Meteor Infrasound

The Norwegian Fireball of June 7th, 2006

Short Range Infrasound

 

 

As the closest infrasonic (sub-acoustic frequencies <20 Hz) instruments to the event the airwaves produced by the fireball were particularly strong. At the closest station Kiruna the signal is so large in amplitude that it saturated the instrument and so the initial part of the observation is clipped. The same is the case for the largest amplitude portions at Jamton and Lycksele as well. Three distinct pulses are clearly visible as they propagate across the length of Sweden . Each of the instruments consist of three separate field microphones separated by 75m. Cross correlating the signals as recorded by all three microphones (beamforming) allows the direction from which the sound came from to be determined. Intersections of these projected directions can be used to estimate the position of the sounds source, the June 7^th, 2006 Norwegian Fireball.

 

Beamforming Azimuths (degrees measured East from North)

 

Kiruna:

45 deg. (clipped portion of signal)

23.9 – 31.7 deg (unclipped portion of signal)

Jamton:

                        1.74 – 353.6 deg.

 

Lycksele:

                        14.63 – 17.93 deg.

 

Uppsala :

                        9.1 – 9.97 deg.

 

Research Activities