Physics Dept. Seminar-FR

Event Details:

Dr. Jim Labelle, Department of Physics, Dartmouth College, USA, will discuss, "Auroral hiss and kilometric radiation at South Pole Station."

"South Pole station is ideally suited to see auroral radio emissions which are of four main types: cyclotron harmonic radiation, medium-frequency bursts, auroral hiss, and auroral kilometric radiation (AKR). Incidentally these emissions should also be observable at the magnetically conjugate point near Qikiqtarjuaq where we hope to initiate observations soon in collaboration with UNB; there has been little investigation of magnetic conjugacy of these phenomena, except for auroral hiss at very low frequencies. In this talk I review recent discoveries related to two of these phenomena, hiss and AKR. Analysis of >100 auroral hiss events observed at South Pole in 2019 reveals examples of "flickering hiss," modulated at ~100 Hz. Frequency dispersion of the modulations allows the source height to be determined and provides an experimental test of the source mechanism, believed to be electron acceleration by ion cyclotron waves at several thousand kilometers altitude. Analysis of scores of AKR observations at South Pole and the Cluster satellites during conjunctions reveals a few examples of similar or identical fine structure between these widely separated measurements. These observations point toward a mechanism whereby wave excitations in close proximity in the auroral acceleration region simultaneously produce upgoing ("escaping") and downgoing ("leaked") AKR. Initiation of conjugate observations at South Pole and Qikiqtarjuaq will allow the first-ever conjugate studies of these and other auroral radio emissions."
 
NOTE: This is an in-person event and will not be video conferenced, in person attendance only. 
 

Building: Science Library

Room Number: 107