Speaker
Description
Using incoherent scatter radar (ISR) to determine the neutral wind velocity in the ionosphere has been done for nearly 50 years. The method for finding the velocity of the neutral wind uses the ion velocity which is one of the parameters that the ISRs measure. The ion velocity is connected to the neutral wind velocity through collisions, and to electrical field through the Lorentz force where neither of these are directly known. However, at high altitudes, the ion motion is mostly dominated by the Lorentz force. When assuming that the electrical field is constant along the magnetic field lines, the neutral wind in the E region can be found. This procedure was first described by Brekke et al. [1973], and has been used and improved since [see Heinselman and Nicolls 2008, Nygrén (2011), and references therein].
One of the advancements of the upcoming ISR EISCAT 3D (E3D) is that it will be able to measure three components of the ion velocity simultaneously at all ranges [McCrea et al. 2015]. We estimate the ISR spectrum and its uncertainty to find the accuracy of ion velocity measurements of E3D. We find that it is strongly dependent on the electron density.
In reality, the electrical field might vary over height. If letting it do so, the underdetermined nature of the problem is revealed. By using other constraints, one can show that it is possible to obtain estimates of the electrical field in the upper E region as well.
References:
Asgeir Brekke, Joe R. Doupnik, and Peter M. Banks (1973): “A Preliminary Study of the Neutral Wind in the Auroral E Region”. In: Journal of Geophysical Research 78.34 (1973), pp. 8235–8250.
Craig J. Heinselman and Michael J. Nicolls (2008): “A Bayesian approach to electric field and E-region neutral wind estimation with the Poker Flat Advanced Modular Incoherent Scatter Radar”. In: Radio science 43.RS5013 (2008).
Ian McCrea, Anita Aikio, Lucilla Alfonsi, Evgenia Belova, Stephan Buchert, Mark Clilverd, Norbert Engler, Björn Gustavsson, et al. (2015): “The science case for the EISCAT_3D radar”. In: Progress in Earth and Planetary Science 2.21. DOI : 10.1186/s40645-015-0051-8.
Tuomo Nygrén, Anita T. Aikio, Ritva Kuula, and Mirela Voiculescu (2011): “Electric fields and neutral winds from monostatic incoherent scatter measurements by means of stochastic inversion”. In: Journal of Geophysical Research 116.A05305 (2011). DOI: 10.1029/2010JA016347.
