1. D. Sibeck, R. Millan, H. Spence
Loss Processes
D. Sibeck, R. Millan, H. Spence

2. Outline 1. Quantify magnetopause losses
Magnetopause motion and shell splitting
ULF waves
Orbit bifurcation
Ring current inflation
2. Quantify precipitation mechanisms
3. Quantify relative importance over solar cycle

3. Losses and Magnetopause Motion
Compression
Rapid (1-2 min) increase in dayside field strengths (betatron acceleration and flux increase),
Gradual decrease in nightside equatorial field strengths
Enhanced drift shell splitting
90° pitch angle particles on closed paths gain access to magnetopause and are lost from outer magnetosphere.

4. Losses and Magnetopause Motion
Causes of Magnetopause Motion
Erosion (requires minutes)
No change in subsolar magnetic field strength
therefore no opening of drift paths.
R1 currents gradually diminish dayside field strengths while cross-tail currents gradually reduce nightside equatorial magnetic field strengths 
High energy 90° pitch angle particles conserve 1st ad. inv. and move inward, low energy particles also conserve 3rd ad. inv. and move outward, lose energy but may not be lost to the magnetosphere.

5. Diffusion Driven By ULF Waves
Diffusion resulting from ULF (and other) waves requires
~1 hr [Shprits et al., 2006]
days [Morley et al., 2010] to remove electrons
from locations deep in
the magnetosphere. May
need some other process to
help [Ukhorskiy et al., 2009]

6. Bifurcation Enhanced Diffusion
1 MeV electrons at 4 times. Bifurcation moves electrons both outwards to MP and inwards

7. Ring Current Inflation Removes Electrons
Ukhorskiy et al. [2015]
With ring current Without ring current
MeV e 90° P. A.
P.A.
# Particles
Drift echoes
Adiabatic Cooling
Compressional
Energization

8. Tasks
1. Survey radiation belt responses to abrupt solar wind pressure and IMF Bz variations.
2. Survey ULF wave activity and cf. radiation belt behavior.
3. Look for enhanced losses on field lines subject to bifurcation.
4. Look for ring current effects on loss from inner magnetosphere.
5. Use MMS/THEMIS to survey losses at the magnetopause, cf. with particle loss deeper in the magnetosphere.

9. Quantify Precipitation Mechanisms
1. Quantify extent, significance of
EMIC waves [Halford et al., 2010; Usanova et al., 2014; Kersten et al., 2014].
Chorus [Thorne et al., 2010]
not only as function of geomagnetic indices or solar wind conditions, but of storm phase.
2. Compare with precipitation patterns (cubesats, BARREL).

10. Solar Cycle Variations
More substorms and particle injections during declining phase of solar cycle 
More chorus waves 
More particle loss?
Work with MMS/ERG/THEMIS to determine extent of wave fields, rate of loss, cf. observations, compare at different stages of solar cycle.