Dartmouth Events

Physics and Astronomy Space Plasma Seminer - Sarah McGregor, Boston University

Title: "Modeling Magnetospheric Response to Synthetic Alfvenic Fluctuations in the Solar Wind"

Tuesday, September 24, 2013
Wilder 111
Intended Audience(s): Public
Categories: Lectures & Seminars

Abstract:  Large amplitude fluctuations of the z-component of the magnetic field from Alfven waves within the solar wind Corotating Interacting Regions (CIRs) and High Speed Streams (HSS) are thought to cause the associated moderate-weak activity within geospace seen during CIRs.  These small scale fluctuations are important for driving magnetospheric phenomena but are not currently included in solar wind model outputs. As a first step towards including them, we impose simple Alfvenic fluctuations on predicted solar wind parameters.  We then investigate the role that the Alfvenic fluctuations play in magnetospheric activity by driving the LFM magnetospheric code with WSA-Enlil predicted solar wind parameters with and without the synthetic Alfvenic fluctuations (sAf). In particular we investigate the ULF wave power and plasmoid evolution in the magnetosphere.  We find that there is a definite increase in ULF wave power in the dayside magnetosphere and along the flanks when driven by sAf.  Increase in dayside ULF wave power is caused by dynamic pressure variations that accompany Alfven like fluctuations, while the ULF wave power on the flanks is an enhancement of KH instability already present. We find that plasmoid evolution, initiation, and release are all affected by the sAf, allowing for more plasmoids during Bz northward, and larger, longer and more evolved plasmoids during Bz southward. 

For more information, contact:
Tressena Manning

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