1. T-NAWDEX THORPEX - North Atlantic Waveguide and Downstream Impact Experiment Outline of scientific background Heini Wernli, Andreas Dörnbrack, George Craig, Sarah Jones with contributions from: Huw Davies, Pat Harr, John Methven and participants of 1st planning meeting (Erding, Feb 2009)

2. T-NAWDEX Has been proposed by the THORPEX working group Predictability and Dynamical Processes for the European THORPEX Science Plan Its overarching scientific goal is to investigate in detail the physical processes that are primarily responsible for degradation in 1-7 day forecast skill in global prediction systems and of their representation in NWP models. Planned for autumn 2012 as an international field experiment in conjunction with HYMEX - the Hydrological Cycle in the Mediterranean Experiment

3. T-NAWDEX will have - experimental (international field experiment) and - theoretical/diagnostic/modeling research components which investigate the different phases of wave guide disturbances: 1) Triggering of wave guide disturbances by different dynamical processes 2) Downstream evolution of the disturbances along the wave guide 3) Downstream impact of wave guide disturbances over Europe and North Africa

4. Triggering Science Issues 1.What are the important triggering mechanisms, their climatology and their predictive skill? ---- Underlying science questions that need to be examined before the field program and retested during the field phase 2.Organized diabatic forcing is one main triggering mechanism and the triggering mechanisms include: 1.Diabatic processes in developing extratropical cyclones 2.Warm conveyer belt/negative PV processes 3.Tropical convection including ETs moving energy into the wave guide 4.Polar positive PV features 5.Orography, especially associated with Greenland 6. Upstream unknowns (MJO, etc)

5. PV error on 315 K (forecast - analysis) Triggering: Sources of errors in upper-level PV field [pvu] 2-pvu tropopause forecast, analysis from Marco Didone

6. analysis forecast pvu from Marco Didone Lagrangian history (96 hour) from positive & negative “PV error” regions Triggering: Sources of errors in upper-level PV field

7. Downstream Evolution Science Issues What are the major forecast issues associated with the structural evolution of the waveguide? Does the formation of PV streamers over the western and central Atlantic, contrast with what happens at the end of the storm track over the eastern Atlantic? relative role of baroclinic processes relative role of diabatic processes How do low-PV anomalies evolve as they move downstream? effect of cirrus clouds, radiation, mixing Warm conveyor belt origin tropical cyclone origin tropical convection origin role(s) of diabatic processes on magnitude and timing of forecast errors role(s) of processes acting over a variety of space and time scales synoptic scale associated with primary wave diabatic Rossby waves

8. ana +3.5 fc +3.5 ana +5 fc +5 - WCB - + - WCB too weak Warm conveyor belts & downstream impacts

9. MODIS (Aqua) 14:55 UTC 24 November 2003 Horizontal wind speed Difference LIDAR - ECMWF analysis Substantial analysis errors associated with intense wind features N S Example: Wind lidar observations of Greenland tip jet from Andreas Dörnbrack

10. Downstream Impacts Science Issues Focus: cyclonic features, including fronts, and associated high impact weather Geography: east of 15W. Strategy: detailed measurements in the vicinity of cyclonic features, in both clear & cloudy areas, to: Assess the local influence of diabatic and other physical processes on the development of significant features Assess the relative influence of these processes in determining the location of high-impact weather such as severe wind & precipitation events, Ultimately promote numerical model development in the key process areas.

11. PV distribution on 310 K surface Error > 15 m/s Wind speed Aircraft measurements ECMWF analysis NCEP analysis Example: Aircraft observations within upper-level jet stream from Sandro Buss & Huw C. Davies

12. T-NAWDEX: Partners & funding components Germany (DLR, Karlsruhe, Munich, Hohenheim) HALO-THORPEX: so-called “demo mission” for the new German research aircraft HALO (~50 flight hours - tentative) Switzerland (ETH Zürich) HALO flight hours (~ 30 - tentative) United Kingdom (East Anglia, Reading, Manchester, Leeds) FAAM pilot flights in 2010 NERC application FranceLinkage with HYMEX, joint activities envisaged U.S.A.HIAPER Canada Others?

