Investigating the viscous interaction and its role in generating the ionospheric potential during the Whole Heliosphere Interval

Bruntz, R.; López, Ramón; Bhattarai, Santosh; Pham, Kevin; Deng, Yue; Huang, Yanshi; Wiltberger, M. J.; Lyon, J. G.

doi:10.1016/j.jastp.2012.03.016

Cited by 8 publications

(17 citation statements)

References 30 publications

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“…Bruntz et al [] used the Lyon‐Fedder‐Mobarry (LFM) simulation [ Lyon et al , ] to study the viscous potential for various solar wind parameters during steady states and derived a quasi‐empirical formula to calculate the viscous potential using a constant ionospheric conductivity of 10 mhos, φ V =(0.00431) n 0.439 V 1.33 kV where n is the solar wind density in cm −3 and V is the magnitude of solar wind velocity in km/s. This formula obtained by Bruntz et al [] has also been seen to be in good agreement with the LFM simulation driven with real solar wind input for which solar wind was not “steady” [ Bruntz et al , ]. In this paper, we will use the results obtained from LFM simulation for purely northward IMF (i.e., without B x and B y IMF component) to show the reduction of viscous potential.…”

Section: Introductionsupporting

confidence: 72%

“…Hence, we chose the 16th hour into the simulation to evaluate our data for all runs to use a consistent time step and also to make sure that we were well within the steady state. The LFM simulation has been able to model different real magnetospheric events [ Lyon et al , ; Lopez et al , ; Bruntz et al , ; Lopez et al , ; Wiltberger et al , ] showing that the results obtained from the LFM simulation predict the real magnetosphere well.…”

Section: Introduction To the Lfm Simulationmentioning

confidence: 99%

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Reduction of viscous potential for northward interplanetary magnetic field as seen in the LFM simulation

Bhattarai

López

2013

JGR Space Physics

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[1] The two primary methods responsible for solar wind magnetosphere coupling are magnetic reconnection and the viscous interaction. The viscous interaction is generated due to the antisunward dragging of plasma inside the magnetopause by the plasma flowing in the magnetosheath, creating a return flow deeper inside the magnetosphere and producing a circulation pattern. This viscous circulation pattern is mapped into the ionosphere via magnetic field lines, which results in ionospheric electric field in the nonrotating Earth's frame. We measure this interaction in terms of an electric potential, the viscous potential. In this paper, we use the results obtained from the Lyon-Fedder-Mobarry (LFM) simulation model during periods of purely northward interplanetary magnetic field (IMF) for different solar wind velocity and ionospheric conductivity, showing a reduction of the viscous potential with increasing magnitude of northward IMF. The viscous potential is found to settle around 5-10 kV for large +B z values. The decrease in viscous potential was found to be associated with a weak or nonexistent sunward plasma flow in the nightside plasmasheet. Instead, the return flow to the dayside occurs at high latitudes and is associated with the reconnection topology and dynamics that occur during northward IMF periods. We also show that the magnetosphere remains closed during purely northward IMF, except for two small regions-one on each hemisphere, where the magnetic reconnection occur. We argue that the reduction of the viscous potential is due to a reduction of the velocity shear across the magnetopause and the lack of sunward convection in the equatorial tail.Citation: Bhattarai, S. K., and R. E. Lopez (2013), Reduction of viscous potential for northward interplanetary magnetic field as seen in the LFM simulation,

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Section: Introductionsupporting

confidence: 72%

Section: Introduction To the Lfm Simulationmentioning

confidence: 99%

Reduction of viscous potential for northward interplanetary magnetic field as seen in the LFM simulation

Bhattarai

López

2013

JGR Space Physics

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“…Both events were simulated for a constant ionospheric conductivity of 5 mhos. During both events we found that variation pattern of PCP was consistent with behavior of PCP observed in previous research by Bhattarai et al (), Lopez et al ( and ), Bruntz, Lopez, Bhattarai, et al, and Bruntz, Lopez, Wiltberger, & Lyon, ), and Mitchell et al (), although most of these previous works dealt with steady state IMF conditions.…”

Section: Discussionsupporting

confidence: 91%

“…Thus, the PCP obtained in this case is purely mechanical in nature, that is, solely due to dragging of magnetopause plasma due to velocity difference between the magnetopause and magnetosheath plasma, thus forming a convection pattern inside the magnetosphere which gets mapped to the ionosphere along magnetic field lines producing viscous potential (Bruntz et al, ). The value of viscous potential is seen to increase with increase in solar wind speed and density which has also been confirmed by various authors by analyzing in situ observation data (Boyle et al, ; Newell et al, ) as well as simulation models (Bruntz, Lopez, Bhattarai, et al, ; Sonnerup et al, ). BATS‐R‐US is seen to be more sensitive to density fluctuation compared to LFM, although PCP obtained from both of them are very close, which might be due to better resolution and/or different numerical solving schemes.…”

