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. The sensors collect weather and climate data including fluxes of carbon, water, and energy between terrestrial ecosystems and the atmosphere. The flux tower typically extends past the top of the vegetation canopy to capture a full vertical profile of atmospheric conditions from the top of the vegetation canopy to the ground.