amma-based case-studies major interest and difficulty of the west africa monsoon : involves about...
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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
AMMA-based case-studies
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
F. Guichard, with material from N. Asencio, A. Gounou, C. Rio, D. Bouniol, B. Campistron F. Couvreux, M. Chong, M. Lothon, A. Boone
AMMA-based case-studies
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
F. Guichard, with material from N. Asencio, A. Gounou, C. Rio, D. Bouniol, B. Campistron F. Couvreux, M. Chong, M. Lothon, A. Boone
AMMA-based case-studies
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)
F. Guichard, with material from N. Asencio, A. Gounou, C. Rio, D. Bouniol, B. Campistron F. Couvreux, M. Chong, M. Lothon, A. Boone
AMMA-based case-studies
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)
3) interactions & coupling among processes operating within the monsoon system: 2D “idealized” framework (Peyrille et al 2007), AMMA-CROSS (Hourdin et al.)
F. Guichard, with material from N. Asencio, A. Gounou, C. Rio, D. Bouniol, B. Campistron F. Couvreux, M. Chong, M. Lothon, A. Boone
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
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