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Solar‐terrestrial coupling: Low‐latitude thermospheric nitric oxide
Author(s) -
Barth Charles A.,
Tobiska W. Kent,
Siskind David E.,
Cleary David D.
Publication year - 1988
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/gl015i001p00092
Subject(s) - thermosphere , atmospheric sciences , solar irradiance , irradiance , flux (metallurgy) , solar maximum , solar minimum , physics , mesosphere , ionosphere , solar cycle , environmental science , astronomy , materials science , optics , stratosphere , solar wind , plasma , metallurgy , quantum mechanics
As measured by the Solar Mesosphere Explorer satellite, the density of nitric oxide at low latitudes (30°S to 30°N) and at 110 km (E‐region) decreased from a mean value of 3 × 10 7 molecules/cm³ in January 1982 to a mean value of 4 × 10 6 molecules/cm³ in April 1985. In addition, the nitric oxide density varied ±50% with a 27‐day period during times of high solar activity. The variation of nitric oxide correlates with variations in the solar Lyman‐alpha irradiance which is also measured by the Solar Mesosphere Explorer satellite. The Lyman alpha irradiance is interpreted as an index of the variations in the solar EUV and soft X‐ray flux. The hypothesis is proposed that the solar X‐ray flux between 20 and 100 Å has a larger variation than the solar EUV flux between 100 and 1050 Å and that the solar X‐rays produce photoelectrons which are the source of the nitric oxide.