Work Description

Title: Event List for "Interchange Injections at Saturn: Statistical Survey of Energetic H+ Sudden Flux Intensifications"
Attribute NameValues
Methodology
  • We created an event detection algorithm (classification) based off of intensifications above background statistics as a function of radial distance, energy, and flux to identify interchange injection events at Saturn using the Cassini CHarge Energy Mass Spectrometer (CHEMS) H+ data. Interchange injections are thought to arise from a Rayleigh-Taylor like plasma instability driven by Saturn’s rapid rotation (period ~ 10.8 hours) and the dense plasma population that is created from Enceladus’ plume neutrals. Interchange is a critical process in transporting plasma within the Saturnian magnetosphere. We identified the signatures of inward bound (toward Saturn) interchange events by evaluating intensifications in H+ flux data from H+ CHEMS flux data from equatorial orbits between early 2005 through 2016. Additionally we evaluated these events against previous surveys developed from Cassini data.
Description
  • ABSTRACT: We present a statistical study of interchange injections in Saturn's inner and middle magnetosphere focusing on the dependence of occurrence rate and properties on radial distance, partial pressure, and local time distribution. Events are evaluated from over the entirety of the Cassini mission’s equatorial orbits between 2005 and 2016. We identified interchange events from CHarge Energy Mass Spectrometer (CHEMS) H+ data using a trained and tested automated algorithm, which has been compared with manual event identification for optimization. We provide estimates of interchange based on intensity, which we use to investigate current inconsistencies in local time occurrence rates. This represents the first automated detection method of interchange, estimation of injection event intensity, and comparison between interchange injection survey results. We find the peak rates of interchange occur between 7 - 9 Saturn radii and that this range coincides with the most intense events as defined by H+ partial particle pressure. We determine that nightside occurrence dominates as compared to the dayside injection rate, supporting the hypothesis of an inversely dependent instability growth rate on local Pedersen ionospheric conductivity. Additionally, we observe a slight preference for intense events on the dawn side, supporting a triggering mechanism related to large-scale injections from downtail reconnection. Our observed local time dependence paints a dynamic picture of interchange triggering due to both the large-scale injection driven process and ionospheric conductivity. Within this repository we provide a readme file (description of data file and usage) and the event list provided as a .txt file. The event list includes start and stop times, comparison to previous surveys, and the average location of events identified. Additional formats are available on request.
  • Further details on this method can be found in "Interchange Injections at Saturn: Statistical Survey of Energetic H+ Sudden Flux Intensifications" by Azari et al., 2018 in the Journal of Geophysical Research: Space Physics. https://doi.org/10.1029/2018JA025391.
Creator
  • Azari, A. R.
Depositor
  • azari@umich.edu
Contact Information
Discipline
  • Science
Funding Agency
  • National Science Foundation (NSF)
Keyword
  • Planetary Science
  • Automated Event Detection
  • Space Physics
  • Magnetospheric Physics
  • Interchange Injections
  • Saturn
Date coverage
  • 2005 to 2017
Citation to related material
  • Azari, A. R., Liemohn, M. W., Jia, X., Thomsen, M. F., Mitchell, D. G., Sergis, N., Rymer, A. M., Hospodarsky, G. B., Paranicas, C. , and Vandegriff, J. (2018). Interchange Injections at Saturn: Statistical Survey of Energetic H+ Sudden Flux Intensifications. Journal of Geophysical Research: Space Physics, 123. https://doi.org/10.1029/2018JA025391
Language
  • English
Total File Count
  • 3
Total File Size
  • 173 KB
DOI
  • doi:10.7302/Z2WM1BMN
Visibility
  • Open Access
Rights


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