Impact of emissions from shipping, land, and the ocean on stratocumulus cloud water elemental composition during the 2011 E-PEACE field campaign
Author
Wang, Z.
Sorooshian, A.
Prabhakar, G.
Coggon, M.M.
Jonsson, H.H.
Date
2014Metadata
Show full item recordAbstract
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.
Description
The article of record as published may be found at http://dx.doi.org/10.1016/j.atmosenv.2014.01.020
includes supplementary material