ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-11-3673-2011 Airborne observation of aerosol optical depth during ARCTAS: vertical profiles, inter-comparison and fine-mode fraction Shinozuka Y. 1 2 Redemann J. 2 Livingston J. M. 3 Russell P. B. 4 Clarke A. D. 5 Howell S. G. 5 Freitag S. 5 O'Neill N. T. 6 Reid E. A. 7 Johnson R. 4 Ramachandran S. 1 8 McNaughton C. S. 5 11 Kapustin V. N. 5 Brekhovskikh V. 5 Holben B. N. 9 McArthur L. J. B. 10 NASA Postdoctoral Program, NASA Ames Research Center, Moffett Field, California, USA Bay Area Environmental Research Institute, Sonoma, California, USA SRI International, Menlo Park, California, USA NASA Ames Research Center, Moffett Field, California, USA School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, Hawaii, USA CARTEL, Université de Sherbrooke, Sherbrooke, Québec, Canada Marine Meteorology Division, Naval Research Laboratory, Monterey, California, USA Physical Research Laboratory, Ahmedabad, India NASA Goddard Space Flight Center, Greenbelt, Maryland, USA Environment Canada, Toronto, Ontario, Canada now at: Aina Kai Environmental, LLC, Aiea, Hawaii, USA 20 04 2011 11 8 3673 3688 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/11/3673/2011/acp-11-3673-2011.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/3673/2011/acp-11-3673-2011.pdf

We describe aerosol optical depth (AOD) measured during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) experiment, focusing on vertical profiles, inter-comparison with correlative observations and fine-mode fraction. Arctic haze observed in <2 km and 2–4 km over Alaska in April 2008 originated mainly from anthropogenic emission and biomass burning, respectively, according to aerosol mass spectrometry and black carbon incandescence measurements. The Ångström exponent for these air masses is 1.4 ± 0.3 and 1.7 ± 0.1, respectively, when derived at 499 nm from a second-order polynomial fit to the AOD spectra measured with the 14-channel Ames Airborne Tracking Sunphotometer (AATS-14) over 354–2139 nm. We examine 55 vertical profiles selected from all phases of the experiment. For two thirds of them, the AOD spectra are within 3% + 0.02 of the vertical integral of local visible-light scattering and absorption. The horizontal structure of smoke plumes from local biomass burning observed in central Canada in June and July 2008 explains most outliers. The differences in mid-visible Ångström exponent are <0.10 for 63% of the profiles with 499-nm AOD > 0.1. The retrieved fine-mode fraction of AOD is mostly between 0.7 and 1.0, and its root mean square difference (in both directions) from column-integral submicron fraction (measured with nephelometers, absorption photometers and an impactor) is 0.12. These AOD measurements from the NASA P-3 aircraft, after compensation for below-aircraft light attenuation by vertical extrapolation, mostly fall within ±0.02 of AERONET ground-based measurements between 340–1640 nm for five overpass events.

