A successful PIRATA-FR26 campaign (PREFACE MS8 and MS15).

PIRATA maintains 18 buoys in the Tropical Atlantic, with yearly dedicated cruises by PIRATA's partners: Brazil, the US and France. France is in charge of 6 ATLAS moorings (at 23°W-0°N, 10°W-0°N, 0°E-0°N, 10°W-6°S, 10°W-10°S, 8°E-6°S) and 2 current meter (ADCP) moorings (at 23°W-0°N and 10°W-0°N). The most recent French PIRATA cruise (PIRATA FR26) was carried out from March 7th to April 13th 2016, from Mindelo (Cabo Verde), onboard the R/V THALASSA. During this PIRATA FR26 survey, the French PIRATA group notably ensured:

  • The deployment of a new ADCP mooring at 0°E-0°N, that is a commitment of PIRATA-FR towards PREFACE (MS15); such a mooring will allow current measurements at three longitudes along the equator. The ADCP moorings at 10°W-0°N and 23°W-0°N were serviced in 2015, respectively in March during PIRATA FR25 and in October during the survey lead by GEOMAR.
  • The servicing of the PIRATA/PREFACE ATLAS buoy at 6°S-8°E, off Congo, that is also a commitment of PIRATA-FR towards PREFACE (MS8).
  • The deployment of two new PIRATA T-Flex systems at 23°W-0°N and 10°W-10°S, that will progressively replace the ATLAS ones.

    (Presently, due to an increasing need of real time data and parameters induced by progresses in operational systems and climate research, NOAA developed a new T-Flex system to progressively replace the ATLAS. These new T-Flex systems will allow: i) to deploy more oceanographic sensors along the mooring line with data transmission in real time; ii) to ensure more reliable data transmission with higher time resolution (every hour with Iridium); iii) to double atmospheric sensors in order to reduce data acquisition loss induced by sensors failure; iv) to add systematically current sensors at subsurface (Aquadopp); v) to increase the sensors security in order to limit the impact of eventual vandalism actions or shocks; vi) to ensure a higher flexibility of the sensors types that could be added along the moorings (so to be less limited by sensors technology); vii) to ensure a longer autonomy of moorings (that could be extended up to 18 months). After a 1st T-Flex deployment by US at 12°N-23°W in 2015, these three new systems open a new era for PIRATA, with more data in real-time, potentially more sensors etc…)
  • The servicing of the 3 other ATLAS sites at 0°E-0°N, 10°W-6°S, and 10°W-0°E.
  • The servicing of the CO2 parameters sensor installed at 10°W-6°S from 2006 (also component of the EU H2020 project AtlantOS WP3.5).
  • The deployment of 15 surface drifting buoys (SVP-B), as contribution of MF-CNRM to the AtlantOS WP3.6.
  • The deployment of 6 ARGO profilers (also as contribution to CORIOLIS), three of them with double programming (so allowing some profiles every two days during three months from the surface down to 300m depth).
  • The servicing of turbulence sensors (Xpods), installed from 2014 at 23°W-0°N and 10°W-0°N (5 on each mooring between 20m and 80m) (collaboration with Oregon State University, Corvallis, USA).
  • The servicing of acoustic receivers (OTN), installed from 2014 at the PIRATA buoys (one per site) (collaboration with Dalhousie University, Halifax, Nova Scotia, Canada).
  • 50 CTDO2-LADCP profiles (from the surface down to 2000m depth; so useful for ARGO profilers validation) every 1/2° (latitude/longitude) along 23°W, 10°W (done yearly), 0°E, and 6°S (around the ATLAS buoy at 6°S-8°E). Data transmitted in quasi-real time to CORIOLIS for operational centers.
  • 70 temperature profiles (XBT) during transits. Data transmitted in quasi-real time to CORIOLIS for operational centers.
  • 615 sea water samplings (at the surface and during CTDO2/LADCP profiles) to analyze salinity, dissolved oxygen, nutrients, carbon parameters (DIC et TA) and primary production (pigments).
  • Acoustic measurements (EK60 sounders: 6 vertical and one transversal) all along the trackline of the vessel and, if possible, to proceed to plankton sampling (from the surface down to about 200m) with a « bongo » net at the ATLAS sites.
  • Continuous measurements, all along the trackline, of the sea surface temperature and salinity with the thermosalinograph, fluorimetry and meteorological parameters.

A very warm congratulations to PIRATA; Bernard Bourlès, chief scientist for this mission; the scientific team on-board and the R/V Thalassa crew (GENAVIR & IFREMER), particularly Fabrice Roubaud and Jacques Grelet, the IRD electronicians who ensured the deployment of the T-Flex systems; and of course to NOAA and PMEL for this technical evolution.

Trackline of the PIRATA FR26 survey, together with CTDO2/LADCP profiles positions (Courtesy: J. Grelet, IRD)

T-FLEX buoy before its deployment at 23°W-0°N

Last preparation of the T-FLEX buoy before its deployment at 10°W-10°S and sensors installation along the first 60m of the cable; the buoy of the left is the ATLAS just retrieved, the T-FLEX is on the right (Courtesy: B.Bourlès, IRD)
The Buoy-Observatory "MELAX": a pilot site for the West African upwelling. On 26th January 2015, and with main support from PREFACE, an oceanographic and meteorological buoy was deployed, aimed at scientific research and operational environmental monitoring, dedicated to the important area of the Senegal-Mauritania upwelling. This buoy is the first measuring buoy launched as part of a flagship project involving several PREFACE beneficiaries and associate laboratories across West Africa -notably the Joint International Laboratory ECLAIRS (UCAD / IRD / UPMC)-, and aiming towards the deployment of a network of measurement instruments capable of continuously informing researchers on short and long term changes in climate, atmosphere and the marine environment off the West African coast*. Unique in this sub-region, this buoy’s sensors are able to give real-time information to scientists around the world about the development of climate off the West African coast: surface winds, solar radiation, humidity, precipitation, ocean temperatures, salinity, and currents at various depths. These valuable and freely available data are expected to enable the scientific community to build new predictive models for studying climate changes and to better understand the interactions between the ocean and the atmosphere off the African Atlantic coast.
* The science topics motivating the observatory are:

  • African monsoon
  • climate change in the atmosphere and ocean
  • air-sea interactions off West African coasts
  • currents, temperatures, and biochemical elements, controlling the fisheries resource
  • the passage of extreme cyclonic atmospheric disturbances in the hot season
  • swells responsible for accelerating coastal erosion

The data collected are:
-for the atmosphere: surface wind, solar radiation, humidity, rain
-for the ocean: temperatures, salinity, and currents (from the surface to the bottom), oxygen, and surface CO2.
Most of measurements are to be relayed by satellite in real time to the ECLAIRS laboratory control centres, and to those of the international meteorological monitoring centres. Scientists will exploit them to understand and predict the disturbances of the West-African marine climate.
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