References

ACP

Atmospheric Chemistry and Physics

ACP

Atmos. Chem. Phys.

1680-7324

Copernicus Publications

Göttingen, Germany

10.5194/acp-11-6245-2011

Simultaneous retrieval of aerosol and cloud properties during the MILAGRO field campaign

Knobelspiesse

¹ Cairns

² Redemann

³ ⁴ Bergstrom

R. W.

³ Stohl

⁵

NASA Postdoctoral Program Fellow, NASA Goddard Institute for Space Studies, New York, New York, USA

NASA Goddard Institute for Space Studies, New York, New York, USA

Bay Area Environmental Research Institute, Sonoma, California, USA

NASA Ames Research Center, Moffett Field, California, USA

Norwegian Institute for Air Research, Kjeller, Norway

01 07 2011

11 13 6245 6263

2011

This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/

This article is available from https://acp.copernicus.org/articles/11/6245/2011/acp-11-6245-2011.html

The full text article is available as a PDF file from https://acp.copernicus.org/articles/11/6245/2011/acp-11-6245-2011.pdf

Estimation of Direct Climate Forcing (DCF) due to aerosols in cloudy areas has historically been a difficult task, mainly because of a lack of appropriate measurements. Recently, passive remote sensing instruments have been developed that have the potential to retrieve both cloud and aerosol properties using polarimetric, multiple view angle, and multi spectral observations, and therefore determine DCF from aerosols above clouds. One such instrument is the Research Scanning Polarimeter (RSP), an airborne prototype of a sensor on the NASA Glory satellite, which unfortunately failed to reach orbit during its launch in March of 2011. In the spring of 2006, the RSP was deployed on an aircraft based in Veracruz, Mexico, as part of the Megacity Initiative: Local and Global Research Observations (MILAGRO) field campaign. On 13 March, the RSP over flew an aerosol layer lofted above a low altitude marine stratocumulus cloud close to shore in the Gulf of Mexico. We investigate the feasibility of retrieving aerosol properties over clouds using these data. Our approach is to first determine cloud droplet size distribution using the angular location of the cloud bow and other features in the polarized reflectance. The selected cloud was then used in a multiple scattering radiative transfer model optimization to determine the aerosol optical properties and fine tune the cloud size distribution. In this scene, we were able to retrieve aerosol optical depth, the fine mode aerosol size distribution parameters and the cloud droplet size distribution parameters to a degree of accuracy required for climate modeling. This required assumptions about the aerosol vertical distribution and the optical properties of the coarse aerosol size mode. A sensitivity study was also performed to place this study in the context of future systematic scanning polarimeter observations, which found that the aerosol complex refractive index can also be observed accurately if the aerosol optical depth is larger than roughly 0.8 at a wavelength of (0.555 μm).

References 1

Bergstrom, R. W., Schmidt, K. S., Coddington, O., Pilewskie, P., Guan, H., Livingston, J. M., Redemann, J., and Russell, P. B.: Aerosol spectral absorption in the Mexico City area: results from airborne measurements during MILAGRO/INTEX B, Atmos. Chem. Phys., 10, 6333–6343, <a href="http://dx.doi.org/10.5194/acp-10-6333-2010">https://doi.org/10.5194/acp-10-6333-2010</a>, 2010.

Bond, T.: Spectral dependence of visible light absorption by carbonaceous particles emitted from coal combustion, Geophys. Res. Lett., 28, 4075–4078, 2001.

Breon, F. and Goloub, P.: Cloud droplet effective radius from spaceborne polarization measurements, Geophys. Res. Lett., 25, 1879–1882, 1998.

Cairns, B.: Polarimetric Remote Sensing of Aerosols, IEEE Trans. Geosci. Remote Sens., 518–520, 2003.

Cairns, B., Travis, L., and Russell, E.: An analysis of polarization: ground based upward looking and aircraft/satellite based downward looking measurements, in: Satellite Remote Sensing of Clouds and the Atmosphere II, SPIE, 1997.

Chand, D., Anderson, T., Wood, R., Charlson, R., Hu, Y., Liu, Z., and Vaughan, M.: Quantifying above-cloud aerosol using spaceborne lidar for improved understanding of cloudy-sky direct climate forcing, J. Geophys. Res, 113, D13206; <a href="http://dx.doi.org/10.1029/2007JD009433">https://doi.org/10.1029/2007JD009433</a>, 2008.

Chen, Y. and Bond, T.: Light absorption by organic carbon from wood combustion, Atmos. Chem. Phys, 10, 1773–1787, <a href="http://dx.doi.org/10.5194/acp-10-1773-2010">https://doi.org/10.5194/acp-10-1773-2010</a>, 2010.

