A slow mode wave as a possible source of Pi 2 and associated particle precipitation: a case study

• Main Authors: Saka, O., Watanabe, O., Okada, K., Baker, D. N.
• Other Authors: Department of Physics, Okayama University, Department of Earth and Planetary Sciences Kobe, Kobe University, Laboratory for Atmospheric and Space Physics Boulder (LASP), University of Colorado Boulder
• 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; Syowa Station; Antarc*; Antarctica
• Online Access: https://hal.science/hal-00316598; https://hal.science/hal-00316598/document; https://hal.science/hal-00316598/file/angeo-17-674-1999.pdf

International audience An intensification of auroral luminosity referred to as an auroral break-up often accompanies the onset of geomagnetic pulsation (Pi 2) at the dip-equator. One such auroral break-up occurred at 2239 UT on 16 June, 1986, being accompanied by weak substorm activity (AE~50 nT) which was recorded in all-sky image of Syowa Station, Antarctica (66.2°S, 71.8°E in geomagnetic coordinates). The associated Pi 2 magnetic pulsation was detected by a fluxgate magnetometer in the afternoon sector at the dip-equator (Huancayo, Peru; 1.44°N, 355.9° in geomagnetic coordinates; 12.1°S, 75.2°W in geographic coordinates; L =1.00). In spite of the large separation of the two stations in longitude and latitude, the auroral break-up and subsequent luminosity modulation were seen to be correlated with the wave form of the ground Pi 2 pulsation. This occurred in such a way that the luminosity maximum was seen to occur at the phase of maximum amplitudes of Pi 2 wave form. We argue that the observed correlation could be interpreted as indicating a Pi 2-modulation of a field-aligned acceleration of the low energy electrons that may occur near the equator of the midnight magnetosphere.