HR: 10:20h
AN: SA42A-01 INVITED     [Abstracts]
TI: Comparative Ionospheres: All Planets Enjoy Sunshine
AU: * Mendillo, M
EM: mendillo@bu.edu
AF: Boston University, Center for Space Physics, 725 Commonwealth Avenue, Boston, MA 02215 United States
AB: The ionization of a planet's (or moon's) upper atmosphere is caused by energetic photons (EUV and X-rays), augmented by the influx of energetic particles (meteoritic, heliospheric, magnetospheric). The primary structure of an ionosphere, its electron density profile with height Ne(h), results from photochemical processes, with modifications (sometimes dramatically so) due to transport. Typically, the Ne(h) profiles on Venus and Mars conform to photochemical equilibrium, while at Earth both photochemistry and dynamics are needed. For the giant planets, photochemistry alone is unable to match observations. This suggests the need for dynamical processes (winds, E-fields), energetics (e.g., loss via vibrationally-excited molecules), and possible influxes of material (e.g., water products)--- all poorly constrained by observations. Variable solar activity affects all planetary ionospheres, and local plasma instabilities may occur as well. This brief paper provides an overview of known characteristics of planetary ionospheres, and then gives examples of regional and episodic disturbances on Mars as a way to encourage the study of solar-terrestrial planet-relationships (STPR) as a future direction for aeronomy.
DE: 2400 IONOSPHERE (6929)
DE: 2439 Ionospheric irregularities
DE: 2459 Planetary ionospheres (5435, 5729, 6026)
DE: 2479 Solar radiation and cosmic ray effects
DE: 7974 Solar effects
SC: SPA-Aeronomy [SA]
MN: Fall Meeting 2005