A DESIGN FOR UNATTENDED MONITORING OF CARBON-DIOXIDE ON A VERY TALL TOWER

Unattended measurements of carbon dioxide (CO2) mixing ratio at three altitudes up to 496 m above the surface on a television transmitter to wer in the southeastern United States have been made for a period of 4 yr. This report describes the design of the automatic tower measuring system in detail. A nondispersive infrared (NDIR) analyzer is used to measure the CO2 concentration continuously. Real-time control and dat a collection uses a PC 486 running under the multitasking operating sy stem QNX. The CO2 data show strong diurnal and seasonal variations, an d large vertical gradients. A comparison of this study's continental t ower data with data from ''background'' sites should provide a strong constraint for regional and global models of terrestrial CO2 fluxes.