Eddy Covariance System

What an Ecosystem Inhales, Exhales, and Loses to the Sky

Every ecosystem (a forest, a paddy field, a peatland, a mangrove) is in constant gas exchange with the atmosphere. Carbon dioxide moves down during the day as plants photosynthesise and up at night as they respire. Water vapour rises through transpiration. Heat moves both ways depending on the surface energy balance.

Eddy covariance is the measurement technique that quantifies these fluxes directly. By sampling vertical wind and gas concentrations at ten or more times per second and correlating the fluctuations, it produces a continuous record of net ecosystem exchange (NEE), evapotranspiration, sensible heat, and latent heat. It is the method behind global flux networks such as FLUXNET, AsiaFlux, and ICOS, and the gold standard for carbon accounting at ecosystem scale.

Wetec design, supply, installs, and supports complete eddy covariance systems built around Campbell Scientific instrumentation, primarily the CPEC310 closed-path system and the IRGASON open-path integrated analyser. Both platforms produce publication-grade data and are used widely across the global flux research community. The choice between them comes down to site conditions, power availability, and the data continuity profile each project needs.

• Campbell Scientific IRGASON (open-path integrated analyser): an integrated open-path CO2 and H2O gas analyser combined with a CSAT3A sonic anemometer in a single sensor head. Sensor separation is effectively zero, which removes the spatial correction that other open-path setups require. Low power draw makes IRGASON the natural choice for remote, solar-powered, and tower-top installations.

• Campbell Scientific CPEC310 (closed-path eddy covariance system): a complete closed-path system built around the EC155 closed-path gas analyser, the CSAT3A sonic anemometer, and an integrated pump module with heated sample intake and automatic zero and span options. CPEC310 is the right choice for high-humidity tropical sites, dusty or salt-laden environments, and any installation where long-term data continuity matters more than power consumption.

• Optional methane (CH4) analyser: Campbell Scientific or Picarro fast-response CH4 analysers for wetland, rice paddy, livestock, and landfill flux studies, integrated into the CPEC310 or IRGASON tower as a complete CH4 channel.

• Net radiometer and four-component radiation: incoming and outgoing shortwave and longwave radiation, required for surface energy balance closure and gap-filling.

• Soil heat flux, soil temperature, and soil moisture: multi-depth profiles supporting the storage term in the energy balance and the soil component of NEE partitioning.

• Standard meteorological sensors: air temperature, humidity, pressure, wind, and precipitation at canopy reference height, providing the ancillary data needed for flux corrections and footprint analysis.

• Tower, power, and data infrastructure: walk-up or tilt-down towers sized to canopy height, solar or grid power with battery backup, and Campbell Scientific CR6 or CR1000X data loggers configured for FLUXNET-compatible output.