 References Allan, J. D., Coe, H., Bower, K. N., Alfarra, M. R., Delia, A. E., Jimenez, J. L., Middlebrook, A. M., Drewnick, F., Onasch, T. B., Canagaratna, M. R., Jayne, J. T., and Worsnop, D. R.: Technical Note: Extraction of Chemically Resolved Mass Spectra from Aerodyne Aerosol Mass Spectrometer Data, J. Aerosol Sci., 35, 909–922, 2004. Anderson, T. L. and Ogren, J. A.: Determining aerosol radiative properties using the TSI 3563 integrating nephelometer, Aerosol Sci. Technol., 29, 57–69, 1998. Anderson, T. L., Covert, D. S., Marshall, S. F., Laucks, M. L., Charlson, R. J., Waggoner, A. P., Ogren, J. A., Caldow, R., Holm, R. L., Quant, F. R., Sem, G. J., Wiedensohler, A., Ahlquist, N. A., and Bates, T. S.: Performance characteristics of a high-sensitivity, three-wavelength, total scatter/backscatter nephelometer, J. Atmos. Ocean. Tech., 13, 967–986, 1996. Anderson, T. L., Charlson, R. J., Winker, D. M., Ogren, J. A., and Holmen, K.: Mesoscale variations of tropospheric aerosols, J. Atmos. Sci., 60, 119-136, 2003. Anderson, T. L., Wu, Y. H., Chu, D. A., Schmid, B., Redemann, J., and Dubovik, O.: Testing the MODIS satellite retrieval of aerosol fine-mode fraction, J. Geophys. Res.-Atmos., 110, D18204, doi:10.1029/2005JD005978, 2005. Campbell, J. R., Hlavka, D. L., Welton, E. J., Flynn, C. J., Turner, D. D., Spinhirne, J. D., Scott, V. S., and Hwang, I. H.: Full-time, Eye-Safe Cloud and Aerosol Lidar Observation at Atmospheric Radiation Measurement Program Sites: Instrument and Data Processing, J. Atmos. Oceanic Tech., 19, 431–442, 2002. Canagaratna, M. R., Jayne, J. T., Jimenez, J. L., Allan, J. D., Alfarra, M. R., Zhang, Q., Onasch, T. B., Drewnick, F., Coe, H., Middlebrook, A., Delia, A., Williams, L. R., Trimborn, A. M., Northway, M. J., DeCarlo, P. F., Kolb, C. E., Davidovits, P., and Worsnop, D. R.: Chemical and Microphysical Characterization of Ambient Aerosols with the Aerodyne Aerosol Mass Spectrometer, Mass Spectrom. Rev., 26, 185–22, 2007. Chu, D. A., Remer, L. A., Kaufman, Y. J., Schmid, B., Redemann, J., Knobelspiesse, K., Chern, J.-D., Livingston, J., Russell, P. B., Xiong, X., and Ridgway, W.: Evaluation of aerosol properties over ocean from Moderate Resolution Imaging Spectroradiometer (MODIS) during ACE-Asia, J. Geophys. Res., 110, D07308, doi:07310.01029/02004JD005208, 2005. Clarke, A. D., Varner, J. L., Eisele, F., Mauldin, R. L., Tanner, D., and Litchy, M.: Particle production in the remote marine atmosphere: Cloud outflow and subsidence during ACE 1, J. Geophys. Res., 103, 16397–316409, 1998. DeCarlo, P. F., Kimmel, J. R., Trimborn, A., Northway, M. J., Jayne, J. T., Aiken, A. C., Gonin, M., Fuhrer, K., Horvath, T., Docherty, K., Worsnop, D. R., and Jimenez, J. L.: Field-Deployable, High-Resolution, Time-of-Flight Aerosol Mass Spectrometer, Anal. Chem., 78, 8281–8289, 2006. Dubovik, O. and King, M. D.: A flexible inversion algorithm for retrieval of aerosol optical properties from Sun and sky radiance measurements, J. Geophys. Res., 105, 20673–20696, 2000. Dubovik, O., Smirnov, A., Holben, B. N., King, M. D., Kaufman, Y. J., Eck T. F., and Slutsker, I.: Accuracy assessment of aerosol optical properties retrieval from AERONET sun and sky radiance measurements, J. Geophys. Res., 105, 9791–9806, 2000. Dubovik, O., Holben, B., Eck, T. F., Smirnov, A., Kaufman, Y. J., King, M. D., Tanre, D., and Slutsker, I.: Variability of absorption and optical properties of key aerosol types observed in worldwide locations, J. Atmos. Sci., 59, 590–608, 2002. Eck, T. F., Holben, B. N., Reid, J. S., Dubovik, O., Smirnov, A., O'Neill, N. T. O., Slutsker, I., and Kinne, S.: Wavelength dependence of the optical depth of biomass burning, urban, and desert dust aerosols, J. Geophys. Res., 104, 31333–31349, 1999. Eck, T. F., Holben, B. N., Dubovik, O., Smirnov, A., Slutsker, I., Lobert, J. M., and Ramanathan, V.: Column-integrated aerosol optical properties over the Maldives during the northeast monsoon for 1998&#8211;2000, J. Geophys. Res., 106, 