HR: 11:05h
AN: A42A-04    [Abstracts]
TI: Regional and Global Megacity Impacts: A comparison of boundary layer and free troposphere airmasses over Mexico, the Gulf of Mexico, and the Eastern North Pacific
AU: * McNaughton, C S
EM: cameronm@soest.hawaii.edu
AF: School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, HI 96822, United States
AU: Clarke, A D
EM: tclarke@soest.hawaii.edu
AF: School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, HI 96822, United States
AU: Shinozuka, Y
EM: yohei@hawaii.edu
AF: School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, HI 96822, United States
AU: Kapustin, V
EM: kapustin@soest.hawaii.edu
AF: School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, HI 96822, United States
AU: Dibb, J E
EM: jack.dibb@unh.edu
AF: Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824, United States
AU: Anderson, B E
EM: b.e.anderson@larc.nasa.gov
AF: NASA Langley Research Center, Mail Stop 483, Hampton, VA 23681, United States
AU: Avery, M
EM: m.a.avery@larc.nasa.gov
AF: NASA Langley Research Center, Mail Stop 483, Hampton, VA 23681, United States
AU: Sachse, G
EM: g.w.sachse@larc.nasa.gov
AF: NASA Langley Research Center, Mail Stop 483, Hampton, VA 23681, United States
AB: During March 2006 both the NASA/UND DC-8 and NSF/NCAR C-130 aircraft were used to characterize natural and anthropogenic aerosols over Central Mexico and the Gulf as part of MILAGRO. In late April and early May the same aircraft were used to characterize airmasses over the remote Eastern North Pacific (20-60N, 120-180W) as part of INTEX. The upper troposphere (6-12 km) over Mexico and the Gulf was found to be relatively pristine compared to mid- latitudes reflecting the well aged nature of the airmasses; a combination of long-range transport over the sub- tropical Pacific, and dilution due to inter-hemispheric exchange. The continental boundary layer over Mexico was heavily influenced by anthropogenic pollution from Mexico City. Measurements of scattering and absorption Angstrom exponent as well as the increase in light scattering as a function of relative humidity, f(RH) show that aerosols in the boundary layer are complex mixtures of both fresh and aged pollution, biomass burning and mineral dust. Few episodes of deep convection were observed during MILAGRO. However, anthropogenically influenced boundary layer and lower free troposphere air was transported from Mexico City toward the Gulf of Mexico forming a 1-2 km deep transitional layer above the marine boundary layer. The marine boundary layer over the Gulf is heavily influenced by both anthropogenic and biomass burning emissions from the United States and Mexico. The upper troposphere over the North Pacific was found to be influenced by pollution and dust transported from Asia. Measurements in the Pacific MBL ranged from relatively pristine to polluted due to the entrainment of Asian pollution and dust from the lower troposphere. Vertical profiles of gas and aerosol phase tracers are compared with an emphasis on the in-situ measurements' ability to discriminate between airmasess of different origin. We examine the aerosol size distribution, chemistry and optical properties with an emphasis on the Angstrom exponent for light scattering and absorption as well as f(RH) as a function of relative humidity. The events are put into a broader context through the use of models and satellite imagery.
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly