HR: 0830h
AN: SA21B-0083    [PDF]
TI: The Linear Dependence of the Post-sunset Equatorial Anomaly Electron Density on Solar Flux, and its Relation to the Linear Dependence of the Maximum Pre-reversal ExB Drift Velocity on Solar Flux.
AU: * Whalen, J A
EM: james.whalen@hanscom.af.mil
AF: Space Vehicles Directorate Air Force Research Laboratory, 29 Randolph Road, Hanscom AFB, MA 01731 United States
AB: The maximum F layer electron density which occurs in the post sunset equatorial anomaly near 2100 LT, Nemax, has been found to be a linear function of the maximum pre-reversal ExB drift velocity. The results, based on measurements on each day of a solar maximum year, are extended here to study the dependence of this relation on solar flux. The source of the data is an array of 10 ionospheric sounders located from eastern Asia through the Pacific to the Americas, and situated at both north and south dip latitudes. Nemax recorded at each location is examined as a function of solar flux over the range from 70 to 285 solar flux units on a monthly basis during the 13 years of an entire solar cycle. The principal result is that the monthly median Nemax increases linearly with the monthly average solar flux, Sa, at each location for each month for the entire range of time and Sa. The linear function varies continuously by month at each location, and although magnitudes differ between locations, at each location maxima are in the equinoxes and minima are in the solstices. Because of this linearity, the entire dependence of Nemax on Sa over the solar cycle can be represented the 2 parameters, slope and intercept of the line for each month for each location. The further understanding of this linearity lies in the fact that ExB drift also increases linearly with Sa. As measured at Jicamarca, the linear function is greatest in the equinoxes, least near June and intermediate near December, a seasonal dependence which is very similar to that of Nemax measured at the same longitude as Jicamarca. As derived from these two relations to Sa, Nemax is nearly the same linear function of ExB as that found in the earlier study, implying that the function is independent of solar flux.
DE: 2415 Equatorial ionosphere
DE: 2437 Ionospheric dynamics
DE: 2463 Plasma convection
DE: 2712 Electric fields (2411)
SC: SPA - Aeronomy [SA]
MN: 2003 Fall Meeting