Understanding the Sources, Recirculation, and Impacts of Cold Plasma with Self-Consistent Modeling
Project URL: https://lwstrt.gsfc.nasa.gov/focusedsciencetopics/NNH21ZDA001N/ColdPlasma/
ROSES ID: NNH21ZDA001N Selection Year: 2021
Program Element: Focused Science Topic
Principal Investigator: Mei-Ching Fok
Affiliation(s): Goddard Space Flight Center
Project Member(s):
Glocer, Alex Collaborator NASA Goddard Space Flight Center
Ferradas, Cristian P Co-I Catholic University Of America
Kang, Suk-Bin Co-I Catholic University Of America
Huba, Joseph Co-I Syntek Technologies Inc.
Summary:
Science Objectives:
SO1. Understand the factors controlling the refilling rate of the plasmasphere.
SO2. Follow the pathways of cold plasma from its source to the drainage plume, to the magnetotail and back to the plasmasphere region.
SO3. Determine the impacts of cold plasma on reconnection rates and mass loading in the magnetospheric system.
The plasmasphere is the cold (< 10 eV) plasma population that resides in the inner magnetosphere. It is well established that the plasmasphere provides the environment for the generation and excitation of various plasma wave modes. These plasma waves, in turn, serve as agents or avenues for cross-energy coupling between the ring current and radiation belt particles. Nevertheless, relatively little attention is given to quantify the sources of the plasmasphere particles. What are the controlling factors of the refilling rate? On the other hand, the fate of the plasmasphere particles that encounter the dayside magnetopause is also poorly understood. Are they just lost in the solar wind? What fraction of them re-enter the magnetosphere? Moreover, what fraction of these re-entered particles are transported back to the inner magnetosphere? Furthermore, what are the impacts of the cold plasma on the global magnetospheric system? How much does the drainage plume reduce the dayside reconnection rate and thus the efficiency of energy coupling between the solar wind and the magnetosphere? How much does the mass loading effect from the plasmasphere influence the dynamics of the global magnetosphere?
Methodology:
A combination of global simulation and data analysis will be employed to address our science objectives. In this investigation, a multifluid MHD code (Block-Adaptive-Tree Solar-wind Roe-type Upwind Scheme [BATS-R-US]) combined with a comprehensive inner magnetosphere-ionosphere (CIMI) model will be our main modeling tool. A plasmasphere model has been embedded in the CIMI model. The plasmasphere model calculates spatiotemporal plasmaspheric density distribution considering corotation, convection, daytime refilling, and nightside diffusion. In this investigation, the refilling rate will be estimated by the SAMI3 (Sami3 is Also a Model of the Ionosphere) model. Critical to this investigation is the recent inclusion of a separate plasmasphere fluid in the multifluid BATS-R-US code. That fluid is filled from the CIMI code based on its embedded plasmasphere model. Outside the CIMI domain, the plasmasphere fluid continues to evolve based on the MHD calculation. We thus are able to follow the cold plasma from its source to the plasmasphere region and to the global magnetosphere. Our simulation results will be compared with observations. The main data sets that will be analyzed are the particle and field data from the NASA Van Allen Probes mission. The plasmasphere density can be inferred either from the upper hybrid wave frequency or from the spacecraft potential.
Relevance:
The proposed study is relevant to Focused Science Topic #2: Pathways of Cold Plasma through the Magnetosphere. The investigation directly addresses the Focused Science goals of understanding the sources, evolution, recirculation and impacts of the cold plasma in the magnetosphere. This investigation will improve our predictive capability of the temporal and spatial characteristics of the plasmasphere. Our investigation has significant space weather relevance since the plasmasphere region constitutes a safe haven for spacecraft surface charging. We will perform CIMI-BATS-R-US simulations for events selected by the Focused Science Team. We will also provide simulation support to the team as needed.
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