Extensive new information on the daytime column abundance of atmospheric OH is presented from spectroscopic observations of sunlight absorption by the P•(1)•I2Y. + -X2•0, 0) transition of OH at 3081.7/!•, taken with a Pepsios spectrometer. The observations were made from the NOAA Aeronomy Observatory at Fritz Peak, Colorado, between December 1976 and December 1979. An overall seasonal dependence on the depth of penetration of the solar ultraviolet flux, which is believed to initiate the photochemistry of daytime OH, was found. The overall averaged data is represented by an empirical curve, N(sec X), where X is the solar zenith angle, showing an overhead sun maximum abundance of 7.1 x 1013/cm•; decreasing to 4.9 x 1013/cm •-at sec X --2.0. The OH abundance and the sec X variation agree reasonably well with predictions given by recent theoretical models of the stratosphere and mesophere and with the analysis of earlier in situ measurements of stratospheric and mesospheric OH by Anderson. An OH abundance increase of about 1 x 10•3/cm ,. per year is found for the 1976-1979 period. There was a seasonal variation in 1978 with a 25-30% decrease from a springtime maximum to a fall minimum. The 1978 abundances also show a 30-40% diurnal oscillation whose cause is as yet undetermined. This effect is shown to be dependent on solar flux on both a diurnal and an annual basis, and the 1978-1979 observations exhibit additional long-term changes, possibly related to the solar cycle, which will be monitored in future work. INTRODUCTION The role of the odd-hydrogen free radicals in the chemistry of the upper atmosphere has been an important feature in theoretical models describing the behavior of stratospheric ozone since the phOtochemical model for an oxygen atmosphere of Chapman [1943] was found to be inadequate [Bates and Nicolet, 1950]. The addition of stratospheric water vapor to this model with the associated photochemical production of the odd-hydrogen free radicals H, OH, and HO2 led to reasonable agreement with available ozone data for altitudes above about 40 km [Nicolet, 1975]. The predicted ozone densities for the main ozone layer at about 25 km remained substantially greater than observed values. The significance of the catalytic reactions of the odd-nitrogen free radicals (NO, NO,_) as the final important natural control mechanism for the main ozone layer was established by Crutzen [1970]. Concern was soon voiced about the possible perturbation of these natural equilibrium conditions by the projected operation of a large fleet of supersonic transports in this region of the stratosphere [Johnston, 1971]. Molina and Rowland [1974] identified the freon compounds (CC1,.F,. and CC13F) as additional anthropogenic pollutants which furnish free radicals of chlorine (C10, C1) which were shown to destroy ozone in catalytic reactions similar to those for odd nitrogen. New theoretical models assessing possible ozone damage renewed the interest in odd hydrogen compounds since they influence the partitioning of the odd-nitrogen an...
A divertor, designed to reduce the flow of impurities from the wall into a gas discharge, has been used with a small stellarator. In the divertor an outer shell of magnetic flux is bent away from the discharge channel into a large auxiliary chamber. Ions diffusing toward the wall tend to follow the lines of force of this outer shell into the divertor chamber. Impurities produced by wall bombardment in this chamber do not readily return to the discharge. The magnetic design of this device is described, and a phenomenological theory of its performance is outlined. The spectroscopic data with and without the divertor activated indicate that the divertor reduces the influx of impurities by a factor of two to three, while the impurity concentration at the core, or central region, may be diminished by an order of magnitude when the divertor is activated. Kinetic temperatures of positive ions determined from spectroscopic measurements of Doppler broadening increase from 40 ev without the divertor to 60 ev for He+ and to 130 ev for O++++ with use of the divertor.
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.
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