Understanding the Dynamics of the Radiation Belts

ROSES ID: NNH11ZDA001N      Selection Year: 2012      

Program Element: Focused Science Topic

Principal Investigator: Janet Green

Affiliation(s): LASP, University of Colorado

Project Member(s):
Rodriguez, Juan V Co-I University of Colorado at Boulder
Huang, Chia-Lin Co-I University Of New Hampshire
Machol, Janet Co-I NOAA

Summary:

The goal of the proposed work is to determine if changes in particle drifts and the open closed boundary control whether the outer radiation belt flux is depleted or enhanced. More specifically, we propose to test the following hypotheses: 1) The outer electron radiation belt will be depleted due to direct transport out the magnetopause and enhanced outward radial diffusion if the open/closed boundary of radiation belt electrons intersects the magnetopause and 2) The outer electron radiation belt will be enhanced only when the last closed drift orbit of seed electrons is inside the magnetopause, allowing those electrons access to the inner magnetosphere from the tail. We do this using a four step method. First, we create a dataset of phase space density at fixed invariants with error estimates for the GOES and POES proton and electron data to determine how often decreases are just adiabatic. Next, we calculate proton and electron drift orbits in TS05 field with the Volland-Stern electric field model to find which particle energies and pitch angles should be lost to the magnetopause and compare to the GOES data set. Then, we use observed PSD radial gradients and ULF wave measurements from multiple GOES and POES satellites to determine whether outward radial diffusion and direct magnetopause loss can explain decreases. Lastly, we identify storms with small, medium and large PSD enhancements in the GOES dataset. We calculate the width of the forbidden region by tracing particles in the TS05 model with a Volland-Stern electric field and use a superposed epoch analysis to determine whether the width of the forbidden region dictates whether the radiation belts are enhanced. Ultimately, the impact of the proposed work is that it will clarify and possibly alter our understanding of both radiation belt loss and acceleration processes leading to more realistic modeling and predictive power for anticipating events with societal impacts. Additionally, the work will provide a new dataset of PSD as a function of the adiabatic invariants that can be used to complement the upcoming RBSP mission as well as future NASA missions.

Publications:

Performance Year	Reference	Investigation Type	Actions
1	Hartley, D. P.; Denton, M. H.; Green, J. C.; Onsage...	not set

Presentations:

Performance Year	Reference	Actions
1	Hartley, D. P.; Denton, M. H.; Green, J. C.; Onsager, T. G.;...

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