English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Interplanetary coronal mass ejections (ICMEs) are defined as ''coherent'' ifthey are capable of responding to external perturbations in a collectivemanner. This implies that information must be able to propagate across ICMEstructures, and if this is not the case, single-point in-situ measurementscannot be considered as indicative of global ICME properties. Here, weinvestigate the role of Alfvenic fluctuations (AFs) as mediators of ICMEcoherence. We consider multi-point magnetic field and plasma measurements of 10ICMEs observed by the ACE and Wind spacecraft at 1 au at longitudinalseparations of 0.5{\deg}-0.7{\deg}. For each event, we analyze the Alfvenicityin terms of the residual energy and cross helicity of fluctuations, and thecoherence in terms of the magnetic correlation between Wind and ACE. We findthat ~65% and 90% of ICME sheaths and magnetic ejecta (MEs), respectively,present extended AFs covering at least 20% of the structure. Cross helicitysuggests AFs of solar and interplanetary origin may co-exist in the ICMEpopulation at 1 au. AFs are mainly concentrated downstream of shocks and in theback of MEs. The magnetic field is poorly correlated within sheaths, while thecorrelation decreases from the front to the back of the MEs for most magneticfield components. AFs are also associated with lower magnetic fieldcorrelations. This suggests either that ICME coherence is not mediated byAlfven waves, implying that the coherence scale may be smaller than previouslypredicted, or that the magnetic field correlation is not a measure ofcoherence.

On the Role of Alfvenic Fluctuations as Mediators of Coherence within  Interplanetary Coronal Mass Ejections: Investigation of Multi-Spacecraft  Measurements at 1 au