Chau Chong Shing, Jorge LuisHysell, D. L.2018-07-132018-07-132004-12-24Chau, J. L., & Hysell, D. L. (2004). High altitude large-scale plasma waves in the equatorial electrojet at twilight.==$Annales Geophysicae, 22$==(12), 4071-4076. https://doi.org/10.5194/angeo-22-4071-2004index-oti2018http://hdl.handle.net/20.500.12816/1829Jicamarca radar observations of a new class of large-scale plasma waves in the equatorial electrojet (EEJ) are presented and characterized. The study is based on long-term (204 days), single-baseline interferometry observations made in 2003 using a low-power radar mode, also known as JULIA mode, along with a few hours of observations made in an aperture synthesis imaging mode. The large-scale waves are found to occur at high altitudes in the E-region, mainly between 120 and 140km, around twilight (between 18:30 and 20:00 LT), with durations of a few minutes to an hour. In our long-term observations, these large-scale waves occur very often (between 1 and 5 out 10 nights), drift westward (~70 ms–1), exhibit very narrow spectral widths, and have both positive and negative Doppler shifts. The imaging results show that the large-scale waves occur along tilted bands that sweep westward and downward (~30–60ms–1), with a horizontal separation between bands of about 10–15km. The cause of the waves remains unknown.application/pdfenginfo:eu-repo/semantics/openAccessIonosphereIonospheric irregularitiesEquatorial ionosphereInstruments and techniquesinfo:eu-repo/semantics/articlehttp://purl.org/pe-repo/ocde/ford#1.05.01Annales Geophysicaehttps://doi.org/10.5194/angeo-22-4071-2004