Modeling the solar cycle change in nitric oxide in the thermosphere and upper mesosphere

Journal Article · Mon Feb 01 04:00:00 EST 1993 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/92JA02201· OSTI ID:7065338

Fuller-Rowell, T J ^[1]

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1. Univ. of Colorado, Boulder (United States)

Measurements from the Solar Mesosphere Explorer (SME) satellite have shown that low-latitude nitric oxide densities at 110 km decrease by about a factor of 8 from January 1982 to April 1985. This time period corresponds to the descending phase of the last solar cycle where the monthly smoothed sunspot number decreased from more than 150 to less than 25. In addition, nitric oxide was observed to vary by a factor of 2 over a solar rotation, during high solar activity. A one-dimensional, globally averaged model of the thermosphere and upper mesosphere has been used to study the height distribution of nitric oxide (NO) and its response to changes in the solar extreme ultraviolet radiation (EUV) through the solar cycle and over a solar rotation. The primary source of nitric oxide is the reaction of excited atomic nitrogen, N([sup 2]D), with molecular oxygen. The atomic nitrogen is created by a number of ion-neutral reactions and by direct dissociation of molecular nitrogen by photons and photoelectrons. The occurrence of the peak nitric oxide density at or below 115 km is a direct consequence of ionization and dissociation of molecular nitrogen by photoelectrons, which are produced by the solar flux below 30.0 nm (XUV). Nitric oxide is shown to vary over the solar cycle by a factor of 7 at low latitudes in the lower thermosphere E region, due to the estimated change in the solar EUV flux, in good agreement with the SME satellite observations. The NO density is shown to be strongly dependent on the temperature profile in the lower thermosphere and accounts for the difference between the current model and previous work. Wavelengths less than 1.8 nm have little impact on the NO profile. A factor of 3 change in solar flux below 5.0 nm at high solar activity produced a factor of 2 change in the peak NO density, consistent with SME observations over a solar rotation; this change also lowered the peak to 100 km, consistent with rocket data. 52 refs., 10 figs., 5 tabs.

• OSTI ID: 7065338
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 98:A2; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540120* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
661320 -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAE
BOSONS
CHALCOGENIDES
DENSITY
DISSOCIATION
DISTRIBUTION
E REGION
EARTH ATMOSPHERE
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
ELEMENTS
EXTREME ULTRAVIOLET RADIATION
GLOBAL ANALYSIS
GLOBAL ASPECTS
IONIZATION
IONOSPHERE
MASSLESS PARTICLES
MATHEMATICAL MODELS
MATHEMATICS
MESOSPHERE
MOTION
NITRIC OXIDE
NITROGEN
NITROGEN COMPOUNDS
NITROGEN OXIDES
NONMETALS
ONE-DIMENSIONAL CALCULATIONS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PHOTONS
PHYSICAL PROPERTIES
PLANETARY IONOSPHERES
RADIATIONS
ROTATION
SOLAR ACTIVITY
SOLAR CYCLE
SOLAR FLUX
SPECTRA
THERMOSPHERE
ULTRAVIOLET RADIATION
WAVELENGTHS