Physical oceanography in the Gulf of Guinea

Physical oceanography in the Gulf of Guinea PLAN 1. Recalls & scientific context 2. International & regional programs and main goals of EGEE/AMMA, PIRATA & TACE (this presentation) 3. What is RIPIECSA and goals of RIPIECSA-Ocean 4. Goals and discussions about RIPIECSA-Ocean

1: PIRATA (Pilot Research moored Array in the Tropical Atlantic) (1997-200??) Tripartite Programme as a contribution to CLIVAR, GCOS and GOOS : - FRANCE (IRD & Météo-France) - BRAZIL (INPE & DHN) - USA (NOAA/PMEL & AOML) * 1997-2001 : «Pilote» period * 2001-2006 : Consolidation period 2006-2008 : continuation PIRATA has been under review process (positive ) by CLIVAR and Ocean Observations Panel for Climate -OOPC- in 2006 2007: Editing of a new Memorandum of Understanding, for 2008-2012 Define the commitments of the partners for the next years Photo: A.Kartavtseff

Scientific main goals of PIRATA : The overarching goals of the PIRATA program are to: - improve the description of the intra-seasonal to inter-annual variability in the atmospheric and oceanic boundary layers in the tropical Atlantic; - improve our understanding of the relative contributions of airsea fluxes and ocean dynamics to variability in sea surface temperature (SST) and sub-surface heat content at intraseasonal to interannual time scales; - provide a set of data useful for developing and improving the predictive models of the ocean-atmosphere coupled system; - document interactions between tropical Atlantic climate and variability outside the region, including the Pacific ENSO, the North Atlantic Oscillation, and the Southern Annular Mode; -design, deploy, and maintain an array of moored oceanic buoys and collect and transmit a set of oceanic and atmospheric data, via satellite in real-time, to monitor and study the upper ocean and atmosphere of the tropical Atlantic. (from Bourlès et al., submitted in BAMS, 2007)

PIRATA Steering Scientific Committee : 2006-2007 Bernard Bourlès (Co-Chair), IRD/LEGOS, France Edmo Campos (Co-Chair), USP, Brazil Rick Lumpkin (Co-Chair), NOAA/AOML, USA Fabrice Hernandez, IRD/US025, France Michael McPhaden, NOAA/PMEL, USA Paulo Nobre, INPE, Brazil Serge Planton, Météo-France, France Lisan Yu, WHOI, USA Moacyr Araujo, LOFEC/UFPE, Brazil

PIRATA evolution from 1997 until now PIRATA ATLAS buoys network in October 2005 (Brazilian SW extension => 13 buoys) First PIRATA ATLAS buoys network in 1997 (12 then 10 buoys) PIRATA ATLAS buoys network from June 2006 US NorthEast extension along 23 W (carried out by NOAA, R/V Ron Brown in June 2006 & 2007) BCLME & South Africa SouthEast extension at 6 S-8 E (carried out by IRD, R/V L Atalante in June 2006) 16 ATLAS buoys actually operationnal From July 2006 to July 2007; => 18 from June 2007

PIRATA network status: Maintained by USA : 4 Atlas buoys : 2 deployed in 2006, at 4N & 11N/23W, 2 at 20N/23W & 38W deployed in 2007 Maintained by Brazil: 8 Atlas buoys Maintained by France : 6 Atlas buoys + At 23 W-Equator : surface ADCP mooring since 2001; Buoy at 6S-8E deployed in 2006 and retrieved in 2007 (test period for a Southeastern Extension by South Africa & BCLME).