Chowdhary, J., Cairns, B., Mishchenko, M., and Travis, L.: Retrieval of aerosol properties over the ocean using multispectral and multiangle photopolarimetric measurements from the Research Scanning Polarimeter, Geophys. Res. Lett., 28, 243–246, 2001.

Chowdhary, J., Cairns, B., and Travis, L.: Case Studies of Aerosol Retrievals over the Ocean from Multiangle, Multispectral Photopolarimetric Remote Sensing Data, J. Atmos. Sci., 59, 383–397, 2002.

Chowdhary, J., Cairns, B., Mishchenko, M., Hobbs, P., Cota, G., Redemann, J., Rutledge, K., Holben, B., and Russell, E.: Retrieval of Aerosol Scattering and Absorption Properties from Photopolarimetric Observations over the Ocean during the CLAMS Experiment, J. Atmos. Sci., 62, 1093–1117, 2005{a}.

Chowdhary, J., Cairns, B., Mishchenko, M., and Travis, L.: Using multi-angle multispectral photo-polarimetry of the NASA Glory mission to constrain optical properties of aerosols and clouds: results from four field experiments, Proc. SPIE, 5978, 59 780G, 2005{b}.

Coddington, O., Pilewskie, P., Redemann, J., Platnick, S., Russell, P., Schmidt, K., Gore, W., Livingston, J., Wind, G., and Vukicevic, T.: Examining the impact of overlying aerosols on the retrieval of cloud optical properties from passive remote sensing, J. Geophys. Res., 115, D10211, <a href="http://dx.doi.org/10.1029/2009JD012829">https://doi.org/10.1029/2009JD012829</a>, 2010.

Crounse, J. D., DeCarlo, P. F., Blake, D. R., Emmons, L. K., Campos, T. L., Apel, E. C., Clarke, A. D., Weinheimer, A. J., McCabe, D. C., Yokelson, R. J., Jimenez, J. L., and Wennberg, P. O.: Biomass burning and urban air pollution over the Central Mexican Plateau, Atmos. Chem. Phys., 9, 4929–4944, <a href="http://dx.doi.org/10.5194/acp-9-4929-2009">https://doi.org/10.5194/acp-9-4929-2009</a>, 2009.

de Foy, B., Krotkov, N. A., Bei, N., Herndon, S. C., Huey, L. G., Mart{\'\i}nez, A.-P., Ruiz-Su{á}rez, L. G., Wood, E. C., Zavala, M., and Molina, L. T.: Hit from both sides: tracking industrial and volcanic plumes in Mexico City with surface measurements and OMI SO<sub>2</sub> retrievals during the MILAGRO field campaign, Atmos. Chem. Phys., 9, 9599–9617, <a href="http://dx.doi.org/10.5194/acp-9-9599-2009">https://doi.org/10.5194/acp-9-9599-2009</a>, 2009.

De Graaf, M., Stammes, P., and Aben, E.: Analysis of reflectance spectra of UV-absorbing aerosol scenes measured by SCIAMACHY, J. Geophys. Res, 112, D02206, <a href="http://dx.doi.org/10.1029/2006JD007249">https://doi.org/10.1029/2006JD007249</a>, 2007.

De Haan, J., Bosma, P., and Hovenier, J.: The adding method for multiple scattering calculations of polarized light, Astron. Astrophys., 183, 371–391, 1987.

Dinar, E., Riziq, A., Spindler, C., Erlick, C., Kiss, G., and Rudich, Y.: The complex refractive index of atmospheric and model humic-like substances (HULIS) retrieved by a cavity ring down aerosol spectrometer (CRD-AS), Faraday Discussions, 137, 279–295, 2008.

Doran, J. C., Barnard, J. C., Arnott, W. P., Cary, R., Coulter, R., Fast, J. D., Kassianov, E. I., Kleinman, L., Laulainen, N. S., Martin, T., Paredes-Miranda, G., Pekour, M. S., Shaw, W. J., Smith, D. F., Springston, S. R., and Yu, X.-Y.: The T1-T2 study: evolution of aerosol properties downwind of Mexico City, Atmos. Chem. Phys., 7, 1585–1598, <a href="http://dx.doi.org/10.5194/acp-7-1585-2007">https://doi.org/10.5194/acp-7-1585-2007</a>, 2007.

Dubovik, O., Holben, B., Eck, T., Smirnov, A., Kaufman, Y., King, M., Tanr{é}, 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.

Elias, T., Cairns, B., and Chowdhary, J.: Surface optical properties measured by the airborne research scanning polarimeter during the CLAMS experiment, Remote Sensing of Clouds and the Atmosphere VIII, edited by: Schaefer, K., Comeron, A., Carleer, M. R., and Picard, R. H., Proc. SPIE,, 5235, 595–606, 2004.

