WMO workshop, Hamburg, July, 2004 Some aspects of the STERAO case study simulated by Méso-NH by Jean-Pierre PINTY, Céline MARI Christelle BARTHE and Jean-Pierre CHABOUREAU Laboratoire d’Aérologie, Toulouse

WMO workshop, Hamburg, July, 2004 Multidisciplinary modeling of the STERAO case study Dynamics: resolved and turbulent flow Microphysics: mixed-phase processes Chemistry: Transport of +/- soluble species Electricity: lightning flash and NO x production (simulations performed on a large domain but at moderate resolution,  x=1km)  Strong coupling between the flow structure, the water cycle, the cloud electrisation and the scavenging of gases  Requires a simultaneous integration of all the processes

Kinetic approach of mass transfer for soluble gases WMO workshop, Hamburg, July, gas phase: C g and 2 aqueous phases: C c (cloud droplets), C r (raindrops) With Mass Transfer terms as in Chaumerliac et al., 1987, Barth et al., 1992, … k tc : mass transfer coef. (particle size dependent) K H : Henry’s law coef.

Flow chart of the electrical scheme Microphysical and dynamical processes Charge separation and exchange Charge transport Electric field computation ||E|| > ||E|| trig no Lightning channel radial extension Lightning channel vertical extension Bi-leader phase ||E|| > ||E|| prop Pseudo-fractal scheme Partial neutralization of charges yes WMO workshop, Hamburg, July, 2004

Set-up of Méso-NH Domain horizontal grid : 120 x 120 points at 1 km resolution with open LBC 50 levels : from 70 m (bot) up to 600 m (top) with wave damping Physics transport with MPDATA scheme microphysics: Pinty-Jabouille electricity: Barthe-Pinty-Molinié gas scavenging & LiNOx: Mari-Pinty 3D turbulence (TKE): Cuxart-B-R Initialization R/S with 3 warm bubbles (3K) profiles of HCHO, H 2 O 2, HNO 3 profiles of CO, NO x, O 3 3 hour run on the 12 LINUX LA Ice and Wind fields T=1 Z=10 km

WMO workshop, Hamburg, July, 2004 Upper level z=10 km Time = 1 hourTime = 2.5 hours W~45 m/s A B W~25 m/s C D

WMO workshop, Hamburg, July, 2004 Peak vertical velocity /electrical activity Multicell stage Transition to Supercell Electric field < 200 kV/m Flash length < 1000 km/min

Microphysical fields  Radar  reflectivity Gravity waves Graupels (coloured) Rain Ice+Snow Time = 1 hourTime = 2.5 hours

WMO workshop, Hamburg, July, 2004 Mixing ratio and Z peak values Radar reflectivity < 45 dBZ which is less than observed  Presence of hail ? Rc max ~ 4.0 g/kg Rr max ~ 2.0 g/kg Ri max ~ 1.5 g/kg Rs max ~ 1.0 g/kg Rg max ~ 9.0 g/kg

Transport of H 2 O, CO and O 3 (1) WMO workshop, Hamburg, July, 2004 Stratosphere 5 %<Relative Humidity<95 % 75 ppb<CO<130 ppb 50 ppb<O 3 <130 ppb Time = 1 hour

Transport of H 2 O, CO and O 3 (2) WMO workshop, Hamburg, July, 2004 Stratosphere 5 %<Relative Humidity<95 % 75 ppb<CO<130 ppb 50 ppb<O 3 <130 ppb Stratosphere Time = 2.5 hours

Gas Transport & Scavenging WMO workshop, Hamburg, July, 2004 Stratosphere  HCHO H 2 O 2   HNO 3 (Scale is [0, 2 ppb]) Time = 2.5 hours

WMO workshop, Hamburg, July, 2004 LNOx z=10 km Time = 1 hourTime = 2.5 hours The net LNOx production rate is continuously derived from the electrical scheme with  LiNOx)/  t = F(L flash  after Wang et al. (2000) Peak value ~ 3.5 ppbPeak value ~ 0.1 ppb  High spatial and temporal variability LNOX scale in ppb LNOX scale in 100 ppt

WMO workshop, Hamburg, July, 2004 Conclusion and Perspectives STERAO is a good modeling exercise for several aspects of the deep convection: dynamics and microphysics gas transport and scavenging cloud electricity and LNOx production Results are recent and need a careful evaluation against the available dataset Model runs on a larger domain to produce more realistic fluxes and budgets Parts of the model will be improved lightning flash algorithm inclusion of the ice phase for the gas scavenging careful evaluation of the LNOx production rate

WMO workshop, Hamburg, July, 2004 Anvil flux density computation

WMO workshop, Hamburg, July, 2004 Anvil flux densities (where  r glace > 0.01g/kg) Lightning NOx flux is {LNOx-TNOx} flux Max flux (air) = 5.46 kg/m 2 /s Max flux (CO) = 1.90 e-5 mole/m 2 /s Max flux (O 3 ) = 2.28 e-5 mole/m 2 /s Max flux (NO x ) = 4.65 e-8 mole/m 2 /s

WMO workshop, Hamburg, July, 2004 Anvil flux densities (where  r glace > 0.01g/kg) After 3 hours: Flux (HCHO) = 1.11 e-7 mole/m 2 /s Flux (H2O 2 ) = 1.10 e-7 mole/m 2 /s Flux (HNO 3 ) = 8.41 e-8 mole/m 2 /s

WMO workshop, Hamburg, July, 2004 Precipitation field 3 hour rainfall ~ 6.2 mm Instantaneous rate < 25 mm/h « Cell pulsating » precipitation pattern

WMO workshop, Hamburg, July, 2004 Lightning NO x field Instantaneous peak value ~ 8 ppb Total mass max ~ 8800 kg