Physical Sciences and Mathematics Commons^™

Observations Of Solar Cyclical Variations In Geocoronal Hα Column Emission Intensities, S. M. Nossal, F. L. Roesler, E. J. Mierkiewicz, R. J. Reynolds

Physical Sciences - Daytona Beach

Observations of thermospheric + exospheric Hα column emissions by the Wisconsin Hα Mapper (WHAM) Fabry-Perot (Kitt Peak, Arizona) over the 1997–2001 rise in solar cycle 23 show a statistically significant solar cyclical variation. The higher signal-to-noise WHAM observations corroborate suggestions of a solar cycle trend in the Hα emissions seen in Wisconsin observations over solar cycle 22. Here we compare WHAM 1997 and 2000–2001 winter solstice geocoronal Hα observations toward regions of the sky with low galactic emission. The observed variation in geocoronal hydrogen column emission intensities over the solar cycle is small compared with variations in hydrogen exobase densities. …