MAGNETIC FIELD OBSERVATIONS ON CLUSTER: AN OVERVIEW OF THE FIRST RESULTS

摘要

The magnetic field investigation on Cluster provides, for the first time, high time resolution observations of the magnetic field vector at four closely-spaced points in space simultaneously. The early results, of which a sample is presented in this paper, show the complexity of space plasma phenomena on the scales of the separation of the four Cluster spacecraft which, in the present phase of the mission, is only about 600 to 1000 km. We first present a status report on the instruments and the calibration of the magnetic field data. Two sets of observations are presented and discussed briefly. The first set gives an account of the bow shock observations on 25 December 2000; the second is a series of observations made on 13 February 2001, starting in the solar wind and concluding with the crossing of the southern cusp. These observations already illustrate the power of the Cluster data set; further studies will involve the combined analysis of data from the different instruments on Cluster.