HR: 0800h
AN: A51E-0837    [Abstracts]
TI: Observations of the Enhancement of Particulate Nitrate by Clouds
AU: * Hayden, K L
EM: katherine.hayden@ec.gc.ca
AF: Environment Canada, 4905 Dufferin Street, Toronto, ON M3H 5T4 Canada
AU: Macdonald, A
EM: Anne Marie.Macdonald@ec.gc.ca
AF: Environment Canada, 4905 Dufferin Street, Toronto, ON M3H 5T4 Canada
AU: Anlauf, K G
EM: kurt.anlauf@ec.gc.ca
AF: Environment Canada, 4905 Dufferin Street, Toronto, ON M3H 5T4 Canada
AU: Gong, W
EM: Wanmin.Gong@ec.gc.ca
AF: Environment Canada, 4905 Dufferin Street, Toronto, ON M3H 5T4 Canada
AU: Leaitch, W R
EM: richard.leaitch@ec.gc.ca
AF: Environment Canada, 4905 Dufferin Street, Toronto, ON M3H 5T4 Canada
AU: Leithead, A
EM: amy.leithead@ec.gc.ca
AF: Environment Canada, 4905 Dufferin Street, Toronto, ON M3H 5T4 Canada
AU: Li, S
EM: shao-meng.li@ec.gc.ca
AF: Environment Canada, 4905 Dufferin Street, Toronto, ON M3H 5T4 Canada
AU: Toom-Sauntry, D
EM: desiree.toom-sauntry@ec.gc.ca
AF: Environment Canada, 4905 Dufferin Street, Toronto, ON M3H 5T4 Canada
AU: Noone, K J
EM: zippy@igbp.kva.se
AF: International Geosphere-Biosphere Program, Box 50005 Lilla Frescativagen 4A, Stockholm, S-10405 Sweden
AU: Schiller, C
EM: corinnes@yorku.ca
AF: York University, 4700 Keele Street, Toronto, ON M3J 1P3 Canada
AU: Gouin, J
EM: jfgouin@yorku.ca
AF: York University, 4700 Keele Street, Toronto, ON M3J 1P3 Canada
AU: Staebler, R
EM: ralf.staebler@ec.gc.ca
AF: Environment Canada, 4905 Dufferin Street, Toronto, ON M3H 5T4 Canada
AU: Strapp, J W
EM: walter.strapp@ec.gc.ca
AF: Environment Canada, 4905 Dufferin Street, Toronto, ON M3H 5T4 Canada
AB: An airborne in-situ sampling study was conducted out of Cleveland, Ohio from 21 July - 18 August, 2004 to investigate the role of clouds in the transport and transformation of pollutants. This study was part of the ICARTT (International Consortium for Atmospheric Research on Transport and Transformation) 2004 field intensive. Measurements of trace gases (including SO$_{2}$, HNO$_{3}$, NH$_{3}$ and H$_{2}$O$_{2}$), particle size distribution and chemistry, and cloud microphysics were made from the National Research Council of Canada Convair 580 aircraft. Cumulus and towering cumulus were sampled at multiple levels on several flights. Cloud droplet residuals from a counterflow virtual impactor (CVI) were sampled with an Aerodyne aerosol mass spectrometer (AMS), a TSI condensation particle counter, and a TSI differential mobility analyzer. Preliminary observations show that the ratio of nitrate to sulphate, determined from the AMS measurements, was often significantly higher in the cloud droplet residuals compared with the clear-air aerosol sampled below the cloud bases. For example, on one afternoon flight over central Ohio, the average NO$_{3}$/SO$_{4}$ value in cloud was 1.5, and in clear air below cloud was 0.09. One possible mechanism is that the increase in nitrate resulted from the scavenging of HNO$_{3}$ by the cloud droplets; although this would likely require some buffering of the acid for the nitrate to remain in the particle phase after the droplet is evaporated in the CVI. This and other possible explanations to account for the enhanced in-cloud nitrate are considered.
UR: http://www.msc-smc.ec.gc.ca/research/icartt/index_e.html
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0320 Cloud physics and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting