O/N₂ changes during 1–4 October 2002 storms: IMAGE SI‐13 and TIMED/GUVI observations

Abstract

[1] Thermospheric O/N 2 column density ratios referenced at a N 2 column density of 10 17 cm À2 are obtained using the IMAGE SI-13 and TIMED/GUVI far-ultraviolet (FUV) dayglow data, AURIC simulation results, and MSIS86 model. Each of the magnetic storms occurring during a 4-day period (1-4 October 2002) caused significant O/N 2 depletion that was detected by both of the IMAGE SI-13 and GUVI instruments. The depletion extended down to latitudes of 10°and À5°in the Northern and Southern Hemispheres, respectively. Simultaneous measurements show an excellent agreement between the SI-13 and GUVI O/N 2 on both global and local scales. The IMAGE SI-13 O/N 2 data provide direct optical evidence that the O/N 2 depletion corotates with the Earth. The GUVI O/N 2 indicate the depletion in both of the hemispheres is not symmetric owing to the seasonal effect and differences in heating and convection induced winds. Both the IMAGE SI-13 and GUVI O/N 2 maps also provide a good opportunity for future modeling efforts.

Ionosphere-thermosphere (IT) response to solar wind forcing during magnetic storms

“…As the thermosphere is heated, upwelling of the atmosphere lifts oxygen-depleted or nitrogenrich air from lower in the atmosphere into the F region (Mayr & Volland 1972;Prolss 1980). This change in composition can be observed in the ultraviolet (UV) images which correspond to altitudes from 135 to 200 km (Zhang et al 2004). The depleted areas proceed from polar to lower latitudes during storms, including the August 5-6, 2011 event (Y.…”

“…The O/N 2 ratio provides indirect information on Joule heating of atomic oxygen at altitudes of approximately 135-200 km (Zhang et al 2004). The GUVI data for the August 2011 storm shows heated neutrals at the highest latitudes detectable by the instrument (Y.…”

“…We also refer to the observed O/N 2 ratio detected by the Global Ultraviolet Imager (GUVI) on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite, and the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) on the DMSP satellite. The UV images offer a proxy for Joule heating of neutral oxygen at altitudes between 135 and 200 km (Zhang et al 2004). The O/N 2 observations, combined with the in situ observations from GOCE and GRACE, enable an altitude profile of heated neutrals during the storms.…”

Ionospheric response to a geomagnetic storm during November 8–10, 2004

“…The strong upwelling of the atmosphere transports oxygen-depleted, or nitrogen-rich, air up from much lower in the thermosphere into the F region (Mayr and Volland, 1972;Mayr et al, 1978;Prolss, 1980). The nitrogen-rich/oxygen-depleted air causes a reduction in the ionospheric electron density and oxygen rich/nitrogendepleted air causes an increase in the ionospheric electron density (Zhang et al, 2004).…”

Multi-Periodic Auroral and Thermospheric Variations in 2006

“…In this study, HP data from NOAA space weather center are used. Furthermore, thermospheric O/N 2 column density ratios based on GUVI data (Zhang et al 2004) are examined for their response to the auroral variations.…”