Vertical column abundance measurements of atmospheric hydroxyl From 26°, 40°, and 65°N

Abstract

Hydroxyl (OH) vertical column abundances measured with Pepsios spectrometers from Fritz Peak, Colorado (40°N), Boca Raton, Florida (26.4°N), and Poker Flat, Alaska (65°N), are presented. The Colorado normalized abundances have remained nearly constant since 1980 at levels about 1.7 times the 1977 values. Theoretical models agree well with the pre‐1980 abundances, but recent data appear to require a significant change in the atmospheric photochemistry. The Colorado seasonal diurnal asymmetry and its correlation with total ozone are shown to persist. The Florida data show little seasonal variation and have diurnal asymmetry characteristics which differ considerably from those of the Colorado asymmetry. Large Florida OH abundance excursions with respect to Colorado levels are seen in the wintertime of 1980, 1984, and 1986, which suggests the possibility of a relationship with the quasi‐biennial oscillation in tropical stratospheric winds. Responses of the Florida OH column to the passage of a tropical storm (July 1985) and to a partial solar eclipse (October 1986) are also documented. An anomalous drop of 80% in OH column abundances on March 18, 1986, is discussed. Hydroxyl abundance values at Poker Flat (June–July 1983) are 40% higher than corresponding Colorado or Florida values.