Volume emission rate profiles of the 6300‐Å tropical nightglow obtained from the AE‐E satellite: Latitudinal and seasonal variations

Abstract

Surface brightnesses at 6300-.& measured by the visible airglow experiment on board the AE-E satellite have been inverted to obtain altitude profiles of volume emission rate. A morphological picture of the emission at low latitudes is developed and qualitatively interpreted in terms of the behavior of electfic fields and neutral winds in the nighttime ionosphere. Global pictures of the emission are presented for solstice and equinox conditions between 1800 and 0400 LT. Observed regions of depleted and enhanced emission are in agreement with the emission pattern expected from the effect of E x B dfifts on the ionization. Other features observed are interpreted in terms of a transequatofial wind and the presence of a pressure maximum near local midnight. These data suggest that the location of the pressure bulge changes seasonally with respect to the goeographic equator. Average bottomside electron density altitude profiles are derived from the 6300-A volume emission profiles. The local time vafiation of the height of the peak electron density deduced from the airglow measurements is in agreement with incoherent scatter measurements made at Arecibo, Puerto Rico, dufing the same time pefiod.

Low‐latitude thermospheric neutral winds determined from AE‐E measurements of the 6300‐Å nightglow at solar maximum

“…The AE-E 6300-}• data base has The morphology of the 6300-,• emission has been studied by Abreu et al [1982]. The volume emission rates were converted to electron density profiles, which provided estimates of the F 2 layer height.…”

“…The AE-E 6300-}• data base has The morphology of the 6300-,• emission has been studied by Abreu et al [1982]. In a steady state the volume emission rate may be related to the electron density by [Abreu et al, 1982[Abreu et al, , 1986 Since the height of the 6300-}i emission peak is always less than hmax, the electron density maximum is at a level where the emission is relatively weak. The level of geomagnetic activity was low to moderate for all of these orbits with Ap in the range 0-15.…”

Midnight latitude‐altitude distribution of 630 nm airglow in the Asian sector measured with FORMOSAT‐2/ISUAL

“…On the basis of theoretical expectations that airglow intensity is negatively correlated with altitude, they concluded that the asymmetry resulted from differences in the F region height in the north/south hemispheres [e.g., Reed et al , 1973; Thuilleir and Blamont , 1973; Blamont et al , 1974]. Abreu et al [1982], analyzing the data from the Visible Airglow Experiment (VAE) on board the Atmosphere Explorer E (AE‐E) satellite, derived the altitude profile of 630 nm airglow and suggested the roles of E × B plasma drift and the neutral wind in controlling the structure of the F region ionosphere. Burrage et al [1990] also analyzed VAE/AE‐E data and estimated the strength of the interhemispheric wind.…”

Thermospheric distribution of fast O(1D) atoms

“…The energetic atoms relax by elastic and inelastic collisions to an equilibrium velocity distribution. The departure of the velocity distribution from the thermal Maxwellian distribution in the thermosphere at altitudes above 200 km and its influence on the red line profile has been investigated by Schmitt et al [1981, 1982], Abreu et al [1982], Yee [1988], Shematovich et al [1999], and Hubert et al [2001]. Evidence that the distribution departs from Maxwellian has been provided by observations of an excess intensity of the red lines at high altitudes [ Schmitt et al , 1981, 1982] and by apparently anomalous temperatures derived from measurements of red line profiles [ Hubert et al , 2001].…”