eprintid: 10196979 rev_number: 7 eprint_status: archive userid: 699 dir: disk0/10/19/69/79 datestamp: 2024-09-16 12:24:07 lastmod: 2024-09-16 12:24:07 status_changed: 2024-09-16 12:24:07 type: article metadata_visibility: show sword_depositor: 699 creators_name: Boldu, JJ creators_name: Graham, DB creators_name: Morooka, M creators_name: Andre, M creators_name: Khotyaintsev, Yu V creators_name: Dimmock, A creators_name: Pisa, D creators_name: Soucek, J creators_name: Maksimovic, M creators_name: Louarn, P creators_name: Fedorov, A creators_name: Nicolaou, G creators_name: Owen, C title: Ion-Acoustic Waves Associated With Interplanetary Shocks ispublished: pub divisions: UCL divisions: B04 divisions: C06 divisions: F63 keywords: Collisionless shock; plasma waves; instabilities note: Copyright © 2024. The Author(s). Geophysical Research Letters published by Wiley Periodicals LLC on behalf of American Geophysical Union. This is an open access article under the terms of the Creative Commons Attribution License, https://creativecommons.org/licenses/by/4.0/, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. abstract: Ion-acoustic waves (IAWs) commonly occur near interplanetary (IP) shocks. These waves are important because of their potential role in the dissipation required for collisionless shocks to exist. We study IAW occurrence statistically at different heliocentric distances using Solar Orbiter to identify the processes responsible for IAW generation near IP shocks. We show that close to IP shocks the occurrence rate of IAW increases and peaks at the ramp. In the upstream region, the IAW activity is highly variable among different shocks and increases with decreasing distance from the Sun. We show that the observed currents near IP shocks are insufficient to reach the threshold for the current-driven instability. We argue that two-stream proton distributions and suprathermal electrons are likely sources of the waves. date: 2024-08-28 date_type: published publisher: AMER GEOPHYSICAL UNION official_url: http://dx.doi.org/10.1029/2024gl109956 oa_status: green full_text_type: pub language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 2308886 doi: 10.1029/2024GL109956 lyricists_name: Owen, Christopher lyricists_name: Nicolaou, Georgios lyricists_id: CJOWE13 lyricists_id: GNICO14 actors_name: Owen, Christopher actors_id: CJOWE13 actors_role: owner funding_acknowledgements: 22-10775S [Czech Science Foundation] full_text_status: public publication: Geophysical Research Letters volume: 51 number: 16 article_number: e2024GL109956 pages: 10 issn: 0094-8276 citation: Boldu, JJ; Graham, DB; Morooka, M; Andre, M; Khotyaintsev, Yu V; Dimmock, A; Pisa, D; ... Owen, C; + view all <#> Boldu, JJ; Graham, DB; Morooka, M; Andre, M; Khotyaintsev, Yu V; Dimmock, A; Pisa, D; Soucek, J; Maksimovic, M; Louarn, P; Fedorov, A; Nicolaou, G; Owen, C; - view fewer <#> (2024) Ion-Acoustic Waves Associated With Interplanetary Shocks. Geophysical Research Letters , 51 (16) , Article e2024GL109956. 10.1029/2024GL109956 <https://doi.org/10.1029/2024GL109956>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10196979/1/Boldu_et_al_e2024GL109956.pdf