Characteristics of the Effective Scale Height in the Topside Ionosphere
Extracted from Swarm A and Digisonde Observations: preliminary results
Abstract
The ionospheric scale height is a key parameter that defines the shape
of the electron density profile. Its main characteristic, including the
diurnal variation and its altitudinal dependence are still under
investigation. This paper analyses the characteristics of the effective
scale height at middle latitudes based on coincident Digisonde and Swarm
A satellite data. Based on the assumption that the topside electron
density function with altitude is approximated with the α-Chapman model,
the effective scale height at the Swarm A altitude is calculated and it
is compared with the effective scale height at hmF2. A general
conclusion is that the effective scale height in the topside at
~450 km exhibits a diurnal variation with highest values
in the early morning and evening sectors, while at hmF2 it gets its
maximum values at noon. At night, the effective scale height tends to
increase with altitude, however in the daytime, its behavior is more
complex. At local scale, evidence for connection between spread F
irregularities and high variability in the topside effective scale
height is reported. Although the analysis is in progress to include data
from the whole Swarm mission, these preliminary results indicate the
potential to further exploit Swarm and Digisonde data for effective
scale height modeling and for setting up a nowcasting system for the
probability of occurrence of ionospheric instabilities in the topside
ionosphere based on the bottomside stratification.