ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-12-207-2012 Aerosol concentration and size distribution measured below, in, and above cloud from the DOE G-1 during VOCALS-REx Kleinman L. I. 1 Daum P. H. 1 Lee Y.-N. 1 Lewis E. R. 1 Sedlacek III A. J. 1 Senum G. I. 1 Springston S. R. 1 Wang J. 1 Hubbe J. 2 Jayne J. 3 Min Q. 4 Yum S. S. 5 Allen G. 6 Atmospheric Sciences Division, Brookhaven National Laboratory, Upton, New York, USA Atmospheric Sciences & Global Change Division, Pacific Northwest National Laboratory, Richland, Washington, USA Aerodyne Research Inc., Billerica, Massachusetts, USA Atmospheric Sciences Research Center, State University of New York, Albany, New York, USA Department of Atmospheric Sciences, Yonsei University, Seoul 120749, South Korea Centre for atmospheric Science, University of Manchester, Manchester M13 9PL, UK 04 01 2012 12 1 207 223 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/12/207/2012/acp-12-207-2012.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/12/207/2012/acp-12-207-2012.pdf

During the VOCALS Regional Experiment, the DOE G-1 aircraft was used to sample a varying aerosol environment pertinent to properties of stratocumulus clouds over a longitude band extending 800 km west from the Chilean coast at Arica. Trace gas and aerosol measurements are presented as a function of longitude, altitude, and dew point in this study. Spatial distributions are consistent with an upper atmospheric source for O<sub>3</sub> and South American coastal sources for marine boundary layer (MBL) CO and aerosol, most of which is acidic sulfate. Pollutant layers in the free troposphere (FT) can be a result of emissions to the north in Peru or long range transport from the west. At a given altitude in the FT (up to 3 km), dew point varies by 40 °C with dry air descending from the upper atmospheric and moist air having a boundary layer (BL) contribution. Ascent of BL air to a cold high altitude results in the condensation and precipitation removal of all but a few percent of BL water along with aerosol that served as CCN. Thus, aerosol volume decreases with dew point in the FT. Aerosol size spectra have a bimodal structure in the MBL and an intermediate diameter unimodal distribution in the FT. Comparing cloud droplet number concentration (CDNC) and pre-cloud aerosol (<i>D</i><sub><i>p</i></sub>>100 nm) gives a linear relation up to a number concentration of ~150 cm<sup>−3</sup>, followed by a less than proportional increase in CDNC at higher aerosol number concentration. A number balance between below cloud aerosol and cloud droplets indicates that ~25 % of aerosol with <i>D</i><sub><i>p</i></sub>>100 nm are interstitial (not activated). A direct comparison of pre-cloud and in-cloud aerosol yields a higher estimate. Artifacts in the measurement of interstitial aerosol due to droplet shatter and evaporation are discussed. Within each of 102 constant altitude cloud transects, CDNC and interstitial aerosol were anti-correlated. An examination of one cloud as a case study shows that the interstitial aerosol appears to have a background, upon which is superimposed a high frequency signal that contains the anti-correlation. The anti-correlation is a possible source of information on particle activation or evaporation.

