Signature of the coronal hole near the north crest equatorial anomaly over Egypt during the strong geomagnetic storm 5 April 2010

Abstract

International audienceIn this paper we study the ionospheric-magnetic disturbance during a strong magnetic storm on 5 April 2010 associated to a coronal hole. The Earth was under the influence of a high speed solar wind stream during four days, and IMF was southward during a very long period. The variation of the disturbed magnetic observations and GPS-TEC are compared with the variation of quiet days during the same month in order to obtain the characteristics of GPS-TEC and magnetic disturbances due to the coronal hole effect. We use multi-instruments as SCINDA-GPS station at Helwan, Egypt (29.86 N, 31.32 E) and ASW-MAGDAS station at Aswan, Egypt (23.59 N, 32.51 E) in the equatorial region. At the beginning of the storm our data highlights the effect of the prompt penetration of the magnetosphere electric field which strongly increases the TEC. During the recovery phase of the storm, we observe on TEC and magnetic data, the signature of the ionospheric disturbance dynamo due to wind produced by Joule heating in the auroral zone. It is the first time that we observe an anti-Sq circulation on magnetic data during four consecutive days associated to the high speed solar wind streams

The response of the ionosphere over Ilorin to some geomagnetic storms

“…These decreases were majorly observed during the post-noon as well as the night time period. This is consistent with Danilov and Lastovicka (2001), Yizengaw et al (2005) Olawepo and Adeniyi (2012) and Shimeis et al (2012). It can be attributed to the long duration of the southward orientation of Bz experience during this storm event.…”

“…2a). The solar wind speed increased from around 500-700 km/s at the time of the SSC, reaching a maximum speed of 814 km/s at 1400 UT on 5 April, this speed was reported to have been flowing from a solar coronal hole (Shimeis et al, 2012), shown in Fig. 2c.…”

“…Therefore, variations observed in this study can be attributed to the changes in the EXB forces, season of the Year and neutral compositions. Many authors have also shown that neutral winds and composition also play an important role at low latitudes (Fejer et al, 1983;Sastri, 1988;Yizengaw et al, 2005;Shimeis et al, 2012) both during the quiet and disturbed days.…”

“…with a peak of 11.5 nT at 1200 UT) was noticed, two hours later, it returned southward. Shimeis et al (2012) had earlier reported that the coronal mass ejection (CME) impacted the Earth on 5 April, 2010. This was accompanied by an increase in the Dst, which is indicating a storm sudden commencement (SSC) on that same day (Fig.…”

TEC variations along an East Euro-African chain during 5th April 2010 geomagnetic storm

“…This measurement is named vertical TEC (vTEC). To convert sTEC to vTEC, we used the following equation: We also used the magnetic indices Dst, AU and AL with a time resolution of 1min (http://isgi.latmos.ipsl.fr/lesdonne.htm /), see Shimeis et al (2012) for more details.…”