-- All-sky imager schematic -- Map of South American Sites -- Data Archives |
BU operates two all-sky imaging systems in South America to conduct coordinated research on topics of thermospheric dynamics and ionospheric plasma instabilities. As part of the NSFs MISETA Program (Multi-Instrumented Studies of Equatorial Thermospheric Aeronomy), an optical observatory in Arequipa, Peru houses an all-sky camera (BU) and a Fabry-Perot Interferometer (FPI) operated by Clemson University and the University of Pittsburgh. We use the imaging systems in Peru and Argentina to investigate the latitude dependence of several phenomena that occur in regions near the Earth's magnetic equator. Central to these issues is a remarkably complex instability that occurs in the ionosphere (near 300 km altitude). It has the awful name "Equatorial Spread-F" or ESF, awful in the sense that its name does not convey its meaning. Basically it arises from a small ripple in the bottom of the ionosphere that suddenly grows into a large "bubble" that rises explosively in the ionosphere. The associated perturbations in the ionosphere can cause serious problems for radio signals used for communications or Global Positioning System (GPS) navigation. As these plasma bubbles percolate up through the ionosphere, they leave behind their region of depleted plasma which, in turn, reduce the atmosphere airglow produced at night. The image below gives an example of such a complex 6300 Å airglow depletion. |
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Depletions, extending in the north - south direction, appear as dark bands against the bright airglow. Throughout the night they move from west to east, against the apparent motion of stars. See the two white dots in the image? Stars! (OK, maybe planets.) See the thin, black line running in the east - west direction? A flaw in our intensifier. Please ignore it. |
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