Measurements of carbon dioxide on a very tall tower

Abstract

Presents a continuous, 2-year long record of carbon dioxide (CO2) mixing ratio at three altitudes up to 496 m above the ground on a television transmitter tower in the southeastern United States. The data show strong diurnal and seasonal variations, and large vertical gradients. The diurnal cycles are modulated by surface uptake and release by vegetation and soils, emissions from fossil fuel combustion, and by the diurnal development of the planetary boundary layer. Gradients of 1-2 ppm between 496 m and 51 m are typically observed during summertime afternoons, due to vigorous photosynthetic uptake. With increasing altitude the magnitude of the diurnal cycle is damped, and daily average mixing ratios decrease. -from Authors