French PIRATA dedicated cruises : 18 french cruises from 1997 to 2007 CRUISE NAME Departure date Arrival date Research Vessel Nb Days PIRATA FR 1 September 9, 1997 September 16, 1997 ANTEA 8 PIRATA FR 1b January 30, 1998 February 3, 1998 ANTEA 4 PIRATA FR 2 October 30, 1998 November 10, 1998 ANTEA 11 PIRATA FR 3 January 23, 1999 February 1, 1998 ANTEA 9 PIRATA FR 4 (EQUALANT 99) July 13, 1999 August 21, 1999 THALASSA 39 PIRATA FR 5 October 25, 1999 November 8, 1999 ANTEA 14 PIRATA FR 6 March 8, 2000 March 19, 2000 LE SUROIT 11 PIRATA FR 7 (EQUALANT 2000) July 23, 2000 August 21, 2000 THALASSA 29 PIRATA FR 8 November 17, 2000 December 3, 2000 ATALANTE 16 PIRATA FR 9 October 20, 2001 November 11, 2001 ATALANTE 22 PIRATA FR 10 December 6, 2001 December 21, 2001 ATALANTE 15 PIRATA FR 11 December 17, 2002 January 3, 2003 LE SUROIT 17 PIRATA FR 12 January 28, 2004 February 20, 2004 ATALANTE 23 PIRATA FR 13 May 24, 2005 June 2, 2005 LE SUROIT 13 PIRATA FR 14 (EGEE 1; 1st leg) June 7, 2005 June 23, 2005 LE SUROIT 16 PIRATA FR 15 (EGEE 3 with PIRATA SEE) May 24, 2006 July 6, 2006 ATALANTE 39 PIRATA FR 16 May 19, 2007 June 2, 2007 ANTEA 14 PIRATA FR 17 (EGEE 5; 2 nd leg) June 20, 2007 July 5, 2007 ANTEA 15 => ~ 335 days at sea Buoys have to be replaced yearly (at least)

Vandalism problems in the Gulf of Guinea (fishing activities ) Total lost: about 7 buoys lost or damaged Lost of data, time, money, energy.. Many thanks to NIOMR (Regina) and DOF (Armah) for their efficient help in retrieving precious sensors and data sets! The 10 W-6 S buoy as found on June 6, 2006!!! Shock => all atm sensors & argos transmission system broken Pr A.K.Armah team and the Pirata 10w-Eq atm sensors (March 2006)

A Pirata Atlas buoy has been found beached near Cotonou in 2005: Should be retrieved back in France (or Cotonou, if any Pirata base is possible ) in the next months.

PIRATA time series 1997-2006 (free access by internet) 10 S-10 W 6 S-10 W Eq-0 E NEW 6 S-8 E

«PIRATA «piggy back» program: CO2 sensor installed at 6 S-10 W in June 2006. Description of the PCO2 sensor installed on the Pirata Buoy (6S/10W) the 6 june 2006 : Argos Antenna Argos Antenna : half wave, 1W, transmission every 90s 24h/24, electrically insulated from aluminium structure. Datalogger, Argos Emitter, Batteries PCO2 Sensor and support Aluminium box with Argos emitter, electronics, batteries, atmospheric pressure sensor. Weight : 10 kg Support in white 20 mm marine plywood Fiberglass container with Pco2 sensor (Carioca type), electronics, Oxygen sensor (Optode 3830 from Aanderaa), water pump; Buoyancy : +7kg 316 stainless steel fixing PI: Nathalie Lefevre, IRD/LOCEAN. Collaborations with Nicolas Metzl (CNRS), Georges Kouadio & Urbain Koffi (LAPA). More infos on the web page : http://www.lodyc.jussieu.fr/co2tropiques/

APRIL 2006 (document mis à disposition sur la page web de PIRATA: http://www.brest.ird.fr/pirata/infos_fr.html )

2: AMMA (African Monsoon Multidisciplinary Analysis) (2002-2010) African Monsoon Multidisciplinary Analyses Afrikanske Monsun: Multidisiplinære Analyser Afrikaanse Moesson Multidisciplinaire Analyse Analisi Multidisciplinare per il Monsone Africano Afrikanischer Monsun: Multidisziplinäre Analysen Analisis Multidiciplinar de los Monzones Africanos Analyses Multidisciplinaires de la Mousson Africaine International programme Based on a French initiative (Météo-France, IRD, CNRS), AMMA was built by an international scientific group and is currently funded by a large number of agencies, especially from France, UK, US and Africa and the European Community s Sixth Framework Research Programme. For more information about AMMA, see: http://www.amma-international.org.

Interests of the AMMA program - importance of climate in regard to economical consequences (fishery, agriculture ), and for societies (health, infrastructures, transports, ) - Better comprehension of the climatic system: : => better numerical simulations => better climate predictions at a regional (and seasonal) scale

climatic impact <-> vegetation coverage Dry areas Humide areas

Lac Tchad 14 N 13 N Janvier 1973 12 N 14 E 15 E Janvier 1987

Recall: why AMMA? Sahel Rainfall index Humid Indice pluviométrique Sahel Dry Niger à Malanville: 10 6 km²

Potentiel role of the Ocean at decennal scale? Sea surface temperature evolution: (1970 to 1996) minus (1958 to 1969) Warmer sea surface waters in the Central Atlantic and GG Celsius Weaker ocean-continent energy gradient Limited northward migration of the ITCZ? TO BE PROVED!!!

