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WMO workshop, Hamburg, July, 2004
Some aspects of the STERAO case study simulated by
Méso-NH
by
Jean-Pierre PINTY, Céline MARIChristelle BARTHE and Jean-Pierre CHABOUREAU
Laboratoire d’Aérologie, Toulouse
<http://www.aero.obs-mip.fr/mesonh>
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 NOx 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, 2004
-
z
CVPACCRPAUTOr
C
t
C
dt
Cd
PACCRPAUTOr
C
t
C
dt
Cd
t
C
dt
Cd
rr
SEDc
cr
MT
r
c
cc
MT
c
g
MT
g
)ρ()(ρ)ρ(
***)ρ(
)(ρ)ρ(
***)ρ(
)ρ(***
)ρ(
gas phase: Cg and 2 aqueous phases: Cc (cloud droplets), Cr (raindrops)
)Kk()rk()ρ(
H,tc,c,tc, coutginc
MT
CRCRt
C
With Mass Transfer terms as in Chaumerliac et al., 1987, Barth et al., 1992, …
ktc: mass transfer coef. (particle size dependent)KH: 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, H2O2, HNO3
• profiles of CO, NOx, O3
• 3 hour run on the 12 LINUX cluster @ LA
Ice and Wind fieldsT=1 hour @ Z=10 km
WMO workshop, Hamburg, July, 2004
Upper level flow @ z=10 km
Time = 1 hour Time = 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/mFlash length < 1000 km/min
Microphysical fields
Radarreflectivity
Gravity waves
Graupels(coloured)
Rain
Ice+Snow
Time = 1 hour Time = 2.5 hours
WMO workshop, Hamburg, July, 2004
Mixing ratio and Z peak values
Radar reflectivity < 45 dBZwhich is less than observed Presence of hail ?
Rc max ~ 4.0 g/kgRr max ~ 2.0 g/kgRi max ~ 1.5 g/kgRs max ~ 1.0 g/kgRg max ~ 9.0 g/kg
Transport of H2O, CO and O3 (1)
WMO workshop, Hamburg, July, 2004
Stratosphere
Stratosphere
5 %<Relative Humidity<95 %
75 ppb<CO<130 ppb
50 ppb<O3<130 ppb
Time = 1 hour
Transport of H2O, CO and O3 (2)
WMO workshop, Hamburg, July, 2004
Stratosphere
5 %<Relative Humidity<95 %
75 ppb<CO<130 ppb
50 ppb<O3<130 ppb
Stratosphere
Time = 2.5 hours
Gas Transport & Scavenging
WMO workshop, Hamburg, July, 2004
Stratosphere
HCHO
H2O2
HNO3
(Scale is [0, 2 ppb])
Time = 2.5 hours
WMO workshop, Hamburg, July, 2004
LNOx production @ z=10 km
Time = 1 hour Time = 2.5 hours
The net LNOx production rate is continuously derived from the electricalscheme with LiNOx)/t = F(Lflashafter Wang et al. (2000)
Peak value ~ 3.5 ppb Peak value ~ 0.1 ppb
High spatial and temporal variability
LNOXscale in ppb
LNOXscale
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
dzCdx
dzdxdyCdzlUCyxFluxHoriz
]vu[ρ
])vu([ρ)(][ρ),(.
Ztop
Zbase
22
Ztop
Zbase
Ztop
Zbase
dzyxSurfaceFlux ]vudy)vdxu[(),(.Ztop
Zbase
22
yxyxSurfaceFluxyxFluxHorizDensityFlux
,),(.),(..
WMO workshop, Hamburg, July, 2004
Anvil flux densities(where rglace > 0.01g/kg)
Lightning NOx flux is{LNOx-TNOx} flux
Max flux (air) = 5.46 kg/m2/sMax flux (CO) = 1.90 e-5 mole/m2/sMax flux (O3) = 2.28 e-5 mole/m2/sMax flux (NOx) = 4.65 e-8 mole/m2/s
WMO workshop, Hamburg, July, 2004
Anvil flux densities(where rglace > 0.01g/kg)
After 3 hours:
Flux (HCHO) = 1.11 e-7 mole/m2/sFlux (H2O2) = 1.10 e-7 mole/m2/sFlux (HNO3) = 8.41 e-8 mole/m2/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 NOx fieldInstantaneous peak value ~ 8 ppb
Total mass max ~ 8800 kg