Abstract
Abstract. We present an analysis of ULF geomagnetic field fluctuations at low latitudes during the first CAWSES campaign (29 March-3 April 2004). During the whole campaign, mainly in the prenoon sector, a moderate Pc3-4 pulsation activity is observed, clearly related to interplanetary upstream waves. On 3 April, in correspondence to the Earth's arrival of a coronal mass ejection, two SIs are observed whose waveforms are indicative of a contribution of the high-latitude ionospheric currents to the low-latitude ground field. During the following geomagnetic storm, low frequency (Pc5) waves are observed at discrete frequencies. Their correspondence with the same frequencies detected in the radial components of the interplanetary magnetic field and solar wind speed suggests that Alfvénic solar wind fluctuations may act as direct drivers of magnetospheric fluctuations. A cross-phase analysis, using different pairs of stations, is also presented for identifying field line resonant frequencies and monitoring changes in plasmaspheric mass density. Lastly, an analysis of ionospheric vertical soundings, measured at the Rome ionosonde station (41.8° N, 12.5° E), and vertical TEC measurements deduced from GPS signals within an European network shows the relation between the ULF resonances in the inner magnetosphere and thermal plasma density variations during geomagnetically quiet conditions, in contrast to various storm phases at the end of the CAWSES campaign.
Highlights
In the last several years, research activity has produced a significant improvement in the knowledge of the physical processes which are the foundation of the solar-terrestrial relationships and enable interdisciplinary progresses in understanding the Sun-Earth domain as a whole
At middle and low latitudes, most aspects of the ground Pc3 manifestations are interpreted in terms of penetration of upstream waves, generated by ions reflected off the bow shock along the interplanetary magnetic field (IMF) lines, and related field line resonance (FLR) phenomena (Yumoto, 1986)
In this paper we describe the results obtained from the analysis of ULF geomagnetic field variations and ionospheric measurements at low latitude during the campaign, and, in particular, in correspondence to the geomagnetic storm associated with the Earth’s arrival of a coronal mass ejection
Summary
In the last several years, research activity has produced a significant improvement in the knowledge of the physical processes which are the foundation of the solar-terrestrial relationships and enable interdisciplinary progresses in understanding the Sun-Earth domain as a whole. ULF waves recorded at a dense latitudinal array can be used to monitor the magnetospheric plasma mass density (Menk et al, 1999) We contributed to this international campaign by conducting an analysis of ULF measurements at several low-latitude stations. We used vertical Total Electron Content (TEC) measurements over Northern Italy as deduced from recordings of GPS signals, using receiving stations of the International GPS Service (IGS) all over Europe They are compiled as regional maps of the European sector within the bounds from 20◦ W to 40◦ E geographic longitude and 35◦–70◦ N latitude (see http://www.kn.nz.dlr.de/tec mon). They combine measurements from about 70–110 independent GPS data links for the construction of each TEC pattern in combination with a suitable background model (Jakowski, 1996)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
