Dartmouth Events

Physics & Astronomy - Senior Honor Thesis-Tucker Evans, Dartmouth College

Title: "The Reconstruction of Auroral Zone Plasma Flow Fields and Associated Electric Fields Combining Ground-Based Observation and Multi-Point in Situ Measurements"

Friday, May 24, 2019
2:00pm – 3:00pm
Wilder 202
Intended Audience(s): Public
Categories: Lectures & Seminars

Abstract: The acquisition of in situ plasma flow and electric field data in the auroral zone is generally difficult, requiring expensive measurements. Once data have been collected, direct interpolation to a useful scale is often under-determined: data points are too widely dispersed in space. Three conditions are applied in order to make reconstruction of the plasma flow feasible: (1) plasma flow is primarily perpendicular to the magnetic field, (2) an auroral arc boundary indicates the direction of minimum variance for associated plasma flow, and (3) the plasma flow field is divergence free. Using these three assumptions we propose a flow reconstruction method using divergence-free functions derived from a one-dimensional vector potential. The variance of the flow along the arc boundary is simultaneously minimized with the difference of the reconstructed flow from the observed data. The result is applied to two missions, the ISINGLASS rocket campaign and the ARCS proposed mission concept. In both cases, in situ measurements of the flow are combined with all-sky camera data which provides the location of the auroral arc boundary. We test the performance of the method for a variety of example auroral arc structures using a fractional skill score technique (Roberts and Lean, 2008). This analysis shows that the application of the auroral arc boundary condition allows for reconstructions across large spatial gaps in the data with greater reliability than was previously feasible.

 

For more information, contact:
Tressena Manning
6036462854

Events are free and open to the public unless otherwise noted.