Abel Quevedo Nolasco

Comparison of ozone exposure characteristics in forested regions near Mexico City and Los Angeles

Abstract This comparison of forest exposure to ozone in the vicinity of Mexico City and Los Angeles provides preliminary evidence of the seasonal differences in ozone concentrations. Summer concentrations near Mexico City are not as high as those near Los Angeles because most of the precipitation and associated cloudiness occurs near Mexico City during the months of June through September. Winter concentrations remain nearly as high as summer concentrations at Mexico City, because in winter skies are clearer and incident sunlight remains high. Latitudinal influences on solar zenith angle and the higher altitude of the Mexico City region both contribute to a higher actinic flux than in the Los Angeles region. The primary difference in forest exposure is that there is very little respite from adverse ozone concentrations during the entire year in the Mexico City region. Also, the rainy summer season would likely diminish water stress and result in greater ozone uptake at the Desierto de los Leones compared to dry summer conditions in California. The closer proximity of the Desierto de los Leones monitoring site to the urban area also contributes to high winter exposures. There is some respite from exposure during the winter in the San Bernardino mountain region; however, summer concentrations are higher than near Mexico City. The greater transport distance from the Los Angeles source region also contributes to lower winter exposures.

Sistema de adquisición de datos meteorológicos en tiempo real con PLC

El objetivo de este trabajo fue desarrollar un sistema de adquisicion de datos meteorologicos en tiempo real utilizando un controlador logico programable (PLC) como una alternativa dentro de las estaciones meteorologicas comerciales. Para sensar la: temperatura del aire, humedad relativa, radiacion solar, precipitacion, velocidad y direccion del viento, se usaron sensores comerciales, durante 2013, para probar la estacion, en la estacion meteorologica del Colegio de Postgraduados, Campus Montecillo. El sistema se compone de un PLC (modelo CX1020, marca Beckhoff), una Laptop donde se instalo una aplicacion de monitoreo en tiempo real que se desarrollo en Visual Basic 2010 Express y la base de datos en MySQL para almacenar la informacion, que se puede usar para fines diversos. La interaccion entre el PLC y la aplicacion de monitoreo se realizo mediante comunicacion inalambrica Wi-Fi. Se usaron los programas TwinCAT System Manager (para la configuracion del hardware) y TwinCAT PLC Control (para la programacion del PLC). Se evaluo el funcionamiento del sistema al realizar comparaciones de las lecturas obtenidas de los sensores, contra instrumentos de referencia y sensores de una estacion meteorologica Campbell Scientific. Los resultados indican que es factible el uso del PLC en la implementacion de estaciones meteorologicas.