28555–28566, 2001. Fuelberg, H. E., Harrigan, D. L., and Sessions, W.: A meteorological overview of the ARCTAS 2008 mission, Atmos. Chem. Phys., 10, 817–842, http://dx.doi.org/10.5194/acp-10-817-2010doi:10.5194/acp-10-817-2010, 2010. Ferek, R. J., Hobbs, P. V., Radke, L. F., Herring, J. A., Sturges, W. T., and Cota, G. F.: Dimethyl sulfide in the arctic atmosphere, J. Geophys. Res., 100, 26093–26104, 1995. Garrett, T. J., Hobbs, P. V., and Radke, L. F.: High Aitken Nucleus Concentrations above Cloud Tops in the Arctic, J. Atmos.Sci. , 59, 779–783, 2002. Garrett, T. J., Zhao, C., Dong, X., Mace, G. G., and Hobbs, P. V.: Effects of varying aerosol regimes on low-level Arctic stratus, Geophys. Res. Lett., 31, L17105, doi:10.1029/2004GL019928, 2004. Gassó, S.,and Hegg, D. A.: On the retrieval of columnar aerosol mass and CCN concentration by MODIS, J. Geophys. Res.-Atmos., 108, 4010, doi:10.1029/2002JD002382, 2003. Gassó, S. and O'Neill, N.: Comparisons of remote sensing retrievals and in situ measurements of aerosol fine mode fraction during ACE-Asia, Geophys. Res. Lett., 33, L05807, doi:10.1029/2005GL024926, 2006. Holben, B. N., Eck, T. F., Slutsker, I., Tanre, D., Buis, J. P., Setzer, A., Vermote, E., Reagan, J. A., Kaufman, Y. J., Nakajima, T., Lavenu, F., Jankowiak, I., and Smirnov, A.: AERONET – A federated instrument network and data archive for aerosol characterization, Remote Sens. Environ., 66, 1–16, 1998. Holben, B. N., Tanré, D., Smirnov, A., Eck, T. F., Slutsker, I., Abuhassan, N., Newcomb, W. W., Schafer, J. S., Chatenet, B., Lavenu, F., Kaufman, Y. J., Castle, J. V., Setzer, A., Markham, B., Clark, D., Frouin, R., Halthore, R., Karneli, A., O'Neill, N. T., Pietras, C., Pinker, R. T., Voss, K., and Zibordi, G.: An emerging ground-based aerosol climatology: Aerosol optical depth from AERONET, J. Geophys. Res., 106, 12067–12097, 2001. Jacob, D. J., Crawford, J. H., Maring, H., Clarke, A. D., Dibb, J. E., Emmons, L. K., Ferrare, R. A., Hostetler, C. A., Russell, P. B., Singh, H. B., Thompson, A. M., Shaw, G. E., McCauley, E., Pederson, J. R., and Fisher, J. A.: The Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) mission: design, execution, and first results, Atmos. Chem. Phys., 10, 5191–5212, http://dx.doi.org/10.5194/acp-10-5191-2010doi:10.5194/acp-10-5191-2010, 2010. Jethva, H., Satheesh, S. K., and Srinivasan, J.: Seasonal variability of aerosols over the Indo-Gangetic basin, J. Geophys. Res., 110, D21204, doi:10.1029/2005JD005938, 2005. Jethva, H., Satheesh, S. K., and Srinivasan, J.: Evaluation of Moderate-Resolution Imaging Spectroradiometer (MODIS) Collection 004 (C004) aerosol retrievals at Kanpur, Indo-Gangetic Basin, J. Geophys. Res., 112, D14216, doi:10.1029/2006JD007929, 2007. Kaufman, Y., Tanré, D., and Boucher, O.: A satellite view of aerosols in the climate system, Nature, 419, 215–223, 2002. Kleidman, R. G., O'Neill, N. T., Remer, L. A., Kaufman, Y. J., Eck, T. F., Tanré, D., Dubovik, O., and Holben, B. N.: Comparison of Moderate Resolution Imaging Spectroradiometer (MODIS) and Aerosol Robotic Network (AERONET) remote-sensing retrievals of aerosol fine mode fraction over ocean, J. Geophys. Res., 110, doi:10.1029/2005JD005760, 2005. Levy, R. C., Remer, L. A., Tanré, D., Kaufman, Y. J., Ichoku, C., Holben, B. N., Livingston, J. M., Russell, P. B., and Maring, H. B.: Evaluation of the Moderate-Resolution Imaging Spectroradiometer (MODIS) retrievals of dust aerosol over the ocean during PRIDE, J. Geophys. Res., 