Abstract

The hydroxyl radical (OH) plays a central role in the chemistry of the Earth's lower and middle atmosphere. The determination of its concentration is essential to an understanding of the chemistry of the lower atmosphere since this molecule controls the lifetimes, and therefore the concentrations, of many chemical species under both clean and polluted conditions. Predicted midlatitude tropospheric concentrations of OH range approximately from 0.1 pptv at the noontime maximum in the winter to several tenths pptv at noontime in the summer. These low values are extremely difficult to measure; sensitivity at least a decade smaller is essential to measure the daily growth and decay inorder to understand the photochemical variation of OH.

© 1996 Optical Society of America