African Monsoon not well reproduced & predicted by the atmospheric numerical models Numerical model Observations => model failure : the land surface conditions? (e.g., Taylor and Lebel 1998) the atmospheric circulation? (e.g., Roca et al. 2005) - SST variability (ocean)? (e.g., Okumura and Xie 2004) - Air sea fluxes? (e.g., Okumura and Xie 2004) Observed and modeled rainfall (with labels for onset and retreat) for Niamey based on area-average of 50 gauges and model simulated rainfall ( Lebel et al, 2000).

AMMA observation strategy: three periods LOP: Long Term Observations EOP: Re-enforced Observations Interannual variability & dedacal Seasonnal cycle & interannual memory SOP: Sustained Observations 10 3 S O P Short scale processes 1 2 3 IOPs IOPs IOPs 2001 2005 2006 2007 2008 2010 Years

EGEE (Etudes du climat et de la circulation Océanique dans le Golfe de Guinée) Oceanographic component of AMMA - France EGEE cruises : => 6 cruises, 2 per year in 2005, 2006 & 2007 interannual variability (Egée 1->6) + intra-annual (Egée 3) Egée 1 trackline (June-July 2005) Egée 2 trackline (Sept. 2005) Repeated sections at 10 W, 3 E & 6 E. -continuous SST, SSS, surface currents measurements, meteorological measurements - CTD-02 profiles and current profiles + temperature profiles (XBT) every ½ or ¼ -oceanic turbulence (MSS - IFM/GEOMAR-) during EGEE 2 - water samplings (CO2, O18 & C13, nutrients, + Helium -Univ.Bremen-) - ARGO profilers + NOAA/GDC surface drifters deployment (SVP)

AMMA African Monsoon Multidisciplinary Analyses EGEE cruises : => 6 cruises, 2 per year in 2005, 2006 & 2007 interannual variability (Egée 1->6) + intra-annual (Egée 3) Egée 3 trackline (May-July 2006) Egée 4 trackline (Nov-Dec 2006) 1st leg 2nd leg Repeated sections at 10 W, 3 E & 6 E (EGEE 3). -continuous SST, SSS, surface currents measurements, meteorological measurements - CTD-02 profiles and current profiles + temperature profiles (XBT) every ½ or ¼ -oceanic turbulence (MSS - IFM/GEOMAR-) during EGEE 3 & 4 - water samplings (CO2, O18 & C13, nutrients + Helium -Univ.Bremen- EGEE 3) - ARGO profilers + NOAA/GDC surface drifters deployment (SVP) - EGEE 3

AMMA African Monsoon Multidisciplinary Analyses EGEE cruises : => 6 cruises, 2 per year in 2005, 2006 & 2007 interannual variability (Egée 1->6) + intra-annual (Egée 3) Egée 5 trackline (June-July 2007) Egée 6 trackline (Sept 2007) 10 o N 5 o N EGEE 6 cruise - First leg - Second option 1st leg 0 o 5 o S Stations CTD 1000 m Stations CTD 2000 m EGEE 6 cruise - Second leg - 17 september to 27 september 2007 10 o N 5 o N 15 o W 10 o W 5 o W 0 o 5 o E 10 o E 15 o E 2nd leg 0 o 5 o S Stations CTD 1000 m Stations CTD 2000 m TACE moorings Repeated sections at 10 W; 3 E and 6 E. -continuous SST, SSS, surface currents measurements, meteorological measurements - CTD-02 profiles and current profiles + temperature profiles (XBT) every ½ or ¼ -oceanic turbulence (MSS - IFM/GEOMAR-) - water samplings (CO2, O18 & C13, nutrients) 15 o W 10 o W 5 o W 0 o 5 o E 10 o E 15 o E

HYDROLOGICAL MEASUREMENTS: Bouteilles hydrologiques (=> analyses de plusieurs paramètres) Courantomètres à effet Doppler (=> courants de la surface à 1000m) Sonde et capteurs de T, S, O2, p (=> 24 mesures par seconde; 2 capteurs par paramètre)

