Topside ionospheric irregularities as seen from multisatellite observations

Abstract

We use in situ data from CHAMP and DMSP satellites, along with data of GPS receiver onboard CHAMP satellite and ground-based GPS receivers to study the occurrence and global distribution of ionospheric irregularities during the main phase of the geomagnetic storm of 29-31 August 2004 (minimum Dst excursion of À128 nT). Using the CHAMP GPS measurements, we created maps of GPS phase fluctuation activity and found two specific zones of the most intense irregularities: (1) the region of the auroral oval at high latitudes of both hemispheres and (2) the low latitudes/equatorial region between Africa and South America. At high latitudes, the topside ionospheric irregularities appeared to be more intensive in the southern hemisphere, which is, most likely, due to seasonal variations in the interhemispheric field-aligned currents system. An analysis of multi-instrumental observations reveals reinforcement of the equatorial ionization anomaly after sunset in Atlantic sector on 30 August and formation of the significant plasma depletions and irregularities over a large longitudinal range. Equatorial irregularities were also found in the morning sector at the recovery phase of the storm. In addition to low Earth orbit (LEO) GPS measurements, we analyze the LEO in situ measurements, and we show that these two techniques cannot be interchangeable in all cases because of the altitudinal extent of plasma irregularities. Overall, we demonstrate that the LEO GPS technique can serve a useful tool for detection of the topside ionospheric irregularities during space weather events and may essentially contribute to other methods based on various instruments.

Long-duration positive ionospheric storm during the December 2006 geomagnetic storm: Ionizing effect of forbidden electrons

“…Ionospheric effects of energetic particles, which can penetrate to the D, E, and F ionospheric regions from magnetosphere and interplanetary space, have been known for a long time as well as are studied now (e.g., Abdu et al, 1998;Suvorova et al, 2012Suvorova et al, , 2013Suvorova et al, , 2014Zigman et al, 2014;Zakharenkova and Astafyeva, 2015).…”

First detection of the supersonic upward plasma flow structures in the early morning sector

“…Even more rare events are occurrences of intensive ionospheric irregularities and/or plasma bubbles in the predawn sector. Those were occasionally observed at the recovery phase of magnetic storms [e.g., Yeh et al , ; Li et al , ; Zakharenkova and Astafyeva , ; Zakharenkova et al , ] or even under geomagnetically quiet and during solar minimum conditions [ de la Beaujardière et al , ; Dao et al , ; Gentile et al , ]. The results from Communications/Navigation Outage Forecasting System (C/NOFS) satellite suggested that during geomagnetically quiet conditions, a passage of the solar terminator and the associated upward plasma drifts can serve as a source of such irregularities [ de la Beaujardière et al , ].…”

Topside Ionospheric Conditions During the 7–8 September 2017 Geomagnetic Storm

“…ROTI maps presented for the dusk/nighttime sector in Figure follows a similar presentation of the TEC maps shown in Figure . The ionospheric irregularities are prevalently nighttime events, although there had been reported cases of initiation and enhancement of ionospheric irregularities in the dawn/morning sector due to geomagnetic storm impact (Fukao et al, ; Li et al, ; Zakharenkova & Astafyeva, ). The ionospheric irregularities were quite remarkable at the nighttime during the two main phases of the storm on 8 September which were not observed on the other days (see Figures a–d).…”