Driving dayside convection with northward IMF: Observations by a sounding rocket launched from Svalbard

Abstract. We present a comparative study of the cusp region using the EISCAT Svalbard Radars (ESR) and the Cluster spacecraft. We focus in this paper on 2 February 2001, over the time period from 07:30 UT to 12:00 UT when the oblique ESR antenna pointing northward at a low elevation recorded latitudinal motions of the cusp region in response to the IMF. Meanwhile, the Cluster satellites were flying over the EIS-CAT Svalbard Radar field-of-view around local magnetic noon. The spacecraft first flew near ESR, north-east of Svalbard and then passed over the field-of-view of the antenna at about 11:30 UT. From 08:00 UT to 09:00 UT, the IMF remains primarily southward yet several variations in the Zcomponent are seen to move the cusp. Around 09:00 UT, an abrupt northward turning of the IMF moves the cusp region to higher latitudes. As a result, the Cluster satellites ended up in the northernmost boundary of the high-altitude cusp region where the CIS instrument recorded highly structured plasma due to ion injections in the lobe of the magnetosphere. After 09:00 UT, the IMF remains northward for more than two hours. Over this period, the ESR records sunward plasma flow in the cusp region due to lobe reconnection, while Cluster spacecraft remain in the high-altitude cusp.

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“…Maynard et al, 2000;Pryse et al, 2000;Sandholt et al, 1999a). This paper claims to contribute to this "new" aspect of cusp studies.…”

Section: Introductionmentioning

confidence: 99%

Observations of the cusp region under northward IMF

Pitout

Bosqued²,

Alcaydé³

et al. 2001

Ann. Geophys.

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“…The opposite spatial relations between the cusps and the merging-line segments maintain when IMF By < 0. While questions relating to the domi nance of antiparallel or component merging are not yet resolved, recent sounding rocket results support the an tiparallel hypothesis [Maynard et al, 2000a[Maynard et al, , 2000b.…”

Section: Discussion and Summarymentioning

confidence: 76%

“…Experience teaches that significant variability in the intensities and distributions of convective electric fields cannot be accounted for by the statistical para meters. The purpose of this paper is to summarize re sults from two recent sounding rocket experiments that suggest (1) the dayside ionosphere responds on a much finer scale to interplanetary variations than previously thought, and (2) the timing of near-cusp auroral events depends on all three IMF components [Maynard et al, 2000a]. To help understand the significance of our new results we begin with a brief overview of electric field driven plasma flows in the high-latitude M-I system.…”

Section: Discussion and Summarymentioning

confidence: 99%

Space Weather

2001

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“…Same format as in Figure 4, but for six nights when the ionospheric plasma motion and the speed of the neutrals were significantly different [Maynard et al, 2000]. In this paper, we present auroral emissions seen by two imagers, which were located under the cusp.…”

Section: Statistical Comparison Of Neutral Winds and Scintillation Drmentioning

confidence: 99%