Daylight bolide on 2003, May 31
Läslo Evers
A bolide was observed during the early evening of 2003, May 31. Some
observations were reported; the notification of
Theo Jurriens is
acknowledged. Figure 1 shows recordings of
infrasound in the De Bilt
Infrasound Array (DBN). A waveform
from a blast wave can clearly be identified and arrives at 18h46m21s GMT.
The energy arrives from 315 deg with respect to the North.
Figure 1: Recordings of the 6
KNMI microbarometers
of DBN. The arrival time
of the blast wave is 18h46m21s GMT on 2003, May 31.
Infrasound was also observed in the Deelen Infrasound Array
(DIA). Figure 2 shows
the best beam in red and the time aligned signals in blue. The best
beam is the sum of the time aligned recordings. The blast wave has
been distorted through scattering in the atmosphere.
Figure 2: The time aligned recordings of the 16 microbarometers of
DIA in blue. The best beam is shown in red. The distorted blast wave
arrives in DIA at 18h48m03s GMT.
The energy arrives in DIA with a back azimuth of 303 degrees. In Figure
3 the location of the bolide is given as obtained by cross bearing.
Figure 3: Cross bearing the back azimuths as observed in DBN and DIA.
Infrasound was not detected in the Witteveen Infrasound Array
(WIT). The explanation follows
from Figure 4. Raytracing through atmospheric models from ECMWF
reveals that WIT was located in the shadow zone.
Figure 4: Atmospheric trajectories for the bolide's infrasound assuming
a source height of 40 km. WIT is located in the shadow zone.
For comparison, rays are also shot towards DBN from the bolide's location.
It follows from Figure 5 that the infrasound reaches DBN, as observed.
Figure 5: Ray paths for the direction of DBN.
May 2003
Läslo Evers