Investigating the Relationship between IPDPs and Pi1B Waves

Tanja.Fromm [ at ]


IPDPs (intervals of pulsations with diminishing periods) are a subset of EMIC waves. Pi1Bs (pulsations irregular 1Hz bursts) are ULF waves closely correlated with substorm onset. Prior research has indicated there may be a relationship between the two, but this relationship has not yet been fully fleshed out. In this presentation, we investigate the relationship between evening sector IPDPs and Pi1B. To do so we utilize searchcoil magnetometer, fluxgate magnetometer, riometer, and imaging riometer data from a collection of Antarctic ground stations (Halley Research Station, Neumayer, Maitri, Syowa, and Mawson) that span 10 degrees in CGM latitude, 4 hours in MLT, and L shells 4 through 9. We also utilize magnetometer data from satellites in conjunction including SWARM, which reveals a local unidentified ULF signature equatorward of the ground instrumentation (more work is required to fully understand this). From the ground instrumentation, we observe Pi1B in the late evening MLT region crossing over into the early dawn region, and IPDPs in the early evening MLT region. Despite the 4 hour range in MLT, we observe these events near simultaneously with only a ~15 minute delay between the start of the Pi1B and the start of the IPDP. We observe correlated cosmic noise absorption (CNA) that occurs simultaneously with and encompasses the full duration of these events. The ULF activity we observe aligns well with what we expect from previous work done on the subject-- IPDPs appear at lower geomagnetic latitudes (60-65 degrees) than Pi bursts, which are more prominent at ~70 degrees-- but the CNA we observe has less precedence in prior research. In this presentation, we describe our observations in detail as well as possible mechanisms that might link the Pi1B and IPDP waves, as well as the CNA.

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Conference (Poster)
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AGU Fall Meeting, 09 Dec 2019 - 13 Dec 2019, San Francisco, USA.
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Salzano, M. , Lessard, M. , Kim, H. , Engebretson, M. J. , Horne, R. B. , Clilverd, M. A. , Seemala, G. K. , Sinha, A. K. , Sinha, S. , Kim, K. K. , Fromm, T. , Matzka, J. , Kadokura, A. , Tanaka, Y. and Waters, C. (2019): Investigating the Relationship between IPDPs and Pi1B Waves , AGU Fall Meeting, San Francisco, USA, 9 December 2019 - 13 December 2019 .

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