Bourles_AMMA by jizhen1947

VIEWS: 368 PAGES: 21

									AMMA
    African Monsoon Multidisciplinary Analyses
Analyses Multidisciplinaires de la Mousson Africaine
 Afrikanischer Monsun: Multidisziplinäre Analysen
 Analisis Multidiciplinar de los Monzones Africanos
  Afrikanske Monsun : Multidisiplinære Analyser
Annual rainfall & runoff deficit




                                   Factor 2
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
                               climate
                                The water cycle
                                Surface atmosphere feedbacks
                                Scaling issues in the West African Monsoon


                               Process studies:
                                Convection and atmospheric processes
Process studies are only the    Oceanic Processes
first step towards a better     Physical and biological processes over land-
understanding and prediction   surfaces
of the African monsoon          Aerosol and chemical processes in the
                               atmosphere
                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 Africano
   Afrikanske Monsun : Multidisiplinære Analyser
 Analisis Multidiciplinar de los Monzones Africanos
   Afrikaanse Moesson Multidisciplinaire Analyse




 The European AMMA Integrated Project
            A consortium of 40 partners
 Coordination : IPSL
Core group :                 African partners :
 IRD                          AGRHYMET
 U. Leeds                     CERMES
 U. Köln                      EIER
 DLR                          ACMAD
 CEH
 U Copenhagen
 CNRM                        Industrial partners :
 U. East Anglia               Vaisala
 ISAC/CNR                     OSIL


Other partners : CIRAD, ECMWF, IBIMET, KNMI, ...
       The resources of the consortium
The EU contribution to AMMA will enhance and federate
national initiatives :
 Partner institutions : human resources
 France : INSU, IRD, CNES, Météo-France and MAE are
contributing to a national AMMA program.
 U.K. : NERC proposal
 Germany : IMPETUS and GLOWA-Volta projects
 Italy : Proposal to national agencies
 Denmark : 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 calendar

 October 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.
         The AMMA Periods of Observations

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)
Importance of the Gulf of Guinea for the WAM?




      => 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




                 + High sea surface temperature (<=> fluxes) variability !
                     (cold tongue, equatorial and coastal upwellings, )
EGEE:   French 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
EGEE                     LOP & EOP

  Cruises EOP (boreal spring and fall 2005 & 2007)


Cruises 2005 almost programmed
(Priority 1, with R/V SUROIT )




        Measurements :
       SST, SSS, meteorological parameters, currents VM-ADCP
       Profiles CTD-O2 (0 - 1000 m) + currents L-ADCP + XBT
       SW Analysis for S, O2, nutrients, CO2, O18, C13 parameters
       Deployements of SVP & PROVOR (ARGO-CORIOLIS)
       ? PIRATA moorings maintaining
        Perhaps: 12 Marvor drifters at 800m (resp. M.Ollitrault, LPO)
EGEE
                                    Cruise SOP-1 (boreal spring 2006)
Almost programmed
(Priority 1, with R/V L’ATALANTE)

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 -> Cotonou
   June-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
EGEE                       Cruise SOP-3 (End August-September 2006)
Almost programmed
(Priority 1)

- Dakar-> Cap Vert,
- Guinea Dome,
- 10°W.




       => 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.
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
                    LINKS WITH PIRATA, ARGO & CORIOLIS
EGEE        Pirata FR11b -Feb.2003              ETO_Beautemps-Beaupré, -May.2003




       Pirata FR12 -Jan-Feb.2004
                                                    Next one: Marion-Dufresne -July 2004
                                         - XBT
                                         - SVP
                                         - ARGO profilers
                                         - ADCP + Tsgraph
                                         …




            - Real time transmission of XBT and CTD profiles
            for MERCATOR/GODAE
            (& ADCP from the Beautemps-Beaupré)
EGEE      Measurements at SAO TOME Island (Equ., 6°E)
                                                      1) Installation of
                                                     a meteorological
                                                  station in October 2003


                                                    (same parameters than
                                                        PIRATA buoys
                                                             
                                                     eastward extension of
                                                          the PIRATA
                                                  atmospheric measurements)




   2) Tide gauge maintained by IRD since 1980s.
   - Pressure, Atm. pressure + SST & SSS.
   - Part of GLOOS.
   - GPS positioned (in December 2002)
EGEE                       Meteorological Station at São Tomé

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

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




                                                24h measurements (Nov. 5, 2003)
EGEE                        Meteorological Station at São Tomé

                        Wind fields comparison:
   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

								
To top