 References Allen, G., Coe, H., Clarke, A., Bretherton, C., Wood, R., Abel, S. J., Barrett, P., Brown, P., George, R., Freitag, S., McNaughton, C., Howell, S., Shank, L., Kapustin, V., Brekhovskikh, V., Kleinman, L., Lee, Y.-N., Springston, S., Toniazzo, T., Krejci, R., Fochessato, J., Shaw, G., Krecl, P., Brooks, B., McMeeking, G., Bower, K. N., Williams, P. I., Crosier, J., Crawford, I., Connolly, P., Allan, J. D., Covert, D., Bandy, A. R., Russell, L. M., Trembath, J., Bart, M., McQuaid, J. B., Wang, J., and Chand, D.: Southeast Pacific atmospheric composition and variability sampled along 20° S during VOCALS-REx, Atmos. Chem. Phys., 11, 5237–5262, http://dx.doi.org/10.5194/acp-11-5237-2011doi:10.5194/acp-11-5237-2011, 2011. Ayers, G. P., Penkett, S. A., Gillett, R. W., Bandy, B., Galbally, I. E., Meyer, C. P., Elsworth, C. M., Bentley, S. T., and Forgan, B. W.: Evidence for photochemical control of ozone concentrations in unpolluted marine air, Nature, 360, 446–449, 1992. Brechtel, F. J.: Description and assessment of a new aerosol inlet for the DOE G-1 research aircraft, final technical report of work performed by BMI under contract #0000058843 to Brookhaven National Laboratory, August 2003. Brenguier, J.-L., Pawlowska, H., Schüller, L., Preusker, R., Fisher, J., and Fouquart, Y.: Radiative properties of boundary layer clouds: Droplet effective radius versus number concentration, J. Atmos. Sci., 57, 803–821, 2000. Bretherton, C. S., Wood, R., George, R. C., Leon, D., Allen, G., and Zheng, X.: Southeast Pacific stratocumulus clouds, precipitation and boundary layer structure sampled along 20° S during VOCALS-Rex, Atmos. Chem. Phys., 10, 10639–10654, http://dx.doi.org/10.5194/acp-10-10639-2010doi:10.5194/acp-10-10639-2010, 2010. Cantrell, W., Shaw, G., and Benner, R.: Cloud properties inferred from bimodal aerosol number distribution, J. Geophys. Res., 104, 27615–27624, 1999. Chand, D., Hegg, D. A., Wood, R., Shaw, G. E., Wallace, D., and Covert, D. S.: Source attribution of climatically important aerosol properties measured at Paposo (Chile) during VOCALS, Atmos. Chem. Phys., 10, 10789–10801, http://dx.doi.org/10.5194/acp-10-10789-2010doi:10.5194/acp-10-10789-2010, 2010. Clarke, A. D., Li, Z., and Litchy, M.: Aerosol dynamics in the equatorial Pacific Marine boundary layer: Microphysics, diurnal cycles and entrainment, Geophys. Res. Lett., 23, 773–736, 1996. Clarke, A. D., Uehara, T., and Porter, J. N.: Atmospheric nuclei and related aerosol fields over the Atlantic: Clean subsiding air and continental pollution during ASTEX, J. Geophys. Res., 102, 25281–25292, 1997. Clegg, S. L., Brimblecombe, P., and Wexler, A. S.: A thermodynamic model of the system H$^+$-NH$_4^+$-SO$_4^2-$-NO$_3^-$-H<sub>2</sub>O at tropospheric temperatures, J. Phys. Chem. A, 102, 2137–2154, 1998. Clegg, S. L. and Wexler, A. S.: Densities and apparent molar volumes of atmospherically important electrolyte solutions. 2. The system H$^+$-HSO$_4^-$-SO$_4^2-$-H<sub>2</sub>O from 0-3 mol kg<sup>−1</sup> as a function of temperature and H$^+$-NH$_4^+$-HSO$_4^-$-SO$_4^2-$-H<sub>2</sub>O from 0-6 mol kg<sup>−1</sup> at 25\r C using a Pitzer ion interaction model, and NH<sub>4</sub>HSO<sub>4</sub>-H<sub>2</sub>O and (NH$_4)_3$H(SO$_4)_2$-H<sub>2</sub>O over the entire concentration range. J. Phys. Chem. A 115, 3461–3474, 2011. Collins, D. R., Flagan, R. C., and Seinfeld, J. H., Improved inversion of scanning DMA data, Aerosol Sci. Technol., 36, 1–9, 2002. Draxler, R. R. and Rolph, G. D.: HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) Model access via NOAA ARL READY Website available at: http://ready.arl.noaa.gov/HYSPLIT.php, last access: January 2011, NOAA Air Resources Laboratory, Silver Spring, MD, USA, 2010. Faloona, I., Lenschow, D. H., Campos, T., Stevens, B., van Zanten, M., Blomquist, B., Thornton, D., Bandy, A., and Gerber, H.: Observations of entrainment in Eastern Pacific marine stratocumulus using three conserved scalers, J. Atmos. Sci., 62, 3268–3285, 2005. Fountoukis, C., Nenes, A., Meskhidze, N., Bahreini, R., Conant, W. C., Jonsson, H., Murphy, S., Sorooshian, A., Varutbangkul, V., Brechtel, F., Flagan, R. C., and Seinfeld, J. H.: Aerosol-cloud drop concentration closure for clouds sampled during the Intercontinental Consortium for Atmospheric Research on Transport and Transformation 2004 campaign, J. Geophys. Res., 112, D10S30, http://dx.doi.org/10.1029/2006JD007272doi:10.1029/2006JD007272, 2007. Gerber, H., Arends, B. G., and Ackerman, A. S.: A new microphysics sensor for aircraft use, Atmos, Res., 31, 235–252, 1994. Gerber, H., Frick, G., Malinowski, S. P., Brenguier, J.-L., and Burnet, F.: Holes and entrainment in stratocumulus, J. Atmos. Sci., 62, 443–459, 2005. Gillani, N. V., Schwartz, S. E., Leaitch, W. R., Strapp, J. W., and Isaac, G. A.: Field observations in continental stratiform clouds: Partitioning of cloud particles between droplets and unactivated interstitial aerosols, J. Geophys. Res., 100, 18687–18706, 1995. Guibert, S., Snider, J. R., and Brenguier, J.-L.: Aerosol activation in marine stratocumulus clouds: 1. Measurement validation for a closure study, J. Geophys. Res., 108, 8628, http://dx.doi.org/10.1029/2002JD002678doi:10.1029/2002JD002678, 2003. Gultepe, I., Isaac, G. A., Leaitch, W. R., and Banic, C. M.: Parameterizations of marine stratus microphysics based on in situ observations: Implications for GCMs, J. Climate., 9, 345–357, 1996. Hallar, A. G., Strawa, A. W., Schmid, B., Andrews, E., Ogren, J., Sheridan, P., Ferrare, R., Covert, D., Elleman, R., Jonsson, H., Bokarius, K., and Luu, A.: Atmospheric Radiation Measurements Aerosol Intensive Operating Period: Comparison of aerosol scattering during coordinated flights, J. Geophys. Res., 111, D05S09, http://dx.doi.org/10.1029/2005JD006250doi:10.1029/2005JD006250, 2006. Hallberg, A., Noone, K. J., Ogren, J. A., Svenningsson, I. B., Flossmann, A., Wiedensohler, A., Hansson, H.-C., Heintzenberg, J., Anderson, T. L., Arends, B. G., and Maser, R., Phase partitioning of aerosol particles in clouds at Kleiner Feldberg, J. Atmos. Chem., 19, 107–127, 1994. Henning, S., Weingartner, E., Schmidt, S., Wendisch, M., Gäggeler, H. W., and Baltensperger, U., Size-dependent aerosol activation at the high-alpine site Jungfraujoch (3580 m asl), Tellus, 54B, 82–95, 2002. Hoppel, W. A., Frick, G. M., and Larson, R. E.: Effects of nonprecipitating clouds on the aerosol size distribution in the marine boundary layer, Geophys. Res. Lett., 13, 125–128, 1986. Hudson, J. G. and Frisbie, P. R.: Cloud condensation nuclei near marine stratus, J. Geophys. Res., 96, 20795–20808, 1991. Kleinman, L. I. and Daum, P. H.: Vertical distribution of aerosol particles, water vapor, and insoluble trace gases in convectively mixed air, J. Geophys. Res., 96, 991–1005, 1991. Kleinman, L. I., Daum, P. H., Lee, Y.-N., Senum, G. I., Springston, S. R.,Wang, J., Berkowitz, C., Hubbe, J., Zaveri, R. A., Brechtel, F. J., Jayne, J., Onasch, T. B., and Worsnop, D.: Aircraft observations of aerosol composition and ageing in New England and Mid-Atlantic States during the summer 2002 New England Air Quality Study field campaign, J. Geophys. Res., 112, D09310, http://dx.doi.org/10.1029/2006JD007786doi:10.1029/2006JD007786, 2007. Kleinman, L. I., Springston, S. R., Daum, P. H., Lee, Y.