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Telescopic imaging of streamer and d...

Gerken, Elizabeth Anna.

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Telescopic imaging of streamer and diffuse glow dynamics in sprites.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Telescopic imaging of streamer and diffuse glow dynamics in sprites./
Author:	Gerken, Elizabeth Anna.
Description:	114 p.
Notes:	Source: Dissertation Abstracts International, Volume: 64-10, Section: B, page: 5117.
Contained By:	Dissertation Abstracts International64-10B.
Subject:	Engineering, Electronics and Electrical. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3108863
ISBN:	0496564080

Telescopic imaging of streamer and diffuse glow dynamics in sprites.
Gerken, Elizabeth Anna.

Telescopic imaging of streamer and diffuse glow dynamics in sprites. - 114 p.

Source: Dissertation Abstracts International, Volume: 64-10, Section: B, page: 5117.

Thesis (Ph.D.)--Stanford University, 2003.

Telescopic imaging reveals that decameter-scale fine structures in luminous lightning-related discharges at high altitudes above thunderclouds (known as "sprites") exhibit a wide range of morphologies and time scales. Hundreds of sprites have been observed by the Stanford University telescopic imager with a field of view of &sim;1 degree, allowing the measurement of spatial scales of optical features as low as &sim;10 m. Categories of observed structures include upward and downward branching, beading, propagating diffuse glow striations, transition regions between diffuse glow regions and highly structured shapes which are referred to as streamers. The telescopic imaging system used consisted of a &sim;41 cm diameter, f/4.5 Dobsonian-mounted Newtonian reflecting telescope with an intensified CCD camera attached to its eyepiece and a bore-sighted wide field of view (FOV) camera mounted on its top. Both telescopic and wide field of view photometers were also used in some observations. The FOV of the telescope (0.5 inch CCD) was &sim;0.7 by &sim;0.92 degrees while that of the bore-sighted camera (.33 inch CCD, 50 mm lens, f/1.4) was &sim;9 by &sim;12 degrees. The telescopic imaging system was deployed either in New Mexico or Colorado during the summers of 1998--2000. Electromagnetic signatures of causative lightning discharges, known as radio atmospherics (or sferics), were recorded simultaneously using crossed-loop magnetic antennas and ELF/VLF receivers located at Stanford and in Colorado. Telescopic images indicate that sprite structure can assume a wide variety of shapes, sizes, and time scales, but that certain structures appear repeatedly including beading, faint downward branching, bright upward branching, propagating diffuse glows, and columnar formations. A transition region between streamer formation and diffuse glow is typically observed at &sim;80 km altitude. Quantitative estimates of electrical charge moment (product of charge removed and height) in causative lightning discharges and exponential decay constants of sprite brightness are used to distinguish between diffuse glow and streamer mechanisms in a two-storm case study. Results indicate that storm geometry (e.g., the area the storm covers and cloud heights) plays a large role in the types of sprites produced.

ISBN: 0496564080Subjects--Topical Terms:

626636
Engineering, Electronics and Electrical.

Telescopic imaging of streamer and diffuse glow dynamics in sprites.
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100 1 $a Gerken, Elizabeth Anna. $3 1932243
245 1 0 $a Telescopic imaging of streamer and diffuse glow dynamics in sprites.
300 $a 114 p.
500 $a Source: Dissertation Abstracts International, Volume: 64-10, Section: B, page: 5117.
500 $a Adviser: Umran Inan.
502 $a Thesis (Ph.D.)--Stanford University, 2003.
520 $a Telescopic imaging reveals that decameter-scale fine structures in luminous lightning-related discharges at high altitudes above thunderclouds (known as "sprites") exhibit a wide range of morphologies and time scales. Hundreds of sprites have been observed by the Stanford University telescopic imager with a field of view of &sim;1 degree, allowing the measurement of spatial scales of optical features as low as &sim;10 m. Categories of observed structures include upward and downward branching, beading, propagating diffuse glow striations, transition regions between diffuse glow regions and highly structured shapes which are referred to as streamers. The telescopic imaging system used consisted of a &sim;41 cm diameter, f/4.5 Dobsonian-mounted Newtonian reflecting telescope with an intensified CCD camera attached to its eyepiece and a bore-sighted wide field of view (FOV) camera mounted on its top. Both telescopic and wide field of view photometers were also used in some observations. The FOV of the telescope (0.5 inch CCD) was &sim;0.7 by &sim;0.92 degrees while that of the bore-sighted camera (.33 inch CCD, 50 mm lens, f/1.4) was &sim;9 by &sim;12 degrees. The telescopic imaging system was deployed either in New Mexico or Colorado during the summers of 1998--2000. Electromagnetic signatures of causative lightning discharges, known as radio atmospherics (or sferics), were recorded simultaneously using crossed-loop magnetic antennas and ELF/VLF receivers located at Stanford and in Colorado. Telescopic images indicate that sprite structure can assume a wide variety of shapes, sizes, and time scales, but that certain structures appear repeatedly including beading, faint downward branching, bright upward branching, propagating diffuse glows, and columnar formations. A transition region between streamer formation and diffuse glow is typically observed at &sim;80 km altitude. Quantitative estimates of electrical charge moment (product of charge removed and height) in causative lightning discharges and exponential decay constants of sprite brightness are used to distinguish between diffuse glow and streamer mechanisms in a two-storm case study. Results indicate that storm geometry (e.g., the area the storm covers and cloud heights) plays a large role in the types of sprites produced.
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