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Observations

This study presents data from four spacecraft (WIND, IMP 8, GEOTAIL, and POLAR) on January 10, 1997, 21-24 UT. At that time the WIND spacecraft was located in the upstream solar wind at (92,-53,-23) tex2html_wrap_inline432 in GSM. Figure 1 shows the positions of the other spacecraft in the GSM xy and yz plane; the bow shock (dashed thin lines) and the magnetopause (solid thin lines) are for the average solar wind conditions (dynamic pressure = 2.1 nPa, IMF tex2html_wrap_inline434 = 0). All three spacecraft are almost in the dawn-dusk meridian: IMP 8 is in the solar wind (see Figure 1b), GEOTAIL is in the magnetosphere near the LLBL, and POLAR moves from the northern polar cap towards the equator.

We present electric and magnetic field data from POLAR in spacecraft coordinates. Two of the three electric field components are measured with two perpendicular long antennas in the spin plane [Harvey et al., 1995]: the xy component points radially outward, and the z component points to the north and is perpendicular to xy. The third component, measured along the spin axis with a shorter antenna using probes 5 and 6, points into an azimuthal direction and is called 56 (i.e., tex2html_wrap_inline436 and tex2html_wrap_inline438). The magnetic field, measured at the end of a 6 meter boom, is sampled eight times per second with 11 pT resolution [Russell et al., 1995].





next up previous
Next: Solar wind observations Up: Field-Line Resonances Triggered by Previous: Introduction

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