13. North American THORPEX Interests in T-NAWDEX Focus on: Triggering of wave guide disturbances by different dynamical processes Dynamical Processes: TROPICAL origin: Extratropical transition of Atlantic hurricanes; Organized tropical convection. MIDLATITUDE origin: Warm conveyor belts in extratropical cyclones over the western Atlantic or eastern North America; Downstream development from extratropical cyclones originating in the North Pacific storm track; Diabatic Rossby waves - as a combined tropical/extratropical interaction. POLAR origin: Upper-level PV anomalies; High-latitude orographic forcing.

14. HIAPER North American THORPEX Interests in T-NAWDEX Potential Contribution: –Observations of the evolution and structure of the dynamical processes associated with the triggering of wave-guide disturbances; Remote sensing In situ observations with the High-performance Instrumented Airborne Platform for Environmental Research (HIAPER) G-V aircraft –High-resolution modeling –Data assimilation experiments –Model intercomparisons –Coordination with the operational hurricane field program operated by the NOAA Atlantic Oceanographic and Meteorological Laboratory/ Hurricane Research Division (AOML/HRD) Complement to operations conducted downstream by European THORPEX

15. UK Science Focus in T-NAWDEX Focus on: Downstream evolution of wave guide disturbances by different dynamical processes Focus on moist diabatic processes within mid-latitude weather systems; their influence on system evolution and predictability, and their sensitivity to upstream initial conditions. Dynamical processes from global to convective scale are: 1.Triggering of persistent Rossby wave patterns across NH (e.g., summer 2007 and extreme rainfall across UK). 2.Moist baroclinic growth (diabatic Rossby waves etc). 3.Influence of surface fluxes on system development. 4.Influence of moist processes on negative PV anomalies in outflow of warm conveyor belts and their downstream development. 5.Diabatic erosion of quasi-stationary tropopause anomalies. 6.Influence of diabatic processes on mesoscale structures. 7.PV anomaly creation on the cloud updraft/system scales and integrated effect on parent system.

16. UK contribution to T-NAWDEX field experiment in 2012 FAAM BAe146 aircraft –Focus on low-mid level diabatic processes (e.g., water phase change, BL fluxes over ocean, mixing processes on mesoscale and smaller) –Based from UK for several months –Systems developing near Europe UK ground-based network –Upwind of the continental Europe! –Profiles and boundary layer observations –RADAR coverage  system structure and evolution

17. European THORPEX Interests in T-NAWDEX Focus on: Downstream evolution and impacts of wave guide disturbances by different dynamical processes HALO - High Altitude and Long Range Research Aircraft Oberpfaffenhofen, Germany, 24 January 2009 Key specifications: -max. altitude more than 15 km -range well above 10000 km or more than 10 flight hours -maximum payload of 3 tons Demo-Mission HALO-THORPEX as nucleus for T-NAWDEX field phase

18. T-NAWDEX Time Schedule 20091 st T-NAWDEX Planning Workshop 19/20 Feb. in Erding/Germany Writing of the Science Plan scientific aims, questions and methods (theoretical, numerical, experimental) Start of theoretical/modeling projects 2010Preparation of Implementation Plan UK FAAM T-NAWDEX Pilot Flights (Jan/March) further national/international cooperation and fund raising 2012Field experiment (in autumn)

19. Summary T-NAWDEX is an international PDP-oriented field THORPEX field experiment scheduled for autumn 2012 - plus accompanying theoretical/diagnostic/modeling studies It will primarily investigate the physical processes associated with the triggering, propagation and breaking of wave-guide disturbances and their representation in models and analyses Key words: PV gradients, jet stream, diabatic PV modification, ET, explosive cyclogenesis, warm conveyor belts, surface fluxes, turbulence, RW breaking, heavy precipitation, damaging surface winds Contributions to T-NAWDEX are welcome! Next (2nd) planning workshop: ~ spring 2010 Contact: Andreas Dörnbrackandreas.doernbrack@dlr.de Heini Wernliwernli@uni-mainz.de