Browsing by Author "Sarango, M."
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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 First observations of polar mesosphere summer echoes in Antarctica(American Geophysical Union, 1999-10-01) Woodman Pollitt, Ronald Francisco; Balsley, B. B.; Aquino, F.; Flores, L.; Vásquez, E.; Sarango, M.; Huamán, M. M.; Soldi, H.A 25‐kW peak power 50‐MHz radar was installed at the Peruvian base on King George Island, Antarctica (62°S), in early 1993. A search for polar mesospheric summer echoes (PMSEs) was made during late January and early February of the first year of operation with negative results. These results have been reported in the literature [Balsley et al., 1993; 1995]. We report here results obtained during the austral summer of the second year (1994) of operation. Observations during the second year were begun earlier, i.e., closer to the austral summer solstice. PMSEs were observed during this period, albeit the echoes were much weaker than what one would expect based on earlier Poker Flat radar results at a comparable latitude (65°N) in the Northern Hemisphere. A large and measurable asymmetry in PMSE strength in the two hemispheres therefore exists. We explain this asymmetry by postulating a difference in summer mesopause temperatures between the two hemispheres of ∼7.5 K. This difference has been estimated using an empirical relationship between the variations of the Poker Flat PMSE power as a function of temperature given by the mass spectrometer incoherent scatter extended (MSISE‐90) model.Item Restricted On the lack of southern hemisphere polar mesosphere summer echoes(American Geophysical Union, 1995-06-20) Balsley, B.B.; Woodman Pollitt, Ronald Francisco; Sarango, M.; Rodriguez, R.; Urbina, J.; E. Ragaini; Carey, J.; Huaman, M.; Giraldez, A.We report VHF radar observations of the southern high-latitude mesopause region using wind profilers that were installed recently on King George Island, Antarctica, and Ushuaia, Argentina. Briefly, our observations, which were made during January and February 1993, show almost no evidence of so-called polar mesosphere summer echoes, or PMSE. Since these echoes are a predominant feature of the northern high-latitude mesosphere in summer, their absence in the southern hemisphere is both surprising and intriguing. In this paper we present evidence demonstrating the virtual absence of the echoes and demonstrate that our systems were capable of detecting them had they been present. We also outline some of the consequences of this intriguing result, which are supported by observed hemispheric differences in polar mesospheric clouds, mesospheric temperatures, upper atmospheric gravity wave activity, and mean circulation patterns.Item Restricted Southern-hemisphere PMSE: Where are they?(American Geophysical Union, 1993-09) Balsley, B. B.; Woodman Pollitt, Ronald Francisco; Sarango, M.; Urbina, J.; Rodríguez, R.; Ragaini, E.; Carey, J.We report a surprising absence of PMSE (Polar Mesospheric Summer Echoes) in VHF radar observations of the southern summer high-latitude mesosphere. Our observations cover about twenty days during January-February, 1993, from King George Island, Antarctica.Item Restricted Wind profile radar for study of Antarctic air circulation(Springer, 1992-10-01) Ragaini, E.; Sarango, M.; Vásquez, E.After a brief discussion of meteorological methods used in the Antarctic, the paper gives an outline of a coordinated international research project whose objective is to set up a wind profiler radar station that would give meteorologists information regarding Antarctic atmospheric dynamics useful in their investigation of the causes and effects of the hole in the ozone layer. The radar instrumentation is to provide continuous readings of wind velocity at varying altitudes above the polar continent.Item Restricted Wind profiler installed in Antarctica(American Geophysical Union, 1993-08) Balsley, B. B; Carey, J.; Woodman Pollitt, Ronald Francisco; Sarango, M.; Urbina, J.; Rodríguez, R.; Ragaini, E.A VHF (50 MHz) wind profiler was installed in Antarctica at the Peruvian Base Machu Picchu on King George Island from January 21 to 26. The wind profiler will provide a first look at atmospheric dynamics over the region. The profiler-the first of its kind in Antarctica-is a National Science Foundation sponsored cooperative project of the University of Colorado, the Geophysical Institute of Peru, the University of Piura (Peru), and the Peruvian Navy. This venture was also greatly facilitated by Peru's Comision Nacional de Asuntos Antartidos and Consejo Nacional de Ciencias y Tecnologia, with additional logis tics support provided by the Argentinean Navy and the Uruguayan Air Force.