Evolution of Energetic Proton Parallel Pressure Anisotropy at Geosynchronous Altitudes: Potential Role in Triggering Substorm Expansion Phase Onset
Abstract The sequence of events associated with the triggering of energy release during substorm expansion phase onset is still not well‐understood. Oberhagemann and Mann (2020b, https://doi.org/10.1029/2019gl085271) proposed a new substorm onset mechanism, where the transition toward parallel proto...
Saved in:
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Wiley
2024-06-01
|
| Series: | Geophysical Research Letters |
| Online Access: | https://doi.org/10.1029/2023GL105660 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1850271820688654336 |
|---|---|
| author | S. S. Babu I. R. Mann S. Dimitrakoudis L. G. Ozeke I. J. Rae C. Forsyth A. W. Smith |
| author_facet | S. S. Babu I. R. Mann S. Dimitrakoudis L. G. Ozeke I. J. Rae C. Forsyth A. W. Smith |
| author_sort | S. S. Babu |
| collection | DOAJ |
| description | Abstract The sequence of events associated with the triggering of energy release during substorm expansion phase onset is still not well‐understood. Oberhagemann and Mann (2020b, https://doi.org/10.1029/2019gl085271) proposed a new substorm onset mechanism, where the transition toward parallel proton pressure anisotropy during tail stretching in the late growth phase could trigger a pressure anisotropic ballooning instability. Here we examine the evolution of energetic proton parallel pressure anisotropy at geosynchronous altitudes, seeking evidence in support of the proposed substorm onset mechanism. We use the Geostationary Operational Environment Satellite (GOES) proton flux and magnetometer data combined with substorm onset indicators derived from ground‐based magnetometers. Superposed epoch analysis of substorm onset times for 2014 using the isolated substorm list (Ohtani & Gjerloev, 2020, https://doi.org/10.1029/2020ja027902) clearly shows signatures of energetic proton parallel pressure anisotropy immediately before substorm onset, potentially supportive of the Oberhagemann and Mann theory. |
| format | Article |
| id | doaj-art-c2c465e425fa4c4691aed2da23b06790 |
| institution | OA Journals |
| issn | 0094-8276 1944-8007 |
| language | English |
| publishDate | 2024-06-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geophysical Research Letters |
| spelling | doaj-art-c2c465e425fa4c4691aed2da23b067902025-08-20T01:52:06ZengWileyGeophysical Research Letters0094-82761944-80072024-06-015112n/an/a10.1029/2023GL105660Evolution of Energetic Proton Parallel Pressure Anisotropy at Geosynchronous Altitudes: Potential Role in Triggering Substorm Expansion Phase OnsetS. S. Babu0I. R. Mann1S. Dimitrakoudis2L. G. Ozeke3I. J. Rae4C. Forsyth5A. W. Smith6Department of Physics University of Alberta Edmonton AB CanadaDepartment of Physics University of Alberta Edmonton AB CanadaDepartment of Physics University of Alberta Edmonton AB CanadaDepartment of Physics University of Alberta Edmonton AB CanadaDepartment of Mathematics, Physics and Electrical Engineering Northumbria University Newcastle UKMullard Space Science Laboratory University College London Dorking UKDepartment of Mathematics, Physics and Electrical Engineering Northumbria University Newcastle UKAbstract The sequence of events associated with the triggering of energy release during substorm expansion phase onset is still not well‐understood. Oberhagemann and Mann (2020b, https://doi.org/10.1029/2019gl085271) proposed a new substorm onset mechanism, where the transition toward parallel proton pressure anisotropy during tail stretching in the late growth phase could trigger a pressure anisotropic ballooning instability. Here we examine the evolution of energetic proton parallel pressure anisotropy at geosynchronous altitudes, seeking evidence in support of the proposed substorm onset mechanism. We use the Geostationary Operational Environment Satellite (GOES) proton flux and magnetometer data combined with substorm onset indicators derived from ground‐based magnetometers. Superposed epoch analysis of substorm onset times for 2014 using the isolated substorm list (Ohtani & Gjerloev, 2020, https://doi.org/10.1029/2020ja027902) clearly shows signatures of energetic proton parallel pressure anisotropy immediately before substorm onset, potentially supportive of the Oberhagemann and Mann theory.https://doi.org/10.1029/2023GL105660 |
| spellingShingle | S. S. Babu I. R. Mann S. Dimitrakoudis L. G. Ozeke I. J. Rae C. Forsyth A. W. Smith Evolution of Energetic Proton Parallel Pressure Anisotropy at Geosynchronous Altitudes: Potential Role in Triggering Substorm Expansion Phase Onset Geophysical Research Letters |
| title | Evolution of Energetic Proton Parallel Pressure Anisotropy at Geosynchronous Altitudes: Potential Role in Triggering Substorm Expansion Phase Onset |
| title_full | Evolution of Energetic Proton Parallel Pressure Anisotropy at Geosynchronous Altitudes: Potential Role in Triggering Substorm Expansion Phase Onset |
| title_fullStr | Evolution of Energetic Proton Parallel Pressure Anisotropy at Geosynchronous Altitudes: Potential Role in Triggering Substorm Expansion Phase Onset |
| title_full_unstemmed | Evolution of Energetic Proton Parallel Pressure Anisotropy at Geosynchronous Altitudes: Potential Role in Triggering Substorm Expansion Phase Onset |
| title_short | Evolution of Energetic Proton Parallel Pressure Anisotropy at Geosynchronous Altitudes: Potential Role in Triggering Substorm Expansion Phase Onset |
| title_sort | evolution of energetic proton parallel pressure anisotropy at geosynchronous altitudes potential role in triggering substorm expansion phase onset |
| url | https://doi.org/10.1029/2023GL105660 |
| work_keys_str_mv | AT ssbabu evolutionofenergeticprotonparallelpressureanisotropyatgeosynchronousaltitudespotentialroleintriggeringsubstormexpansionphaseonset AT irmann evolutionofenergeticprotonparallelpressureanisotropyatgeosynchronousaltitudespotentialroleintriggeringsubstormexpansionphaseonset AT sdimitrakoudis evolutionofenergeticprotonparallelpressureanisotropyatgeosynchronousaltitudespotentialroleintriggeringsubstormexpansionphaseonset AT lgozeke evolutionofenergeticprotonparallelpressureanisotropyatgeosynchronousaltitudespotentialroleintriggeringsubstormexpansionphaseonset AT ijrae evolutionofenergeticprotonparallelpressureanisotropyatgeosynchronousaltitudespotentialroleintriggeringsubstormexpansionphaseonset AT cforsyth evolutionofenergeticprotonparallelpressureanisotropyatgeosynchronousaltitudespotentialroleintriggeringsubstormexpansionphaseonset AT awsmith evolutionofenergeticprotonparallelpressureanisotropyatgeosynchronousaltitudespotentialroleintriggeringsubstormexpansionphaseonset |