Global aspects of solar wind–ionosphere interactions

Moore, T. E.; Fok, M.‐C.; Delcourt, Dominique; Slinker, S. P.; Fedder, J. A.

doi:10.1016/j.jastp.2006.08.009

Cited by 29 publications

(33 citation statements)

References 26 publications

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“…Therefore, a lower density is chosen, so the density is better represented at distances of 5-6 R E in the equatorial plane. At high latitudes, there are a significant number of studies currently being conducted on the actual density, field-aligned flow velocities and/or particle fluxes at high altitudes (Gombosi and Nagy, 1989;Abe et al, 1993;Strangeway et al, 2000Strangeway et al, , 2005Moore et al, 2007;Yao et al, 2008;Nosé et al, 2009). Recently, Glocer et al (2009) implemented a coupling between BATSRUS and a Polar Wind Outflow Model that provided a more-realistic representation of the inner magnetospheric density and structure.…”

Section: Modeling the Magnetospherementioning

confidence: 99%

Numerical considerations in simulating the global magnetosphere

et al. 2010

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Abstract. Magnetohydrodynamic (MHD) models of the global magnetosphere are very good research tools for investigating the topology and dynamics of the near-Earth space environment. While these models have obvious limitations in regions that are not well described by the MHD equations, they can typically be used (or are used) to investigate the majority of magnetosphere. Often, a secondary consideration is overlooked by researchers when utilizing global models -the effects of solving the MHD equations on a grid, instead of analytically. Any discretization unavoidably introduces numerical artifacts that affect the solution to various degrees. This paper investigates some of the consequences of the numerical schemes and grids that are used to solve the MHD equations in the global magnetosphere. Specifically, the University of Michigan's MHD code is used to investigate the role of grid resolution, numerical schemes, limiters, inner magnetospheric density boundary conditions, and the artificial lowering of the speed of light on the strength of the ionospheric cross polar cap potential and the build up of the ring current in the inner magnetosphere. It is concluded that even with a very good solver and the highest affordable grid resolution, the inner magnetosphere is not grid converged. Artificially reducing the speed of light reduces the numerical diffusion that helps to achieve better agreement with data. It is further concluded that many numerical effects work nonlinearly to complicate the interpretation of the physics within the magnetosphere, and so simulation results should be scrutinized very carefully before a physical interpretation of the results is made. Our conclusions are not limited to the Michigan MHD code, but apply to all MHD models due to the limitations of computational resources.

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Section: Modeling the Magnetospherementioning

confidence: 99%

Numerical considerations in simulating the global magnetosphere

et al. 2010

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“…[6] We employ the same outflow condition for ionospheric H + and O + as in our previous studies [Moore et al, 2007]. Ions are released at both hemispheres at 1000 km altitude at latitudes greater than 60°.…”

Section: Ion Outflow From the Ionospherementioning

confidence: 99%

“…Ions are released at both hemispheres at 1000 km altitude at latitudes greater than 60°. The flux of the polar wind H + outflow depends on solar zenith angle (SZA) with much higher flux on the dayside than on the nightside [Su et al, 1998;Moore et al, 2007]:…”

Section: Ion Outflow From the Ionospherementioning

confidence: 99%

“…By analyzing data from the FAST and POLAR missions, it was suggested that two major energy sources are the electron precipitation and dissipation of downward Poynting flux Zheng et al, 2005]. We model the local O + outflow flux in the same way as Moore et al [2007]:…”

Section: Ion Outflow From the Ionospherementioning

confidence: 99%

“…[7] The thermal energy of the upwelling H + and O + is assumed to have a dependence on Poynting flux as [Moore et al, 2007] The parallel energy is assigned as the sum of thermal energy and parallel energy given from the auroral parallel potential drop, which is scaled with the upward parallel current density as [Lyons, 1981] …”

Section: Ion Outflow From the Ionospherementioning

confidence: 99%

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Modeling the superstorm in November 2003

et al. 2011

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[1] The superstorm on 20-21 November 2003 was the largest geomagnetic storm in solar cycle 23 as measured by Dst, which attained a minimum value of −422 nT. We have simulated this storm to understand how particles originating from the solar wind and ionosphere get access to the magnetosphere and how the subsequent transport and energization processes contribute to the buildup of the ring current. The global electromagnetic configuration and the solar wind H + distribution are specified by the Lyon-Fedder-Mobarry (LFM) magnetohydrodynamics model. The outflow of H + and O + ions from the ionosphere are also considered. Their trajectories in the magnetosphere are followed by a test-particle code. The particle distributions at the inner plasma sheet established by the LFM model and test-particle calculations are then used as boundary conditions for a ring current model. Our simulations reproduce the rapid decrease of Dst during the storm main phase and the fast initial phase of recovery. Shielding in the inner magnetosphere is established at early main phase. This shielding field lasts several hours and then breaks down at late main phase. At the peak of the storm, strong penetration of ions earthward to L shell of 1.5 is revealed in the simulation. It is surprising that O + is significant but not the dominant species in the ring current in our calculation for this major storm. It is very likely that substorm effects are not well represented in the models and O + energization is underestimated. Ring current simulation with O + energy density at the boundary set comparable to Geotail observations produces excellent agreement with the observed symH. As expected in superstorms, ring current O + is the dominant species over H + during the main to midrecovery phase of the storm.

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The two‐way relationship between ionospheric outflow and the ring current

et al. 2015

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It is now well established that the ionosphere, because it acts as a significant source of plasma, plays a critical role in ring current dynamics. However, because the ring current deposits energy into the ionosphere, the inverse may also be true: the ring current can play a critical role in the dynamics of ionospheric outflow. This study uses a set of coupled, first‐principles‐based numerical models to test the dependence of ionospheric outflow on ring current‐driven region 2 field‐aligned currents (FACs). A moderate magnetospheric storm event is modeled with the Space Weather Modeling Framework using a global MHD code (Block Adaptive Tree Solar wind Roe‐type Upwind Scheme, BATS‐R‐US), a polar wind model (Polar Wind Outflow Model), and a bounce‐averaged kinetic ring current model (ring current atmosphere interaction model with self‐consistent magnetic field, RAM‐SCB). Initially, each code is two‐way coupled to all others except for RAM‐SCB, which receives inputs from the other models but is not allowed to feed back pressure into the MHD model. The simulation is repeated with pressure coupling activated, which drives strong pressure gradients and region 2 FACs in BATS‐R‐US. It is found that the region 2 FACs increase heavy ion outflow by up to 6 times over the noncoupled results. The additional outflow further energizes the ring current, establishing an ionosphere‐magnetosphere mass feedback loop. This study further demonstrates that ionospheric outflow is not merely a plasma source for the magnetosphere but an integral part in the nonlinear ionosphere‐magnetosphere‐ring current system.

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Global aspects of solar wind–ionosphere interactions

Cited by 29 publications

References 26 publications

Numerical considerations in simulating the global magnetosphere

Numerical considerations in simulating the global magnetosphere

Modeling the superstorm in November 2003

The two‐way relationship between ionospheric outflow and the ring current

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