Browsing by Author "Reyes, P."
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Item Open Access A high-resolution study of mesospheric fine structure with the Jicamarca MST radar(European Geosciences Union (EGU), 2006-07-03) Sheth, R.; Kudeki, E.; Lehmacher, G.; Sarango, M.; Woodman Pollitt, Ronald Francisco; Chau Chong Shing, Jorge Luis; Guo, L.; Reyes, P.Correlation studies performed on data from recent mesospheric experiments conducted with the 50-MHz Jicamarca radar in May 2003 and July 2004 are reported. The study is based on signals detected from a combination of vertical and off-vertical beams. The nominal height resolution was 150 m and spectral estimates were obtained after ~1 min integration. Spectral widths and backscattered power generally show positive correlations at upper mesospheric heights in agreement with earlier findings (e.g., Fukao et al., 1980) that upper mesospheric echoes are dominated by isotropic Bragg scatter. In many instances in the upper mesosphere, a weakening of positive correlation away from layer centers (towards top and bottom boundaries) was observed with the aid of improved height resolution. This finding supports the idea that layer edges are dominated by anisotropic turbulence. The data also suggests that negative correlations observed at lower mesospheric heights are caused by scattering from anisotropic structures rather than reflections from sharp vertical gradients in electron density.Item Open Access Calibrated radar observations of the equatorial mesosphere and ionosphere during an 11-day campaign(Instituto Geofísico del Perú, 2009) Kudeki, E.; Milla, Marco; Reyes, P.; Lehmacher, G.; Chau Chong Shing, Jorge Luis; Kuyeng, K. M.; De la Jara, CésarPresentado en MST12 - 12th Workshop on Technical and Scientific Aspects of MST Radars, London, Ontario, Canada, 17-23 May 2009.Item Open Access Estudio de los efectos de grandes erupciones solares sobre Jicamarca durante campañas MST-ISR(Instituto Geofísico del Perú, 2010) Kudeki, E.; Reyes, P.; Lehmacher, G.; Woodman Pollitt, Ronald Francisco; Chau Chong Shing, Jorge Luis; Milla, MarcoDiapositivas presentadas en el XIII Encuentro Científico Internacional, (ECI 2010v), realizado del 5 al 8 de enero de 2010 en la ciudad de Lima, Perú.Item Open Access Incoherent scatter measurements of F-region temperatures with the Jicamarca radar beam pointing perpendicular to B(Instituto Geofísico del Perú, 2008) Reyes, P.; Milla, Marco; Kudeki, E.Diapositivas presentadas en: ISEA 12 - 12th International Symposium on Equatorial Aeronomy, May 18-24, 2008. Crete, Greece.Item Open Access Radar cross sections for mesospheric echoes at Jicamarca(European Geosciences Union (EGU), 2009-07-06) Lehmacher, G. A.; Kudeki, E.; Akgiray, A.; Guo, L.; Reyes, P.; Chau Chong Shing, Jorge LuisRadar cross sections (RCS) of mesospheric layers at 50 MHz observed at Jicamarca, Peru, range from 10−18 to 10−16 m−1, three orders of magnitudes smaller than cross sections reported for polar mesospheric winter echoes during solar proton events and six orders of magnitude smaller than polar mesospheric summer echoes. Large RCS are found in thick layers around 70 km that also show wide radar spectra, which is interpreted as turbulent broadening. For typical atmospheric and ionospheric conditions, volume scattering RCS for stationary, homogeneous, isotropic turbulence at 3 m are also in the range 10−18 to 10−16 m−1, in reasonable agreement with measurements. Moreover, theory predicts maximum cross sections around 70 km, also in agreement with observations. Theoretical values are still a matter of order-of-magnitude estimation, since the Bragg scale of 3 m is near or inside the viscous subrange, where the form of the turbulence spectrum is not well known. In addition, steep electron density gradients can increase cross-sections significantly. For thin layers with large RCS and narrow spectra, isotropic turbulence theory fails and scattering or reflection from anisotropic irregularities may gain relevance.Item Open Access Sousy radar at Jicamarca system description(Instituto Geofísico del Perú, Radio Observatorio de Jicamarca, 2003) Woodman Pollitt, Ronald Francisco; Castillo, O.; Michhue, G.; Reyes, P.; Villegas, S.The main characteristics that differentiate the SOUSY radar from the Jicamarca radar are: (1) its bandwidth (4 MHz against 700 KHz for the Jicamarca radar) and (2) its steerability. The wider bandwidth allows an altitude resolution of at least 75 meters. The Sousy radar is a phased array that allows for a wide and agile steerability of its antenna (+/- 15°). In order to satisfy our scientific need, we have redesigned the antenna to have two main positions, zenithal and 15° south.