Flux Tower Measurements

NEON collects data using sensors mounted on towers at terrestrial field sites across the US. Tower sensors monitor physical and chemical properties of atmosphere-related processes, such as humidity and wind. They also measure net ecosystem exchange or the amount of gas that is exchanged between the atmosphere and the ecosystem. Find flux tower data on the NEON Data Portal.

Measurement methods

Each flux tower has multiple measurement levels outfitted with suites of sensors. The number of measurement levels on a tower vary from four to eight levels depending on the ecosystem structure at each site. Each boom arm is 4 m long, which is double the width of the tower to minimize the impact of flow distortion caused by the tower on wind measurements. 

Towers extend past the top of the vegetation canopy at each site to allow sensors mounted at the top and along the tower to capture the full profile of atmospheric conditions from the top of the vegetation canopy to the ground. Automated tower sensors collect data continuously to capture patterns and cycles across various time periods, ranging from seconds to years. NEON calibrates and quality checks sensors to minimize measurement errors and maximize the quality of collected data.

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Integrated sampling design

Soil sampling and organismal sampling covering plants, animals and microbes, occur within or near the airshed of the tower at each site. This integrated sampling approach supports the ecosystem-level study of carbon dioxide, water vapor and energy fluxes, as they cycle through the atmosphere, vegetation and the soil. Tower data combined with soil and airborne remote sensing data supports scaling of fluxes, soil moisture and evapotranspiration to a continental scale. Data collected from the tower support greater understanding of ecological processes and change, such as changes in air quality and climate. 

Key flux tower measurements

NEON tower sensors regularly measure the following key data:

Ancillary measurements

• Precipitation via Double Fence Intercomparison Reference (DFIR); this device is not located on the tower but nearby and provides the most accurate precipitation measurement

Examples of high-level data products derived from flux tower measurements

• Turbulent exchange of:
  • Carbon dioxide (CO₂)
  • Latent and sensible heat
• Storage of carbon dioxide (CO₂)
• Net ecosystem exchange
• Energy balance