ANGEO Annales Geophysicae ANGEO Ann. Geophys. 1432-0576 Copernicus Publications Göttingen, Germany 10.5194/angeo-24-1333-2006 F-region electron density and <i>T<sub>e</sub> / T<sub>i</sub></i> measurements using incoherent scatter power data collected at ALTAIR Milla M. 1 Kudeki E. 1 Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Illinois, USA 03 07 2006 24 5 1333 1342 Copyright: © 2006 M. Milla 2006 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/24/1333/2006/angeo-24-1333-2006.html The full text article is available as a PDF file from https://angeo.copernicus.org/articles/24/1333/2006/angeo-24-1333-2006.pdf

The ALTAIR UHF radar was used in an incoherent scatter experiment to observe the low-latitude ionosphere during the Equis&nbsp;2 rocket campaign. The measurements provided the first high-resolution electron density maps of the low-latitude D- and E-region in the Pacific sector and also extended into the F-region and topside ionosphere. Although the sampling frequency was well below the Nyquist frequency of F-region returns, we were able to estimate <i>T<sub>e</sub> / T<sub>i</sub></i> ratio and infer unbiased electron density estimates using a regularized inversion technique described here. The technique exploits magnetic aspect angle dependence of ISR cross-section for <i>T<sub>e</sub></i>&gt;<i>T<sub>i</sub></i>.