Journal of the Royal Meteorological Society, 136: 1457–1472. doi: 10.1002/qj.662Bormann, N. and Bauer, P. (2010), Estimates of spatial and interchannel observation-error characteristics for current sounder radiances for numerical weather prediction. I: Methods and application to ATOVS data. Quarterly Journal of the Royal Meteorological Society, 136: 1036–1050. doi: 10.1002/qj.616Gelaro, R., R.H. Langland, S. Pellerin, and R. Todling, 2010: The Thorpex observation impact intercomparison experiment. (to appear in Monthly Weather Review).Rabier, F., Gauthier, P., Cardinali, C., Langland, R., Tsyrulnikov, M., Lorenc, A., Steinle, P., Gelaro, R., Koizumi, K., 2008: An update on THORPEX-related research in Data Assimilation and Observing Strategies. Nonlinear Processes in Geophysics, 15, 81-94, 2008.Third THORPEX DAOS working group meeting: all presentation have been posted on a website located at http://web.sca.uqam.ca/~wgne/DAOS/DAOS3_meeting/.

http://web.sca.uqam.ca/~wgne/DAOS/DAOS3_meeting/

http://tigge.ecmwf.int/references.html

http://www.earthobservations.org/documents/geo_vii/geo7_crafting_geoinformation.pdf

http://www.earthobservations.org/documents/geo_vii/geo7_crafting_geoinformation.pdf


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