-N., Nunnermacker, L. J., Senum, G. I., Wang, J., Weinstein-Lloyd, J., Alexander, M. L., Hubbe, J., Ortega, J., Canagaratna, M. R., and Jayne, J.: The time evolution of aerosol composition over the Mexico City plateau, Atmos. Chem. Phys., 8, 1559–1575, http://dx.doi.org/10.5194/acp-8-1559-2008doi:10.5194/acp-8-1559-2008, 2008. Kleinman, L I. et al.: Interactive comment on "Aerosol concentration and size distribution below, in, and above cloud from the DOE G-1 during VOCALS-REx", Atmos. Chem. Phys. Discuss., 11, C6380–C6384, http://dx.doi.org/10.5194/acpd-11-C6380-2011doi:10.5194/acpd-11-C6380-2011, 2011. Kley, D., Crutzen, P. J., Smit, H. G. J., Vömel, H., Oltmans, S. J., Grassl, H., and Ramamathan, V.: Observations of near-zero ozone concentrations over the convective Pacific: Effects on air chemistry, Science, 274, 230–233, 2006. Lance, S., Brock, C. A., Rogers, D., and Gordon, J. A.: Water droplet calibration of the Cloud Droplet Probe (CDP) and in-flight performance in liquid, ice, and mixed-phase clouds during ARPAC, Atmos. Meas. Tech., 3, 1683–1706, http://dx.doi.org/10.5194/amt-3-1683-2010doi:10.5194/amt-3-1683-2010, 2010. Lance, S.: Interactive comment on "Aerosol concentration and size distribution measured below, in, and above cloud from the DOE G-1 during VOCALS-REx" by L I. Kleinman et al., Atmos. Chem. Phys. Discuss., 11, C5622–C5623, http://dx.doi.org/10.5194/acpd-11-C5622-2011doi:10.5194/acpd-11-C5622-2011, 2011. Leaitch, W. R., Strapp, J., and Isaac, G. A.: Cloud droplet nucleation and cloud scavenging of aerosol sulphate in polluted atmospheres, Tellus, 38B, 328–344, 1986. Leaitch, W. R., Banic, C. M., Isaac, G. A., Couture, M. D., Liu, P. S. K., Gultepe, I., Li, S.-M., Kleinman, L. I., Daum, P. H., and MacPherson, J. I.: Physical and chemical observations in marine stratus during the 1993 North Atlantic Regional Experiment: Factors controlling cloud droplet number concentrations, J. Geophys. Res., 101, 29123–29135, 1996. Lee, Y.-N., Springston, S., Jayne, J., Wang, J., Senum, G., Hubbe, J., Alexander, L., Brioude, J., Spak, S., Mena-Carrasco, M., Kleinman, L., and Daum, P.: Aerosol composition, chemistry, and source characterization during the 2008 VOCALS Experiment, Atmos. Chem. Phys. Discuss., in preparation, 2011. Martinsson, B. G., Frank, G., Cederfelt, S.-I., Swietlicki, E., Berg, O. H., Zhou, J., Bower, K. N., Bradbury, C., Birmili, W., Stratmann, F., Wendisch, M., Wiedensohler, A., and Yuskiewicz, B. A.: Droplet nucleation and growth in orographic clouds in relation to the aerosol population, Atmos. Res., 50, 289–315, 1999. McGraw, R., and Liu, Y.: Brownian drift-diffusion model for evolution of droplet size distributions in turbulent clouds, Geophys. Res. Lett., 33, L03802, http://dx.doi.org/10.1029/2005GL023545doi:10.1029/2005GL023545, 2006. Mertes, S., Lehmann, K., Nowak, A., Massling, A., and Wiedensohler, A.: Link between aerosol hygroscopic growth and droplet activation observed for hill-capped clouds at connected flow conditions during FEBUKO, Atmos. Environ., 39, 4247–4256, 2005. Parrish, D. D., Trainer, M., Holloway, J. S., Yee, J. E., Warshawsky, M. S., Fehsenfeld, F. C., Forbes, G. L., and Mody, J. L.: Relationship between ozone and carbon monoxide at surface sites in the North Atlantic region, J. Geophys. Res., 103, 13357–13376, 1998. Rahn, D. A., and Garreaud, R.: Marine boundary layer over the subtropical southeast Pacific during VOCALS-REx – Part 1: Mean structure and diurnal cycle, Atmos. Chem. Phys., 10, 4491–4506, http://dx.doi.org/10.5194/acp-10-4491-2010doi:10.5194/acp-10-4491-2010, 2010. Ramanathan, V., Crutzen, P. J., Kiehl, J. T., and Rosenfeld, D.: Aerosols, climate, and the hydrological cycle, Science, 294, 2119–2124, 2001. Robinson, N. F.: The efficient numerical calculation of condensational cloud droplet growth, J. Atmos. Sci., 41, 698–700, 1984. Schwartz, S. E. and Slingo, A.: Enhanced shortwave cloud radiative forcing due to anthropogenic aerosols, in Clouds, Chemistry and Climate – Proceedings of NATO Advanced Research Workshop, Ringberg, Germany, 21–25 March 1994, edited by: Crutzen, P. and Ramanathan, V., Springer, Heidelberg, Germany, 191–236, 1996. Snider, J. R. and Brenguier, J.