1. Observations of a Global Coherence Scale Modulating Electron Loss Due to Plasmaspheric Hiss Van Allen Probes/BARREL 2014 cooperative campaign EFW team: Aaron Breneman, John Wygant, Cynthia Cattell, David Malaspina, and others University of Minnesota BARREL team: Alexa Halford, Robyn Millan, Michael McCarthy, Leslie Woodger, John Sample and others Dartmouth EMFISIS team: Craig Kletzing, Scott Bounds, George Hospodarsky, Bill Kurth and others MagEIS team: Joe Fennell Jerry Goldstein team: Jerry Goldstein Sadie Tetrick Augsburg Aaron Breneman, University of Minnesota (awbrenem@gmail.com)

2. Nature, 2015

3. Quick results ULF fluctuations of density/magnetic field cause global coherence scale in hiss source region and therefore electron loss in plasmasphere Experimental verification that hiss causes e- loss (predicted over 40 years ago [Lyons, 1973] ) 9 Aaron Breneman, University of Minnesota (awbrenem@gmail.com)

4. Jan 6 th correlations Multiple payloads allows determination of coherence scale Distinctive double-peaked feature observed on nearly all payloads Aaron Breneman, University of Minnesota (awbrenem@gmail.com)

5. Since high coherence was observed on all combinations of payloads, the overall coherence scale covers, at a minimum, all baselines formed by the probes and balloons 6 hours of MLT (from 11<MLT<17) 3.5 L (from 3<L<6.5). ULF period fluctuations (1-20 min) of density and magnetic field create global-scale coherence to hiss source region that significantly modifies electron loss. Coherence scale of hiss source and electron loss…quantified Jan 6 th, 2014 Aaron Breneman, University of Minnesota (awbrenem@gmail.com) 3.3 min period fluctuations

6. Double-peaked event originates in the solar wind or magnetosheath Propagates at 0.03-0.1 MLT/sec at 6.6 RE (300 – 1000 km/s) Thanks to Kyle Murphy And Jerry Goldstein Source of the ULF fluctuations CARISMA: Mann et al., 2008 Aaron Breneman, University of Minnesota (awbrenem@gmail.com)

7. Quantify coherence for entire second BARREL mission as function of: – balloon position – balloon separation – ULF period Balloon K Balloon L Coherence (> 0.7)

8. Max coherence (1-20min) Inside plasmasphere only Balloon combinations (IK, IL, IW, KL, KW) for entire mission. Identified coherence storms only coh>0.7 only Coherence vs MLT Coherence vs L Inside plasmasphere Outside plasmasphere

9. Coherence vs delta-MLTCoherence vs delta-L Max coherence (1-20min) Inside plasmasphere only Balloon combinations (IK, IL, IW, KL, KW) for entire mission. Identified coherence storms only coh>0.7 only Coherence vs delta-MLTCoherence vs delta-L Inside plasmasphere Outside plasmasphere

10. To do Analyze all BARREL payload combinations, not just the obvious “coherence storms” Determine coherence scale as a function of driving solar wind parameters How common is large-scale occurrence? S. Kavosi, J. Raeder KHW occurrence

11. Hiss definitively causes observed precipitation Four lines of evidence showing with high confidence that the hiss, modulated by ULF fluctuations of density and magnetic field, directly causes the observed precipitation 1: Hiss and X-rays have similar trends. Not true with density, magnetic field 2: Precipitation energies consistent with in situ-determined first order cyclotron resonance energies 3: Hiss and X-ray spectra nearly identical for 1-20 min periods 4: Calculated scattering rate into loss cone consistent with inferred precipitation rate from X-ray inversion Aaron Breneman, University of Minnesota (awbrenem@gmail.com)

12. 1: Similar trends Hiss/X-rays have similar trend over 2 hour conjunction Not true of – Density/X-rays – Magnetic field/X-rays – 30 keV flux/X-rays (from MagEIS) Aaron Breneman, University of Minnesota (awbrenem@gmail.com)

13. 2: Precipitation energies 1 st order cyclotron resonance causes the precipitation Some balloons do not see precipitation b/c they map to field lines with few resonant electrons Aaron Breneman, University of Minnesota (awbrenem@gmail.com)

