Magnetospheric response to the arrival of the shock wave in front of the magnetic cloud of January 10, 1997 Original Research Article

We are studying the magnetic cloud of January 6–11, 1997. Specifically, we have investigated the response of the magnetosphere to the shock front ahead of the magnetic cloud on January 10, 1997 using data from Wind, Geotail and Polar spacecraft as well as ground magnetometer data. The Wind spacecraft, which was located at about 85 Re upstream from the Earth at (85.1, −55.2, −22.1) ReGSM, observed the arrival of the shock wave front at 0052 UT. Geotail was located at the equatorial magnetopause (∼8.7 Re, 10.7 MLT, −7.46 MLAT), while Polar was located in the northern dawn sector above the auroral zone at 8.4 Re, 6.1 MLT and 61.1 MLAT. A magnetic signature was nearly simultaneously observed at about 0105 UT at the Polar and Geotail spacecraft. The Geotail spacecraft entered from the magnetosphere into the magnetosheath. Particle density increases were observed on Wind and Geotail, but not on Polar. Two instruments on the Polar spacecraft (TIDE and TIMAS) actually observed a slight reduction in energy, density and temperature. The UV aurora shows a dawnside intensification. The shock wave did not cause an auroral substorm and therefore was not geoeffective.