AMMAAfrican Monsoon Multidisciplinary Analyses

Analyses Multidisciplinaires de la Mousson Africaine

Afrikanischer Monsun: Multidisziplinäre Analysen Analisis Multidiciplinar de los Monzones Africanos

Afrikanske Monsun : Multidisiplinære Analyser

Niger at Malanville: 2.106 km²

Factor 2

Annual rainfall & runoff deficit

How well do GCMs simulate the annual cycle?

GCMs tend to have

an early rainfall onset

+ higher precipitation

than really observed

Short background: West African Monsoon

• Still numerous fundamental issues:

# Reasons for the rainfall deficit are still uncertain (The largest regionally observed one over the last 50 years)

# GCM weakness for the simulation of WAM and its variability

# Weak skills for weather and seasonal forecasts

# WA an important source for atmospheric chemistry & aerosols: convective transports, exchanges tropo-strato, … not quantified

# Dynamical structures known but their interactions not quantified

# …

A major difficulty: Interactions of numerous processes that develop over a wide range of scales

The geophysical sphere

Integrative science:West African Monsoon and the global

climateThe water cycleSurface atmosphere feedbacksScaling issues in the West African Monsoon

Process studies:Convection and atmospheric processesOceanic ProcessesPhysical and biological processes over land-

surfacesAerosol and chemical processes in the

atmosphere

Process studies are only the first step towards a better understanding and prediction of the African monsoon

From a french initiative …towards AMMA 2000: French community selected the WAM as a major research topic with the support of the french agencies

(CNES, CNRS/INSU, IRD, Meteo-France) Observational and modeling activities exist over WA:

(CATCH, IMPETUS, JET2000, PROMISE, AMIP, individual works, ….) Need of coordination & re-enforcement Numerous coming satellites missions (research & operational) presenting a strong interest for the WAM (Clouds,

Aerosols, Chemistry, Hydrology) Need of specific & coordinated efforts over Africa Favorable international context: CLIVAR-Africa, GEWEX (GHP, GCSS, …), EU programs (WAMP, PROMISE, …), ... Help to re-enforce collaborations between countries & disciplinaries

2001: French proposition open at the International Community (White book) 2002: Increasing international activity to build up AMMA

Meetings in Africa (Niger), Europe (UK, Germany), USA Numerous researchers and agencies from African countries, Europe, USA have declared their strong interest to participate

2003: - AMMA becomes in France a ‘Inter-Organisms National Program’- AMMA Scientific Steering Committees exist in Africa (AMMANET), UK, US and France- First draft of International Science Plan is nearly finished- « Commitments » exist from funding agencies (USA, UK, France, Germany)- Projects endorsed by CLIVAR & GEWEX

2004: - AMMA becomes an European Integrated Project

- the AMMA International Scientific Steering Committee is formed (1st meeting July 26th).

African Monsoon Multidisciplinary Analyses

Analyses Multidisciplinaires de la Mousson Africaine Afrikanischer Monsun: Multidisziplinäre Analysen

Analisi Multidisciplinare per il Monsone AfricanoAfrikanske Monsun : Multidisiplinære Analyser

Analisis Multidiciplinar de los Monzones AfricanosAfrikaanse Moesson Multidisciplinaire Analyse

The European AMMA Integrated Project

A consortium of 40 partners

Coordination : IPSL

Core group :IRDU. LeedsU. KölnDLRCEHU CopenhagenCNRMU. East AngliaISAC/CNR

African partners :AGRHYMETCERMESEIERACMAD

Industrial partners :VaisalaOSIL

Other partners : CIRAD, ECMWF, IBIMET, KNMI, ...

The resources of the consortiumThe EU contribution to AMMA will enhance and federate national initiatives :Partner institutions : human resourcesFrance : INSU, IRD, CNES, Météo-France and MAE

are contributing to a national AMMA program.U.K. : NERC proposalGermany : IMPETUS and GLOWA-Volta projectsItaly : Proposal to national agenciesDenmark : INTEO project

A total of 578 person.years will be dedicated to the AMMA-IP over the next 5 years. 133 person.years will be funded by the EU.

The AMMA IP calendarOctober 2003 : the AMMA-IP pre-proposal submitted to the EU.December 2003 : Solicitation for a full proposal.February 2004 : full proposal submitted.June 2004 : Definition of the first 18 month plan and negotiation with the EU.October 2004 : Signature of the consortium agreement by all partners.December 2004 : signature of the contract with the EU.January 2005 : start of the project and the enhanced observing period.2006 : Special observing periods.2010 : end of the AMMA-IP project.

Descrip PERIODS 

Long Term Observation Period (LOP)Inter-annual and decadal variability Numerous historical data exist, but need of a tremendous effort to

collect, homogenize, document and distribute those data. New observations for the 2002-2010 period

Enhanced Observation Period (EOP) Two whole seasons (2005-2006-2007) Document along the zonal and meridional transects, the seasonal

cycle (surface & atmosphere) “Surface memory” Document the chemical species and aerosols

Special Observation Periods (SOP) Rainy season of 2006 (IOPs of 2 to 4 days)

SOP 1 Pre-monsoon & Onset stages (~ 10 May- 5 July)

SOP 2 Monsoon maximum (~ 15 July - 15 Aug)

SOP 3 Late Monsoon (~ 15 Aug. - 15 Sept)

 

The AMMA Periods of Observations

Importance of the Gulf of Guinea for the WAM?Importance of the Gulf of Guinea for the WAM?