Fast, J. D., de Foy, B., Acevedo Rosas, F., Caetano, E., Carmichael, G., Emmons, L., McKenna, D., Mena, M., Skamarock, W., Tie, X., Coulter, R. L., Barnard, J. C., Wiedinmyer, C., and Madronich, S.: A meteorological overview of the MILAGRO field campaigns, Atmos. Chem. Phys., 7, 2233–2257, <a href="http://dx.doi.org/10.5194/acp-7-2233-2007">https://doi.org/10.5194/acp-7-2233-2007</a>, 2007.

Flowers, B. A., Dubey, M. K., Mazzoleni, C., Stone, E. A., Schauer, J. J., Kim, S.-W., and Yoon, S. C.: Optical-chemical-microphysical relationships and closure studies for mixed carbonaceous aerosols observed at Jeju Island; 3-laser photoacoustic spectrometer, particle sizing, and filter analysis, Atmos. Chem. Phys., 10, 10387–10398, <a href="http://dx.doi.org/10.5194/acp-10-10387-2010">https://doi.org/10.5194/acp-10-10387-2010</a>, 2010.

Gatebe, C. K., Dubovik, O., King, M. D., and Sinyuk, A.: Simultaneous retrieval of aerosol and surface optical properties from combined airborne- and ground-based direct and diffuse radiometric measurements, Atmos. Chem. Phys., 10, 2777–2794, <a href="http://dx.doi.org/10.5194/acp-10-2777-2010">https://doi.org/10.5194/acp-10-2777-2010</a>, 2010.

Goloub, P., Deuz{é}, J., Herman, M., and Fouquart, Y.: Analysis of the POLDER polarization measurements performed overcloud covers, IEEE Trans. Geosci. Remote Sens., 32, 78–88, 1994.

Goloub, P., Herman, M., Chepfer, H., Riedi, J., Brogniez, G., Couvert, P., and S{è}ze, G.: Cloud thermodynamical phase classification from the POLDER spaceborne instrument, J. Geophys. Res., 105(D11), 14747–14759, 2000.

Gonzalez, R. and Woods, R.: Digital Image Processing, Addison Wesley Publishing Company, New York, NY, USA, 209–213, 1992.

Grutter, M., Basaldud, R., Rivera, C., Harig, R., Junkerman, W., Caetano, E., and Delgado-Granados, H.: SO<sub>2</sub> emissions from Popocat{é}petl volcano: emission rates and plume imaging using optical remote sensing techniques, Atmos. Chem. Phys., 8, 6655–6663, <a href="http://dx.doi.org/10.5194/acp-8-6655-2008">https://doi.org/10.5194/acp-8-6655-2008</a>, 2008.

Hair, J. W., Caldwell, L. M., Krueger, D. A., and She, C.-Y.: High-Spectral-Resolution Lidar with Iodine-Vapor Filters: Measurement of Atmospheric-State and Aerosol Profiles, Appl. Opt., 40, 5280–5294, 2001.

Hair, J. W., Hostetler, C. A., Cook, A. L., Harper, D. B., Ferrare, R. A., Mack, T. L., Welch, W., Izquierdo, L. R., and Hovis, F. E.: Airborne High Spectral Resolution Lidar for profiling aerosol optical properties, Appl. Opt., 47, 6734–6752, 2008.

Hansen, J. and Travis, L.: Light scattering in planetary atmospheres, Space Sci. Rev., 16, 527–610., 1974.

Hasekamp, O. and Landgraf, J.: Retrieval of aerosol properties over land surfaces: capabilities of multiple-viewing-angle intensity and polarization measurements, Appl. Opt., 46, 3332–3344, 2007.

Hasekamp, O. P.: Capability of multi-viewing-angle photo-polarimetric measurements for the simultaneous retrieval of aerosol and cloud properties, Atmos. Meas. Tech., 3, 839–851, <a href="http://dx.doi.org/10.5194/amt-3-839-2010">https://doi.org/10.5194/amt-3-839-2010</a>, 2010.

Haywood, J., Roberts, D., Slingo, A., Edwards, J., and Shine, K.: General circulation model calculations of the direct radiative forcing by anthropogenic sulfate and fossil-fuel soot aerosol, J. Climate, 10, 1562–1577, 1997.

Hoffer, A., Gelencser, A., Guyon, P., Kiss, G., Schmid, O., Frank, G., Artaxo, P., and Andreae, M.: Optical properties of humic-like substances(HULIS) in biomass-burning aerosols, Atmos. Chem. Phys., 6, 3563–3570, <a href="http://dx.doi.org/10.5194/acp-6-3563-2006">https://doi.org/10.5194/acp-6-3563-2006</a>, 2006.

IPCC: Climate Change 2007 - The Physical Science Basis : Contribution of the Working Group I to the Fourth Assessment Report of the IPCC, Cambridge University Press, New York, NY, USA, 2007.