108, 8594, doi:8510.1029/2002JD002460, 2003. Levy, R.C., L.A. Remer, J.V. Martins, Y.J. Kaufman, A. Plana-Fattori, J. Redemann, B. Wenny, Evaluation of the MODIS aerosol retrievals over ocean and land during CLAMS, J. Atmos. Sci., 62(4), 974–992, 2005. Livingston, J. M., Russell, P. B., Reid, J. S., Redemann, J., Schmid, B., Allen, D. A., Torres, O., Levy, R. C., Remer, L. A., Holben, B. N., Smirnov, A., Dubovik, O., Welton, E. J., Campbell, J. R., Wang, J., and Christopher, S. A.: Airborne Sun photometer measurements of aerosol optical depth and columnar water vapor during the Puerto Rico Dust Experiment and comparison with land, aircraft, and satellite measurements, J. Geophys. Res., 108, 8588, doi:8510.1029/2002JD002520, 2003. Livingston, J. M., Schmid, B., Russell, P. B., Eilers, J. A., Kolyer, R. W., Redemann, J., Ramirez, S. R., Yee, J.-H., Swartz, W. H., Trepte, C. R., Thomason, L. W., Pitts, M. C., Avery, M. A., Randall, C. E., Lumpe, J. D., Bevilacqua, R. M., Bittner, M., Erbertseder, T., McPeters, R. D., Shetter, R. E., Browell, E. V., Kerr, J. B., and Lamb, K.: Retrieval of ozone column content from airborne Sun photometer measurements during SOLVE II: comparison with coincident satellite and aircraft measurements, Atmos. Chem. Phys., 5, 2035–2054, http://dx.doi.org/10.5194/acp-5-2035-2005doi:10.5194/acp-5-2035-2005, 2005. Livingston, J. M., Schmid, B., Redemann, J., Russell, P. B., Ramirez, S. A., Eilers, J., Gore, W., Howard, S., Pommier, J., Fetzer, E. J., Seemann, S. W., Borbas, E., Wolfe, D. E., and Thompson, A. M., Comparison of water vapor measurements by airborne Sun photometer and near-coincident in situ and satellite sensors during INTEX/ITCT 2004, J. Geophys. Res., 112, D12S16, http://dx.doi.org/10.1029/2006JD007733doi:10.1029/2006JD007733, 2007. Livingston, J. M., Redemann, J., Russell, P. B., Torres, O., Veihelmann, B., Veefkind, P., Braak, R., Smirnov, A., Remer, L., Bergstrom, R. W., Coddington, O., Schmidt, K. S., Pilewskie, P., Johnson, R., and Zhang, Q.: Comparison of aerosol optical depths from the Ozone Monitoring Instrument (OMI) on Aura with results from airborne sunphotometry, other space and ground measurements during MILAGRO/INTEX-B, Atmos. Chem. Phys., 9, 6743–6765, http://dx.doi.org/10.5194/acp-9-6743-2009doi:10.5194/acp-9-6743-2009, 2009. Matsumoto, T., Russell, P., Mina, C., Van Ark, W., and Banta, V.: Airborne Tracking Sunphotometer, J. Atmos. Ocean. Tech., 4, 336–339, 1987. McNaughton, C. S., Clarke, A. D., Kapustin, V., Shinozuka, Y., Howell, S. G., Anderson, B. E., Winstead, E., Dibb, J., Scheuer, E., Cohen, R. C., Wooldridge, P., Perring, A., Huey, L. G., Kim, S., Jimenez, J. L., Dunlea, E. J., DeCarlo, P. F., Wennberg, P. O., Crounse, J. D., Weinheimer, A. J., and Flocke, F.: Observations of heterogeneous reactions between Asian pollution and mineral dust over the Eastern North Pacific during INTEX-B, Atmos. Chem. Phys., 9, 8283–8308, http://dx.doi.org/10.5194/acp-9-8283-2009doi:10.5194/acp-9-8283-2009, 2009. McNaughton,~C S., Clarke,~A D., Freitag,~S., Kapustin,~V N., Kondo,~Y., Moteki,~N., Sahu,~L., Takegawa,~N., Schwarz,~J P., Spackman,~J R., Watts,~L., Diskin,~G., Podolske,~J., Holloway,~J S., Wisthaler,~A., Mikoviny,~T., de~Gouw,~J., Warneke,~C., Jimenez,~J., Cubison,~M., Howell,~S G., Middlebrook,~A., Bahreini,~R., Anderson,~B E., Winstead,~E., Thornhill,~K L., Lack,~D., Cozic,~J., and Brock,~C A.: Absorbing aerosol in the troposphere of the Western Arctic during the 2008 ARCTAS/ARCPAC airborne field campaigns, Atmos. Chem. Phys. Discuss., 11, 1543–1594, http://dx.doi.org/10.5194/acpd-11-1543-2011doi:10.5194/acpd-11-1543-2011, 2011. O'Neill, N. T., Dubovik, O., and Eck, T. F.: Modified Ångström exponent for the characterization of submicrometer aerosols, Appl. Optics, 40, 2368–2375, 2001. O'Neill, N. T., Eck, T. F., Smirnov, A., Holben, B. N., and Thulasiraman, S.: Spectral discrimination of coarse and fine mode optical depth, J. Geophys. Res., 108, 4559, doi:4510.1029/2002JD002975, 2003. O'Neill, N. T., Eck, T. F., Smirnov, A., Holben B. N., S. Thulasiraman, Spectral Deconvolution algorithm Technical memo, 2008a. O'Neill, N. T., Eck, T. F., Reid, J. S., Smirnov, A., and Pancrati, O.: Coarse mode optical information retrievable using ultraviolet to shortwave infrared sunphotometry; application to UAE<sup>2</sup>, J. Geophys. Res., 113, D05212, http://dx.doi.org/10.1029/2007JD009052doi:10.1029/2007JD009052, 2008b. Radke, L. F., Hobbs, P. V., and Bailey, I. H.: Airborne observations of Arctic aerosols. III: Origins and effects of airmasses, Geophys. Res. Lett., 11(5), 401–404, http://dx.doi.org/10.1029/GL011i005p00401doi:10.1029/GL011i005p00401, 1984. Ramachandran, S.: Aerosol optical depth and fine mode fraction variations deduced from Moderate Resolution Imaging Spectroradiometer (MODIS) over four urban areas in India, J. Geophys. Res., 112, D16207, doi:16210.11029/12007JD008500, 2007. Redemann, J., Masonis, S. J., Schmid, B., Anderson, T. L., Russell, P. B., Livingston, J. M., Dubovik, O., and Clarke, A. D.: Clear-column closure studies of aerosols and water vapor aboard the NCAR C-130 during ACE-Asia, 2001, J. Geophys. Res., 108, 8655, doi:8610.1029/2003JD003442, 2003. Redemann, J., Schmid, B., Eilers, J. A., Kahn, R., Levy, R. C., Russell, P. B., Livingston, J. M., Hobbs, P. V., Smith, W. L., and Holben, B. N.: Suborbital measurements of spectral aerosol optical depth and its variability at subsatellite grid scales in support of CLAMS 2001, J. Atmos. Sci., 62, 993–1007, 2005. Redemann, J., Zhang, Q., Schmid, B., Russell, P. B., Livingston, J. M., Jonsson, H., and Remer, L. A.: Assessment of MODIS-derived visible and near-IR aerosol optical properties and their spatial variability in the presence of mineral dust, Geophysical Research Letters, 33, L18814, doi:18810.11029/12006GL026626, 2006. Redemann, J., Shinozuka, Y., Livingston, J., Russell, P., Pilewskie, P., Schmidt, S., Bierwirth, E., Johnson, R., Clarke, A., Howell, S., McNaughton, C., Freitag, S., Remer, L., Mattoo, S., Torres, O., Veefkind, P., Ferrare, R., Hostetler, C., Hair, J., Cairns, B., Knobelspiesse, K., Ottaviani, M., and Bucholtz, A.: The coordinated multi-sensor, multi-platform ARCTAS fire plume study on 30~June~2008, Eos Trans. AGU, 90(52), Fall Meet. Suppl., Abstract 719884, 2009. Redemann, J., Zhang, Q., Russell, P. B., Livingston, J. M., and Remer, L. A.: Case studies of aerosol remote sensing in the vicinity of clouds, J. Geophys. Res., 114, D06209, doi:06210.01029/02008JD010774, 2009a. Redemann, J., Zhang, Q., Livingston, J., Russell, P., Shinozuka, Y., Clarke, A., Johnson, R., and Levy, R.: Testing aerosol properties in MODIS Collection 4 and 5 using airborne sunphotometer observations in INTEX-B/MILAGRO, Atmos. Chem. Phys., 9, 8159–8172, http://dx.doi.org/10.5194/acp-9-8159-2009doi:10.5194/acp-9-8159-2009, 2009b. Russell, P. B., Livingston, J. M., Dutton, E. G., Pueschel, R. F., Reagan, J. A., DeFoor, T. E., Box, M. A., Allen, D., Pilewskie, P., Herman, B. M., Kinne, S. A., and