Browsing by Autor "Ronald Winkelmann"

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Atmospheric Eletric Field on Cosmic Rays Rate
(2011) Ronald Winkelmann
From the moment of their formation all particles produced by a primary cosmic ray are influenced by atmospheric conditions, such as pressure, temperature, air density, and others. Atmospheric Electric Field (AEF) is one of these factors. There is evidence of a considerable increase of the counting rate of particles during electrical storms. In the present work at the Chacaltaya Cosmic Rays Physics Laboratory (5220 m a.s.l.), the existent relation between AEF and secondary particles produced by primary cosmic rays under two different weather conditions is searched, during fair weather days and disturbed weather days.
Efecto del campo eléctrico atmosférico sobre el conteo de partículas cargadas detectadas por un centellador en el laboratorio de física cósmica de Chacaltaya
(2010) Ronald Winkelmann
Las part´iculas secundarias que son producidas por rayos c´osmicos primarios se ven afectadas por diversos factores en la atm´osfera, como presi´on, temperatura, y otros. El Campo El´ectrico Atmosf ´erico (CEA) es uno de estos factores. Se observa que durante tormentas el´ectricas la tasa de conteo de las part´iculas puede incrementarse considerablemente. En el presente trabajo se busca observar en el Laboratorio de F´isica C´osmica de Chacaltaya (5220 msnm) la relaci´on existente entre el CEA y las part´iculas secundarias producidas por rayos c´osmicos primarios, bajo dos distintas condiciones clim´aticas: buen tiempo meteorol´ogico y tiempo meteorol´ogico perturbado
Radar-Observed Characteristics of Precipitation in the Tropical High Andes of Southern Peru and Bolivia
(American Meteorological Society, 2018) Jason L. Endries; L. Baker Perry; Sandra E. Yuter; Anton Seimon; Marcos Andrade; Ronald Winkelmann; Nelson Quispe; Maxwell Rado; Nilton Montoya; Fernando Velarde
Abstract This study used the first detailed radar measurements of the vertical structure of precipitation obtained in the central Andes of southern Peru and Bolivia to investigate the diurnal cycle and vertical structure of precipitation and melting-layer heights in the tropical Andes. Vertically pointing 24.1-GHz Micro Rain Radars in Cusco, Peru (3350 m MSL, August 2014–February 2015), and La Paz, Bolivia (3440 m MSL, October 2015–February 2017), provided continuous 1-min profiles of reflectivity and Doppler velocity. The time–height data enabled the determination of precipitation timing, melting-layer heights, and the identification of convective and stratiform precipitation features. Rawinsonde data, hourly observations of meteorological variables, and satellite and reanalysis data provided additional insight into the characteristics of these precipitation events. The radar data revealed a diurnal cycle with frequent precipitation and higher rain rates in the afternoon and overnight. Short periods with strong convective cells occurred in several storms. Longer-duration events with stratiform precipitation structures were more common at night than in the afternoon. Backward air trajectories confirmed previous work indicating an Amazon basin origin of storm moisture. For the entire dataset, median melting-layer heights were above the altitude of nearby glacier termini approximately 17% of the time in Cusco and 30% of the time in La Paz, indicating that some precipitation was falling as rain rather than snow on nearby glacier surfaces. During the 2015–16 El Niño, almost half of storms in La Paz had melting layers above 5000 m MSL.