MICROBURST PHENOMENA. I. AURORAL ZONE X-RAYS

• Main Authors: Oliven,N. M., Venkatesan,D., Edwards,P. J., McCracken,K. G., Steinbock,M.
• Other Authors: IOWA UNIV IOWA CITY DEPT OF PHYSICS AND ASTRONOMY
• Format: Text
• Language: English
• Published: 1967
• Subjects: Atmospheric Physics; (*X RAYS; POLAR REGIONS); CANADA; BREMSSTRAHLUNG; BALLOONS; ATMOSPHERIC SOUNDING; UPPER ATMOSPHERE; ELECTRONS; GEOMAGNETISM; AURORAE; RADIATION MEASURING INSTRUMENTS; MAGNETOSPHERE; Canada; Churchill
• Online Access: http://www.dtic.mil/docs/citations/AD0660196; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0660196

High-time resolution x-ray equipment flown from Ft. Churchill, Manitoba, Canada on August 11, 1965 provides evidence for species of auroral zone x-ray microbursts with an asymmetric time profile. These asymmetric microbursts are characterized by a rise of the form 1 - e to the power (-t/tau sub R) where tau sub R is about 30 milliseconds, and a decay of the form of e to the power (-t/tau sub D) where tau sub D is about 200 milliseconds, and a typical peak flux for the largest events of Jo (Ex-ray > 60 keV) of about 100 photons/cm squared sec at 10 g/sq. cm. An episode of these asymmetric bursts was observed in the early morning hours (after 4:30 local time) and an episode of the more common symmetric microbursts began after 9:30 local time. The fast rise times, and the lack of dispersion approximately = or > 10 milliseconds in the x-ray bursts observed at different energies implies restrictions on the nature, and propagation of the parent electron microbursts. (Author) Prepared in cooperation with Calgary Univ. (Alberta), and Southwest Center for Advanced STUDIES( Dallas, Tex., Contract NASr-198.