Hofmann, D. J.: Pinatubo And Pre-Pinatubo Optical Depth Spectra: Mauna Loa Measurements, Comparisons, Inferred Particle Size Distributions, Radiative Effects, And Relationship To Lidar Data, J. Geophys. Res., 98, 22969–22985, 1993a. Russell, P. B., Livingston, J. M., Pueschel, R. F., Reagan, J. A., Browell, E. V., Toon, G. C., Newman, P. A., Schoeberl, M. R., Lait, L. R., Pfister, L., Gao, Q., and Herman, B. M.: Post-Pinatubo optical depth spectra vs. latitude and vortex structure: Airborne tracking sunphotometer measurements in AASE II, Geophys. Res. Lett., 20, 2571–2574, 1993b. Russell, P. B., Livingston, J. M., Hignett, P., Kinne, S., Wong, J., and Hobbs, P. V.: Aerosol-induced radiative flux changes off the United States Mid-Atlantic coast, Comparison of values calculated from sunphotometer and in situ data with those measured by airborne pyranometer, J. Geophys. Res., 104, 2289–2307, 1999. Russell, P. B., Livingston, J. M., Dubovik, O., Ramirez, S. A., Wang, J., Redemann, J., Schmid, B., Box, M., and Holben, B. N.: Sunlight transmission through desert dust and marine aerosols: Diffuse light corrections to Sun photometry and pyrheliometry, J. Geophys. Res., 109, D08207, http://dx.doi.org/10.1029/2003JD004292doi:10.1029/2003JD004292, 2004. Russell, P., Livingston, J., Schmid, B., Eilers, J., Kolyer, R., Redemann, J., Ramirez, S., Yee, J.-H., Swartz, W., Shetter, R., Trepte, C., Risley Jr., A., Wenny, B., Zawodny, J., Chu, W., Pitts, M., Lumpe, J., Fromm, M., Randall, C., Hoppel, K., and Bevilacqua, R.: Aerosol optical depth measurements by airborne sun photometer in SOLVE II: Comparisons to SAGE III, POAM III and airborne spectrometer measurements, Atmos. Chem. Phys., 5, 1311–1339, http://dx.doi.org/10.5194/acp-5-1311-2005doi:10.5194/acp-5-1311-2005, 2005. Russell, P. B., Livingston, J. M., Redemann, J., Schmid, B., Ramirez, S. A., Eilers, J., Khan, R., Chu, A., Remer, L., Quinn, P. K., Rood, M. J., and Wang, W.: Multi-Grid-Cell Validation of Satellite Aerosol Property Retrievals in INTEX/ITCT/ICARTT 2004, J. Geophys. Res., 112, D12S09, http://dx.doi.org/10.1029/2006JD007606doi:10.1029/2006JD007606, 2007. Russell, P. B., Bergstrom, R. W., Shinozuka, Y., Clarke, A. D., DeCarlo, P. F., Jimenez, J. L., Livingston, J. M., Redemann, J., Dubovik, O., and Strawa, A.: Absorption Angstrom Exponent in AERONET and related data as an indicator of aerosol composition, Atmos. Chem. Phys., 10, 1155–1169, doi:10.5194/acp-10-1155-2010, 2010. Saha, A., O'Neill, N. T., Eloranta, E., Stone, R. S., Eck, T. F., Zidane, S., Daou, D., Lupu, A., Lesins, G., Shiobara, M., and McArthur, L. J. B.: Pan-Arctic sunphotometry during the ARCTAS-A campaign of April 2008, Geophys. Res. Lett., 37, L05803, doi:05810.01029/02009GL041375, 2010. Scheuer, E., Talbot, R. W., Dibb, J. E., Seid, G. K., DeBell, L., and Lefer, B.: Seasonal distributions of fine aerosol sulfate in the North American Arctic basin during TOPSE, J. Geophys. Res., 108(D4), 8370, http://dx.doi.org/10.1029/2001JD001364doi:10.1029/2001JD001364, 2003. Schmid, B. and Wehrli, C.: Comparison of sun photometer calibration by Langley technique and standard lamp, Appl. Optics, 34, 4500–4512, 1995. Schmid, B., Thome, K. J., Demoulin, P., Peter, R., Mätzler, C., and Sekler, J.: Comparison of Modeled and Empirical Approaches for Retrieving Columnar Water Vapor from Solar Transmittance Measurements in the 0.94 Micron Region. J. Geophys. Res., 101 (D5), 9345–,9358, 