The concentrations of the HO2-RO 2 species measured during July 11, 1990, in the ROSE (Rural Oxidants in the Southern Environment) study in Alabama are compared to those expected in theory from calculations based upon detailed hourly measurements of a variety of trace gases including the hydrocarbons, NO, NO2, carbonyl compounds, CO, PAN (peroxyacetylnitrate) and calculated Jo-values. The measurements are also compared with the [HO 2] + [RO 2] as estimated from deviations from the NO2 + hv (+02) • NO + 03 photostationary state. Within the error of the measurements all of the data appear to be in reasonable accord. 20,671 20,672 CANTREI•I• E'r AL.: PEROXY RADICALS peroxy radical measurements, submitted to Journal of Geophysical Research, 1992] (hereinafter referred to as Cantrell et al., submitted paper), developed by Cantrell et al., [1984] was employed to make continuous (night and day) atmospheric measurements over a period of several weeks. This is the most extensive study of the peroxy radical which has been made to date using a calibrated instrument. The H O2/RO 2 concentration versus time data from these experiments has been published elsewhere previously [Cantrell et al., 1992;Calvert et al., 1991]. In this paper we utilize the simultaneous measurements during the ROSE (Rural Oxidants in the Southern Environment) study of the many other trace gases which relate to the peroxy radical generation and removal to test our understanding of the atmospheric chemistry of the peroxy radicals.
EXPERIMENTAL TECHNIQUES The Measurement SiteThe site was located in west-central Alabama (longitude, 88ø!2'7 ", latitude 32ø21'42 ", elevation 91 m) in a forest preserve which consisted of unpaved roads through a moderately dense forest, primarily loblally pine; it was reasonably well isolated from any nearby anthropogenic emissions. The site and the surrounding area for several miles are timberlands owned by the James River Corporation, a paper company that operates a mill in the vicinity. The site was often hazy and with significant broken-cloud cover on most days.
The Peroxy Radical MeasurementsThe HO2/RO 2 instrument has been described previously by Cantrell et al., [1991Cantrell et al., [ , 1992 submitted paper,] and was an improved version of that first reported in the early 1980s [Cantrell and Stedman, 1982; Wendel et al., 1983;