Imaging spread‐F structures using GPS observations at Alcântara, Brazil

Abstract

During October 1994, a dual‐frequency GPS receiver was operated in Alcântara, Brazil, at the same site where the Cornell University Portable Radar Interferometer (CUPRI) was performing spread‐F measurements for an ongoing rocket campaign. We present data for two nights during which several spread‐F plumes drifted through the field‐of‐view of CUPRI. Fluctuations in the total electron content (TEC) measured with the GPS receiver were correlated with those plumes. We define a “roughness” measure from a specialized high frequency filter. Plots of “roughness” in a magnetic longitude versus time space show initially low activity followed by regions of dramatic localized onsets and a slower subsequent decline. Features in the roughness image are well‐correlated with plumes in the CUPRI backscatter power map.