Environmental data

Work-Package 2 description

Objectives

This working group aims to process, analyze and archive the physico-chemical and bio-optical data in formats that are compatible with the data storage system developed by working group no.1 (Organization and archiving).

These data come from sensors deployed aboard Tara during the expedition (more than 650 profiles were recorded down to 1500 m); from samples collected for subsequent analysis in partner laboratories; and from analysis of data from satellites and automatic sensors deployed in situ by international programs near TARA collection sites. This corresponds to over 50 physico-biogeochemical parameters (temperature, salinity, nitrates, oxygen, multispectral fluorescence, chlorophyll pigments, concentration of particles) plus satellite data (color of water, altimetry, currents, temperature) and data from autonomous sensors (temperature, salinity, fluorescence and sometimes O2).

This information is grouped under the term "environmental data" and will be used to characterize the water masses (and their level of organic production) from which were taken the imaging and sequencing data (working groups no. 3 and 4).

lars_stemman.jpg

Lars Stemmann coordinates the working group Environmental data

This working group is coordinated by Lars Stemmann at the Villefranche Oceanographic Observatory and involves the Oceans Physics Laboratory in Brest, the Dynamic Meteorology Laboratory in Paris, Pangaea and UMR 7144 of the Roscoff Biological Station.

In situ physical data - Task 2.1

A Conductivity Temperature Depth sensor (CTD) deployed aboard Tara was used to measure the pressure, temperature and conductivity -- data from which salinity and density can be calculated. This information was processed and verified. Both the temperature and salinity were measured continuously by an on-board thermosalinograph. At some stations, underwater gliders were used. Recorded data were processed and validated.

Remote sensing physical data - Task 2.2

Acquisition of information by satellites has been crucial for Tara Oceans in order to determine the most relevant places for collecting biological samples. These data will be stored and used to describe the context of each sampling station done during the expedition. By means of continuously-orbiting satellites, it will be possible to reconstruct the history of water bodies before the passage of Tara.

Bio-optical data - Task 2.3

In addition to the CTD sensor, throughout the expedition other bio-optical sensors were used to measure nitrates, oxygen levels, and fluorescence at different wavelengths. An on-board imaging sensor measured the concentration of particulate material. Together with the continuous measurement of temperature and salinity by the thermosalinometer, optical biosensors were used to measure the concentration of phytoplankton as well as particles. All bio-optical data from Tara Oceans have been treated with appropriate calibration factors, converted to optical coefficients using algorithms, and their quality verified.

Biochemical data - Task 2.4

Biochemical data include all analyses of nutrients (nitrogen, phosphorus), the chemistry of carbonates (to determine acidity) and chlorophyll pigments contained in algae. These analyses have already been performed and the data is available and archived (Task 2.5).