Seasonal and solar activity variability of D-region electron density at 69°N

A narrow beam Doppler radar operating at 3.17 MHz and installed close to the Andøya Rocket Range in Andenes, Norway, (69.3°N, 16.0°E) has been providing electron densities in the lower ionosphere since summer 2003. The experiment utilizes partial reflection of ordinary and extraordinary component waves from scatterers in the altitude range 50–95 km to estimate electron densities from differential absorption and differential phase measurements. These ground-based observations are in good agreement with concurrent rocket-borne radio wave propagation measurements at Andenes. Results of the diurnal and seasonal variability of electron densities and the response of D-region electron densities to solar activity storms are presented.

Research highlights
► Lower ionosphere electron densities between 55 and 90 km at 69°N.
► 3-MHz Doppler radar observations of differential absorption/phase.
► Measurements extend high latitude data base of electron densities to a lower limit of 1×108 m−3.
► Ground-based observations are in good agreement with in-situ measurements.