Browsing by Author "Lehmacher, G."

Now showing 1 - 4 of 4
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    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.
    Palabras clave:Atmospheric dynamicsTurbulenceRadio wave propagation
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    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, César
    Presentado en MST12 - 12th Workshop on Technical and Scientific Aspects of MST Radars, London, Ontario, Canada, 17-23 May 2009.
    Palabras clave:RadarMesosphereIonosphere
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    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, Marco
    Diapositivas presentadas en el XIII Encuentro Científico Internacional, (ECI 2010v), realizado del 5 al 8 de enero de 2010 en la ciudad de Lima, Perú.
    Palabras clave:Erupciones solaresElectronesMesósfera
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    First meteor radar observations of tidal oscillations over Jicamarca (11.95° S, 76.87° W)
    (European Geosciences Union (EGU), 2009-06) Guo, L.; Lehmacher, G.
    Tidal oscillations in the equatorial mesosphere and lower thermosphere (MLT) region over Jicamarca (11.95° S, 76.87° W) are studied using the observations from the newly installed Jicamarca All-sky Specular MEteor Radar (JASMET). The vertical structure and seasonal variability of diurnal and semidiurnal tides from 80-100 km are presented. The analyses show a strong diurnal tide over Jicamarca for both zonal and meridional components with the meridional amplitudes being larger than the zonal ones. Maximal diurnal amplitudes, 45 m/s for zonal and 55 m/s for meridional, are observed around equinox. The zonal diurnal amplitudes reach maxima at 90-96 km, while the meridional diurnal amplitudes grow with altitude for most months. Semidiurnal amplitudes vary not as strong as diurnal amplitudes. The vertical structures of the tidal components are compared with Global Scale Wave Model (GSWM02) prediction and the tidal wind analysis results from TIDI measurements onboard of the TIMED satellite. The data from JASMET and TIDI show similar amplitudes for both diurnal and semidiurnal tides. GSWM02 overestimates diurnal amplitudes, but underestimates semidiurnal amplitudes for both zonal and meridional components.
    Palabras clave:Middle atmosphere dynamicsThermospheric dynamicsWaves and tides