Electricité atmosphérique et Production d’oxydes d’azote par les éclairs: Etat des lieux et perspectives Christelle Barthe 1 et Jean-Pierre Pinty Laboratoire d’Aérologie 1 Now at National Center for Atmospheric Research 4 th Meso-NH user’s MeetingApril 23-24, 2007

4 th Meso-NH user’s MeetingApril 23-24, 2007 ice water content [Petersen et al., 2005] ice flux [Deierling, 2006] precipitation rate [Baker et al., 1995; Soula and Chauzy, 2001] NO x production [Lee et al, 1997; Huntrieser et al., 1998] water vapor in the upper troposphere [Price, 2000] climate change index [Reeve and Toumi, 1999] tropical cyclones intensification [Molinari et al., 1994; Fierro et al., 2007] … - A better understanding of a cloud natural process … - An index of storm severity : hail, heavy precipitations, gust winds and … lightning flashes - Lightning flashes are routinely detected  tracers of physical parameters ? Why to model the lightning flashes ?

4 th Meso-NH user’s MeetingApril 23-24, 2007 Meso-NH-elec : flow chart Charges separation Charges transfer and transport Electric field computation Bidirectional leader Branches Charge neutralization NO x production E > E trig E > E prop Dynamical and microphysical processes yes no yes Barthe et al. [2005] Vertical extension of the flash Horizontal extension of the flash

4 th Meso-NH user’s MeetingApril 23-24, 2007 Lightning flashes structure Volume of charge neutralized by an individual flash Barthe and Pinty [2007] Rison et al. [1999] Electric charges are neutralized along the flash channel leading to a decrease of the electric field

4 th Meso-NH user’s MeetingApril 23-24, 2007 Lightning-produced NOx – July 10, 1996 STERAO storm  Physical packages transport : MPDATA microphysics : ICE3 [ Pinty et Jabouille, 1998] electrical scheme [ Barthe et al., 2005] gas scavenging [C. Mari] LiNOx [ Barthe et al., 2007]  flash length and depends on the altitude  n NO (P) = a + b x P (10 21 molecules m -1 ) [ Wang et al., 1998] turbulence 3D : TKE [ Cuxart et al., 2000]  Initialization 10 July STERAO storm 160 x 160 x 50 gridpoints with  x =  y = 1 km and  z variable initial sounding + 3 warm bubbles [ Skamarock et al., 2000] chemical species profiles (HCHO, H 2 O 2, HNO 3, O 3, CO and NO x ) [ Barth et al., 2001]

4 th Meso-NH user’s MeetingApril 23-24, 2007 July 10, 1996 STERAO storm: transition from multicell to supercell 2202 UTC 0102 UTC Meso-NH : 2048 flashes Defer et al. [2001] : 5428 flashes with 50% short duration flashes (< 1 km)

4 th Meso-NH user’s MeetingApril 23-24, 2007 July 10, 1996 STERAO storm: LNOx production NO concentrations measured by the Citation at 11.6 km msl from 2305 to 2311 UTC, km downwind of the core [Dye et al., 2000]  transport of NO x from the boundary layer to the upper troposphere (~ 200 pptv)  LNOx production between 7500 and 13,500 m (peak value ~ 6000 pptv) and dilution (~ 1000 pptv) Vertical cross section of the NO x concentration and the total electric charge density (±0.1, ±0.3 and ± 0.5 nC m -3 ) in the multicellular stage Barthe et al. [2007]

4 th Meso-NH user’s MeetingApril 23-24, 2007 July 10, 1996 STERAO storm: intercomparison exercise Intercomparison exercise STERAO: July 10, 1996 Barth et al., to be submitted to ACPD

4 th Meso-NH user’s MeetingApril 23-24, 2007 Conclusions  Full electric charge cycle in a mesoscale model charges separation, transfer, transport and neutralization  Lightning flash treatment original branching scheme with wide horizontal extension good neutralization efficiency of the flash scheme  Explicit formation of lightning-produced NO x great potential for gaseous chemistry  Simulations in different idealized convective conditions squall line, supercell, multicell storms in 2D and 3D  Cloud electrification crucial to reproduce the cloud polarity high sensitivity to the treatment of the NI processes [Barthe and Pinty, J. Geophys. Res., in revision] part of the code is implemented in the UK MetOffice LEM  Ensemble simulations of electrified clouds [Pinty and Barthe, submitted to Month. Wea. Rev.]

4 th Meso-NH user’s MeetingApril 23-24, 2007 Perspectives  Parallelization efficiency of the lightning algorithm  Integration of the full electrical scheme in the next (4.8) version of Meso-NH ? (***)  Explicit treatment of the ions (**)  Sensitivity to surface properties for coronae effects (*)  Real case simulations: MAP, TELEX, STEPS, AMMA, Mediterranean storms, COPS … (***)  LNOx impact on some chemical species: HNO 3, O 3 … (***)