On the response of the equatorial and low latitude ionospheric regions in the Indian sector to the large magnetic disturbance of 29 October 2003

Abstract

Abstract. The present paper investigates the response of the equatorial and low latitude ionosphere over the Indian longitudes to the events on 29 October 2003 using ionosonde data at Trivandrum (8. . Following the storm sudden commencement, the TEC at all the three stations showed an overall enhancement in association with episodes of interplanetary electric field penetration. Interestingly, real ionospheric height profiles derived using the ionosonde data at both Trivandrum and SHAR showed significant short-term excursions and recoveries. In the post noon sector, these features are more pronounced over SHAR, an off equatorial station, than those over Trivandrum indicating the increased effects of neutral winds.

A multi-technique study of the 29–31 October 2003 geomagnetic storm effect on low latitude ionosphere over Indian region with magnetometer, ionosonde, and GPS observations

“…Notable to say, all the stations from equator to anomaly crest latitude witnessed night-time depressions below mean CQ-Days level and this concur well with global ionospheric reports of Perevalova et al (2008) pointing ↓50-100 % reduction at mid and low latitudes. It is to be mentioned that studies of Manju et al (2009) on storm time excursion of plasma at the equatorial (Trivandrum) and off-equatorial (Sriharikota) ionosonde stations agrees well with the TEC developments in a range of GPS-TEC stations across Indian longitudes. However the storm time TEC at these stations (Fig.…”

“…Deviations at other stations are seen to be within the range of 60-90 %. However observations of Manju et al (2009) report storm day diurnal peaks of 120 (↑50 %), 130 (↑85 %) and 115 (↑92 %) TECU by comparing with a single control day (5 Nov 2003) at Ahmedabad, Jodhpur, and Delhi respectively. These results certainly differ from our results due to our selectively chosen CQ-Days on the basis of EEJ strength and pattern.…”

“…In particular, the storm effects in the low latitude ionosphere across the Indian region have been vastly studied since last few decades. Revisions suggest that most of these studies are based on the comparison of ionospheric characteristics during the storm period with the preceding/succeeding control days (Lin et al 2005b;Dashora and Pandey 2006;Perevalova et al 2008;Manju et al 2009;de Abreu et al 2011;Balan et al 2012), mean quiet days (Q-Days) (Sahai et al 2005;Sharma et al 2011;Uma et al 2012), or monthly median values (Huang 1985;Maltseva et al 2012). However, it has been proved that the dynamics of the equatorial ionosphere is greatly influenced by the generation of equatorial electrojet (EEJ), a daytime eastward electric current in the ionospheric E-layer, within a narrow belt of ±3 • latitude over the dip equator.…”

“…Ionosonde, MAG-Magnetometer, GPS-Global Positioning System a(Manju et al 2009), b(Cander and Mihajlovic 2005), c(Tsurutani et al 2005), d (Panda andGedam 2012) 15.5 E, 47.1 N) and Hailsham (Geographic. 0.3 E, 50.9 N).…”

Impact of Sudden Stratospheric Warming of 2009 on the Equatorial and Low‐Latitude Ionosphere of the Indian Longitudes: A Case Study

“…Over the Indian sector, in general, the EIA crest is found to be located in the latitude zone of 15° to 25°N geographic latitudes (5° to 15°N geomagnetic latitudes) during the low solar activity period (Rama Rao et al, ). The anomaly crest was observed to extend beyond 25°N only during the geomagnetic disturbances (Dabas et al, ; Manju et al, ). On the other hand, the present study shows that the region located beyond the EIA crest during solar minimum and quiet geophysical conditions also gets affected significantly by the equatorial fountain effect during special geophysical phenomena like the SSW events.…”