It's Tuesday, and time for another blog post about EISCAT-related science results. This time we look at a study combining radar measurements with a rocket campaign and optical observations. If you want to increase visibility for your science results, please let us know!
Simultaneous observations were conducted with a Fabry-Perot Interferometer (FPI) and an all-sky camera, both at a wavelength of 557.7 nm, as well as the EISCAT UHF radar during the Dynamics and Energetics of the Lower Thermosphere in Aurora 2 (DELTA-2) rocket campaign in January 2009. This paper concentrates on two events during periods of pulsating aurora. The lower-thermospheric wind velocity measured with the FPI showed obvious fluctuations in both vertical and horizontal components. Of particular interest is that the location of the fluctuations was found to be in a darker area that appeared within the pulsating aurora.
During the same time period, the EISCAT radar observed sporadic enhancements in the backscattered power from the F region, which suggests the presence of low-energy electron precipitation (<=1 keV) coinciding with the increase of the amplitude of the electromagnetic wave (order of 10 Hz or higher). While we have not yet identified the dominant mechanism causing the fluctuations in FPI-derived wind velocity during pulsating aurora, the frictional heating energy dissipated by the electric-field perturbations may be responsible for the increase in ionospheric thermal energy thus modifying the local wind dynamics in the lower thermosphere.
Original article: S. Oyama, K. Shiokawa, J. Kurihara, T. T. Tsuda, S. Nozawa, Y. Ogawa, Y. Otsuka, and B. J. Watkins, Lower-thermospheric wind fluctuations measured with an FPI in pulsating aurora at Tromsoe, Norway, Ann. Geophys., 28, 1847-1857, 2010.