PROSOPE  -  Sept. 4   -> Oct. 4, 1999

La Thalassa

H. CLAUSTRE : head of mission  and project leader

GOALS

The PROSOPE (PROductivity of Oceanic PElagic Systems) cruise took place from the 4^th of September (Agadir, Morocco) to the 4^th of October (Toulon, France) 1999 aboard the RV Thalassa. There were four main scientific objectives:

To carry out classical process studies, typical of JGOFS
To focus on small scale biogeochemical processes, in particular at a daily scale.
To study the influence of nitrogen, phosphorus and iron on oceanic fertility.
To conduct a calibration/validation operation for the SeaWIFS color sensor.

CRUISE TRACK

CRUISE  PLAN

To reach these objectives, the studied areas as well as the cruise plan had to respond to a number of criteria :

To investigate different trophic regimes
To investigate systems characterized by different degrees of limitation in nitrogen and phosphorus
To study stable ("steady state") systems for a sufficiently long period

The cruise track was thus designed to encompass a variety of trophic systems ranging from eutrophic conditions associated to the Moroccan upwelling to the typical ultra-oligotrophic conditions of the eastern Mediterranean sea during summer stratification . Two main types of stations were occupied :

9 short (4-hour) stations. These sites were occupied around the solar noon and were essentially designed to conduct objectives 1 (JGOFS process studies) and 4 (SeaWIFS validation/calibration)
3 "long" (5-day) stations, where all four objectives were investigated with a particular emphasis on objectives 2 (processes at a daily scale) and 3 (nutrient resources and oceanic fertility).

Between each station, continuous multiparametric (hydrological, optical, biological and chemical) surface acquisitions were performed.

For the particular case of the Moroccan upwelling, the position of the sampling station was not defined a priori but had to respond to two criteria:

to be close enough from the upwelling core, here defined as the area with the lowest temperature and the highest pCO₂ content
to be located in waters deeper than 100 m, i.e. twice the height (50 m) of the mooring (1m² sediment trap plus carioca buoy)

The location was determined using quasi real-time SeaWIFS images to pre-determine an area (actually a rectangle of 1° latitude and 0.5° longitude) while continuous surface acquisition provided a more precise identification of the station location

CRUISE  PARTICIPANTS

Part I : from 4^th to 14^th September, 1999

Part II : from 14^th September, to 14^th October, 1999

LPCM: Laboratoire de Physique et Chimie Marines, Villefranche-sur-mer, France
LSCE: Laboratoire des Sciences du Climat et de l'Environnement, Gif-sur-Yvette, France
WHOI: Woods Hole Institution of Oceanographie, Woods Hole, USA
SBR: Station Biologique de Roscoff, France
LEV : Laboratoire d'Ecologie Végétale, Orsay, France
NASA: National Aeronautic and Space Administration, Greenbelt, MD, USA
LODYC: Laboratoire d'Océanographie Dynamique, Paris, France
IO : Institut Océanographique, Paris, France
LOB: Laboratoire Océanographie et de Biogéochimie, Marseille, France
LP: Laboratory of Photosynthesis, Trebon, Tchéquie
LOBEPM : Laboratoire d'Océanographie Biologique et d'Ecologie du Plancton marin, Villefranche-sur-mer, France
LMM : Laboratoire de Microbiologie Marine, Marseille, France
INRH: Institut National des Recherches Halieutiques, Casablanca, Maroc

Note : The complete list of the PROSOPE group also includes people who are involved in data exploitation.

DATA ORGANIZATION

The database comprises six main groups of data:

The ctd data : profiles and bottle files. PDF files allow the visualization of depth profiles for selected variables.

The ship data : (meteorological data, navigation, ship thermosalinograph….)

The discrete data concern all optical, biological and chemical measurements performed from either bottles or pumped seawater.

The profiler and optical data : inherent and apparent optical properties as well as variable fluorescence and particle number and size were measured using in situ profilers.

The surface data: multiparametric (optical, biological and chemical) surface data obtained from measurements of pumped seawater. PDF files allow the vizualisation of the daily variations for selected parameters.

The mooring data concerns sediment trap and carioca buoy data.