-L.: Cloud condensation nuclei and cloud droplet measurements during ACE-2, Tellus, 52B, 828–842, 2000. Snider, J. R. and Petters, M. D., Optical particle counter measurement of marine aerosol hygroscopic growth, Atmos. Chem. Phys., 8, 1949–1962, http://dx.doi.org/10.5194/acp-8-1949-2008doi:10.5194/acp-8-1949-2008, 2008. Snider, J. R., Guibert, S., Brenguier, J.-L., and Putard, J.-P.: Aerosol activation in marine stratocumulus clouds: 2. Köhler and parcel theory closure studies, J. Geophys. Res., 108, 8629, http://dx.doi.org/10.1029/2002JD002692doi:10.1029/2002JD002692, 2003. Stevens, B. and Feingold, G.: Untangling aerosol effects on clouds and precipitation in a buffered system, Nature, 461, 607–613, 2009. Strapp, J. W., Leaitch, W. R., and Liu, P. S. K.: Hydrated and dried aerosol-size distribution measurements fro the Particle Measuring Systems FSSP-300 Probe and the deiced PCASP-100X Probe, J. Atmos. Oceanic Technol., 9, 548–555, 1992. Springston, S. R., Kleinman, L. I., Nunnermacker, L. J., Brechtel, F., Lee, Y.-N., and Wang, J.: Chemical evolution of an isolated power plant plume during the TexAQs 2000 study, Atmos. Environ., 39, 3431–3443, 2005. Twohy, C. H., Petters, M. D., Snider, J. R., Stevens, B., Tahnk, W., Wetzel, M., Russell, L., and Burnet, F.: Evaluation of the aerosol indirect effect in marine stratocumulus clouds: Droplet number, size, liquid water path, and radiative impact, J. Geophys. Res., 110, D08203, http://dx.doi.org/10.1029/2004JD005116doi:10.1029/2004JD005116, 2005. Wang, J., Daum, P. H., Yum, S. S., Liu, Y., Senum, G. I., Lu, M.-L., Seinfeld, J. H., and Jonsson, H.: Observations of marine stratocumulus microphysics and implications for processes controlling droplet spectra: Results from the Marine Stratus/Stratocumulus Experiment, J. Geophys. Res., 114, D18210, http://dx.doi.org/10.1029/2008JD011035doi:10.1029/2008JD011035, 2009. Weber, R. J., Clarke, A. D., Litchy, M., Li, J., Kok, G., Schillawski, R. D., and McMurry, P. H.: Spurious aerosol measurements when sampling from aircraft in the vicinity of clouds, J Geophys. Res., 103, 28337–28346, 1998. Wood, R., Bretherton, C., Huebert, B., Mechoso, C. R., and Weller, R., VOCALS-SouthEast Pacific Regional Experiment (REx) Scientific Program Overview, available online at: http://www.eol.ucar.edu/projects/vocals/documentation/vocals_overview.pdf last access: January 2011, June 2007. Wood, R., Mechoso, C. R., Bretherton, C. S., Weller, R. A., Huebert, B., Straneo, F., Albrecht, B. A., Coe, H., Allen, G., Vaughan, G., Daum, P., Fairall, C., Chand, D., Gallardo Klenner, L., Garreaud, R., Grados, C., Covert, D. S., Bates, T. S., Krejci, R., Russell, L. M., de Szoeke, S., Brewer, A., Yuter, S. E., Springston, S. R., Chaigneau, A., Toniazzo, T., Minnis, P., Palikonda, R., Abel, S. J., Brown, W. O. J., Williams, S., Fochesatto, J., Brioude, J., and Bower, K. N.: The VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx): goals, platforms, and field operations, Atmos. Chem. Phys., 11, 627–654, http://dx.doi.org/10.5194/acp-11-627-2011doi:10.5194/acp-11-627-2011, 2011. Yang, Q., W. I. Gustafson Jr., Fast, J. D., Wang, H., Easter, R. C., Morrison, H., Lee, Y.-N., Chapman, E. G., Spak, S. N., and Mena-Carrasco, M. A.: Assessing regional scale predictions of aerosols, marine stratocumulus, and their interactions during VOCALS-REx using WRF-Chem, Atmos. Chem. Phys., 11, 11951–11975, http://dx.doi.org/10.5194/acp-11-11951-2011doi:10.5194/acp-11-11951-2011, 2011.