Acquisition System

Platforms at sea. The SSS measurements originate from the Ship Of Opportunity Programs (SOOP) operated from Brest, France, and Nouméa, New Caledonia. Additional pCO2 data are collected from two tropical Atlantic shipping lines. On average, each selected ship provides one to three sections per season along a regular track.

Number of SSS observations per 1° longitude and 1° latitude, expressed in decimal logarithm scale, as obtained from voluntary observing ships during 1993-2021. Click here for more details of the shipping routes equiped with thermosalinograph instruments (in the past and presently).

Instruments. The SSS measurements are mainly based on SeaBird SBE-21 ThermoSalinoGraph (TSG) instruments fitted with bubble traps, the whole system being located as close as possible to the ship’s engine water intake. PCO2 measurements are also done on some ships. Detailed information about the TSG installation and maintenance is available in a dedicated report.

TSG installation.
TSG and pCO2 measurement installation.

Data Acquisition and Transmission. Most of the TSG measurements are collected every 15 s, and a median filter over 5 mn is applied to reduce small scale signal and/or noise. The 5 mn resolution data are recorded in memory, and processed at laboratories : these are the Delayed Mode Data. For some ships, reduced data are transmitted by Inmarsat C or Iridium satellite system : these are the Real Time Data. Details by ships are given here.