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