© University of Reading T-NAWDEX/DOWNSTREAM conference call, 8 th Nov 2013 T-NAWDEX project Contribution from the UK John Methven and Suzanne Gray, Department of Meteorology, University of Reading Thanks to the DIAMET team. Figures from Geraint Vaughan, Jeffrey Chagnon, Tom Frame, Nigel Roberts, Alan Blyth & Chris Dearden

Building on 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

Science Objectives - to examine: I.Role of surface fluxes in cyclone development and WCB outflow –Behaviour of turbulent fluxes at high wind speed –Horizontal moisture flux convergence within BL –Influence on properties of WCB inflow –Sporadic nature of meridional heat fluxes and link to the climate research (taking obs relevant to them) –Influence of turbulent fluxes on sea state and forcing of ocean II.Two-way interaction between clouds and mesoscale dynamics –Importance of clouds for distribution of diabatic heating –Effects of heating on dynamics, vertical motion and cloud –Relation to turbulence and mixing within WCBs III.Transformation of air masses via diabatic processes and mixing –net change in θ and influence on WCB outflow structure

Science Objectives - to examine: IV.Structure and effects of diabatic PV anomalies –On induced circulation → indirect diabatic modification –PV lenses in WCB outflow and their effects on cloud, radiative transfer and remote diabatic PV anomalies (e.g., above tpp) –Influence of diabatic PV on downstream propagation V.Downstream impacts on predictability of mesoscale phenomena –How much is ensemble spread downstream influenced by diabatic processes upstream (e.g., Rodwell et al, BAMS, 2013)? –Relation to mesoscale structure and high impact weather? –Phenomena: frontal cyclones, multiple rainbands, sting jets, …

DIAMET Observations - and relation to science objectives I.Role of surface fluxes in cyclone development and WCB outflow Momentum exchange coefficient obtained from turbulence probe measurements from 26 flights. Stronger wind dependence than in current parameterisations. Requires straight legs at z=30-50m ASL. Wind direction important. Higher C D for cross-wind legs. Evidence for anisotropy in turbulence. Cook and Renfrew, QJ, 2013

DIAMET Observations - and relation to science objectives II.Interaction between clouds and mesoscale dynamics Example Distinctive precipitation banding observed on south side of intense cyclone (DIAMET IOP8) Vaughan et al, BAMS, submitted

DIAMET Observations - and relation to science objectives II.Interaction between clouds and mesoscale dynamics Example Distinctive precipitation banding observed on south side of intense cyclone (DIAMET IOP8) Aircraft crossed banding at several levels in strong wind region Vaughan et al, BAMS, submitted

DIAMET Observations - and relation to science objectives II.Interaction between clouds and mesoscale dynamics Cloud bands contain mixed phase Heating by deposition onto ice within bands, but evaporational cooling inbetween Wind speed lower within bands Both a signature of mesoscale circulations?

Recent research - and relation to science objectives III.Transformation of air masses by diabatic processes Example from T-NAWDEX pilot, flight 3 Collaboration between DIAMET and PANDOWAE WCB branches have similar origins, but WCB1 experiences stronger net heating, reaches higher θ and turns anticyclonically. Heating occurs in narrow line at cold front. WCB2 experiences slower ascent at later stage crossing warm front. Martinez-Alvarado, Joos et al, QJ, 2013

Recent research - and relation to science objectives IV.Structure and effects of diabatic PV anomalies Chagnon et al, QJ, 2013 PV tracers accumulate tendencies from different processes (in model) Total PV = sum of diabatic PV tracers + I.C. tracer e.g., flight 3 of T-NAWDEX pilot

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 (2013), Q J R Met S

Recent research - and relation to science objectives V.Downstream impacts on predictability of mesoscale phenomena Precipitation rate from 4 ensemble members of a high resolution forecast for the IOP8 cyclone. Trial of Met Office MOGREPS-UK ensemble (2.2km grid) Some members match radar out to T+36 for scales of 25km and greater – therefore some skill in forecasts of mesoscale banding Vaughan et al, BAMS, submitted

Recent research - and relation to science objectives V.Downstream impacts on predictability of mesoscale phenomena Wind speed (850 hPa) from the same 4 ensemble members. Strongest winds occur between the precip bands. Also, seen in surface obs. Implications for predictability of wind damage in intense cyclones. Vaughan et al, BAMS, submitted

I.Role of surface fluxes in cyclone development and WCB outflow –Low level aircraft legs with turbulence probe and high res SST –Near WCB inflow region (SE USA) –Frontal box patterns (along and across cold front) II.Two-way interaction between clouds and mesoscale dynamics –In situ aircraft legs with cloud physics instruments –Best aircraft position, East coast USA (in WCBs) –Research radar in the UK (Chilbolton) III.Transformation of air masses via diabatic processes and mixing –Quasi-Lagrangian expt with FAAM aircraft upstream at low levels, downstream aircraft in upper tropospheric ridge IV.Structure and effects of –ve PV lenses in WCB outflow –In collaboration with downstream aircraft V.Downstream impacts on predictability of mesoscale phenomena – Enhancing ground-based network across UK Observing strategy - and relation to science objectives

FAAM aircraft from NCAR C130 during RICO. Courtesy of Bjorn Stevens Observational capabilities FAAM aircraft and UK ground networks

One of the two pylons with cloud physics and and aerosol instruments. Cloud Probes: CIP-15 (Cloud Imagine probe)  m CIP-100 (Cloud Imaging probe)  m CDP (Cloud Droplet Probe), 2-50  m. CAPS (Cloud, Aerosol and Precipitation) 3V-CPI (Three-View Cloud Particle Imager) 2D-S (Stereo) probe. Images and  m. SID (Small Ice Detector). Aerosol Instruments: Aerosol Mass Spectrometer (AMS) Aerosol particle size distributions Radiation: Broadband Radiometers. Radiometers for various parts of EM spectrum. Range ~ 4.5-5hrs Science speed = 100 ms -1 Altitude ≈ 9km (300 hPa)

Ground-based instruments Radars: Chilbolton S-band (3 cm) Doppler, dual-polarisation radar FGAM Mobile X-band (10 cm) Doppler, dual-polar. radar Met Office network Doppler C-band (4-8 cm) radars. Now dual-polarisation providing radial wind component. Wind Profilers: MST, Aberystwyth. Met Office network + FGAM mobile wind profiler. Lidars: Several HALO Photonics Doppler lidars. FGAM mobile ozone and aerosol lidar. Met Office network of lidars coming into operation. Radiosonde stations: Four mobile (Leeds, Manchester, Reading and Met Office). FGAM mobile radar with the large Chilbolton radar. Met Office network radars

Timeline If T-NAWDEX experiment is to be in autumn Now - state interest in period with FAAM operations 2.March Outline bid to NERC large grant round 3.Dec 2014 – Full bid to NERC 4.June 2015 – Decision on funding 5.Oct 2015 – Earliest start of project