2003-2004 USAP Field Season

Aeronomy & Astrophysics

Dr. Vladimir Papitashvili
Program Manager

A-136-S

NSF/OPP 01-32576
Station: South Pole Station
RPSC POC: Charles Kaminski
Research Site(s): South Pole Station
Dates in Antarctica: Mid December to mid January
Measurement and analysis of extremely-low-frequency (ELF) waves at South Pole Station
Dr. Marc R. Lessard
Dartmouth College
Thayer School of Engineering
marc.lessard@dartmouth.edu
 
ELF magnetic sensor coil, receiver, and the data acquisition system. Inside the receiver (inset). Photo by Hyomin Kim.
Deploying Team Members: Hyomin Kim . Marc R. Lessard . Paul Riley
Research Objectives: This project aims to detect and record magnetic field fluctuations in the extremely-low-frequency (ELF) range at South Pole Station, specifically auroral ion cyclotron waves, which have been well correlated with flickering aurora. Theory predicts that these waves modulate precipitating electron fluxes, thereby causing the flickering in luminosity emissions. Substantial evidence now supports this theory, although the excitation mechanism responsible for the ion cyclotron waves is somewhat uncertain. Perhaps the most well-developed theory suggests that the waves result from an electron-beam instability. In any case, the frequency of the flickering or, equivalently, the frequency of the ground-based observations of ion cyclotron waves can be used to infer the altitude of the excitation mechanism, since the wave frequency depends on the strength of the background magnetic field, which is a known quantity. As such, the information that will be acquired can be used to test models of auroral acceleration mechanisms, as well as study dispersive ELF waves, a type of wave that has been reported in the literature only a few times, but one that may provide important information on substorm onset or, perhaps, the boundaries of open and closed magnetic fields.

A first step is to identify the wave mode and to determine the location and geomagnetic conditions under which these waves can be observed. The equipment used to make these observations consists of an induction coil magnetometer and data acquisition system. The induction coil is a commercially available device, one that was originally designed for geophysical exploration. Data will be returned to Dartmouth College for analysis.