Tracking corotating interaction regions from the Sun through to the orbit of Mars using ACE, MEX, VEX, and STEREO

Abstract

We study the propagation of corotating interaction regions (CIRs) through the inner heliosphere during the solar minimum of 2007-2008 using the Advanced Composition Explorer (ACE), Mars Express (MEX), Venus Express (VEX), and the Solar Terrestrial Relations Observatory (STEREO). We present observations of 24 CIRs observed during the period from 1 July 2007 to 31 August 2008. Using data from ACE, we demonstrate a method for predicting the arrival of CIRs at other locations within the heliosphere. The efficacy of the technique is assessed using observations at Mars and Venus, from MEX and VEX, respectively, and at the STEREO A and STEREO B spacecraft. We also use observations from the STEREO Heliospheric Imagers (HI) to produce another set of CIR arrival time estimates. We show that the estimated arrival times from ACE agree well with the arrival times at other spacecraft, whereas the estimates from STEREO/HI tend to agree less well. This latter difference can be explained through uncertainties in estimates due to difficulties in the unambiguous identification of the corresponding events in the STEREO/HI data. Copyright © 2011 by the American Geophysical Union.