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) Asencio Barthe Chong max dBZ 400x400km max dBZ 200x200km 25 Jul26 Jul27 Jul model configuration 10 km grid / x,y 5 km grid / x,y 2.5 km grid / x,y init & bound. cond.: NWP analysis ecoclimap, 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 ARPEGE analysis ECMWF analysis land surface modelling 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)

Agadez June 2006 TOGA-COARE Tropical Pacific 4-month average Parakou Aug 2006 Niamey JJAS 2006  v at different sites Parakou Niamey Agadez (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q RH wind speed  e 06 h 12 h 18 h 24h

10 July 2006 Niamey from soundings almost no surface evapotranspiration

10 July 2006 Niamey from soundings almost no surface 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 data Sahel, Gourma (15°N) daytime monthly composites

surface met data Sahel, 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) 18h20 17h20 16h40 reflectivity (x,y) (dx,dy~1km, dz ~ 1km) 16h (dx,dy~600m, dz ~ 300m) (high-pass filtered) 60km 100 km 10 km 100 km 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 model not 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 model not much synoptic activity (african easterly waves) estimated advection : weak fairly distinct from regimes explored so far e.g. LBA SGP case-studies parametrized conv. too early here could be too late... the case-study : first SCM simulations from 2 models LMDZ : C. Rio & MesoNH : A. Gounou

liquid water content cloud liquid water (g/kg) (g/kg) LMDZmesoNH a 1 st glance at SCM results hour in day (mb)(km) For more see Poster Catherine Rio et al. 06 h 12 h 18 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