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Two Classes of Auroral Infrasound at I53US. By Charles R. Wilson, John V. Wilson, Curt Szuberla and Daniel L.Osborne, Geophysical Institute, University of Alaska, Fairbanks AK. Huge AIW Bow Wave signal at I53US at 15:49 UT, 04/14/03 during magnetic storm. - PowerPoint PPT Presentation
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Two Classes of Auroral Infrasound at I53US
By Charles R. Wilson, John V. Wilson, Curt Szuberla and Daniel L.Osborne,
Geophysical Institute, University of Alaska, Fairbanks AK
Huge AIW Bow Wave signal at I53US at15:49 UT, 04/14/03 during magnetic storm
Trace velocity = 0.602 km/s, Az = 276 deg, Cij = 0.916
Uncertainty in Vel and Theta for AIW at I53US April 14,2003,(Dr.Curt Szuberla)
Uncertainty Ellipse in Velocity Space
Vel = 614 m/sec +/- 60 m/sec
Azimuth = 276.5 +/- 5.8 deg.
Three component Magnetometer traces at Fairbanks April 14, 2003 Strong magnetic bay at 12:00 to 16:00 UT
Time of Huge AIW
All-SKY camera images at 30 second intervals at Fairbanks
AIW – Bow wave at 09:59 UT
Zenith crossingAt 09:51 UT
Bow Wave model for AIW signals fromsupersonic aurora electrojet arcs
Auroral Oval
Direction of supersonic motion of Source auroral arcs for AIW as aFunction of UT time
Azimuths of arrival ofAIW at each hour of UT at I53US
(I53US)
Inuvik N.W.T.
April 14,2003 auroral infrasound event of AIW Bow-Wave Type
MCCM
Tracevelocity
Azimuth ofarrival
AIW signals
Vel = 1.03 km/sAZ = 347 deg.
Vel = 0.875AZ = 316
Vel = 0.643AZ = 283
Vel = 0.871AZ = 280
April 14, 2003 AIW associated with auroral-electrojet supersonic motions
Azimuth versusTrace velocityIn meters/secAIW Bow Wave Signals
Mean trace velocity for Bow Wave AIW Signals is = 0.865 km/sec
New Type of Pulsating Aurora AIW
• Pulsating Aurora
• An Example of a Typical All Sky TV Camera Capture of Pulsating Aurora. Image Circle Is About 160 Degrees Edge to Edge (fisheye lens). Images are played in real speed, at 15 fps, the B&W image utilizes all visible light.
Pulsating Aurora from GI/UA’s Ester Dome Observatory
West East
North
Three images of pulsatingAurora patches above I53US On March 6, 2003 , images takenAt 20 second intervals at 12:25 to 12:26 UT
I53US Pulsating Aurora Infrasound March 06, 2003, 12:25 to 12:43 UT
Vel = 1.213 Az = 144 deg
Peak-to-peak amplitude = 0.3 Pascal
abs(fft) March 6 P-AIW signal
44.8 sec
32.2 sec
20.8 sec
Vel = 1.517 km/secAz = 202 deg.
P-AIW from March 06, 2003 at I53US 16:00 to 16:20 UT
MCCM detector output for March 6, 2003at I53US showing both MAW from 180 deg
and high velocity P-AIW signals from all azimuths
MAWsignals
High VelocityP-AIW signals
MAW signals
MCCM
Velocity
Azimuth
NorthSouth
East
West
MAW at I53US 03/06/2003 20:00 to 20:20 UT
March 6,2003, 20:00 to 20:20 UT
Simultaneous MAW EventVelocity = 0.497 km/sec, Az = 181
Trace velocitym/sec versusAzimuth for MAW And for high velocityP-AIW signals 06/03/2003
MAW
P-AIWP-AIW
Other high velocity infrasound putative pulsating aurora events
• Two examples, on Dec 15 and 25, 2002 at I53US,of infrasonic signals during magnetic storm/auroral events with the same signal characteristics of very high trace velocity, widely scattered azimuth of arrival, and similar spectra. There was no photographic aurora data available of visible pulsating auroral patches during these two events.
Phase-aligned 0verlayAll 8 sensors
15 December
abs(fft) Dec 15 P-AIW signal
41.5 sec
31.2 sec
25.4 sec
17.5 sec
Uncertainty in Velocity and Azimuth for highvelocity auroral infrasound event Dec 15,2002
Vel = 2.941 km/sec +/- 0.938 km/sec
Azimuth = 130 +/- 17 deg.Uncertainty Ellipse in Velocity Space
MCCM
Trace VelocityKm/sec
Azimuth
NorthSouth
West
East
Phase-Aligned Pulsating Aurora Infrasound I53US 12/15/02twenty minutes of data at 12,15,18 and 21 hours UT
Vel =3.35 km/sec
Vel = 5.26 km/s
Vel = 1.48 km/s
Vel =1.00 km/s
Az =127
Az = 171
Az = 229
Az = 129
Auroral Infrasound signal azimuths observed at PullmanWashington, Boulder Colorado and Washington DCThousands of kilometers away from the source region