Properties of the HPS‐ICME‐CIR Interaction Event of 9–10 September 2011

Abstract

During 9–10 September 2011 the ACE, Wind, and SOHO spacecraft measured the complex interaction between an interplanetary coronal mass ejection (ICME) and a corotating interaction region (CIR) associated with the heliospheric sector boundary. Except for a few short periods, the suprathermal electrons are unidirectional, suggesting that the ICME magnetic field has opened through interchange reconnection. Signatures of interaction are distributed throughout the event suggesting that the structures have become entangled or embedded. Since the ICME speed is relatively low, the strong forward shock must be caused by the ICME‐CIR interaction. Other interesting features are the upstream heating flux discontinuity, the very high proton density in the frontal boundary of the heliospheric plasma sheet and the forward shock, the significant speed elevation within the sheath, the distortion of Bz in the magnetic cloud, the indistinct location of the stream interface, the unidirectional domination of the suprathermal electrons, and the reverse shock at the CIR rear boundary. There is an unusual delay between the proton density and temperature profiles. Furthermore, large differences in proton speed and forward shock density measured between L1 spacecraft indicate high variation at small spatial scales. A few days earlier, STEREO B recorded the undisturbed CIR, which shows that (i) some general features of the CIR are preserved, (ii) the CIR is compressed by a factor of ∼4 by the ICME, and (iii) a magnetic exhausted region at the front of the CIR is a continuous feature and is not formed due to the ICME interaction.

Properties and Geoeffectiveness of Solar Wind High‐Speed Streams and Stream Interaction Regions During Solar Cycles 23 and 24

“…This issue is not severe during solar minimum years, but becomes important during solar maximum years. One must also keep in mind that some of the rejected events may be real SIR/HSS events that are interacting with a simultaneously occurring ICME event near the ecliptic plane [see, e.g., Al-Shakarchi and Morgan, 2018;Shugay et al, 2018].…”

Solar Origins of August 26, 2018 Geomagnetic Storm: Responses of the Interplanetary Medium and Equatorial/Low‐Latitude Ionosphere to the Storm

“…In fact, occurrences of space weather events, e.g., geomagnetic storms are now matters of major concerns. More so, recent works, like Al‐Shakarchi and Morgan (2018), on the likely interactions between CME transients and CIR transients have laid further credence on the need for the space weather community to explore deeply, all the coupling processes from the Sun to the Earth. As earlier reported, geomagnetic storms have the potential to damage ground‐based and space‐based infrastructures (Eastwood et al., 2017; NRC, 2008), as well as being injurious to human health (Lanzerotti, 2001; Pulkkinen et al., 2017).…”

Operational Dst index prediction model based on combination of artificial neural network and empirical model

“…For performance optimization, all hidden layers with node numbers of 7-50, a learning rate of 0.0001-0.01, and learning cycles of 1200-1500 were trained and validated (see table 2). For the ANN training, we used the data observed in , 2001, 2004, 2007, 2008, 2011, 2012, 2014, 2016. For the model validation, we use 2000, and 2013 The red dots (ANN model) in Figure 2 show the RMSE and the correlation coefficients obtained by comparing the prediction results with the observed Dst index during the test period.…”

“…Space weather operators can easily recognize whether CME or CIR will cause magnetic storms from solar images. However, sometimes CMEs could be embedded in a CIR and resulting in a compound storm event (Al-Shakarchi & Morgan, 2018). In this case, the decision for selecting CME or CIR mode remains to the operators.…”