Storm time enhancements of 630.0 nm airglow associated with polar cap patches

Abstract

AbstractWe examined the brightness of 630.0 nm airglow, I630, associated with polar cap patches observed during a magnetic storm that occurred on 22 January 2012. Brightness was measured using an all‐sky imager (ASI) located at Longyearbyen, Svalbard. The observed I630 was compared with the F region electron density observed by the European Incoherent Scatter Svalbard Radar (ESR). The I630 was positively correlated with the F2 layer peak electron density, NmF2, and inversely correlated with the altitude of the F2layer peak electron density, hmF2, as expected from the known relationship between these parameters. To estimate the altitude of the peak emission of the airglow, we performed model calculations of the volume emission rate, V630, under quiet and disturbed conditions, using Mass Spectrometer Incoherent Scatter modeled neutral gas profiles and the electron density profile obtained from the ESR data. In order to validate the V630 calculation, I630 was calculated by integrating the V630 along altitude and then compared with the ASI‐observed I630. During the observation periods the measured brightness frequently exceeded the calculated I630; we infer that in most cases, low‐energy particle precipitation is responsible for the extra brightness. However, when there was less particle precipitation, the observed values were in good agreement with the calculated values. Under the magnetically disturbed conditions during our observations, the model calculation showed that the altitude of V630 peak increases, the thickness of the emission layer increases, and patch brightness increases.