The Earth's passage of the April 11, 1997 coronal ejecta: geomagnetic field fluctuations at high and low latitude during northward interplanetary magnetic field conditions

• Main Authors: Lepidi, S., Francia, P., Villante, U., Meloni, A., Lazarus, A. J., Lepping, R. P.
• Other Authors: Dipartimento di Fisica, Istituto Nazionale di Geofisica, Center for Space Research Cambridge (CSR), Massachusetts Institute of Technology (MIT), GSFC Laboratory for Extraterrestrial Physics, NASA Goddard Space Flight Center (GSFC)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 1999
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Antarctic; Terra Nova Bay; Antarc*
• Online Access: https://hal.science/hal-00316670; https://hal.science/hal-00316670/document; https://hal.science/hal-00316670/file/angeo-17-1245-1999.pdf

International audience An analysis of the low frequency geomagnetic field fluctuations at an Antarctic (Terra Nova Bay) and a low latitude (L'Aquila, Italy) station during the Earth's passage of a coronal ejecta on April 11, 1997 shows that major solar wind pressure variations were followed at both stations by a high fluctuation level. During northward interplanetary magnetic field conditions and when Terra Nova Bay is close to the local geomagnetic noon, coherent fluctuations, at the same frequency (3.6 mHz) and with polarization characteristics indicating an antisunward propagation, were observed simultaneously at the two stations. An analysis of simultaneous measurements from geosynchronous satellites shows evidence for pulsations at approximately the same frequencies also in the magnetospheric field. The observed waves might then be interpreted as oscillation modes, triggered by an external stimulation, extending to a major portion of the Earth's magnetosphere. Key words. Magnetospheric physics (MHD waves and instabilities; solar wind-magnetosphere interactions)