1996. Schmid, B., Spyak, P. R., Biggar, S. F., Wehrli, C., Sekler, J., Ingold, T., Mätzler, C., and Nämpfer, K.: Evaluation of the applicability of solar and lamp radiometric calibrations of a precision Sun photometer operating between 300 and 1025 nm. Appl. Optics, 37(18), 3923-3941, 1998. Schmid, B., J. J., Michalsky, D. W., Slater, J. C., Barnard, R. N., Halthore, J. C., Liljegren, B. N., Holben, T. F., Eck, J. M., Livingston, P. B., Russell, T., Ingold, and I. Slutsker, : Comparison of columnar water-vapor measurements from solar transmittance methods, Appl. Optics, 40(12), 1886–1896, 2001. Schmid, B., Hegg, D. A., Wang, J., Bates, D., Redemann, J., Russell, P. B., Livingston, J. M., Jonsson, H. H., Welton, E. J., Seinfeld, J. H., Flagan, R. C., Covert, D. S., Dubovik, O., and Jefferson, A.: Column closure studies of lower tropospheric aerosol and water vapor during ACE-Asia using airborne Sun photometer and airborne in situ and ship-based lidar measurements, J. Geophys. Res., 108, 8656, doi:10.1029/2002JD003361, 2003a. Schmid, B., Redemann, J., Russell P. B., Hobbs, P. V., Hlavka, D. L., McGill, M. J., Holben, B. N., Welton, E. J., Campbell, J. R., Torres, O., Kahn, R. A., Diner, D. J., Helmlinger, M. C., Chu, D. A., Robles-Gonzalez, C., and de Leeuw, G., Coordinated airborne, spaceborne, and ground-based measurements of massive, thick aerosol layers during the dry season in Southern Africa, J. Geophys. Res., 108 (D13), 8496, http://dx.doi.org/10.1029/2002JD002297doi:10.1029/2002JD002297, 2003b. Smirnov, A., Holben, B. N., Eck, T. F., Dubovik, O., and Slutsker, I.: Cloud screening and quality control algorithms for the AERONET database, Remote Sens. Environ., 73, 337–349, 2000. Stephens, M., Turner, N., and Sandberg, J.: Particle Identification by Laser-Induced Incandescence in a Solid-State Laser Cavity, Appl. Optics, 42, 3726–3736, 2003. Stone, R. S., Herber, A., Vitale, V., Mazzola, M., Lupi, A., Schnell, R. C., Dutton, E. G., Liu, P. S. K., Li, S. M., Dethloff, K., Lampert, A., Ritter, C., Stock, M., Neuber, R., and Maturilli, M.: A three-dimensional characterization of Arctic aerosols from airborne Sun photometer observations: PAM-ARCMIP, April~2009, J. Geophys. Res., 115, D13203, doi:13210.11029/12009JD013605, 2010. Virkkula, A.: Correction of the Calibration of the 3-wavelength Particle Soot Absorption Photometer (3λ PSAP), Aerosol Sci. Technol., 44, 706–712, 2010. Virkkula, A., Ahlquist, N. C., Covert, D. S., Arnott, W. P., Sheridan, P. J., Quinn, P. K., and Coffman, D. J.: Modification, Calibration and a Field Test of an Instrument for Measuring Light Absorption by Particles, Aerosol Sci. Technol., 39, 68–83, 2005. Warneke, C., Froyd, K. D., Brioude, J., Bahreini, R., Brock, C. A., Cozic, J., de Gouw, J. A., Fahey, D. W., Ferrare, R., Holloway, J. S., Middlebrook, A. M., Miller, L., Montzka, S., Schwarz, J. P., Sodemann, H., Spackman, J. R., and Stohl, A.: An important contribution to springtime Arctic aerosol from biomass burning in Russia, Geophys. Res. Lett., 37, L01801, doi:10.1029/2009GL041816, 2010. Welton, E. J. and Campbell, J. R.: Micro-pulse Lidar Signals: Uncertainty Analysis, J. Atmos. Ocean. Tech., 19, 2089–2094, 2002. Welton, E. J., Campbell, J. R., Spinhirne, J. D., and Scott, V. S.: Global monitoring of clouds and aerosols using a network of micro-pulse lidar systems, in: Lidar Remote Sensing for Industry and Environmental Monitoring, edited by: Singh, U. N., Itabe, T., and Sugimoto, N., (eds.), SPIE, 4153, 151–158, 2001.