Low‐latitude ionosphere response to super geomagnetic storm of 17/18 March 2015: Results from a chain of ground‐based observations over Indian sector. Issue 12 (16th December 2015)

• Record Type: Journal Article
• Authors: Sripathi, S.; Sreekumar, Sreeba; Banola, S.; Emperumal, K.; Tiwari, P.; Kumar, Burudu Suneel
• Is Part Of: Journal of geophysical research. Volume 120:Issue 12(2015:Dec.)
• Page Start: 10, 864
• Page End: 10, 882
• Publication Date: 2015-12-16
• Subjects: equatorial ionosphere -- ionospheric dynamics -- ionospheric irregularities -- radio wave propagation -- geomagnetic storms -- space weather; Magnetospheric physics -- Periodicals; Space environment -- Periodicals; Cosmic physics -- Periodicals; Planets -- Atmospheres -- Periodicals; Heliosphere (Astrophysics) -- Periodicals; Geophysics -- Periodicals; 523.01
• DOI: 10.1002/2015JA021509
• Languages: English
• ISSNs: 2169-9380

Abstract

Abstract: In this paper, we present unique results of equatorial and low‐latitude ionosphere response to one of the major geomagnetic storms of the current solar cycle that occurred during 17–18 March 2015, where Dst reached its minimum of −228 nT. Here we utilized data from magnetometers, chain of ionosondes located at Tirunelveli (8.73°N, 77.70°E; geometry: 0.32°N), Hyderabad (17.36°N, 78.47°E; geometry 8.76°N), and Allahabad (25.45°N, 81.85°E; geometry 16.5°N) along with multistation GPS receivers over Indian sector. The observations showed a remarkable increase of h ′ F to as high as ~560 km over Tirunelveli (magnetic equator) with vertical drift of ~70 m/s at 13:30 UT due to direct penetration of storm time eastward electric fields which exactly coincided with the local time of pre‐reversal enhancement (PRE) and caused intense equatorial spread F irregularities in ionosondes and scintillations in GPS receivers at wide latitudes. Plasma irregularities are so intense that their signatures are seen in Allahabad/Lucknow. Storm time thermospheric meridional winds as estimated using two ionosondes suggest the equatorward surge of gravity waves with period of ~2 h. Suppression of anomaly crest on the subsequent day of the storm suggests the complex role of disturbance dynamo electric fields and disturbance wind effects. Our results also show an interesting feature of traveling ionospheric disturbances possibly associated with disturbance meridional wind surge during recovery phase. In addition, noteworthy observations are nighttime westward zonal drifts and PRE‐related total electron content enhancements at anomaly crests during main phase and counter electrojet signatures during recovery phase. Key Points: Storm‐induced plasma density irregularities/scintillations over Indian longitude Impact of prompt penetration electric fields on PRE, h ′ F, and EIA density Suppression of EIA on the following day due to disturbance dynamo