PIRATA is a multinational program initialized in 1997 within the international CLIVAR program framework and realized in the framework of an international cooperation between USA, Brazil and France (committed countries through a Memorandum of Understanding). It constitutes the main observations network in the tropical Atlantic (CLIVAR, OOPC, GOOS, GCOS) for climate prediction and research, and contributes to OceanSITES.

PIRATA is a program for the studies of air-sea interaction in the Tropical Atlantic to seasonal, interannual or longer timescale. It maintains a network of 18 met-ocean buoys from summer 2013. Observed parameters are notably used to monitor and analyze the exchanges at the air-sea interface along with the oceanic thermohaline structure down to 500m depth. Oceanic (current, temperature and salinity between the surface and 500m) and atmospheric at the ocean surface (wind direction, wind velocity, air temperature, relative humidity, rainfall, shortwave radiation) data are transmitted daily in real time through ARGOS or IRIDIUM, and available through internet. Three equatorial subsurface current-meter moorings (ADCP) at 23°W-0°N (from 2001), at 10°W-0°N (from 2006) and at 0°E-0°N (from 2016 and move westward in 2022) are also associated to this network. PIRATA needs yearly cruises to replace all the buoys and, in this framework, France (through IRD) is in charge of 6 met-ocean buoys located in the Eastern Tropical Atlantic (at 23°W-0°N, 3°W-0°N, 10°W-10°S, 10°W-6°S, 10°W-0°N and 20°S-10°W ) and of three equatorial currentmeter moorings at 23°W-0°N, 10°W-0°N and 3°W-0°N).

The PIRATA-FR33 (33th cruise of this program) main objective was the yearly servicing of these 6 air-sea exchange buoys located at 23°W-0°N, 10°W-10°S, 10°W-6°S, 10°W-0°N, 3°W-0°N and 10°W-20°S (this latter was deployed for the first time in 2020 as part of a future extension of the PIRATA network and to replace the buoy located off CONGO at 6 °S-8 ° E deployed and maintained in the area since 2013 but vandalized in 2018 and 2019) along with one of the three equatorial current-meter moorings, the one located at 10°W-0°N. CO2 sensors are also serviced at 10°W-6°S (from 2006) and at 10°W-0°N (from 2020 replacing the sensor initially installed at 6°S-8°E since 2017) as well as an analogical fluorimeter ECO-FL installed since 2021 at 10°W-0°N. New sensors, funded by the EU H2020 TRIATLAS project, were installed on the buoys this year : 2 T/C sensors (5m and 10m) at 0°N-3°W, 1 T/C sensor (5m) at 10°W-6°S and 1 T/C/O2 sensor installed for the first time at 299m at 10°W-0°N. Two NORTEK Aquadopps current meters (funded by CNES, request by F. Gasparin and S. Cravatte) were also installed at 7m depth at 3°W-0°N and 23°W-0°N.

The PIRATA-FR33 cruise also validated transits by carrying out CTDO2/LADCP profiles along sections at 10°W (repeated annually), along with XBT profiles along the trackline. Additional CTDO2/LADCP hydrological profiles were also carried out in the Guinea Dome area between 23°W-11°N and 17°W-6°N following the deployments of Bio-ARGO profilers in the region during the PIRATA-FR31 cruise as a contribution to the LEFE-GMMC SEANOX project (PI: X.Capet and E. Machu). A 48h fixed point near a meteo-oceanic buoy at 10°W, 0°N was carried out with a series of CTDO2/LADCP hydrological profiles of about 200m depth carried out every 3h as a contribution to the LEGOS LEFE-GMMC project (PODIOM project PI: S. Cravatte and F. Gasparin). Surface drifting buoys (10 in total) were  deployed (type SVP-B for Meteo-France as a contribution to the NOAA/AOML GDP) along with 5 ARGO autonomous profilers (ARVOR T/C Iridium) for CORIOLIS and 2 BGC-ARGO deployed in contribution to the ERC-REFINE project (PI: H. Claustre, LOV). Numerous seawater samplings (surface and during CTDO₂ casts) were collected for analysis of dissolved oxygen, salinity, nutrients, pH (since 2022), carbon parameters (DIC, TA), primary production (Chl pigments), ¹³C and ¹⁸O isotopes and particulate organic matter (POM). In addition, for the first time during a PIRATA cruise, Total Alkalinity measurements were carried out on board. This year, samples were taken for specific analyses of cytometry, phytoplankton taxonomy and Particulate Organic Carbon/Particulate Inorganic Carbon (POC/PIC) for the LOV. Additional continuous measurements of acoustics (vertical sounder) and CO2 parameters were also carried out. Finally, 6 additional CTDO2/LADCP hydrological profiles of about 500m depth were carried out around the island of St Helena in collaboration with the St Helena Research Institute (Dr R. Cairns-Wicks).