Van Allen Probes, NOAA, and Ground Observations of an Intense Pc 1 Wave Event Extending 12 Hours in MLT and its Resulting Depletion of the Outer Radiation Belt

Mark J. Engebretson1, Jennifer L Posch2, John R Wygant3, Craig Kletzing4, Marc Lessard5, Chia-Lin Huang6, Harlan E Spence6, Alexander J Boyd6, Daniel N Baker7, Charles William Smith5, Howard J Singer8, Richard Bertram Horne9, Geoffrey D Reeves10, Matina Gkioulidou11,12, Kjellmar Oksavik13, Ian Robert Mann14, Raita Tero15 and Kazuo Shiokawa16, (1)Augsburg University, Physics, Minneapolis, United States, (2)Augsburg University, Minneapolis, MN, United States, (3)University of Minnesota Twin Cities, Minneapolis, MN, United States, (4)University of Iowa, Physics and Astronomy, Iowa City, United States, (5)University of New Hampshire, Durham, United States, (6)University of New Hampshire, Durham, NH, United States, (7)University of Colorado, Laboratory for Atmospheric and Space Physics, Boulder, United States, (8)NOAA-Space Weather Prediction Center, Boulder, CO, United States, (9)British Antarctic Survey, Cambridge, United Kingdom, (10)Los Alamos National Laboratory, Los Alamos, United States, (11)Johns Hopkins Applied Physics Laboratory, Laurel, United States, (12)JHU/APL, Laurel, United States, (13)University of Bergen, Birkeland Centre for Space Science, Bergen, Norway, (14)University of Alberta, Department of Physics, Edmonton, AB, Canada, (15)University of Oulu, Sodankyla Geophysical Observatory, Sodankyla, Finland, (16)Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan

Contact First Author: Mark J. Engebretson; engebret@augsburg.edu

Previously Published Material: Preliminary results were presented at the Fall 2014 AGU Meeting.

Abstract ID#: 34446

 

English Abstract:
Although most studies of the effect of EMIC waves on relativistic electrons have focused on wave events in the afternoon sector in the outer plasmasphere or plume region, strong magnetospheric compressions provide an additional stimulus for EMIC wave generation across a large range of local times and L shells. We present here observations of the effects of an intense, long-duration wave event on February 23, 2014. Waves extending 8 hours in UT and over 12 hours in MLT were stimulated by a gradual 4-hour rise and subsequent sharp increases in solar wind pressure. Large-amplitude linearly polarized hydrogen band EMIC waves (up to 25 nT p-p) appeared for over 4 hours at both Van Allen Probes as they moved near apogee from late morning through local noon, when these spacecraft were outside the plasmapause, in a region with densities ~5-20 cm-3. Wave activity was also observed by ground-based induction magnetometers in Finland, Antarctica, Canada, Russia, and Japan, and briefly by GOES-13 and -15 in the midnight sector. Ten passes of NOAA-POES and METOP satellites near the northern hemisphere footpoint of the Van Allen Probes (over Siberia) showed the presence of 30-80 keV subauroral proton precipitation, often over extended L shell ranges; other passes identified a narrow L-shell region of precipitation over Canada. Observations of relativistic electrons by both Van Allen Probes showed that this wave event preferentially reduced the fluxes of more field-aligned and more energetic radiation belt electrons at both L* = 4.5 and 5.2, confirming the effectiveness of EMIC-induced loss processes, as predicted in recent theoretical studies, for this event.
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