HR: 1400h
AN: A43A-05    [Abstracts]
TI: Influence of Anthropogenic Sources on the Cloud Condensation Nuclei (CCN) in zones near to Mexico City
AU: * Frias-Cisneros, M
EM: mildred@correo.unam.mx
AF: Centro de Ciencias de la Atmosfera, Universidad Nacional Autonoma de Mexico, Mexico City, 04510, Mexico
AU: Baumgardner, D
EM: darrel@servidor.unam.mx
AF: Centro de Ciencias de la Atmosfera, Universidad Nacional Autonoma de Mexico, Mexico City, 04510, Mexico
AU: Marin, J
EM: juliocma@atmosfera.unam.mx
AF: Centro de Ciencias de la Atmosfera, Universidad Nacional Autonoma de Mexico, Mexico City, 04510, Mexico
AB: During March 2006, a field experiment was conducted at the Paso de Cortes site, 60 km SE of Mexico City, at an altitude (4000 m, a.s.l.) where the site is sometimes in the free troposphere and otherwise within the boundary layer. During this experiment, cloud condensation nuclei (CCN) concentrations were measured with a thermal gradient diffusion chamber at applied supersaturations that ranged from 0.2 to 0.7 %. In addition, aerosol size distributions were obtained with a differential mobility analyzer (DMA and concentrations of condensation nuclei (CN) with a TSI Model 3010 CPC. The wind trajectories were computed for the altitude of the observation site from NCEP analysis. In this work the methodological approach was to determine the relationships between CN and CCN concentration and associated size distributions for various air masses arriving at the observation site from different directions according to the potential origin of the anthropogenic particles. Air masses are classified into four principal types: 1) Mexico City (NW), 2) Puebla (SE), 3) Cuernavaca (SW) and 4) local biomass burning. The CCN concentrations clearly depend on the source of the air mass, i.e., the highest concentrations are related to the biomass burning and the lowest from Cuernavaca. Moreover, a typical range can be attributed to each air mass type for the CCN/CN ratio. The objective of this study is to evaluate the evolution of CN and CCN as related to the anthropogenic sources.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 3311 Clouds and aerosols
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly