Auroral Acoustics Project Info

AURORA RELATED SOUNDS

(modified 24.5.2004/ page opened 9.10.2001 / ukl)

AURORAL ACOUSTICS - PROJECT IN SHORT

The work around the topic of aurora related sounds and auroral acoustics started spring 2000 at HUT. At the same time a co-operation with Sodankylä Geophysical Observatory started. The initiative to start these studies come from the Laboratory of Acoustics and Audio signal Processing at HUT. Later, researchers from Finnish Meteorological Institute have also co-operated in the project.

Main steps in the project:

Spring 2000 the design and test of portable measuring system
Spring 2000 collection of Finnish observations of aurora related sounds started (Oct. 2003 about 300 reports collected)
April 6.-7. 2000 first measurements of aurora related sounds with a non professional system (see ref [5] publications)
Summer 2000 first measurements by using high quality, low noise and highly sensitive microphone system
Fall 2000 first testing with very simple VLF receiver to be included in the measuring system
Winter 2000-2001 many measurements during aurora nights
April 11.-12. 2001 successful measurements at Koli (eastern part of Finland, see our old news dated Nov 12 2001)
August 2002 first international publication of measurements of aurora related sounds in Finland (see ref [4] publications)
Winter 2002-2003 collection of new data and analysis of the collected data continued
Fall 2003 analysis of data collected during the April 6-7 2000 geomagnetic storm
Spring 2004 some more auroral nights measurements - preparing a new international publication (see ref [5] publications)
Summer 2004 analysis of the data continues...

We have digitally recorded acoustic signals together with VLF signal during more than 60 nights (Oct. 2003). Each night generates 8-12 Gb data! We are still facing many methodological problems:
- how to analyze automatically the data
- how to compare and correlate the data with other simultaneous measurements
- how to select and preprocess the right features of the data
- how to finally find out those acoustical events possible produced by the geomagnetic storm
- ...

Thus we are still working with many complicated practical and methodological problems.

Dr. Robert Eather, a well known Norwegian aurora researcher mentioned in his book "Majestic Lights" ('Majestic Lights; the aurora in science, history and arts'. American Geophysical Union, Washington D.C. 1980. ISBN 0-87590-215-41980) that to proof that the aurora makes noise is not an easy scientific task. He seems to have right!

Our present status is that the collected and analyzed observations seems to speak for an objective phenomena. Our audio measurements have material which fits well the descriptions of the sounds. We have published the first, preliminary reports on the found high cross correlations between the variation of the audio range acoustic power and the geomagnetic activity (see ref [4] publications). We presently work for new and more detailed publications.

Go to: The MAIN PROJECT PAGE.