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GEOPHYSICAL RESEARCH LETTERS, VOL. 6, NO. 10, PAGES 771–774, 1979

Ionization Frequencies for Major Thermospheric Constituents as a Function of Solar Cycle 21

Marsha R. Torr

Space Physics Research Laboratory, Department of Atmospheric and Oceanic Science, University of Michigan, Ann Arbor, Michigan 48109

D. G. Torr

Space Physics Research Laboratory, Department of Atmospheric and Oceanic Science, University of Michigan, Ann Arbor, Michigan 48109

R. A. Ong

Space Physics Research Laboratory, Department of Atmospheric and Oceanic Science, University of Michigan, Ann Arbor, Michigan 48109

H. E. Hinteregger

Air Force Geophysics Laboratory, Hanscom Air Force Base, Bedford, Massachusetts 01731

Abstract

Increases in the solar ultraviolet flux (λ < 1250Å) over the past five years of rising solar activity have been larger than anticipated. This increase in UV flux dramatically affects the production of ionization of the various constituents in the thermosphere. In this paper we use measurements of the solar UV flux by the Atmosphere Explorer satellites to determine ionization frequencies for the major thermospheric species for various dates exhibiting notably different levels of solar activity. For the convenience of users of such data, a reduced set of cross section and flux data is presented for the wavelength range below 1027Å, comprising 37 wavelength intervals.

Received 6 July 1979; accepted 24 July 1979.

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Citation: Torr, M. R., D. G. Torr, R. A. Ong, and H. E. Hinteregger (1979), Ionization Frequencies for Major Thermospheric Constituents as a Function of Solar Cycle 21, Geophys. Res. Lett., 6(10), 771–774.

Copyright 1979 by the American Geophysical Union.