+ High sea surface temperature (<=> fluxes) variability !

(cold tongue, equatorial and coastal upwellings, )

=> Northward penetration of moist air from the Gulf of Guinea up to

the Sahelian domain that strongly conditions the WAM (onset and intensity)

Feb. 2000 Aug. 2000

EGEE: EGEE: French oceanographic component of AMMAFrench oceanographic component of AMMA

Exchanges at the ocean-atmosphere interface : - Restitution of flux fields over the GG - Analysis from numerical OGCM - Experiments from high resolution models - Analyzis of the influence of surface heterogeneities

Circulation and oceanic processes in the GG (+ off Senegal+Guinea Dome): - Coastal and equatorial upwellings studies + Cold tongue - Mixing processes and water masses conversion studies - Currents and hydrological measurements + analysis - Zonal currents dynamic and their termination in the GG- Tropical Instability Waves Studies (Jason projects). - Coastal upwelling off Canaries (with ROMS numerical model)- Dispersion/diffusion experiment in the GG (numerical and profilers)

Hydrology of the upper layers in the GG :- Comparative studies of SST products- Salinity in the GG studies (barrier layer effet? Influence on dynamic and SST?). - Mixed Layer depth and heat content studies - Models results analysis and validation, diagnostic studies

LOP & EOPEGEEEGEE

 Measurements :SST, SSS, meteorological parameters, currents VM-ADCPProfiles CTD-O2 (0 - 1000 m) + currents L-ADCP + XBTSW Analysis for S, O2, nutrients, CO2, O18, C13 parametersDeployements of SVP & PROVOR (ARGO-CORIOLIS)? PIRATA moorings maintainingPerhaps: 12 Marvor drifters at 800m (resp. M.Ollitrault, LPO)

Cruises EOP (boreal spring and fall 2005 &

2007)

Cruises 2005 almost programmed

(Priority 1, with R/V SUROIT )

EGEEEGEECruise SOP-1 (boreal spring 2006)

Flux measurements Turbulent Fluxes Hydrological parameters Currents + nutrients

=> ? Deep layers with tracers ?

Atmospheric measurements at the interface : - Instrumented mast (or similar) for HF measurements (50Hz) of turbulence, Thermodynamical parameters and radiation (0.1Hz). -Radio-soundings (complementation of the radiosoundings network on the continent & sampling of the vertical profile of the flux entering over West African during the monsoon onset period. -Surface drifters “Marisonde”.  Mai-June : Cotonou -> section 3°E -> Pointe Noire -> Sao Tome -> CotonouJune-July : Cotonou -> section 3°E -> section 6°S -> 10°W -> Abidjan (?)

Repetition of the « Bénin » section at 3°E (to have measurements during the ITCZ latitudinal drop)=> Maybe a second R/V (Antéa) along the 3°E section

Almost programmed

(Priority 1, with R/V L’ATALANTE)

=> Air-Sea Interactions over warm waters in relationship with / during “cyclogenesis”- Atmospheric Mesurements at the interface- Radio-sounding- Drifting buoys “Marisonde” (surface & subsurface)  & maybe “Aeroclippers” from Cap Vert

=> During both SOP cruises: - Need of PIRATA buoys in the GG and farther west and north - Close connections with TACE project studies

- Links and coordination with TACE & US-AMMA cruises (Ron brown)- Links and coordination with IFM-Kiel in the framework of the EU IP.

EGEEEGEE Cruise SOP-3 (End August-September 2006)

- Dakar-> Cap Vert,

- Guinea Dome,

- 10°W.

Almost programmed (Priority 1)

2006 –SOP: US-AMMA & TACE field works implementation

+ attempts to get second R/V available, Antéa in the GG during SOP 1 off Bénin,Senegalese R/V during SOP 3 off Dakar

EGEEEGEELINKS WITH PIRATA, ARGO & CORIOLIS

Pirata FR11b -Feb.2003 ETO_Beautemps-Beaupré, -May.2003

Pirata FR12 -Jan-Feb.2004

- XBT- SVP- ARGO profilers- ADCP + Tsgraph…

Next one: Marion-Dufresne -July 2004

- Real time transmission of XBT and CTD profilesfor MERCATOR/GODAE (& ADCP from the Beautemps-Beaupré)

 

Measurements at SAO TOME Island (Equ., 6°E)

1) Installation ofa meteorological

station in October 2003

(same parameters than PIRATA buoys

eastward extension of

the PIRATAatmospheric measurements)

EGEEEGEE

 

EGEEEGEEFailed in December 2003!(rare electronic component failure…)Next intervention ASAP!!!

However, HF (10mn) measurements fromOctober, 17, 11h30 to December, 11, 24h.

Meteorological Station at São Tomé

24h measurements (Nov. 5, 2003)

Wind fields comparison:

EGEEEGEE Meteorological Station at São Tomé

Quickscat (black)-SãoTomé (red) Pirata 0-0 (blue); Quickscat (black); ECMWF (green)

Very first and raw conclusions:- Be careful to the used product…- Quickscat known to overestimate for weak wind speed values but about OK in open sea (pirata sites) - ? Effect of sensors height not corrected + orography effect on diffusiometry (Quickscat)

and probably on São Tomé measurements to evaluate!

For air-sea exchanges and flux estimates (=> & coupled models),urgent need of precise winds (& humidity) in situ measurements