Imprint of Storm Enhanced Density in Ground‐Based OI 630.0 nm Dayglow Measurements

Abstract

The mid‐latitude upper atmosphere is directly affected by the inner magnetosphere through the interactions at the closed geomagnetic field line boundary. Several space weather phenomena associated with magnetospheric‐plasmaspheric exchanges can be mapped to mid‐latitudes. One such phenomena that occurs over mid‐latitudes during geomagnetic storms is the storm enhanced density (SED). So far, storm time ionospheric features have been studied primarily using radar, GPS and in‐situ measurements. We present high spectral resolution ground‐based measurements of OI 630.0 nm dayglow emissions obtained from Boston to investigate thermospheric behaviour during both geomagnetic quiet and disturbed times, as these are very sensitive to changes in the ionospheric plasma temperatures, and densities. During a geomagnetic storm on 7‐9 Nov 2004 (Kp=9‐), an anomalous enhancement in brightness (>1 kR) was observed in the dayglow for about an hour duration near local sunset (dusk hours), which was not seen on other neighbouring days. This enhancement in OI 630.0 nm dayglow observed on 9 Nov 2004 is confirmed to be a SED event as seen from the complimentary datasets, the Millstone Hill incoherent scatter radar (ISR), DMSP satellite and GPS total electron content. Further, model estimates of OI 630.0 nm dayglow intensities using ISR measured electron/ion temperature and electron densities as inputs show good agreement with our measurements. These results make this study possibly the first report on the daytime optical signatures of SED.This article is protected by copyright. All rights reserved.

Estimation of Downward Heat Flux Into the F‐Region From the Inner‐Magnetosphere During Stable Auroral Red (SAR) Arc Events in the Daytime Obtained Using OI 630.0 nm Red‐Line Emissions

“…WEM predictions have been shown to match well with the HIRISE measured OI 630.0 nm dayglow during geomagnetically quiet days (D. Pallamraju et al, 2020, Shepherd & Cho, 2021. Upadhyay et al (2023) showed that by applying the scaling factor between HIRISE data and WEM predictions obtained during geomagnetically quiet days, the dayglow brightness values can be obtained during geomagnetic disturbances. The same approach has been applied in this study as well.…”

“…Also, positive and negative ionospheric storms can alter the ionospheric electron densities from their mean quiet time behavior at a given latitude. Therefore, in several earlier studies, small time scale variations in Ne during geomagnetic disturbances have been shown to affect the 630.0 nm dayglow intensity variability at all latitudes (e.g., Pallamraju & Chakrabarti, 2005; D. Pallamraju et al., 1996, 2001, 2010; Upadhyay et al., 2023). Temporal variations in the dayglow emissions can also occur through the photoelectron impact mechanism on occasions, such as, occurrence of solar flares (e.g., Das et al., 2010; Sumod et al., 2014).…”

“…Pallamraju et al, 1996D. Pallamraju et al, , 2001Upadhyay et al, 2023). Temporal variations in the dayglow emissions can also occur through the photoelectron impact mechanism on occasions, such as, occurrence of solar flares (e.g., Das et al, 2010;Sumod et al, 2014).…”

“…Upadhyay et al. (2023) showed that by applying the scaling factor between HIRISE data and WEM predictions obtained during geomagnetically quiet days, the dayglow brightness values can be obtained during geomagnetic disturbances. The same approach has been applied in this study as well.…”

First Daytime Red‐Line Emission Measurements of the Stable Auroral Red (SAR) Arcs

“…Therefore, small time-scale temporal variation has been shown to be mainly due to the DR mechanism. Thus, it has been shown in earlier studies that variations in the Flayer Ne can be readily noticed in the O( 1 D) dayglow emission intensity variability (e.g., Pallamraju et al, 2001;Upadhyay et al, 2023). Shorter duration temporal variations can also be brought out due to changes in energetic electron flux through the PEI mechanism as in the case of magnetospheric cusps (Pallamraju et al, 2004) or solar flares (Das et al, 2010).…”