Observations and computations of twilight helium 10,830-Angstrom emission

Observations of helium 10,830-A radiation with a grille spectrometer at Socorro, New Mexico, from 1967 to 1970 are presented. The data are discussed in light of new computations of the excitation and emission profiles. The observational data show an intensity increase of a factor of 3 during this period that is closely related to a corresponding change in the solar EUV radiation (λ<380 A). A large seasonal variation is discussed that is caused in part by a 5∶1 variation in the neutral helium abundance and that is augmented by seasonal variation in the conjugate photoelectron flux. In addition, a diurnal variation of the helium abundance of about 30% with a maximum in the morning is suggested.

[1]  W. Kasprzak.  EVIDENCE FOR A HELIUM FLUX IN THE LOWER THERMOSPHERE. , 1969 .

[2]  D. Hunten,et al.  N2+ emission in the twilight☆ , 1966 .

[3]  G. Keating,et al.  The winter helium bulge. , 1967 .

[4]  V. I. Krassovsky,et al.  Atlas of the airglow spectrum 3000-12400 Å , 1962 .

[5]  Michael B. McElroy,et al.  Excitation of atmospheric helium , 1965 .

[6]  J. Geisler,et al.  EXCHANGE OF ENERGY BETWEEN THE IONOSPHERE AND THE PROTONOSPHERE , 1965 .

[7]  J. Geisler,et al.  Ionospheric temperatures at sunspot minimum , 1965 .

[8]  G. Keating,et al.  Simultaneous measurements of exospheric densities near opposite poles , 1970 .

[9]  N. N. Shefov.  Twilight helium emission during low and high geomagnetic activity , 1968 .

[10]  A. Nier,et al.  A study of day-night variations in the neutral composition of the lower thermosphere. , 1968 .

[11]  E. Ferguson,et al.  Metastable helium atom concentrations in the earth's atmosphere , 1962 .

[12]  T. Patterson.  METASTABLE HELIUM IN THE UPPER ATMOSPHERE. , 1967 .

[13]  F. S. Johnson,et al.  Composition changes in the lower thermosphere. , 1969 .

[14]  I. Harris,et al.  THEORETICAL MODELS FOR THE SOLAR-CYCLE VARIATION OF THE UPPER ATMOSPHERE , 1962 .

[15]  M. McElroy,et al.  Electron Impact Excitation of the Dayglow , 1969 .

[16]  H. Hinteregger,et al.  Solar‐cycle variation of extreme ultraviolet radiation , 1969 .

[17]  A. Nier,et al.  Mass spectrometric studies of the composition of the lower thermosphere during summer 1967 , 1968 .

[18]  H. N. Rundle,et al.  AN IDENTIFICATION OF TWILIGHT HELIUM 10,830-A EMISSION WITH INCREASED RESOLUTION AND PRELIMINARY PHOTOMETRIC MEASUREMENTS. , 1969 .

[19]  M. McElroy,et al.  The Detection of λ 3889 OF Orthohelium in the Twilight Airglow. , 1965 .

[20]  M. McElroy,et al.  ELECTRON TEMPERATURES IN THE IONOSPHERE , 1963 .

[21]  B. Tinsley,et al.  Measurements of twilight helium 10,830 Å emission , 1968 .

[22]  B. Tinsley.  The circularly symmetric grille spectrometer. , 1966, Applied optics.

[23]  M. Nicolet,et al.  Investigation of the major constituents of the April–May 1963 heterosphere by the explorer XVII satellite , 1965 .

[24]  G. Hartmann,et al.  A mass spectrometric investigation of the lower thermosphere above Fort Churchill with special emphasis on the helium content , 1969 .