Journal of Geophysical Research: Space Physics
© American Geophysical Union
Impact Factor: 3.426
ISI Journal Citation Reports © Ranking: 2014: 19/175 (Geosciences Multidisciplinary)
Online ISSN: 2169-9402
Associated Title(s): Journal of Geophysical Research
Large-scale observationsof flows in the ionosphere
At midlatitudes in the ionosphere, just below the auroral region, narrow channels of strong westward flow have been observed. These flows, known as subauroral polarization streams (SAPS), are driven by pressure gradients in near-Earth space and are a manifestation of the coupling between the upper atmosphere and the magnetosphere. To better understand these flows, Clausen et al. (2012) measured the flow velocities inside a SAPS using the new midlatitude chain of Super Dual Auroral Radar Network (SuperDARN) radars. The observations, which lasted for 3 h and covered the entire North American continent, are the first large-scale simultaneous observations of the velocity structure of a SAPS. The authors found that the flow direction stayed constant during the course of the SAPS event, but the velocity decreased exponentially with magnetic local time. Comparing their observations with models, they conclude that variations in the plasma pressure in the magnetosphere are indeed consistent with the variations of the ionospheric flow velocity inside the SAPS channel.