Variations in Cosmic Noise Absorption in Association With Equatorward Development of the Pulsating Auroral Patch: A Case Study to Estimate the Energy Spectra of Auroral Precipitating Electrons

This study focused on a pulsating aurora event associated with morphological changes in Fennoscandia the early morning March 7, 2017. A high-speed sampling all-sky camera captured equatorward development of auroral patch association substorm centered over Greenland/North America region. Of particular interest this is interconnection between intensity and cosmic noise absorption (CNA) derived from three riometers aligned meridionally Finland (from north to south: Ivalo, Sodankylä, Rovaniemi). The analysis was made by dividing optical measurements into two oscillation components: longer shorter than 40 s, that is, nonpulsating modulations. interrelation brightness CNA showed linear correlation. inclination regression line changed time depending latitudes, which interpreted as hardening or softening precipitating electron spectrum. Especially case low-pass component, CNA-vs-intensity increased at riometer latitudes recovery phase. On other hand, for high-pass decreased Rovaniemi (lower latitude) but remained uniform Sodankylä (higher latitude). These features suggest spectrum has softened hardened component lower latitude part proposes new application riometer-camera examine particle precipitation.