Diabatic modification of PV and weather systems John Methven, Department of Meteorology, University of Reading Thanks to the DIAMET team. Figures from Jeffrey Chagnon, Oscar Martinez-Alvarado, Geraint Vaughan, Laura Baker & Hylke de Vries

DIAbatic influences on Mesoscale structures in Extratropical sTorms DIAMET DIAbatic influences on Mesoscale structures in Extratropical sTorms Geraint Vaughan, Manchester PI John Methven, Reading PI Ian Renfrew, East Anglia PI Doug Parker, Leeds PI

Looking Ahead Ideas pulling together work within DIAMET National activities Relation to current NERC projects in SRM and CWC Future national activities International activities PANDOWAE-2 T-NAWDEX Falcon experiment THORPEX/WGNE conference on model errors Future of THORPEX and related WMO programmes T-NAWDEX international experiment plans

DIAMET Aims To describe the structure, origin and dynamical consequences of heating (condensation/evaporation on the mesoscale – e.g., fronts). To make a link between the simulation of mesoscale structure and forecasts of surface weather (high winds and precipitation). To investigate the implications for predictability and the skill of numerical weather prediction Especially convection-resolving forecasts (1-2 days)

Ideas for integrative work Contrast between winter and summer cyclone cases Relating structure of vertical motion to cyclone speed Water vapour transport and cloud processes Relation to hemispheric wave patterns on jetstream TEMPEST – representation in climate models Processing of air along WCBs Net modification associated with different processes Link with climate work on “atmospheric rivers” Origin and relevance of segmentation along cold fronts Shear instability and role of diabatic processes Link to severe weather (e.g. tornados) Predictive skill of convection-resolving ensembles Origin of predictability for “weather variables” Design of ensembles

Link to NERC programmes Storm Risk Mitigation TEMPEST Have submitted their papers for IPCC AR5 on representation of stormtracks in CMIP5 models Open to ideas linking in with DIAMET SRM integration project DEMON Flood action on 1st May 2012 case Changing Water Cycle HYDEF Statistics of atmospheric rivers from analyses and climate models PAGODA Stormtrack/blocking behaviour and link to heat waves/ water scarcity

Storm risk mitigation integration Project linking DIAMET, TEMPEST and DEMON (PIs: Len Shaffrey, John Methven and Kevin Hodges) Held metric workshop – characteristics of cyclones important to flooding Case study from summer 2007 using climate model down to 1.5km (Met Office Unified Model) Using 5-day accumulated precip (over UK) to sample long HIGEM climate run and pull out related cyclones Characteristics of these cyclones? Statistics of precipitation accumulations cf England-Wales Precip OK on daily, although low bias across precip histogram cf, ERA-Interim ~ 76% of EWP observed Extremes greatly underestimated for longer accumulations (relevant for flooding)

Future national programmes LWEC Drought Programme Call in November UK-centric Outline had two components Persistent behaviour in precipitation Links to large scale dynamics and blocking Angling for “predictability” rather than “climatology” Will probably have some hydrology component linking precip to river and ground water levels Impacts on environment, society and economy Trying to cover multi-disciplinary remit “messy” in town meeting in Birmingham (October 15th)

International Activities PANDOWAE-2 Linking with DIAMET (Oscar and Jeffrey) on WCBs Focus on T-NAWDEX pilot flight 24/11/09 Comparing humidity tracers influenced by different model processes in MetUM with similar partition using German COSMO model DIAMET using tracer fields and all processes PANDOWAE (Joos, Böttcher, Wernli) using trajectories and focus on microphysics (with finer partition between processes) Grand goal is a “virtual field experiment” considering systems on the North Atlantic waveguide and influence of diabatic processes on downstream development.

Periods of interest in autumn DIAMET field campaigns 16-30 Sep 2011 Frontal waves across UK 25 Nov – 15 Dec 2011 Severe cyclone sequence across Scotland (into Jan 2012) PANDOWAE case study focus 11 Sep 2011 Extratropical transition and downstream development 7-10 Oct 2011 Downstream development and extreme precip (N. Alps) 7-8 Nov 2011 “Medicane” and extreme precip (S. Alps)

International Activities T-NAWDEX Falcon experiment Aiming to perform quasi-Lagrangian experiment focussing on diabatic processes within warm conveyor belts Aircraft time: 5-18th October 2012 Achieved two IOPs: 11/12th Oct – WCB inflow over S. France eve of 11th (link with HYMEX) - downstream flight in WCB ascent over N. Italy 14/15th Oct – WCB inflow on eve of 14th - two flights sampling WCB: 9-13LT and 16-20LT

