Artigo Revisado por pares

Satellite observations of Bremsstrahlung from widespread energetic electron precipitation events

1974; American Geophysical Union; Volume: 79; Issue: 4 Linguagem: Inglês

10.1029/ja079i004p00565

ISSN

2156-2202

Autores

W. L. Imhof, G. H. Nakano, R. G. Johnson, J. B. Reagan,

Tópico(s)

Geomagnetism and Paleomagnetism Studies

Resumo

Journal of Geophysical Research (1896-1977)Volume 79, Issue 4 p. 565-574 Satellite observations of Bremsstrahlung from widespread energetic electron precipitation events W. L. Imhof, W. L. ImhofSearch for more papers by this authorG. H. Nakano, G. H. NakanoSearch for more papers by this authorR. G. Johnson, R. G. JohnsonSearch for more papers by this authorJ. B. Reagan, J. B. ReaganSearch for more papers by this author W. L. Imhof, W. L. ImhofSearch for more papers by this authorG. H. Nakano, G. H. NakanoSearch for more papers by this authorR. G. Johnson, R. G. JohnsonSearch for more papers by this authorJ. B. Reagan, J. B. ReaganSearch for more papers by this author First published: 1 February 1974 https://doi.org/10.1029/JA079i004p00565Citations: 47AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Abstract This is a preliminary report of the first satellite observations that have been made of the intensities and energy spectra of the bremsstrahlung >50 keV produced in the atmosphere by intense widespread precipitations of energetic electrons from the outer radiation belt. The measurements afford the opportunity to investigate nearly simultaneously the energetic electron behavior on a worldwide scale during magnetic disturbances. With such a technique, one may study different features of the precipitation processes than those covered by satellite-borne particle detectors, which can provide more detailed particle information in a local region but without simultaneous measurements from many satellites can provide worldwide particle precipitation information only from long-term statistical studies. The observations are made with a 50-cm³ Ge(Li) gamma ray spectrometer that was launched aboard the spin-stabilized satellite 1972–076B into a nearly circular polar orbit at 750-km altitude on October 2, 1972. Correlative measurements of precipitating electrons are also made with an energetic electron spectrometer on board the same satellite. The longitude and hence local time extents of the precipitations are derived by least square fitting techniques from the gamma ray spectrometer responses at various spin angle orientations and satellite locations. The observations indicate the occurrence of nearly simultaneous precipitations over a wide range of local times. Significant variations occur in the intensity versus local time, but in the limited number of cases studied to date the intensities near noon are generally greater than those in the early morning hours. References Akasofu, S.-I., The dynamical morphology of the aurora polaris, J. Geophys. Res., 68, 1667, 1963. Anderson, K. A., Balloon measurements of X-rays in the auroral zone, Auroral Phenomena, M. Walt, chap. 4, 46–83, Stanford University Press, Palo Alto. Calif., 1965. Anger, C. D., Optical emissions in the polar cap54th Annual MeetingAGUWashington, D.C., 1973. Bailey, D. K., Some quantitative aspects of electron precipitation in and near the auroral zone, Rev. Geophys. Space Phys., 6, 289, 1968. Barcus, J. R., T. J. Rosenberg, Energy spectrum for auroral zone X rays, 1, Diurnal and type effects, J. Geophys. Res., 71, 803, 1966. Berger, M. J., S. M. Seltzer, Bremsstrahlung in the atmosphere, J. Atmos. Terr. Phys., 34, 85, 1972. Brown, R. R., Electron precipitation in the auroral zone, Space Sci. Rev., 5, 311, 1966. Frank, L. A., J. A. Van Allen, J. D. Craven, Large diurnal variations of geomagnetically trapped and of precipitated electrons observed at low altitudes, J. Geophys. Res., 69, 3155, 1964. Fritz, T. A., Study of the high-latitude, outer zone boundary region for ≥40-keV electrons with satellite Injun 3, J. Geophys. Res., 75, 5387, 1970. Imhof, W. L., E. E. Gaines, J. B. Reagan, Dynamic variations in intensity and energy spectra of electrons in the inner radiation belt, J. Geophys. Res., 78, 4568, 1973. Jelly, D., N. Brice, Changes in Van Allen radiation associated with polar substorms, J. Geophys. Res., 72, 5919, 1967. Kremser, G., Balloon measurements of auroral X-rays, Aurora and Airglow B. M. McCormac, 477, Reinhold, New York, 1967. Maral, G., K. Bronstad, H. Trefall, G. Kresmer, H. Specht, P. Tanskanen, J. Kangas, W. Riedler, J. P. Legrand, On the morphology of auroral-zone X-ray events, 3, Largescale observations in the midnight-to-morning sector, J. Atmos. Terr. Phys., 35, 735, 1973. McDiarmid, I. B., J. R. Burrows, Diurnal intensity variations in the outer radiation zone at 1000 km, Can. J. Phys., 42, 1135, 1964. Moore, R. H., R. K. Zeigler, The solution of the general least-squares problem with specific reference to highspeed computersRep. LA-2367Los Alamos Sci. Lab, Los Alamos, N. Mex., 1959. Nakano, G. H., W. L. Imhof, Performance of large germanium detectors at elevated temperatures for satellite applications, IEEE Trans. Nucl. Sci., 181, 258, 1971. O'Brien, B. J., High-latitude geophysical studies with satellite Injun 3, J. Geophys. Res., 69, 13, 1964. Potemra, T. A., T. J. Rosenberg, VLF propagation disturbances and electron precipitation at mid-latitudes, J. Geophys. Res., 78, 1572, 1973. Thorne, R. M., C. F. Kennel, Relativistic electron precipitation during magnetic storm main phase, J. Geophys. Res., 76, 4446, 1971. Vampola, A. L., Electron pitch angle scattering in the outer zone during magnetically disturbed times, J. Geophys. Res., 76, 4685, 1971. Vampola, A. L., H. C. Koons, D. A. McPherson, Outer zone electron precipitation, J. Geophys. Res., 76, 7609, 1971. Citing Literature Volume79, Issue4Space Physics1 February 1974Pages 565-574 ReferencesRelatedInformation

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