Ashrafi, M. and Kosch, M. J. and Kaila, K. (2005) Height triangulation of artificial optical emissions in the F-layer. In: Proceedings of the 31st Annual European Meeting on Atmospheric Studies by Optical Methods and 1st International Riometer Workshop, 1900-01-01.
Abstract
Using the EISCAT high gain high frequency (HF) Heating facility located in northern Scandinavia (69.59deg N, 19.23deg E), HF-induced artificial auroral emissions can be produced at ionospheric F-region altitudes. On 12th November 2001, the EISCAT Heating facility, pumping with O-mode at 5.423 MHz and 550 MW effective radiative power (ERP), produced artificial optical rings which appeared immediately at pump-on and collapsed into blobs after ~60 s whilst descending in altitude. Observations were made using cameras in two different locations, one looking into the magnetic zenith over EISCAT recording in white-light, and the other pointing to the local zenith ~50 km from EISCAT in 630.0 and 557.7 nm (Skibotn, 69.35deg N, 20.36deg E). The altitudes of the initial optical ring and steady-state blob have been estimated by height triangulation. The change in height of all the optical structures during each Heater on cycle has been calculated using two-dimensional cross-correlation of the bistatic images. Consistent descent of the optical signature is similar to the lowering of other effects from ionospheric heating such as the EISCAT UHF radar ion line enhancements and stimulated electromagnetic emissions. We describe the details of the height triangulation technique used.