Recent advances in upper-atmospheric structure

Technical Report · Tue Jan 01 04:00:00 EST 1985

OSTI ID:6286731

Champion, K S.W.

A possible quantitative explanation of the semiannual variation in thermospheric density has been obtained in terms of a semiannual variation in the computed globally averaged vertical energy carried by propagating tides from the lower and middle atmosphere into the thermosphere. The effect is primarily due to seasonal changes in the distribution of water vapor and in the solar declination angle and Sun-Earth distance. An MSIS-83 empirical model of the thermosphere, representing a revision of the earlier MSIS models, was prepared. The database used covers a wider range of solar activity than previous models and an improved magnetic storms representation is included. Atomic oxygen profiles in the 100- to 160-km altitude region of the auroral thermosphere have been recalculated from measured quenching of N2(A 3 sigma +)sub u using the latest laboratory rates and the results are in good agreement with the mean CIRA 1972 profile. A new empirical model of thermospheric variations with geomagnetic activity was developed incorporating variations with local magnetic time, latitude-dependent terms which can vary with the magnitude of the geomagnetic disturbance, and an altitude dependent expression for the equatorial wave. A new index ML, derived from the AL index, was developed that appears to have promise to represent the variations of thermospheric species with geomagnetic activity. Satellite-measured values of solar UV flux, ground-based observations of Ca-K plages, sunspot numbers and 10.7 cm solar radio flux were analyzed for temporal variations. Some difference were identified and the significance to empirical and theoretical upper atmosphere models is discussed.

• Research Organization: Air Force Geophysics Lab., Hanscom AFB, MA (USA)
• OSTI ID: 6286731
• Report Number(s): AD-A-159918/2/XAB; AFGL-TR-85-0207
• Country of Publication: United States
• Language: English

Related Subjects

640104 -- Astrophysics & Cosmology-- Solar Phenomena
640203* -- Atmospheric Physics-- Magnetospheric Phenomena-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAE
DISTRIBUTION
EARTH ATMOSPHERE
ELEMENTS
ENERGY TRANSFER
FLUIDS
GASES
LABORATORIES
MAGNETIC STORMS
NITROGEN
NONMETALS
OXYGEN
QUENCHING
RADIATIONS
SEASONAL VARIATIONS
SOLAR ACTIVITY
SOLAR RADIATION
STARSPOTS
STELLAR ACTIVITY
STELLAR RADIATION
SUNSPOTS
THERMOSPHERE
VAPORS
VARIATIONS
WATER VAPOR