Event Title

Modeling the Interaction Between Convection and Cusp Outflows

Location

Yosemite National Park

Start Date

2-12-2014 6:10 PM

End Date

2-12-2014 6:25 PM

Description

The cusp/cleft ion fountain is a significant source of ion outflow coming from the dayside polar ionosphere. The conic ion distributions observed in this region indicate that these outflows involve transverse acceleration mechanisms that are challenging to model from first principles. Empirical relationships between magnetospheric inputs and the observed outflows are available, but these local relationships ignore any dependence of the outflows on the largescale state of the ionosphere. The convection pattern determines the time a flux tube dwells in the cusp, and thus the time it is exposed to Joule heating, soft precipitation, and wave-particle heating. The convection also determines the centrifugal forces. We examine the interplay between these various processes using a polar wind model that includes a phenomenological treatment of transversely accelerated ions (TAIs) in the cusp. The TAIs are included as an extra fluid that obeys transport equations appropriate for a conic distribution. This model can be driven by inputs from the Coupled Magnetosphere Ionosphere Thermosphere (CMIT) model. We compare runs with identical precipitation and transverse heating inputs but with the high-latitude potentials scaled up and down. The characteristics of the modeled ion fountains are compared in terms of morphology, ion velocities and energies achieved, and ion fluxes.

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Feb 12th, 6:10 PM Feb 12th, 6:25 PM

Modeling the Interaction Between Convection and Cusp Outflows

Yosemite National Park

The cusp/cleft ion fountain is a significant source of ion outflow coming from the dayside polar ionosphere. The conic ion distributions observed in this region indicate that these outflows involve transverse acceleration mechanisms that are challenging to model from first principles. Empirical relationships between magnetospheric inputs and the observed outflows are available, but these local relationships ignore any dependence of the outflows on the largescale state of the ionosphere. The convection pattern determines the time a flux tube dwells in the cusp, and thus the time it is exposed to Joule heating, soft precipitation, and wave-particle heating. The convection also determines the centrifugal forces. We examine the interplay between these various processes using a polar wind model that includes a phenomenological treatment of transversely accelerated ions (TAIs) in the cusp. The TAIs are included as an extra fluid that obeys transport equations appropriate for a conic distribution. This model can be driven by inputs from the Coupled Magnetosphere Ionosphere Thermosphere (CMIT) model. We compare runs with identical precipitation and transverse heating inputs but with the high-latitude potentials scaled up and down. The characteristics of the modeled ion fountains are compared in terms of morphology, ion velocities and energies achieved, and ion fluxes.