Alis, a state-of-the-art optical observation network for the exploration of polar atmospheric processes Original Research Article

An optical group at the Swedish Institute of Space Physics in Kiruna, Sweden has been developing the ALIS (Auroral Large Imaging System) multi-station optical observing network which makes it possible to obtain composite monochromatic 2-D images over a fairly wide field-of-view (FOV), and more interestingly, a CT (Computed Tomography) image set for the retrieval of 3-D structure of aurora by adjusting vergence angles of cameras to a common volume. National Institute of Polar Research, Japan is collaborating in observation and analysis. At the moment, the network has 6 stations separated from each other by about 50 km.Each station houses a monochromatic CCD (Charge Coupled Device) imaging system mounted on the steerable azimuth/elevation drive along with a house keeping unit and supervising computer linked to the control center via a telephone line. Altitude profiles of luminosity for stable arc and aurora vortex at 557.7nm and recently at 427.8nm are analysed by the algebraic reconstruction technique and compared with sophisticated numerical modelling of auroral emission rate. Conjunctions with satellites and radars are now intensively explored towards comprehensive understanding of the formation and electrodynamics of aurora. Imaging of polar stratospheric clouds is also attempted in relation to arctic environmental studies.