Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Sources of nitrate in stratocumulus cloud water: Airborne measurements during the 2011 E-PEACE and 2013 NiCE studies
https://orcid.org/0000-0003-4578-8658
https://orcid.org/0000-0001-9627-9074
https://orcid.org/0000-0002-2243-2264
Abstract This study examines the sources of NO3 − 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 NO3 − air-equivalent concentrations in cloud water samples categorized as having been influenced by ship exhaust (2.5 μg m−3), strong marine emissions (2.5 μg m−3) and fires (2.0 μg m−3) were more than twice that in the background cloud water (0.9 μg m−3). 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 NO3 − levels reaching as high as 9.0 μg m−3. Nucleation scavenging of chloride depleted sea-salt is a source of cloud water NO3 −, with the lowest Cl−:Na+ ratio (1.5) observed in ship-influenced samples. Surface aerosol measurements show that NO3 − concentrations peak in the particle diameter range of 1.0–5.6 μm, similar to Na, Cl− and Si, suggesting that drop activation of crustal particles and sea salt could be an important source of NO3 − in cloud water. The contrasting behavior of NO3 − and SO4 2− is emphasized by the NO3 −:SO4 2− 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 NO3 −:SO4 2− 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.
Graphical abstract Display Omitted
Highlights The major sources of NO3 − in the study region are ship and fire emissions. Entrainment of wildfire emissions can significantly increase NO3 − in clouds. Nitrate is associated with crustal particles in the coastal region. The nitrate-to-sulfate mass ratio decreases rapidly with cloud height. Volatilization during drop evaporation pushes NO3 − to the gas phase.
Sources of nitrate in stratocumulus cloud water: Airborne measurements during the 2011 E-PEACE and 2013 NiCE studies
https://orcid.org/0000-0003-4578-8658
https://orcid.org/0000-0001-9627-9074
https://orcid.org/0000-0002-2243-2264
Abstract This study examines the sources of NO3 − 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 NO3 − air-equivalent concentrations in cloud water samples categorized as having been influenced by ship exhaust (2.5 μg m−3), strong marine emissions (2.5 μg m−3) and fires (2.0 μg m−3) were more than twice that in the background cloud water (0.9 μg m−3). 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 NO3 − levels reaching as high as 9.0 μg m−3. Nucleation scavenging of chloride depleted sea-salt is a source of cloud water NO3 −, with the lowest Cl−:Na+ ratio (1.5) observed in ship-influenced samples. Surface aerosol measurements show that NO3 − concentrations peak in the particle diameter range of 1.0–5.6 μm, similar to Na, Cl− and Si, suggesting that drop activation of crustal particles and sea salt could be an important source of NO3 − in cloud water. The contrasting behavior of NO3 − and SO4 2− is emphasized by the NO3 −:SO4 2− 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 NO3 −:SO4 2− 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.
Graphical abstract Display Omitted
Highlights The major sources of NO3 − in the study region are ship and fire emissions. Entrainment of wildfire emissions can significantly increase NO3 − in clouds. Nitrate is associated with crustal particles in the coastal region. The nitrate-to-sulfate mass ratio decreases rapidly with cloud height. Volatilization during drop evaporation pushes NO3 − to the gas phase.
Sources of nitrate in stratocumulus cloud water: Airborne measurements during the 2011 E-PEACE and 2013 NiCE studies
https://orcid.org/0000-0003-4578-8658
https://orcid.org/0000-0001-9627-9074
https://orcid.org/0000-0002-2243-2264
Abstract This study examines the sources of NO3 − 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 NO3 − air-equivalent concentrations in cloud water samples categorized as having been influenced by ship exhaust (2.5 μg m−3), strong marine emissions (2.5 μg m−3) and fires (2.0 μg m−3) were more than twice that in the background cloud water (0.9 μg m−3). 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 NO3 − levels reaching as high as 9.0 μg m−3. Nucleation scavenging of chloride depleted sea-salt is a source of cloud water NO3 −, with the lowest Cl−:Na+ ratio (1.5) observed in ship-influenced samples. Surface aerosol measurements show that NO3 − concentrations peak in the particle diameter range of 1.0–5.6 μm, similar to Na, Cl− and Si, suggesting that drop activation of crustal particles and sea salt could be an important source of NO3 − in cloud water. The contrasting behavior of NO3 − and SO4 2− is emphasized by the NO3 −:SO4 2− 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 NO3 −:SO4 2− 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.
Graphical abstract Display Omitted
Highlights The major sources of NO3 − in the study region are ship and fire emissions. Entrainment of wildfire emissions can significantly increase NO3 − in clouds. Nitrate is associated with crustal particles in the coastal region. The nitrate-to-sulfate mass ratio decreases rapidly with cloud height. Volatilization during drop evaporation pushes NO3 − to the gas phase.
Sources of nitrate in stratocumulus cloud water: Airborne measurements during the 2011 E-PEACE and 2013 NiCE studies
Prabhakar, Gouri (Autor:in) / Ervens, B. (Autor:in) / Wang, Z. (Autor:in) / Maudlin, L.C. (Autor:in) / Coggon, M.M. (Autor:in) / Jonsson, H.H. (Autor:in) / Seinfeld, J.H. (Autor:in) / Sorooshian, A. (Autor:in)
Atmospheric Environment ; 97 ; 166-173
08.08.2014
8 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Coastal Stratocumulus cloud edge forecasts
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| DOAJ | 2021