The SNO PIRATA is organized around annual campaign which includes:

• The maintenance of 5 meteo-oceanic buoys and 3 equatorial current-meter moorings (Figure 5)
• Numerous samplings of physical and biogeochemical parameters during the campaign,
• Opportunistic deployments directly serving research projects and other National Observation Services (e.g., Argo, COOL, SSS).

We will now briefly describe the three components of SNO PIRATA, highlighting their support for long-term observations, research, and operational applications in the tropical Atlantic.

• 5 meteo-oceanic buoys and 3 equatorial current-meter moorings

Like the other moorings, these five buoys provide high-frequency (hourly) measurements of meteorological variables (e.g., wind, air temperature, humidity, precipitation, solar radiation) as well as oceanic variables at the surface and in the subsurface (temperature, salinity, and currents, Figure 6).

The standard (minimum) configuration of the buoys is as follows:

Oceanic Measurements	Atmospheric Measurements
11 temperature sensors at 1 m, then every 20 m between 20 and 140 m, plus at 180, 300, and 500 m	Air temperature
	Wind (speed and direction)
4 salinity sensors at 1, 20, 40, and 120 m	Shortwave radiation
2 pressure sensors at 300 and 500 m	Precipitation, and relative humidity

Note that several sites have been equipped with additional sensors, including extra temperature/salinity sensors within the mixed layer, a current meter (12m) to determine relative wind, and longwave radiation to estimate the net surface heat flux. All these sensors are aimed at monitoring (i) equatorial currents, (ii) air-sea fluxes of momentum and heat, (iii) upper-ocean stratification, and (iv) mixed-layer budgets.

The PIRATA network’s basin-scale coverage requires long transit times between buoys, which are validated through hydrographic stations, continuous measurements along the track, and opportunistic operations. Annual access to the tropical Atlantic allows regular deployments and sampling that support other ocean observation programs and provide data directly useful to the scientific community. PIRATA cruises also serve as platforms for multidisciplinary operations, contributing to additional projects through specific measurements or sampling—one of the network’s key strengths.

• Numerous samplings of physical and biogeochemical parameters during the campaign

During PIRATA-France cruises, an average of 55 hydrographic stations is conducted continuous CTD-O₂ and L-ADCP profiles from the surface to 2000 m (or deeper) near buoys and along meridional radials (e.g., 10°W). These annual stations provide high-quality time series for multiple purposes: calibrating mooring sensors and Argo floats, supporting specific scientific objectives such as mixed layer or biogeochemical studies (e.g., samplings of nutrients, carbon, isotopes, chlorophyll, pH). These hydrographic stations provide the highest-quality ocean observations, following the best calibration procedures, and serve as a reference for other platforms, including moorings and Argo floats.

• Opportunistic deployments

On each cruise, approximately 90 XBT temperature profiles and 15 surface drifting buoys are deployed, providing real-time ocean data, while 5–7 Argo floats—including 2–3 biogeochemical or oxygen floats—contribute to the tropical Atlantic Argo program. For instance, more than 35% of the Argo profiles collected between 2021 and 2023 in the equatorial Atlantic band (5°S–5°N) were obtained from floats deployed during PIRATA cruises. Surface seawater is sampled for salinity, nutrients, chlorophyll, carbon parameters, and isotopes, supporting SNO SSS and COOL, CORIOLIS, ICOS. Biological sampling includes Sargassum algae, barnacles, zooplankton, particulate organic matter, and tuna, maximizing the scientific value of each cruise and providing reference data for multiple national and international programs.