International Activities: THORPEX Meetings THORPEX conference on ensembles and predictability (Talagrand) Toulouse next week THORPEX/WGNE conference on model error (Andy Brown) Exeter, April 2013 Abstract deadline has just passed (officially) Remit to link model error with physical processes responsible research activity proposed by PDP/WGNE, two themes: extratropical cyclones monsoons Important because WGNE has strong influence on research priorities of operational centres DIAMET work very relevant to it

Total diabatic PV in section across tropopause fold Positive diabatic PV above (on strat side) of tropopause Negative diabatic PV beneath (on trop side) of tropopause Tropopause elevation not significantly altered by direct diabatic PV modification Chagnon, Gray and Methven, QJRMetS (2012)

Partitioning of diabatic PV among physical processes Boundary-lyr heating LW radiation Large-scale cloud Convection

Net diabatic PV near the tropopause Chagnon, Gray and Methven, QJRMetS (2012)

Ramifications for synoptic scale evolution PV conservation equation Using observation of little direct diabatic PV modification at tropopause: However, diabatic effects are felt mainly through induced wind, ui Indirect PV modification by diabatic processes via changes to winds. Links directly with moist baroclinic wave theory (De Vries et al, 2010). Cooperative coupling between diabatic PV in troposphere and Rossby waves along tropopause or lower boundary.

Shading = total diabatic PV anomaly (8.8 km level) Dashed contour = 2PVU for advection-only PV Solid contour = 2PVU for total PV Positive diabatic PV above (on strat side) of tropopause Negative diabatic PV beneath (on trop side) of tropopause Tropopause elevation not significantly altered by direct diabatic PV modification Chagnon, Gray and Methven, QJRMetS (2012)

Diabatic PV near the tropopause Implications for Stratosphere-troposphere exchange LW cooling max at tropopause  “diabatic PV dipole” but no direct PV change at tropopause + continuous diabatic mass transport downwards across tpp. Theory of moist baroclinic waves – growth and propagation

International Activities: THORPEX and beyond Currently has 3 WGs: Predictability and Dynamical Processes, TIGGE/GIFS and Data Assimilation and Observing Systems. DAOS  its own WWRP programme with wider remit TIGGE  group will merge with new activity on subseasonal-seasonal prediction (new database of longer-range forecasts like TIGGE) PDP  disbanding Some WG activity continuing in “polar prediction project” Not a WG relating to mid-latitude predictability and dynamics Group may merge into WGNE

T-NAWDEX International Experiment Re-igniting international experiment that was thwarted by HALO delays. Science remit related to DIAMET but with focus on systems crossing North Atlantic and influences on the waveguide. Still linking to high impact weather forecasts (but longer lead time) German/Swiss (Heini Wernli) PANDOWAE-2 will end 2014 – no continuation Jones and Craig planning a different “weather consortium” HALO and Falcon possible USA (Pat Harr) Strong interest – Chris Davis, Lance Bosart + NCAR mesoscale Want to use G-V (similar to HALO) Need cost estimate by 15th Nov 2012 Need science objectives and experimental design docs by Jan 2013 Earliest field phase would be autumn 2015 France (Gwendal Riviere) Has project similar to PANDOWAE – invited to re-submit in Jan 2013

How would this group like to proceed? DIAMET has been successful in bringing together weather, dynamics and predictability research across UK Bringing together obs, process understanding and prediction in a concrete fashion Better integration between NCAS and NCEO on weather Building activity with Met Office across more groups DIAMET has been a high profile project for them It has been fun! A small community (cf climate) There is more to “climate” than simulation

Trajectory analysis 1800 UTC Wind speed (shading) 650-hPa Relative humidity (RH>80% stippled) 850-hPa Equivalent potential temperature Trajectory position (black dots)

Trajectory analysis 1200 UTC Pressure (hPa) Height (m) Wind speed (m s-1) Relative humidity (%)

Preliminary results IOP8 DIAMET IOP8 cyclone did contain a sting jet Air descending from tip of cold conveyor belt into hook Observed twice, before and after Scotland? First aircraft observations through a sting jet cyclone Cloud banding around cyclone was not slanting Origin of banding? Q.Is evaporation of ice falling into dry air essential for bringing sting jet winds towards ground?

Feature tracking in ensembles Cyclone Friedhelm 8th Dec 2011 (T+36hr) Here cyclonic features coloured by max wind speed at 1km within a 300km radius Cyclonic features identified using methodology of Hewson and Titley (2010), Met. Apps. Identified from the 23 forecasts of the Met Office MOGREPS ensemble

Evolution of one ensemble forecast