Publication Date:
2015-07-01
Description:
An 11 year (1989-1995, 2010-2013) nighttime thermospheric wind (at ~250 km) data set from Fabry-Perot Interferometer (FPI) at Millstone Hill (MH, 42.6°N, 71.5°W) is used to investigate multi-day oscillations (6-30 days) in the thermospheric nighttime winds. Dependencies of multi-day oscillations on solar radiation (F10.7), solar wind speed (SW), and geomagnetic activity (Kp) are determined. We found (1) there exist prominent quasi-27-day oscillations in the thermospheric zonal (meridional) wind, which appears to be more correlated to the same periodic oscillations in Kp and SW than in F10.7 during the solar maximum (solar declining phase and minimum); (2) Quasi-13.5-day oscillations in the zonal wind occur during the solar maximum and increasing phases and are also more correlated to the same periodic oscillations in Kp and SW; and (3) in general the correlations of the multi-day oscillations in the thermospheric winds are more correlated with Kp and SW than F10.7. Our analyses also show that the zonal wind is more sensitive to SW than the meridional wind. We further find: (4) for high F10.7, the pre-midnight zonal wind is more westward toward increasing SW; for low F10.7, the post-midnight zonal wind is also more westward toward increasing SW; and (5) meridional winds tend to be more southward with increasing SW for medium and high F10.7.
Print ISSN:
0148-0227
Topics:
Geosciences
,
Physics
