Hydrography and biogeochemistry dedicated to the Mediterranean BGC-Argo network during a cruise with RV <i>Tethys 2</i> in May 2015

Abstract

Abstract. We report on data from an oceanographic cruise, covering western, central and eastern parts of the Mediterranean Sea, on the French research vessel Tethys 2 in May 2015. This cruise was fully dedicated to the maintenance and the metrological verification of a biogeochemical observing system based on a fleet of BGCArgo floats. During the cruise, a comprehensive data set of parameters sensed by the autonomous network was collected. The measurements include ocean currents, seawater salinity and temperature, and concentrations of inorganic nutrients, dissolved oxygen and chlorophyll pigments. The analytical protocols and data processing methods are detailed, together with a first assessment of the calibration state for all the sensors deployed during the cruise.

Quantifying Observational Errors in Biogeochemical‐Argo Oxygen, Nitrate, and Chlorophyll a Concentrations

“…A complete description of how the ship‐based samples have been collected, measured, and processed can be found in Taillandier et al (). Briefly, O 2 were measured by Winkler titration (Winkler, ) with potentiometric endpoint detection (Oudot et al, ), NO 3 − by a standard automated colorimetric system set up following Aminot and Kérouel () using a Seal Analytical continuous flow AutoAnalyzer III.…”

“…The Mediterranean Sea is an ideal region for the application of the TC analysis on BGC‐Argo float data because (1) there is one of the largest number of matchups between ship and float measurements thanks to the Bio‐Argo Med program (Taillandier et al, ) and (2) of the availability of an operational biogeochemical model system (MedBFM, Teruzzi et al, ).…”

Biogeochemical Argo: The Test Case of the NAOS Mediterranean Array

“…For the CTD sensors, vertical resolution is the same as for the BGC sensors. CTD sensors of the NAOS BGC-Argo network are calibrated and processed following the procedure described in Taillandier et al (2018). For nitrate sensors, the vertical resolution is different: 5 m for the surface layer (0-250 m) and 20 m for the deep layer (250-1000 m).…”

“…The first wave of deployment was carried out between 2012 and 2013 thanks to opportunities raised by oceanographic cruises: the French cruises DEWEX, MOOSE-GE, and SOMBA-GE, the Italian cruises VENUS and ADREX, and the Spanish cruise MEDSEA. The second wave of deployment was completed via a dedicated oceanographic cruise, BIOARGOMED, in May 2015 (Taillandier et al, 2018). In terms of ancillary data and preparation, the dedicated cruise achieved considerable improvements regarding the efficiency of organization, preparation of the floats, and the homogeneity of collected samples of reference.…”

“…The others were cleaned, their batteries changed, and their sensors subjected to simple tests to verify the appropriateness of an eventual re-deployment. Most of the recoveries were associated with a CTD cast with nutrient, CHL, and oxygen samples, providing reference data to verify the calibration of the sensors (see section "Metrological Verification of the Sensors" and Taillandier et al, 2018). Only sensors that passed this simple test and that performed well in comparison with concurrent CTD and sample data (see section "Metrological Verification of the Sensors"), were retained for eventual re-deployment (five floats were redeployed out of 14 recovered) without more in-depth calibration.…”