COMPUTATIONS OF LOCAL ION ENERGY-BALANCE IN THE AURORAL-ZONE

An investigation of the coupling between the ionosphere and the thermo sphere is made using coordinated measurements obtained simultaneously with the Chatanika incoherent-scatter radar and two Fabry-Perot spectr ometers at College, Alaska, during a 2 hr period in February 1982. One of the Fabry-Perot spectrometers measured the line shape of the oxyge n 630.0-nm emission, and the other measured the line shape of the oxyg en 557.7 nm emission. The measurements were used to obtain the neutral and ion velocities, the neutral, ion, and electron temperatures; and the electron densities in the E and F regions. Interpreting these meas urements using the ion energy equation for the F region yields the hei ght(s) at which heat exchange between the ions and neutrals balances t he sum of frictional heating due to differences in the ion and neutral velocities and heat exchange between the electrons and ions. This hei ght can be interpreted as the location of the oxygen 630.0-nm emission profile centroid, thus providing an estimate of the height of the neu tral temperature measurement. Furthermore, the centroid location and e xtent in altitude depend on the processes producing O(1D) in aurorae. A unique balance height was not typically found, but balance often occ urred over a wide range of altitudes, depending on the assumption of a pure O+ or a pure NO+ ionosphere, which is consistent with model calc ulations of the 630.0-nm emission rate profile. Though the coordinated optical-radar measurements available are limited, the initial results demonstrate that important questions relating to ion and neutral comp osition, chemistry, and dynamics can be examined by the methodology em ployed in this study.