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Equatorial Thermospheric Wind Changes During The Solar Cycle: Measurements At Arequipa,Peru From 1983 To 1990, M. A. Biondi, J. W. Meriwether, Bela G. Fejer, S. A. Gonzalesz, D. C. Hallenbeck
Equatorial Thermospheric Wind Changes During The Solar Cycle: Measurements At Arequipa,Peru From 1983 To 1990, M. A. Biondi, J. W. Meriwether, Bela G. Fejer, S. A. Gonzalesz, D. C. Hallenbeck
Bela G. Fejer
Fabry-Perot interferometer measurements of Doppler shifts in the nightglow 630-nm emission line have been used to determine near-equatorial thermospheric wind velocities at Arequipa, Peru, over ∼2/3 of a solar cycle. Monthly-average nocturnal variations in the meridional and zonal wind components were calculated from the nightly data to remove short term (day-to-day) variability, facilitating display of seasonal changes in the wind patterns, as well as any additional changes introduced by the progression of the solar cycle. The measured seasonal variations in the wind patterns are more pronounced than the solar cycle variations and are more readily understandable in terms of the …
Seasonal Variations In Theequatorial Thermospheric Wind Measured At Arequipa, Peru, M. A. Biondi, J. W. Meriwether, Bela G. Fejer, S. A. Gonzalez
Seasonal Variations In Theequatorial Thermospheric Wind Measured At Arequipa, Peru, M. A. Biondi, J. W. Meriwether, Bela G. Fejer, S. A. Gonzalez
Bela G. Fejer
Studies have been carried out at Arequipa, Peru, of the seasonal variations in the thermospheric winds at moderate solar flux levels and low geomagnetic activity. Fabry-Perot interferometer measurements of the Doppler shifts in the 630.0 nm nightglow emission line from March to August 1983 and from April to October 1988 have yielded monthly-average meridional winds that are nearly zero (<50 m/s) and possibly fluctuating in direction through much of the night but develop a southward flow at 50–100 m/s in the early and the late night from May onward. The average zonal winds are eastward throughout the night, reaching peak velocities before local midnight and then decreasing. The peak velocities increase to a maximum around the June solstice. The winds are generally stronger in 1988 than in 1983, even though the solar EUV fluxes are comparable for both years. Comparison of the present results with earlier satellite measurements, as embodied in the Horizontal Wind Model of Hedin et al., reveals generally satisfactory agreement at the equinox and June solstice, except for the June 1988 period. Killeen et al.'s vector spherical harmonic form of the NCAR Thermospheric General Circulation Model, calculated for similar solar flux levels, yields meridional and zonal wind variations which exhibit the same temporal behaviors but generally smaller values than the present measurements. The present wind patterns are also compared with those measured during the same years at Arecibo, Puerto Rico; one finds oppositely directed meridional flows and similar, eastward zonal flows at the two locations, as expected from a consideration of solar EUV heating as the principal driving force.