English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We construct a simple model of the plasma flow,\udmagnetosphere-ionosphere coupling currents, and auroral precipitation in\udJupiter's magnetosphere, and examine how they respond to compressions and\udexpansions of the system induced by changes in solar wind dynamic pressure.\udThe main simplifying assumption is axi-symmetry, the system being modelled\udprincipally to reflect dayside conditions. The model thus describes three\udmagnetospheric regions, namely the middle and outer magnetosphere on closed\udmagnetic field lines bounded by the magnetopause, together with a region of\udopen field lines mapping to the tail. The calculations assume that the\udsystem is initially in a state of steady diffusive outflow of iogenic plasma\udwith a particular equatorial magnetopause radius, and that the magnetopause\udthen moves rapidly in or out due to a change in the solar wind dynamic\udpressure. If the change is sufficiently rapid (~2–3 h or less) the\udplasma angular momentum is conserved during the excursion, allowing the\udmodified plasma angular velocity to be calculated from the radial\uddisplacement of the field lines, together with the modified\udmagnetosphere-ionosphere coupling currents and auroral precipitation. The\udproperties of these transient states are compared with those of the steady\udstates to which they revert over intervals of ~1–2 days. Results\udare shown for rapid compressions of the system from an initially expanded\udstate typical of a solar wind rarefaction region, illustrating the reduction\udin total precipitating electron power that occurs for modest compressions,\udfollowed by partial recovery in the emergent steady state. For major\udcompressions, however, typical of the onset of a solar wind compression\udregion, a brightened transient state occurs in which super-rotation is\udinduced on closed field lines, resulting in a reversal in sense of the usual\udmagnetosphere-ionosphere coupling current system. Current system reversal\udresults in accelerated auroral electron precipitation occurring in the outer\udmagnetosphere region rather than in the middle magnetosphere as is usual,\udwith peak energy fluxes occurring just poleward of the boundary between the\udouter and middle magnetosphere. Plasma sub-corotation is then re-established\udas steady-state conditions re-emerge, together with the usual sense of flow\udof the closed field current system and renewed but weakened accelerated\udelectron precipitation in the middle magnetosphere. Results for rapid\udexpansions of the system from an initially compressed state typical of a\udsolar wind compression region are also shown, illustrating the enhancement\udin precipitating electron power that occurs in the transient state, followed\udby partial reduction as steady conditions re-emerge

annales geophysicae

Modulation of Jupiter's plasma flow, polar currents, and auroral precipitation by solar wind-induced compressions and expansions of the magnetosphere: a simple theoretical model