14. 3: Similar spectra Aaron Breneman, University of Minnesota (awbrenem@gmail.com) Hiss & x-ray spectra very similar from 1-20 min periods More so than -density and x-rays -|B| & x-rays - e- flux and x-rays

15. QL diffusion rate [Summers, 2007] indicates that 50 keV e- will scatter 1 ◦ over 1 sec bounce period (Jan 6 th at 21 UT) MagEIS 50 keV flux at 4 deg: 0.08-2.4 e-/cm2/s Scaling this to 70 km we find 15-450 e-/ cm2/s Balloon 2K observes 26–39 e-/cm2/s at 50 keV Observed e- loss on BARREL consistent with theoretical loss from hiss 4: Loss rate calculation Aaron Breneman, University of Minnesota (awbrenem@gmail.com)

16. Summary ULF fluctuations of density and magnetic field set a global coherence scale of hiss source region. This has significant effect on observed electron loss rate. Suggests that coupling models of ULF wave formation and propagation to radiation belt models is an important component of accurately simulating electron loss caused by hiss Experimental verification that hiss causes precipitation of 30-150 keV e- in plasmasphere What is the source of these ULF fluctuations? Simultaneous satellite and balloon observations are extremely useful! New BARREL mini-campaign in August, 2015 Aaron Breneman, University of Minnesota (awbrenem@gmail.com)

17. References Lyons, R. L., Thorne, R.M. and Kennel, C.F., Pitch-angle diffusion of radiation belt electrons within the plasmasphere, J. Geophys. Res., 77(19), 3455- 3474 (1972) Lyons, L., and Thorne, R.M., Equilibrium structure of radiation belt electrons, J. Geophys. Res., 78(13), 2142-2149 (1973) Li, W., et al., An unusual enhancement of low-frequency plasmaspheric hiss in the outer plasmasphere associated with substorm-injected electrons, Geophys. Res. Lett., 40, 3798-3803 (2013) Chen, L., et al., Generation of unusually low frequency plasmaspheric hiss, Geophys. Res. Lett., 41, 5702-5709 (2014) Ni, B., et al., Resonant scattering of energetic electrons by unusual low- frequency hiss, Geophys. Res. Lett., 41, 1854-1861 (2014) Claudepierre, S. G., Hudson, M. K., Lotko, W., Lyon, J. G. and Denton, R. E., Solar wind driving of magnetospheric ULF waves: Field line resonances driven by dynamic pressure fluctuations, J. Geophys. Res., 115, A11 (2010) Hughes, W. J., Southwood, D. J., Mauk, B., McPherron, R. L. and Barfield, J. N., Alfven waves generated by an inverted plasma energy distribution, Nature, 275, 43-45 (1978) Dai, L., et al., Excitation of poloidal standing Alfven waves through drift res- onance wave-particle interaction, Geophys. Res. Lett., 40, 4127-4132 (2013) Mann, I. R., et al., The upgraded CARISMA magnetometer array in the THEMIS era, Space Sci. Rev., 141, 413-451 (2008) Summers,D., Ni, B., and Meredith, N.P.,Timescales for radiation belt electron acceleration and loss due to resonant wave-particle interactions: 1. Theory, J. Geophys. Res., 112, 4207 (2007) Summers, D., Omura, Y., Nakamura, S. and Kletzing, C. A., Fine structure of plasmaspheric hiss, J. Geophys. Res., 119, 9134-9149 (2014) Tsurutani, B. T., Falkowski, B. J., Pickett, J. S., Santolik, O. and Lakhina, G. S., Plasmaspheric hiss properties: Observations from Polar, J. Geophys. Res., 120, 414–431 (2015) Santolik, O., Parrot, M. and Lefeuvre, F., Singular value decomposition meth- ods for wave propagation analysis, Radio Sci., 38, 1, 1010 (2003) Aaron Breneman, University of Minnesota (awbrenem@gmail.com)

18. Substorms 2014-01-03 – 05:26, 10:11, 16:56 2014-01-06 – 21:51