amma-based case-studies major interest and difficulty of the west africa monsoon : involves about...

AMMA-based case-studies

major interest and difficulty of the West Africa monsoon : involves about every type of moist convective phenomena occuring over land

F. Guichard, with material from N. Asencio, A. Gounou, C. Rio, D. Bouniol, B. Campistron F. Couvreux, M. Chong, M. Lothon, A. Boone


major interest and difficulty of the West Africa monsoon : involves about every type of moist convective phenomena occuring over land shallow cloudy boundary layers from thick semi-arid to shallower very moist ones




deeper precipitating convection from daytime convective elements to wide mesoscale squall lines





case-studies addressing

1) development of daytime convection : SCM-CRM-LES-framework + datasets

2) MCS, their interactions with processes at smaller and larger scales (e.g. surface): 3D high-resolution mesoscale simulations (obs at scales, LSM products)





case-studies addressing

1) development of daytime convection : SCM-CRM-LES-framework + datasets

2) MCS, their interactions with processes at smaller and larger scales (e.g. surface): 3D high-resolution mesoscale simulations (obs at scales, LSM products)

3) interactions & coupling among processes operating within the monsoon system: 2D “idealized” framework (Peyrille et al 2007), AMMA-CROSS (Hourdin et al.)


regarding 2) ORGANIZED CONVECTION, 1-3 DAY, MESO TO SYNOPTIC SCALES

25 July 2006, 9Z

sat. IR imagery (tracking)

MIT radar

(m)

aim/challenge: matching major features of observed situation (question of relevance of findings)

AsencioBartheChong

max dBZ 400x400km

max dBZ 200x200km

25 Jul 26 Jul 27 Jul

model configuration

10 km grid / x,y5 km grid / x,y

2.5 km grid / x,y

init & bound. cond.: NWP analysisecoclimap, ISBA

mesoNH

Validation of simulation (here with radar)

wide use of NWP analysis

20°~

2000km

35° / lon (~3500 km)

soil wetness index SWI

considerations about : surface energy balance & initialization of soil moisture

ARPEGEanalysis

ECMWFanalysis

land surfacemodelling

From offline LSM runs using “observed” rainfall

& incoming radiative fluxes

recent experience built from a case-study simulated by 6 mesoscale models using different configurations (large MCS within an active wave phase)

able to simulate a propagating mesoscale raining feature when using same analysis, but:different speeds, significantly distinct latitudinal migrations & of course various rainfall rates

problems with surface evapotranspiration, links to LSM, rainfall, but also, strongly, due to misrepresentations of clouds, through their radiative properties (surface incoming radiation)

high sensitivity to the passage from “parametrized” to “resolved” moist convection: smaller meso-scales emerge at tens of km for dx=4km northward propagation more significant

(“case-dedicated database” exists for those interested in testing their model)

AgadezJune2006

TOGA-COARETropicalPacific4-monthaverage

ParakouAug 2006

NiameyJJAS 2006

v at different sites

Parakou

NiameyAgadez

(RS per day)

different lands...

more on different lands...

15°N(central Sahel)

15°N(Soundanian zone)

lifting condensation level LCL

(2m met station data)

2 km

4 km

(from D. Bouniol)

cloud base height

ARM mobile facility

DAYTIME MOIST CONVECTION IN A SEMI-ARID ENVIRONMENT

fairly common situation... developed within the MIT radar field of view + AMF + sfc ORE CATCH data

10 July 2006 modelling case study Rio et al. (poster) - identified from

obs by Lothon et al.

DAYTIME MOIST CONVECTION IN A SEMI-ARID ENVIRONMENT

v q RH wind speed

e

06 h12 h18 h24h

10 July 2006Niameyfrom soundings

almost nosurface evapotranspiration

10 July 2006Niameyfrom soundings

almost nosurface evapotransp.(max H ~300W.m-2)

to be compared to SGP late June

surface evaporative fraction ~ 70-80%this day (max H ~100W.m-2)

surface met dataSahel, Gourma (15°N)daytime monthly composites

Niamey in June, all morning soundings [4 UTC, 7 UTC]

Niamey in June, all midday soundings [10 UTC, 13 UTC]

Niamey in June, all late afternoon soundings [16 UTC, 19 UTC]

Niamey in June, monthly composite per hour of day

~ 06 h~ 12 h~ 18 h~ 24h

horizontal cross-section of reflectivity (z=600m)

18h2017h2016h40

reflectivity (x,y)

(dx,dy~1km, dz ~ 1km)

16h (dx,dy~600m, dz ~ 300m)

(high-pass filtered)

60km

60

km

100 km

10 km

100 km

10

0 k

m

restitution of winds

the case-study as seen from the MIT radar (E. Williams & colleagues) processed/analysed by Chong & Lothon

vertical cross-section of reflectivity (z=600m)

from morning rolls

to afternoon deeper convective cells

the case-study : set-up (suitable for SCM, LES, CRM)

initialization - from 6Z early morning sounding - from land surface model outputs (ISBA year 2006 offline simul.) boundary conditions - advection, vertical velocity estimated from ECMWF analysis (6h, 100*100 km2 area) - 1-h surface flux data for simulations without a land surface modelnot much synoptic activity (african easterly waves) estimated advection : weak

the case-study : set-up (suitable for SCM, LES, CRM)

initialization - from 6Z early morning sounding - from land surface model outputs (ISBA year 2006 offline simul.) boundary conditions - advection, vertical velocity estimated from ECMWF analysis (6h, 100*100 km2 area) - 1-h surface flux data for simulations without a land surface modelnot much synoptic activity (african easterly waves) estimated advection : weak

fairly distinct from regimes explored so far e.g. LBA SGP case-studiesparametrized conv. too early

here could be too late...

the case-study : first SCM simulations from 2 models LMDZ : C. Rio & MesoNH : A. Gounou

01234567

900

800

700

600

500

400

3000.240.20.180.140.120.10.060.040

liquid water content0.08

0.07

0.06

0.05

0.04

0.03

0.02

0.01

0

cloud liquid water

(g/kg)

8 101214161820 6 9 12 15 18 21 24

(g/kg)LMDZmesoN

H

a 1st glance at SCM results

hour in day hour in day

(mb)

(km

)

For more

see Poster Catherine Rio et al.

06 h12 h18 h

In summary

choice of a well-suited case-study regarding both sicentific objective & availability of data * data analysis, data use, in close collaboration with “observers” + links with scientists working on related topics surface processes, larger scales, radiation... ...this is needed...

* design of a case-study initialisation of atmosphere & surface larger scale advection

* first SCM simulations performed, distinct “land environment”

for the future : conduct 3D high-resolution simulations in // process analysis, more budgets exploration of sensitivities sensitivities of parametrizations

amma-based case-studies major interest and difficulty of the west africa monsoon : involves about...

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