OH Radicals Via Atmospheric 14CO: An Extended Summary

Abstract

Measurements of 14CO in the lower troposphere show a well-defined seasonal variation between 11 +/- 1 molecules cm-3 in summer and 25 +/- molecules cm-3 in winter at 51 degrees N. The concentration at 27 degrees N in summer is found to be 4.2 +/- 0.7 molecules cm-3. From these data and published 12C O measurements, the average concentration of OH radicals in the troposphere is calculated to be 6.5 +/- 2.5 X 10^5 molecules cm-3 using a 2-D time-dependent model. The corresponding 12C O lifetime is two months; the 14CO lifetime is five months.