Internal reconnection for northward interplanetary magnetic field

Watanabe, Masakazu; Кабин, К.; Sofko, G. J.; Rankin, R.; Gombosi, T. I.; Ridley, A. J.; Clauer, C. R.

doi:10.1029/2004ja010832

Cited by 38 publications

(104 citation statements)

References 26 publications

(72 reference statements)

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“…The dawn-side convection cell, however, is centered on regions with closed field lines. This circulation on closed field lines suggests that it is a "reciprocal" cell and that part of the reconnection driving it is between winter lobe field lines and over-draped summer lobe field lines [Crooker, 1992;Watanabe et al, 2005Watanabe et al, , 2006.…”

Section: Polar Cap Boundaries Observed By Dmspmentioning

confidence: 99%

“…These over-draped field lines then merge with lobe field lines in the winter hemisphere through a process called "internal reconnection" [Crooker, 1992]. Watanabe et al [2005] predicted different geometric features for the reverse convection cells in the summer and winter hemisphere, as well as different particle precipitation features. In the summer hemisphere, where lobe field lines directly merge with the IMF, the traditional round NBZ cells called "lobe cells" form which circulate on open field lines.…”

Section: Introductionmentioning

confidence: 99%

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Interhemispheric observations of dayside convection under northward IMF

et al. 2011

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[1] The reverse convection potential and electric field under northward interplanetary magnetic field (IMF) has been shown to saturate at a larger value in the summer than in the winter. Previous studies of reverse convection under northward IMF have suggested that in the winter hemisphere, much of the reconnection involves "internal reconnection" with over-draped field lines from the summer hemisphere. We present a case study in which reverse convection was simultaneously visible in the northern and southern hemispheres near the northern winter solstice. We use SuperDARN radar velocity measurements to demonstrate that the sunward (reverse) convection along the noon meridian is significantly faster in the summer hemisphere. We also use DMSP energetic particle data to demonstrate that in the winter hemisphere, some of the convection circulates on closed field lines, which is a signature of internal reconnection. These results suggest that internal reconnection is much less effective in transmitting the interplanetary electric field (IEF) into the ionosphere.

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Section: Polar Cap Boundaries Observed By Dmspmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Interhemispheric observations of dayside convection under northward IMF

et al. 2011

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“…The University of Michigan's MHD code is the Block Adaptive Tree Solar-wind Roe-type Upwind Scheme (BAT-SRUS) (Powell et al, 1999b;Ridley et al, 2002; that can model the Earth's global magnetosphere (Kabin et al, 2003Vogt et al, 2004;Ridley et al, 2006;Watanabe et al, 2005;Ridley, 2007;, as well as the solar corona (Manchester et al, 2004b), the inner and outer heliosphere (Opher et al, 2003;Manchester et al, 2004c,a), Mercury (Kabin et al, 2000), Venus, Mars (Ma et al, 2004), Jupiter (Kabin et al, 2001), Saturn (Hansen et al, 2000(Hansen et al, , 2005, Uranus , Titan (Ma et al, 2009), andcomets (Gombosi et al, 1999). Because BATSRUS is a general MHD solver, and is not explicitly designed for solving a specific problem, it has many more options than typical magnetospheric MHD codes.…”

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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“… Watanabe et al [2004] further analyzed the consequences of reconnection between open and closed fields in the MHD model of Tanaka [1999] and, subsequently, in a model developed at the University of Michigan for northward IMF at solstice [ Watanabe et al , 2005]. In both papers, Watanabe et al [2004, 2005] use conceptual models to explain how reconnection between open and closed fields affects a transport of open flux. In subsequent work, Watanabe et al [2007] and Watanabe and Sofko [2008] develop these conceptual models in a rigorous way, substantially building upon a long history of null‐separator and current‐penetration models [e.g., Cowley , 1973; Alekseyev and Belen'kaya , 1983; Siscoe , 1988; Crooker et al , 1990; Siscoe et al , 2001], to demonstrate how interchange reconnection, although not by that name, fits into the larger context of familiar reconnection geometries.…”

Section: Introductionmentioning

confidence: 99%

Solar concept of flux transport by interchange reconnection applied to the magnetosphere

Merkin

Crooker

2008

J. Geophys. Res.

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[1] The traditional concept of steady state convection of magnetic field-line foot points in Earth's ionosphere driven by reconnection between the interplanetary and geomagnetic fields implies that those foot points follow closed contours of circulation. Remote reconnection that occurs when the foot points cross the polar cap boundary controls whether the field lines are open or closed, but the foot points remain firmly rooted to their paths around the closed circulation cells. In steady state MHD models, however, this concept of convection breaks down owing to interchange reconnection between open and closed field lines. In the solar heliospheric community, interchange reconnection has long been understood as a means of flux transport. In the magnetosphere, flux transport by interchange reconnection causes field-line foot points to jump, or saltate, from one side of the polar cap to the other as part of the steady state circulation. We develop a definitive method for identifying interchange reconnection in an MHD model and illustrate the resultant foot point saltation.Citation: Merkin, V. G., and N. U. Crooker (2008), Solar concept of flux transport by interchange reconnection applied to the magnetosphere,

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Internal reconnection for northward interplanetary magnetic field

Cited by 38 publications

References 26 publications

Interhemispheric observations of dayside convection under northward IMF

Interhemispheric observations of dayside convection under northward IMF

Numerical considerations in simulating the global magnetosphere

Solar concept of flux transport by interchange reconnection applied to the magnetosphere

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