Polar-cap diurnal temperature variations: observations and modeling

Technical Report · Fri Jul 01 04:00:00 EDT 1988

OSTI ID:6513059

McCormac, F G; Killeen, T L; Burns, A G; Meriwether, J W; Roble, R G

A diurnal variation in thermospheric temperature in the geomagnetic polar cap at solar minimum (Jan 87) was observed using high spectral-resolution measurements of the O(1D) emission line made with the Fabry-Perot interferometer located at Thule, Greenland. Data from the wind and temperature spectrometer on the Dynamics Explorer 2 satellite show a diurnal variation in the northern polar cap thermospheric temperature for near-solar-maximum conditions. The diagnostics package, developed for use with the NCAR thermospheric general circulation model (TGCM), allows the tracking of individual parcels of gas in both time and space by interpolation through the model grid. Each loci of the parcels influences the thermal balance by decomposing the thermodynamic equation into its constituent terms. Tracing the trajectory of a parcel backward in time and space from the location of Thule (i.e., well inside the geomagnetic polar cap), will show, for a model run with input parameter near the solstice pertaining to day 314, 1976 (i.e., several weeks from solstice near solar minimum), that near the solstice that 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 crusp, (3) the time duration between maximum herat input from the combination solar, cusp, auroral, and Joule source and the time of arrival overhead at Thule.

• Research Organization: Michigan Univ., Ann Arbor (USA). Space Physics Research Lab.
• OSTI ID: 6513059
• Report Number(s): AD-A-200008/1/XAB
• Country of Publication: United States
• Language: English

Related Subjects

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640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAE
DAILY VARIATIONS
EARTH ATMOSPHERE
ELECTRODES
EMISSION SPECTRA
ENERGY
GEOMAGNETIC FIELD
GREENLAND
GRIDS
HEAT
MAGNETIC FIELDS
PARTICLES
POLAR REGIONS
SOLAR ACTIVITY
SPECTRA
TEMPERATURE GRADIENTS
THERMODYNAMICS
THERMOSPHERE
VARIATIONS