Processes responsible for the compositional structure of the thermosphere

Journal Article · Sat Apr 01 04:00:00 EST 1989 · Journal of Geophysical Research; (USA)

DOI:https://doi.org/10.1029/JA094iA04p03670· OSTI ID:6049531

Burns, A G; Killeen, T L ^[1]; Roble, R G ^[2]

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1. Univ. of Michigan, Ann Arbor (USA)
2. National Center for Atmospheric Research, Boulder, CO (USA)

A diagnostic postprocessor analysis package used with runs of the National Center for Atmospheric Research thermospheric general circulation model (NCAR-TGCM) has been extended to include the terms of the neutral composition equation that is solved by this model. The purpose of the development of this capability is to quantify the relative importance of the various physical and chemical mechanisms that force changes in neutral thermospheric composition for given geophysical situations. Compositional term analysis calculations are presented using a diurnally-reproducible TGCM run for a day of moderate geomagnetic activity (Kp = 3) near December solstice. Principal results for F region altitudes are in general agreement with previous work. The principal results at {approximately} 120 km altitude include the following: (1) photodissociation is an important term for O and O{sub 2} in this altitude region, becoming roughly commensurate with molecular diffusion, vertical and horizontal advection; (2) significant increases in the mass mixing ratio of O in the summer hemisphere occur due to photodissociation, especially in the daytime at middle latitudes; (3) downward molecular diffusion of O is important in controlling the mass mixing ratio for O, particularly in the high-latitude winter hemisphere; (4) a complicated morphological pattern of horizontal and vertical advection maintains the mass mixing ratios at these altitudes; (5) vertical advection resulting from Joule heating in the morning and evening sectors of the auroral zone is of importance for the composition of the high-latitude lower thermosphere; (6) typical time scales for maximum changes of 1/e in the mass mixing ratio of N{sub 2} are of the order of 60-90 hours.

• OSTI ID: 6049531
• Journal Information: Journal of Geophysical Research; (USA), Journal Name: Journal of Geophysical Research; (USA) Vol. 94:A4; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ADVECTION
ALTITUDE
ATMOSPHERIC CHEMISTRY
CHEMICAL COMPOSITION
CHEMISTRY
DIFFUSION
DISSOCIATION
DYNAMICS
EARTH ATMOSPHERE
ELECTRON DENSITY
ELEMENTS
F REGION
GENERAL CIRCULATION MODELS
GEOMAGNETIC FIELD
IONOSPHERE
MAGNETIC FIELDS
MASS TRANSFER
MATHEMATICAL MODELS
MECHANICS
MIXING
NEUTRAL-PARTICLE TRANSPORT
NONMETALS
OXYGEN
PLANETARY IONOSPHERES
RADIATION TRANSPORT
THERMOSPHERE
WIND