Remote Sensing of OH in the Atmosphere Using the Technique of Laser-Induced Fluorescene

Abstract

The hydroxyl radical (OH) is a reactive species which controls many of the chemical processes operative in the atmosphere. OH is important in ozone chemistry because it relates to the process of photochemical smog formation in the troposphere and to the partitioning of the odd-nitrogen and odd-chlorine compounds in the stratosphere. Various estimates [Weinstock and Niki, 1972; Liu, 1977; Chameides, 1978; Hameed et al., 1979] place the global yearly averaged OH concentration at between 10⁵ molecules/cm³ and 10⁶ molecules/cm³, depending to a large extent on the assumed perturbations to the natural atmosphere. However, measurements of OH in the troposphere have been scarce, and results of these measurements [Viang et al., 1975; Davis et al., 1976; Perner et al., 1976; Campbell et al., 1979] have been less than satisfactory. For example, the absorption technique [Perner et al., 1976] should in principle provide accurate OH measurements but remains to be developed [Killinger and Wang, 1977]. The isotope tracing technique [Campbell et al., 1979] offers an interesting alternative for OH monitoring, but remains to be calibrated, with possible systematic errors associated with the technique identified and remedied.