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On the diurnal variation of polar mesosphere summer echoes
Author(s) -
Klostermeyer J.
Publication year - 1999
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1999gl003629
Subject(s) - noon , atmospheric sciences , mesosphere , diurnal temperature variation , earth's magnetic field , electron precipitation , solstice , environmental science , physics , latitude , astronomy , magnetosphere , magnetic field , stratosphere , quantum mechanics
During quiet solar and geomagnetic conditions, the observed mean diurnal variation of the reflectivity of polar mesosphere summer echoes is characterized by a distinct maximum near noon and a deep minimum near 20 LT, so that it appears to contain a relatively strong semidiurnal component. Theoretical considerations predict a nonlinear relationship between the reflectivity, the tidal temperature variation, and the electron production by solar radiation and energetic‐particle precipitation. Least squares fits based on model predictions of atmospheric tides, on a Chapman function, and on cosmic noise absorption data indicate that the observed diurnal variation of the reflectivity is predominantly determined by the electron production. Its semidiurnal component is essentially caused by the fact that the ionization rates due to the solar radiation and the energetic‐particle precipitation have maxima at noon and near midnight, respectively.