A Statistical Analysis of Plasma Bubbles Observed by Swarm Constellation during Different Types of Geomagnetic Storms

Abstract

Based on the observations of Ionospheric Bubble Index (IBI) data from the Swarm mission, the characteristics of plasma bubbles are investigated during different types of geomagnetic storms recorded from 2014 to 2020. The geometrical constellation of the Swarm mission enabled us to investigate the altitudinal profile of the IBIs during different activity levels in a statistical mean. Results show that the majority of IBIs associated with moderate storms are observed at low altitudes and the probability of observing IBIs at high altitudes (Swarm-B) increases with the increase in storm level. This is confirmed by observing the F2 layer peak height (hmF2) during super storm events at larger altitudes using COSMIC data. The maximum number of IBIs is recorded within the South Atlantic Anomaly (SAA) region with a long duration time and tends to increase only during dusk time. Both the large duration time and number of IBIs over the South Atlantic Anomaly (SAA) suggest that the gradient in the electron density and the depression in the magnetic field are the main factors controlling IBI events. Also, the IBIs at high altitudes are larger at sunset and at low altitudes pre-midnight. In addition, the occurrence of IBIs is always larger in the northern hemisphere than in the southern hemisphere irrespective of the type of storm, as well as during the summer months. Moreover, there is no correlation between the duration time of IBIs and both the altitudinal observation of the IBIs and the storm type. Seasonal occurrence of IBIs is larger during equinoxes and vice versa during solstices irrespective of both the type of storm and the altitude of the satellite. The large number of IBIs during equinoxes agrees with the previous studies, which expect that the large electron density is a developer of steeper . Large occurrences of super storm IBIs observed within the pre-midnight during summer and at sunset during equinoxes are a novel observation that needs further investigation. Also, the majority of IBIs are observed a few hours after geomagnetic substorms, which reflects the role of the Disturbance Dynamo Electric Field (DDEF) as a main driver of IBIs.

Ionospheric single crest events at different altitudes and activity levels observed by Swarm constellation

“…The trans-equatorial neutral wind which blows from the northern to southern hemisphere during summer months may be the cause of the noon time single crest. This wind causes a reduction in the local conductivity on the upwind side (summer hemisphere) where the layer is raised and cause an increase in the local conductivity on the downwind side (winter hemisphere) where the layer is lowered (Hussien et al 2021). Therefore, the majority of single crests are observed in the southern hemisphere during summer months.…”

Generation of equatorial plasma bubble after the 2022 Tonga volcanic eruption

“…At that time, the satellite was traveling at the height of sunset for the F-region from the Northern to Southern Hemispheres. Referring to the magnitude of the electron density depletion observed by previous satellite observations (39), the phenomenon corresponds to an EPB. The electron density depletions, based on the Arase observations, generally exhibited a good overlap with the ROTI enhancement area in the Asia-Pacific region (Fig.…”

Leveraging the CYGNSS Spaceborne GNSS‐R Observations to Detect Ionospheric Irregularities Over the Oceans: Method and Verification

“…According to the results from Section 3, there are several features on these figures we need to mention. First, although Figures 14 and 15 present that the conventional space‐based GNSS instruments can expand the coverage of ionospheric irregularity observations over the data‐void or data‐sparse oceans (Hussien et al., 2021; Jin et al., 2020; Park et al., 2013; Zakharenkova et al., 2016), the CYGNSS‐derived S4 R index distribution, consisted of several identical satellites with four channels passes, has much better spatial coverage compared to a single pass with in situ measurements from Swarm B and F3/C RO observations from the satellite C1E6 on DOY 251 of 2017. Second, compared with the Swarm and F3/C in Figures 14a and 16c, the eight CYGNSS satellites have a shorter revisit period and closer span of adjacent orbits, which facilitates timely revisit observations or confirmation of the ionospheric disturbances at the same location.…”

“…Swarm is an ESA's constellation mission with three identical satellites, that is, Swarm A (Alpha), B (Bravo), and C (Charlie). The products from the Swarm satellites have been successfully used for detecting ionospheric irregularities based on the in situ electron density observables that are obtained by the Langmuir probe of the Swarm satellites (Hussien et al., 2021; Jin et al., 2020; Park et al., 2013; Rodríguez‐Zuluaga et al., 2017; Zakharenkova et al., 2016).…”