Section: Resultsmentioning

confidence: 99%

“…Viscous interaction occurs due to velocity shear between magnetosheath and magnetopause plasma which gets mapped to the polar cap via magnetic field lines, thus creating viscous potential. Various authors have studied variation of viscous potential using in situ measurements as well as simulations (Axford & Hines, ; Boyle et al, ; Bruntz, Lopez, Bhattarai, et al, ; Reiff et al, ; Sonnerup et al, ). Bruntz, Lopez, Wiltberger, et al, () performed Lyon‐Fedder‐Mobarry (LFM) simulation (Lyon et al, ) to study viscous potential and derived a quasi‐empirical formula to calculate viscous potential for various solar parameters during steady states for a constant ionospheric conductivity of 10 mhos: ∅ V = (0.00431) n 0.439 V 1.33 ( kV ), where “ n ” is the solar wind density (/cm 3 ) and “ V ” is the solar wind velocity (km/s).…”

Section: Introductionmentioning

confidence: 99%

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Study of Variation of Polar Cap Potential During Geomagnetic Storm Events of 24 November 2001 and 24 August 2005 as Observed From LFM and BATS‐R‐US Simulation

Paudel

Bhattarai

Ghimire

et al. 2019

Earth and Space Science

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In this paper we examine variation of polar cap potential (PCP) during two storm events that occurred on 24 November 2001 and 24 August 2005 using Lyon‐Fedder‐Mobarry (LFM) and Block‐Adaptive‐Tree‐Solarwind_Roe‐Upwind‐Scheme (BATS‐R‐US) simulations and compare it to Weimer model. These events were simulated for zero, pure By, pure Bz, and full IMF conditions separately, and the PCP obtained were compared with the zero IMF PCP value as a baseline (viscous) potential. For southward IMF, PCP is defined as sum of reconnection and viscous, whereas for northward IMF, it is peak to peak potential, which either will be viscous potential or reconnection potential, whichever is larger. Both events were simulated for a constant ionospheric conductivity of 5 mhos and the variation of PCP was found to be consistent with previous literatures. Furthermore, we found that BATS‐R‐US PCP fluctuated similar to LFM PCP for most parts although their PCP values did not exactly match. We observed that BATS‐R‐US PCP also goes below viscous value for northward IMF condition, something which was observed previously in LFM simulation only. We also found that BATS‐R‐US PCP is more sensitive to smaller fluctuation of IMF compared to LFM. For 24 August 2005 event, we found the PCP reach up to 550 and 440 kV and the viscous potential reached up to 120 and 110 kV for BATS‐R‐US and LFM, respectively. Similarly, for 24 November 2001 event PCP reached up to 800 and 400 kV and viscous potential reached up to 300 and 200 kV, respectively, for BATS‐R‐US and LFM.

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Linear separation of orthogonal merging component and viscous interactions in solar wind‐geospace coupling

2014

Self Cite

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The general view is that the response of the magnetosphere-ionosphere system to a complex, variable solar wind input will be a complicated and nonlinear function of that input. We investigate this question using a global MHD code to simulate the interaction and determine the responses of the system to isolated aspects of the solar wind input. We present evidence from the simulations that the solar wind-geospace interaction can be linearly decomposed into component merging interactions for interplanetary magnetic field (IMF) B y separate from B z and a separate viscous interaction. One can run the global simulation (in our case, the Lyon-Fedder-Mobarry code) using just the solar wind plasma and B z time series, do a second simulation using just the solar wind plasma and B y time series, add the results of the two simulation outputs, then subtract the output from a simulation done with only the plasma input and no magnetic field, since the sum of the B y and B z runs has two viscous interactions (one for each run), and get an output that is very close to the result of a single run using the entire IMF merging field (B y and B z ) along with the plasma time series. This demonstrates that the components of merging and viscous interactions between the solar wind and geospace are linearly separable to a very large degree.

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Investigating the viscous interaction and its role in generating the ionospheric potential during the Whole Heliosphere Interval

Cited by 8 publications

References 30 publications

Reduction of viscous potential for northward interplanetary magnetic field as seen in the LFM simulation

Reduction of viscous potential for northward interplanetary magnetic field as seen in the LFM simulation

Study of Variation of Polar Cap Potential During Geomagnetic Storm Events of 24 November 2001 and 24 August 2005 as Observed From LFM and BATS‐R‐US Simulation

Linear separation of orthogonal merging component and viscous interactions in solar wind‐geospace coupling

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