Thermal and Hyperthermal Electron Distributions in the Midnight Sector of the Winter Topside Ionosphere.
Environmental research papers,
AIR FORCE GEOPHYSICS LAB HANSCOM AFB MASS
Pagination or Media Count:
A gridded spherical electrostatic analyzer aboard Injun 5 has been used to measure fluxes of thermal and hyperthermal electrons at sub-auroral latitude in the midnight sector of the northern ionosphere between altitudes of 2500 and 850 km. Due to the offset between the geomagnetic and geographic poles, hyperthermal fluxes consisting of energetic photoelectrons that have escaped from the sunlit southern hemisphere are observed along orbits over the Atlantic Ocean and North America but not over Asia. The ambient electron temperatures near 2500 km have their highest values at trough latitudes for all longitudes. Based on these observations it is concluded that At trough latitudes, elevated electron temperatures in the topside ionosphere are produced by sources other than conjugate photoelectrons, Equatorward of the trough in the Atlantic Ocean, North American longitude sector conjugate photoelectrons contribute significantly to the heating of electrons in the topside ionosphere. Much of the photoelectron energy is deposited at altitudes greater than 2500 km, then conducted along magnetic field lines into the ionosphere.
- Atmospheric Physics