TY - JOUR
T1 - Impact of emissions from shipping, land, and the ocean on stratocumulus cloud water elemental composition during the 2011 E-PEACE field campaign
AU - Wang, Z.
AU - Sorooshian, A.
AU - Prabhakar, G.
AU - Coggon, M. M.
AU - Jonsson, H. H.
N1 - Funding Information: This work was funded by ONR grants N00014-11-1-0783 , N00014-10-1-0200 , and N00014-10-1-0811 , and NSF grant AGS-1008848 . We acknowledge Dean Hegg for providing the cloud water collector and Lindsay C. Maudlin for comments on the draft. The authors gratefully acknowledge the NOAA Air Resources Laboratory (ARL) for the provision of the HYSPLIT transport and dispersion model and READY website ( http://ready.arl.noaa.gov ) used in this publication.
PY - 2014/6
Y1 - 2014/6
N2 - This study reports on cloud water chemical and pH measurements off the California coast during the July-August 2011 Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE). Eighty two cloud water samples were collected by a slotted-rod cloud water collector protruding above the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter in boundary layer stratocumulus clouds impacted to varying degrees by ocean-derived emissions, ship exhaust, and land emissions. Cloud water pH ranged between 2.92 and 7.58, with an average of 4.46. Peak pH values were observed north of San Francisco, simultaneous with the highest concentrations of Si, B, and Cs, and air masses originating over land. The lowest pH values were observed south of San Francisco due to ship emissions resulting in the highest concentrations of sulfate, nitrate, V, Fe, Al, P, Cd, Ti, Sb, P, and Mn. Many of these species act as important agents in aqueous-phase reactions in cloud drops and are critical ocean micronutrients after subsequent wet deposition in an ocean system that can be nutrient-limited. E-PEACE measurements suggest that conditions in the California coastal zone region can promote the conversion of micronutrients to more soluble forms, if they are not already, due to acidic cloud water conditions, the ubiquity of important organic agents such as oxalic acid, and the persistence of stratocumulus clouds to allow for continuous cloud processing.
AB - This study reports on cloud water chemical and pH measurements off the California coast during the July-August 2011 Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE). Eighty two cloud water samples were collected by a slotted-rod cloud water collector protruding above the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter in boundary layer stratocumulus clouds impacted to varying degrees by ocean-derived emissions, ship exhaust, and land emissions. Cloud water pH ranged between 2.92 and 7.58, with an average of 4.46. Peak pH values were observed north of San Francisco, simultaneous with the highest concentrations of Si, B, and Cs, and air masses originating over land. The lowest pH values were observed south of San Francisco due to ship emissions resulting in the highest concentrations of sulfate, nitrate, V, Fe, Al, P, Cd, Ti, Sb, P, and Mn. Many of these species act as important agents in aqueous-phase reactions in cloud drops and are critical ocean micronutrients after subsequent wet deposition in an ocean system that can be nutrient-limited. E-PEACE measurements suggest that conditions in the California coastal zone region can promote the conversion of micronutrients to more soluble forms, if they are not already, due to acidic cloud water conditions, the ubiquity of important organic agents such as oxalic acid, and the persistence of stratocumulus clouds to allow for continuous cloud processing.
KW - Cloud processing
KW - Cloud water
KW - Coastal region
KW - Iron
KW - Marine
KW - Metals
KW - Nutrients
KW - Ocean
KW - Shipping
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U2 - 10.1016/j.atmosenv.2014.01.020
DO - 10.1016/j.atmosenv.2014.01.020
M3 - Article
SN - 1352-2310
VL - 89
SP - 570
EP - 580
JO - Atmospheric Environment
JF - Atmospheric Environment
ER -