Assessing ionospheric response during some strong storms in solar cycle 24 using various data sources

Abstract

We present an analysis of a regional ionospheric response during six strong storms (−200 nT ≤Dst≤−100 nT) that occurred in 2012 for the geographic latitudinal coverage of 10°S–40°S within a longitude sector of 10°E–40°E. Although these storms occurred during the same solar activity period and were all coronal mass ejection driven, their impacts and associated features on the ionosphere have been found different due to different contributing factors to their driving mechanisms. With the exception of one case, the rest of the storm periods were characterized by positive storm effects during the main and (or) recovery phases with varying physical mechanisms including low‐latitude electrodynamics, neutral composition changes, and traveling ionospheric disturbances (TIDs). The common result to all the analyzed strong storms was the presence of large‐scale TIDs during the storm main phases. Using total electron content data derived from the Global Navigational Satellite System (GNSS) observations and radio occultation (RO) electron density data on a regional scale, we have attempted to investigate meridional and vertical propagation of TIDs simultaneously during the strong storms. We have showed that it is possible to identify vertical motion of TIDs using RO data in cases when equatorward TIDs, as revealed by GNSS total electron content data, are present. RO results were compared to ionosonde data, and both data sources gave vertical velocities below 100 m/s of the associated TIDs.

Ionospheric Responses to CME‐ and CIR‐Driven Geomagnetic Storms Along 30°E–40°E Over the African Sector From 2001 to 2015

“…There were four cases where they observed PPEF (i.e., the storm periods, 7–11 March, 22–26 April, 15 July, and 29 September to 3 October 2012). For some storm periods where Habarulema et al () observed P ionospheric storm effects over Southern Hemisphere midlatitude, P ionospheric response were also observed over TDOU and HALY for the time when data were available except in one case (i.e., 6–10 October 2012) where NS ionospheric response was observed over both stations. A significant number of NS ionospheric storm effects were observed over TDOU and HALY stations.…”

“…Over South Africa, Ngwira et al () reported that the P ionospheric response that occurred on 15 May 2005 was due to TIDs. Habarulema et al () also studied the ionospheric response during six geomagnetic storm periods that occurred in 2012 for the geographical latitudinal coverage of 10°S–40°S within the longitude sector of 10°E–40°E. They observed TIDs during all storm periods.…”

“…In contrast, CME-driven geomagnetic storms' recovery phases can last 1 or 2 days . Event(s) analyses of ionospheric storm effects over the African sector have been done during either CME-or CIR-driven storms (e.g., Habarulema et al, 2013Habarulema et al, , 2017Ngwira et al, 2012;Prölss et al, 1991;Yizengaw et al, 2011). Statistical analyses of ionospheric storm effects due to geomagnetic storms over middle and low latitude in the African sector have been done separately in different latitude regions (e.g., Adeniyi, 1986;Adeniyi et al, 2014;Adewale et al, 2011;Burešová et al, 2014;Matamba et al, 2015).…”

Performance of MIDAS Over East African Longitude Sector: Case Study During 4–14 March 2012 Quiet to Disturbed Geomagnetic Conditions

“…The study period spans days of quiet and various magnitudes of disturbed geomagnetic conditions as shown in Figure . The storm period between 7 and 11 March 2012 has been previously studied and different ionospheric aspects reported on both regional and global scales (see, e.g., Habarulema et al, , ). The geomagnetic conditions are classified as weak (−30 nT ≤ D s t <− 50 nT), moderate (−50 nT ≤ D s t <− 100 nT), and strong (−100 nT ≤ D s t <− 200 nT) according to the storm classification by Loewe and Prolss ().…”

Critical Issues in Ionospheric Data Quality and Implications for Scientific Studies

“…Models of ionospheric response to geomagnetic storms rely directly on the quality of available data; problems in the data carry straight into these models including biases and larger uncertainty due to erroneous, repeated, and missing observations. To be more specific, the scientific community has used the World Data Center ionospheric database to support innovative research, including studies of both short-and long-term processes (e.g., Araujo-Pradere et al, 2004;Araujo-Pradere et al, 2005;Jarvis et al, 2002;Marin et al, 2001), as well as case studies of individual disturbances, that is, plasma bubble descriptions (Shiokawa et al, 2015), and traveling ionospheric disturbances (Lin et al, 2017), ionospheric response during extreme conditions (Burešová & Laštovička, 2017;Habarulema et al, 2017), and modeling of various purposes (Hernández-Pajares et al, 2017;Liu et al, 2017). Because issues with the quality of the data can substantially affect the outcome of the analyses, feedback from users that are conducting original research based on the data is one of the best ways to detect and possibly correct these issues to decrease their prevalence in the data record.…”