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dc.contributor.authorPrabhakar, Gouri
dc.contributor.authorErvens, B.
dc.contributor.authorWang, Z.
dc.contributor.authorMaudlin, L.C.
dc.contributor.authorCoggon, M.M.
dc.contributor.authorJonsson, H.H.
dc.contributor.authorSeinfeld, J.H.
dc.contributor.authorSorooshian, A.
dc.date2014
dc.date.accessioned2016-08-26T15:31:24Z
dc.date.available2016-08-26T15:31:24Z
dc.date.issued2014
dc.identifier.citationPrabhakar, Gouri, et al. "Sources of nitrate in stratocumulus cloud water: Airborne measurements during the 2011 E-PEACE and 2013 NiCE studies." Atmospheric Environment 97 (2014): 166-173.en_US
dc.identifier.urihttp://hdl.handle.net/10945/49708
dc.descriptionThe article of record as published may be found at http://dx.doi.org/10.1016/j.atmosenv.2014.08.019en_US
dc.descriptionincludes supplementary material
dc.description.abstractThis study examines the sources of NO₃ˉ in stratocumulus clouds over the eastern Pacific Ocean off the California coast using airborne and surface measurement data from the Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE; 2011) and Nucleation in California Experiment (NiCE; 2013). Average NO₃ˉ air-equivalent concentrations in cloud water samples categorized as having been influenced by ship exhaust (2.5 μg m ˉ³), strong marine emissions (2.5 μg m ˉ³) and fires (2.0 μg m ˉ³) were more than twice that in the background cloud water (0.9 μg m ˉ³). During periods when biomass burning plumes resided above cloud top, 16 of 29 cloud water samples were impacted due to instability in the entrainment interface layer with NO₃ˉ levels reaching as high as 9.0 μg m ˉ³. Nucleation scavenging of chloride depleted sea-salt is a source of cloud water NO₃ˉ , with the lowest Cl ˉ:Na⁺ ratio (1.5) observed in shipinfluenced samples. Surface aerosol measurements show that NO₃ˉ concentrations peak in the particle diameter range of 1.0-5.6 μm, similar to Na, Cl ˉ and Si, suggesting that drop activation of crustal particles and sea salt could be an important source of NO₃ˉ in cloud water. The contrasting behavior of NO₃ˉ and SO ²₄ˉ is emphasized by the NO₃ˉ :SO ²₄ˉ mass concentration ratio which is highest in cloud water (by more than a factor of two) followed by above cloud aerosol, droplet residual particles, and below cloud aerosol. Trends of a decreasing NO₃ˉ :SO ²₄ˉ ratio with altitude in clouds are confirmed by parcel model studies due to the higher rate of in-cloud sulfate formation as compared to HNO₃ uptake by droplets.en_US
dc.format.extent8 p.en_US
dc.publisherElsevier Ltd.en_US
dc.rightsThis publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.en_US
dc.titleSources of nitrate in stratocumulus cloud water: Airborne measurements during the 2011 E-PEACE and 2013 NiCE studiesen_US
dc.typeArticleen_US
dc.contributor.corporateNaval Postgraduate School (U.S.)en_US
dc.subject.authorcloud wateren_US
dc.subject.authorchloride depletionen_US
dc.subject.authorstratocumulusen_US
dc.subject.authormarineen_US
dc.subject.authorbiomass burningen_US
dc.subject.authorsea-salten_US
dc.description.funderOffice of Naval Research grants N00014-11-1-0783, N00014-10-1-0200, and N00014-10-1-0811en_US
dc.description.funderNational Science Foundation grant AGS-1008848en_US


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