naa a22 4500 528787284 20180924065503.0 cr unu---uuuuu 180924s2010 xx s 000 0 eng 10.3929/ethz-b-000022281 doi 10.5194/acp-10-7669-2010 doi (ETHRESEARCH)oai:www.research-collection.ethz.ch:20.500.11850/22281 Cloud albedo increase from carbonaceous aerosol [Elektronische Daten] [W.R. Leaitch, Ulrike Lohmann, Lynn M. Russell, Timothy Garrett, N.C. Shantz, Desiree Toom-Sauntry, J.W. Strapp, Katherine L. Hayden, Julia Marshall, Mengistu Wolde, Douglas R. Worsnop, John T. Jayne] Atmos. chem. phys. Open access ethresearch Airborne measurements from two consecutive days, analysed with the aid of an aerosol-adiabatic cloud parcel model, are used to study the effect of carbonaceous aerosol particles on the reflectivity of sunlight by water clouds. The measurements, including aerosol chemistry, aerosol microphysics, cloud microphysics, cloud gust velocities and cloud light extinction, were made below, in and above stratocumulus over the northwest Atlantic Ocean. On the first day, the history of the below-cloud fine particle aerosol was marine and the fine particle sulphate and organic carbon mass concentrations measured at cloud base were 2.4 μg m−3 and 0.9 μg m−3 respectively. On the second day, the below-cloud aerosol was continentally influenced and the fine particle sulphate and organic carbon mass concentrations were 2.3 μg m−3 and 2.6 μg m−3 respectively. Over the range 0.06-0.8 μm diameter, the shapes of the below-cloud size distributions were similar on both days and the number concentrations were approximately a factor of two higher on the second day. The cloud droplet number concentrations (CDNC) on the second day were approximately three times higher than the CDNC measured on the first day. Using the parcel model to separate the influence of the differences in gust velocities, we estimate from the vertically integrated cloud light scattering measurements a 6% increase in the cloud albedo principally due to the increase in the carbonaceous components on the second day. Assuming no additional absorption by this aerosol, a 6% albedo increase translates to a local daytime radiative cooling of ∼12 W m−2. This result provides observational evidence that the role of anthropogenic carbonaceous components in the cloud albedo effect can be much larger than that of anthropogenic sulphate, as some global simulations have indicated. Creative Commons Attribution 3.0 Unported http://creativecommons.org/licenses/by/3.0 ethresearch Leaitch W.R. joint author Lohmann Ulrike joint author Russell Lynn M. joint author Garrett Timothy joint author Shantz N.C. joint author Toom-Sauntry Desiree joint author Strapp J.W. joint author Hayden Katherine L. joint author Marshall Julia joint author Wolde Mengistu joint author Worsnop Douglas R. joint author Jayne John T. joint author Atmospheric Chemistry and Physics Munich : European Geophysical Society 10 (16), pp. 7669-7684 1680-7375 http://hdl.handle.net/20.500.11850/22281 text/html WWW-Backlink auf das Repository (Open access) 1 Journal Article ethresearch ETHRESEARCH 856 40 http://hdl.handle.net/20.500.11850/22281 text/html WWW-Backlink auf das Repository (Open access) ETHRESEARCH 700 1- Leaitch W.R. joint author ETHRESEARCH 700 1- Lohmann Ulrike joint author ETHRESEARCH 700 1- Russell Lynn M. joint author ETHRESEARCH 700 1- Garrett Timothy joint author ETHRESEARCH 700 1- Shantz N.C. joint author ETHRESEARCH 700 1- Toom-Sauntry Desiree joint author ETHRESEARCH 700 1- Strapp J.W. joint author ETHRESEARCH 700 1- Hayden Katherine L. joint author ETHRESEARCH 700 1- Marshall Julia joint author ETHRESEARCH 700 1- Wolde Mengistu joint author ETHRESEARCH 700 1- Worsnop Douglas R. joint author ETHRESEARCH 700 1- Jayne John T. joint author ETHRESEARCH 773 0- Atmospheric Chemistry and Physics Munich : European Geophysical Society 10 (16), pp. 7669-7684 1680-7375 BK010053 XK010053 XK010000 ETHRESEARCH ETHRESEARCH ETHRESEARCH Journal Article Open access