Polar cap diurnal temperature variations: Observations and modeling

Journal Article · Fri Jul 01 04:00:00 EDT 1988 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA093iA07p07466· OSTI ID:5222899

McCormac, F G; Killeen, T L; Burns, A G; Meriwether, Jr, J W ^[1]; Roble, R G ^[2]; Wharton, L E; Spencer, N W ^[3]

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1. Univ. of Michigan, Ann Arbor (USA)
2. National Center for Atmospheric Research, Boulder, CO (USA)
3. NASA Goddard Space Flight Center, Greenbelt, MD (USA)

A diurnal variation in thermospheric temperature in the geomagnetic polar cap minimum (January 1987) has been observed using high spectral resolution measurements of the O({sup 1}D) emission line made with the Fabry-Perot interferometer located at Thule, Greenland (76{degree}32{prime}N, 68{degree}45{prime}W, {Lambda}= 86). The temperature maximum in the diurnal cycle occurs at 1600 UT, which is very near the magnetic local noon period in the northern hemisphere. Data from the wind and temperature spectrometer on the Dynamics Explorer 2 satellite show a similar diurnal variation in the northern polar cap thermospheric temperature for near solar maximum conditions. In an attempt to find the mechanisms responsible for the variation, the authors have used the diagnostics package developed for use with the NCAR thermospheric general circulation model (TGCM), which allows the tracking of individual parcels of gas in both time and space by interpolation through the model grid. At each of the predicted loci of the parcels they have examined the physical factors which influence the thermal balance by decomposing the thermodynamic equation into its constituent terms. By tracing the trajectory of a parcel backward in time and space from the location of Thule, they have been able to show, for a model run with input parameters pertaining to day 314, 1976, that the observed diurnal temperature variation is attributable to the following factors: (1) the degree of solar heat input that a parcel experiences en route to the polar cap, which is dependent on whether or not it crosses the solar terminator, (2) the route a parcel takes through the polar cusp, i.e., whether the parcel skirts the edge or passes directly through the center determines the total quantity of heat added by soft particle impact within the cusp, (3) the time duration between maximum heat input from the combination of solar, cusp, auroral and Joule sources and the time of arrival overhead at Thule.

• OSTI ID: 5222899
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 93:A7; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640200* -- Atmospheric Physics
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
DAILY VARIATIONS
EARTH ATMOSPHERE
ELECTRIC HEATING
ENERGY TRANSFER
FLUID MECHANICS
GENERAL CIRCULATION MODELS
HEAT TRANSFER
HEATING
HYDRODYNAMICS
JOULE HEATING
MATHEMATICAL MODELS
MECHANICS
PLASMA HEATING
POLAR CUSP
POLAR REGIONS
RADIATIONS
RESISTANCE HEATING
SATELLITES
SOLAR RADIATION
STELLAR RADIATION
TEMPERATURE MEASUREMENT
THERMOSPHERE
VARIATIONS