Keogram
A keogram ("keo" from "Keoeeit" – Inuit word for "Aurora Borealis") is a way of displaying the intensity of an auroral display over time. It creates a time-dependent graph by taking a narrow slice of a series of images recorded by a camera, more specifically and ideally a "whole sky camera".[1] Keograms are usually created from a north-south oriented slice of the images, with north at the top in the Northern Hemisphere and south at the top in the Southern Hemisphere.[2][3] This allows one to easily see the general activity of the display that night, interruptions by clouds, and the regions in which the aurora was seen in terms of latitude.[4]
The use of keograms started in the 1970s by Eather et al. to allow a more practical and efficient way of determining the activity of the aurora throughout the recorded night and provide a view of the movements of it.[5] Cameras can also record in wavelengths outside of the human visible spectrum. Thus, keograms can also be used to analyse the conditions of the equatorial plasma bubbles (EPB) in the ionosphere of the Earth, to estimate its zonal drift.[6]
See also
[edit]References
[edit]- ^ Eather, R. H.; Mende, S. B.; Judge, R. J. R. (1976). "Plasma Injection at Synchronous Orbit and Spatial and Temporal Auroral Morphology". Journal of Geophysical Research. 81 (16): 2805–2824. doi:10.1029/JA081i016p02805. ISSN 2156-2202.
- ^ "CMR preview".
- ^ Tesema, Fasil; Partamies, Noora; Whiter, Daniel K.; Ogawa, Yasunobu (2022-01-04). "Types of pulsating aurora: comparison of model and EISCAT electron density observations". Annales Geophysicae. 40 (1): 1–10. Bibcode:2022AnGeo..40....1T. doi:10.5194/angeo-40-1-2022. hdl:11250/2997237. ISSN 1432-0576.
- ^ Kauristie, Kirsti. "FMI Scientist's Guide to Keograms". space.fmi.fi.
- ^ Sebastian Lay, Jo Vermeulen, Charles Perin, Eric Donovan, Raimund Dachselt, Sheelagh Carpendale: "Slicing the Aurora" (October 2016). https://imld.de/cnt/uploads/Lay-2016_Slicing-the-Aurora_VisAP16.pdf
- ^ Vargas, Fabio; Brum, Christiano; Terra, Pedrina; Gobbi, Delano (January 16, 2020). "Mean Zonal Drift Velocities of Plasma Bubbles Estimated from Keograms of Nightglow All-Sky Images from the Brazilian Sector". Atmosphere. 11 (1): 69. Bibcode:2020Atmos..11...69V. doi:10.3390/atmos11010069.
External links
[edit]
Media related to Keogram at Wikimedia Commons
