Authors: Nina Dresing Raúl GómezHerrero Bernd Heber Reinhold MüllerMellin Robert WimmerSchweingruber Andreas Klassen
Publish Date: 2009/04/10
Volume: 256, Issue: 1-2, Pages: 409-425
Abstract
The period between 21 June and 8 October 2007 Carrington rotations 2058 to 2061 comprising the Ulysses ecliptic plane crossing was characterized by low solar activity Excluding the small solar energetic particle events observed during July the ion increases observed in the inner heliosphere between 100 keV/n and 10 MeV/n were associated with Corotating Interaction Regions CIRs In this work we investigate CIRrelated ion increases using multipoint observations from Ulysses ACE and the twin STEREO spacecraft The ballistic backmapping technique has been used to correlate in situ observations of these spacecraft and remotesensing observations of coronal holes Although the radial longitudinal and latitudinal separation of the spacecraft except Ulysses are relatively small we find discrepancies when a detailed comparison of narrow structures like stream interfaces and CIRassociated shocks is performed Therefore we concentrate on the two CIR events from day 5 to day 10 of August 2007 and from day 25 to day 31 of August 2007 which lend themselves to a more undisturbed comparison Using the multispacecraft measurements we could determine a radial gradient of 230±30 AU−1 which is consistent with previous results by van Hollebeke et al J Geophys Res 83 4723 1978 of ∼ 350 AU−1 using Helios and Pioneer data
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