The special PIRATA FR15 / EGEE 3 cruise May 24 July 6, 2006 => during the Special Observation Period (SOP) of AMMA. Hydrologic / current measurements: 72 CTD/ADCP profiles 162 XBT 18 XCTD + drifters & profilers (next slides) Atmospheric / turbulent flux measurements: Foredeck boom (Net radiation sensors) Instrumented mast (classical met. Parameters and turbulence sensors) Central mast (Downward long and shortwave radiation sensors) Radiosounding post

=> Large increase of T/S(z) data in the region June 23, 2005 September 28, 2005 Map of the ARGO profilers in Tropical Atlantic, late August 2006 (from CORIOLIS).??? Green dots: T & S profiles / Blue dots: T profiles only.

EGEE: Deployment of Surface Drifters (NOAA SVP) -Example: Surface Velocity Profiler equiped with T & C sensors (SST & SSS) From t1 = June 6, 2006 to t2 = October 17, 2006 SST SSS t1 t1 t2 t2 t1 t2 HF SSS variability from late September and some bias to be checked and corrected t1 t2

EGEE: Measurements at São Tomé Island (0 N, 6 E) Meteorological Station (EGEE/AMMA) + Tide gauge (PIRATA) 1) Installation of a meteorological station in October 2003 NEW: - DATA transmission through the GTS from late October 2006! => Eastward continuation of PIRATA atmospheric measurements along the equator, daily available in real time - Autonomous thermometer ONSET installed in 2005 (=> SST) 2) Tide gauge maintained by IRD since 1980s. - Pressure, Atm. pressure + SST & SSS. - Part of GLOOS. - GPS positioned (in December 2002)

Other measurements carried out in the framework of EGEE (and from now RIPIECSA-Ocean) Coastal Sea Surface Temperature in the Gulf of Guinea GOAL: coastal upwelling and waves studies => Autonomous thermometers (Onset): ( three years duration, 1h period sampling) - Installed but interrupted in Ivory Coast (2002-2004) - Installed in Bénin (from July 2005). Responsible: CRHOB - Installed in São Tomé -close to the meteorological station- (from September 2005) - Installed in Togo (from October,17 2006). Responsible: CGILE/Univ. Lomé - Goal: extend the installations in Nigeria, Ghana, and to proceed to re-deployment in Ivory Coast SST at Cotonou (09/18/05 12/28/05) hourly data. 30,5 30 29,5 29 28,5 28 27,5 27 26,5 26

3: TACE (Tropical Atlantic Climate Experiment) (1997-2011) International Programme as a contribution to CLIVAR-Atlantic: -USA (RSMAS, NOAA/AOML, several universities), GERMANY (IFM-GEOMAR), The NETHERLAND (KNMI), FRANCE (IRD) * 2002-2006 : Editing and proposal 2007-2011 : Field operation and scientific works

Links with TACE (Tropical Atlantic Climate Experiment: from 2007) Summary of french potential contribution «on the field» during TACE : -EGEE (2007) and PIRATA (2008-?...) cruises linked to TACE cruises (moorings operation) (possible PIRATA South-Eastern Extension servicing if maintained) from 2008 (=> CTD, ADCP, XBT, ARGO, TSgraph & meteo) -Meteorological Station (GTS transmitted) & tide gauge at Sao Tome (yearly servicing) + Lomé??? - 23 W & 10 W -Equator surface ADCP moorings - Ripiecsa coastal SST (Sao Tome, Benin, Togo, RCI, Nigeria); data should be available about every 3-6 months - Glider (from 2008/2009?)

COMMON SCIENTIFIC OBJECTIVES BETWEEN PIRATA, EGEE/AMMA AND TACE: - Ocean / climate studies in the eastern equatorial Atlantic - Ocean-atmosphere exchanges and links with regional climate -Variability of the mixed layer: - sea surface temperature (cold tongue & coastal upwellings) - salinity - air-sea fluxes - processes (mixing, advection, fluxes, waves ) => Provide a sustainable observing system

TACE PIRATA EGEE/AMMA observing network Ripiecsa Ocean coastal network Plan for a glider section by IRD, in 2009 (not funded yet!).