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Black carbon solar absorption suppresses turbulence in the atmospheric boundary layer.
Proc Natl Acad Sci U S A 2016; 113(42):11794-11799PN

Abstract

The introduction of cloud condensation nuclei and radiative heating by sunlight-absorbing aerosols can modify the thickness and coverage of low clouds, yielding significant radiative forcing of climate. The magnitude and sign of changes in cloud coverage and depth in response to changing aerosols are impacted by turbulent dynamics of the cloudy atmosphere, but integrated measurements of aerosol solar absorption and turbulent fluxes have not been reported thus far. Here we report such integrated measurements made from unmanned aerial vehicles (UAVs) during the CARDEX (Cloud Aerosol Radiative Forcing and Dynamics Experiment) investigation conducted over the northern Indian Ocean. The UAV and surface data reveal a reduction in turbulent kinetic energy in the surface mixed layer at the base of the atmosphere concurrent with an increase in absorbing black carbon aerosols. Polluted conditions coincide with a warmer and shallower surface mixed layer because of aerosol radiative heating and reduced turbulence. The polluted surface mixed layer was also observed to be more humid with higher relative humidity. Greater humidity enhances cloud development, as evidenced by polluted clouds that penetrate higher above the top of the surface mixed layer. Reduced entrainment of dry air into the surface layer from above the inversion capping the surface mixed layer, due to weaker turbulence, may contribute to higher relative humidity in the surface layer during polluted conditions. Measurements of turbulence are important for studies of aerosol effects on clouds. Moreover, reduced turbulence can exacerbate both the human health impacts of high concentrations of fine particles and conditions favorable for low-visibility fog events.

Authors+Show Affiliations

Division of Atmospheric Sciences, Desert Research Institute, Reno, NV 89512; Eric.Wilcox@dri.edu r.thomas@bham.ac.uk vramanathan@ucsd.edu.Center for Clouds, Chemistry and Climate, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093; School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom; Eric.Wilcox@dri.edu r.thomas@bham.ac.uk vramanathan@ucsd.edu.Center for Clouds, Chemistry and Climate, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093; International Centre for Integrated Mountain Development, Kathmandu, Nepal.Center for Clouds, Chemistry and Climate, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093; Ames Research Center, Universities Space Research Association, National Aeronautics and Space Administration (NASA), Moffett Field, CA 94035.Department of Meteorology, Stockholm University, 106 91 Stockholm, Sweden; Bolin Centre for Climate Research, Stockholm University, 106 91 Stockholm, Sweden.Center for Clouds, Chemistry and Climate, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093; Eric.Wilcox@dri.edu r.thomas@bham.ac.uk vramanathan@ucsd.edu.

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

27702889

Citation

Wilcox, Eric M., et al. "Black Carbon Solar Absorption Suppresses Turbulence in the Atmospheric Boundary Layer." Proceedings of the National Academy of Sciences of the United States of America, vol. 113, no. 42, 2016, pp. 11794-11799.
Wilcox EM, Thomas RM, Praveen PS, et al. Black carbon solar absorption suppresses turbulence in the atmospheric boundary layer. Proc Natl Acad Sci USA. 2016;113(42):11794-11799.
Wilcox, E. M., Thomas, R. M., Praveen, P. S., Pistone, K., Bender, F. A., & Ramanathan, V. (2016). Black carbon solar absorption suppresses turbulence in the atmospheric boundary layer. Proceedings of the National Academy of Sciences of the United States of America, 113(42), pp. 11794-11799.
Wilcox EM, et al. Black Carbon Solar Absorption Suppresses Turbulence in the Atmospheric Boundary Layer. Proc Natl Acad Sci USA. 2016 10 18;113(42):11794-11799. PubMed PMID: 27702889.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Black carbon solar absorption suppresses turbulence in the atmospheric boundary layer. AU - Wilcox,Eric M, AU - Thomas,Rick M, AU - Praveen,Puppala S, AU - Pistone,Kristina, AU - Bender,Frida A-M, AU - Ramanathan,Veerabhadran, Y1 - 2016/10/04/ PY - 2016/10/30/pubmed PY - 2016/10/30/medline PY - 2016/10/6/entrez KW - aerosols KW - atmospheric turbulence KW - autonomous unmanned aerial vehicles KW - cloud cover KW - radiative forcing SP - 11794 EP - 11799 JF - Proceedings of the National Academy of Sciences of the United States of America JO - Proc. Natl. Acad. Sci. U.S.A. VL - 113 IS - 42 N2 - The introduction of cloud condensation nuclei and radiative heating by sunlight-absorbing aerosols can modify the thickness and coverage of low clouds, yielding significant radiative forcing of climate. The magnitude and sign of changes in cloud coverage and depth in response to changing aerosols are impacted by turbulent dynamics of the cloudy atmosphere, but integrated measurements of aerosol solar absorption and turbulent fluxes have not been reported thus far. Here we report such integrated measurements made from unmanned aerial vehicles (UAVs) during the CARDEX (Cloud Aerosol Radiative Forcing and Dynamics Experiment) investigation conducted over the northern Indian Ocean. The UAV and surface data reveal a reduction in turbulent kinetic energy in the surface mixed layer at the base of the atmosphere concurrent with an increase in absorbing black carbon aerosols. Polluted conditions coincide with a warmer and shallower surface mixed layer because of aerosol radiative heating and reduced turbulence. The polluted surface mixed layer was also observed to be more humid with higher relative humidity. Greater humidity enhances cloud development, as evidenced by polluted clouds that penetrate higher above the top of the surface mixed layer. Reduced entrainment of dry air into the surface layer from above the inversion capping the surface mixed layer, due to weaker turbulence, may contribute to higher relative humidity in the surface layer during polluted conditions. Measurements of turbulence are important for studies of aerosol effects on clouds. Moreover, reduced turbulence can exacerbate both the human health impacts of high concentrations of fine particles and conditions favorable for low-visibility fog events. SN - 1091-6490 UR - https://www.unboundmedicine.com/medline/citation/27702889/Black_carbon_solar_absorption_suppresses_turbulence_in_the_atmospheric_boundary_layer_ L2 - http://www.pnas.org/cgi/pmidlookup?view=long&pmid=27702889 DB - PRIME DP - Unbound Medicine ER -