Observations from Millstone Hill during the geomagnetic disturbances of March and April 1990

Journal Article · Fri Jan 31 23:00:00 EST 1992 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/91JA02428· OSTI ID:5361863

Buonsanto, M J; Foster, J C; Sipler, D P ^[1]

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1. Massachusetts Inst. of Tech. Westford (United States)

The incoherent scatter radars at Millstone Hill operated continuously during the periods March 16-23 and April 6-12, 1990, providing observations of large-scale ionospheric structure and dynamics over a large portion of eastern North America. Major geomagnetic storms occurred during each of these periods, with deep nighttime ionospheric troughs and large magnetospheric convection electric fields observed equatorward of Millstone. The Millstone observations provide a comprehensive data set detailing storm-induced ionospheric effects over a 35{degree} span of latitude during both of these intervals. At the latitude of Millstone the ionospheric peak height hmF2 rose above 600 km the into trough on March 22 and 23 and reached {approx}500 km at night on April 11 and 12. Increased recombination, apparently due to the strong electric fields, te temperature dependent recombination rate coefficient, and neutral composition changes, greatly depleted the F2 region over a wide latitude range during the day on April 10, 1990. This resulted in an ionosphere dominated by molecular ions, with ionospheric peak heights below 200 km on this day. A number of frictional heating events during the disturbed periods are seen from comparison of ion temperature and velocity measurements. The most intense event took place near 1200 UT on April 10, 1990, when Kp reached 8. At 0100 UT on March 21, line of sight ion velocities in excess of 500 ms{sup {minus}1} were observed at the extreme southern limit of the Millstone steerable radar's field of view (40{degree} apex magnetic latitude at an altitude of 700 km). These could be due to penetration of magnetospheric electric fields or electric fields associated with ring current shielding in the storm-time outer plasmasphere. About an hour later, ion outflow was observed just equatorward of Millstone.

• OSTI ID: 5361863
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 97:A2; ISSN JGREA; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CONVECTION
CURRENTS
DIMENSIONS
DYNAMICS
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRIC CURRENTS
ELECTRIC FIELDS
ENERGY TRANSFER
F REGION
F2 LAYER
GEOGRAPHICAL VARIATIONS
HEAT TRANSFER
HEATING
HEIGHT
ION TEMPERATURE
IONOSPHERE
IONOSPHERIC EFFECTS
LATITUDE EFFECT
MAGNETIC STORMS
MASS TRANSFER
MEASURING INSTRUMENTS
MECHANICS
MORPHOLOGY
PLANETARY IONOSPHERES
PLASMA DENSITY
RADAR
RANGE FINDERS
RING CURRENTS
TEMPERATURE DEPENDENCE
VARIATIONS
VIRTUAL HEIGHT