ANGEO Annales Geophysicae ANGEO Ann. Geophys. 1432-0576 Copernicus Publications Göttingen, Germany 10.5194/angeo-28-1299-2010 Ion-acoustic solitary waves and spectrally uniform scattering cross section enhancements Ekeberg J. 1 Wannberg G. 1 Eliasson L. 1 Stasiewicz K. 2 3 Swedish Institute of Space Physics, Kiruna, Sweden Swedish Institute of Space Physics, Uppsala, Sweden Space Research Centre, Polish Academy of Sciences, Warsaw, Poland 21 06 2010 28 6 1299 1306 Copyright: © 2010 J. Ekeberg et al. 2010 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://angeo.copernicus.org/articles/28/1299/2010/angeo-28-1299-2010.html The full text article is available as a PDF file from https://angeo.copernicus.org/articles/28/1299/2010/angeo-28-1299-2010.pdf

Spectra measured by incoherent scatter radars are formed predominantly by scattering of the incident signal off ion-acoustic and Langmuir waves in the ionosphere. Occasionally, the upshifted and/or downshifted lines produced by the ion-acoustic waves are enhanced well above thermal levels and referred to as naturally enhanced ion-acoustic lines. In this paper, we study another kind of enhancement, which is spectrally uniform over the whole ion-line, i.e. the up- and downshifted shoulder and the spectral valley in between. Based on observations made with the EISCAT Svalbard radar (ESR) facility, we investigate the transient and spectrally uniform power enhancements, which can be explained by ion-acoustic solitary waves. We use a theory of nonlinear waves in a magnetized plasma to determine the properties of such waves and evaluate their effects on scattered signals measured by ESR. We suggest a new mechanism that can explain backscattered power enhancements by one order of magnitude above the thermal level and show that it is consistent with observations.

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