Kirchstetter, T., Novakov, T., and Hobbs, P.: Evidence that the spectral dependence of light absorption by aerosols is affected by organic carbon, J. Geophys. Res.-Atmos., 109, D21208, <a href="http://dx.doi.org/10.1029/2004JD004999">https://doi.org/10.1029/2004JD004999</a>, 2004.

Knobelspiesse, K., Cairns, B., Schaaf, C., Schmid, B., and Román, M.: Surface BRDF estimation from an aircraft compared to MODIS and ground estimates at the Southern Great Plains site, J. Geophys. Res., 113, D20105, <a href="http://dx.doi.org/10.1029/2008JD010062">https://doi.org/10.1029/2008JD010062</a>, 2008.

Knobelspiesse, K., Cairns, B., Ottaviani, M., Ferrare, R., Hair, J., Hostetler, C., Obland, M., Rogers, R., Redemann, J., Shinozuka, Y., Clarke, A., Freitag, S., Howell, S., Kapustin, V., and McNaughton, C.: Combined retrievals of boreal forest fire aerosol properties with a polarimeter and lidar, Atmos. Chem. Phys. Discuss., 11, 7909–7969, <a href="http://dx.doi.org/10.5194/acpd-11-7909-2011">https://doi.org/10.5194/acpd-11-7909-2011</a>, 2011.

Lewandowski, P. A., Eichinger, W. E., Holder, H., Prueger, J., Wang, J., and Kleinman, L. I.: Vertical distribution of aerosols in the vicinity of Mexico City during MILAGRO-2006 Campaign, Atmos. Chem. Phys., 10, 1017–1030, <a href="http://dx.doi.org/10.5194/acp-10-1017-2010">https://doi.org/10.5194/acp-10-1017-2010</a>, 2010.

Lewis, K., Arnott, W. P., Moosmuller, H., and Wold, C. E.: Strong spectral variation of biomass smoke light absorption and single scattering albedo observed with a novel dual-wavelength photoacoustic instrument, J. Geophys. Res., 113, D16203, <a href="http://dx.doi.org/10.1029/2007JD009699">https://doi.org/10.1029/2007JD009699</a>, 2008.

Litvinov, P., Hasekamp, O., Cairns, B., and Mishchenko, M.: Reflection models for soil and vegetation surfaces from multiple-viewing angle photopolarimetric measurements, J. Quant. Spectrosc. Radiat. Transfer, 111, 529–539, 2010.

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, <a href="http://dx.doi.org/10.5194/acp-9-6743-2009">https://doi.org/10.5194/acp-9-6743-2009</a>, 2009.

Markwardt, C.: Non-linear Least Squares Fitting in IDL with MPFIT, Arxiv preprint arXiv:0902.2850, 2009.

Marley, N. A., Gaffney, J. S., Castro, T., Salcido, A., and Frederick, J.: Measurements of aerosol absorption and scattering in the Mexico City Metropolitan Area during the MILAGRO field campaign: a comparison of results from the T0 and T1 sites, Atmos. Chem. Phys., 9, 189–206, <a href="http://dx.doi.org/10.5194/acp-9-189-2009">https://doi.org/10.5194/acp-9-189-2009</a>, 2009.

Miles, N., Verlinde, J., and Clothiaux, E.: Cloud droplet size distributions in low-level stratiform clouds, J. Atmos. Sci., 57, 295–311, 2000.

Mishchenko, M. and Travis, L.: Gustav Mie and the evolving discipline of electromagnetic scattering by particles, B. Am. Meteorol. Soc., 89, 1853–1861, 2008.

Mishchenko, M., Cairns, B., Hansen, J., Travis, L., Burg, R., Kaufman, Y., Vanderlei Martins, J., and Shettle, E.: Monitoring of aerosol forcing of climate from space: analysis of measurement requirements, J. Quant. Spectrosc. Radiat. Transfer, 88, 149–161, 2004.

Mishchenko, M., Cairns, B., Kopp, G., Schueler, C., Fafaul, B., Hansen, J., Hooker, R., Itchkawich, T., Maring, H., and Travis, L.: Accurate monitoring of terrestrial aerosols and total solar irradiance: introducing the Glory mission, B. Am. Meteorol. Soc, 88, 677–691, 2007{a}.

Mishchenko, M., Geogdzhayev, I., Cairns, B., Carlson, B., Chowdhary, J., Lacis, A., Liu, L., Rossow, W., and Travis, L.: Past, present, and future of global aerosol climatologies derived from satellite observations: A perspective, J. Quant. Spectrosc. Radiat. Transfer,, 106, 325–347, 2007{b}.

Mishchenko, M., Geogdzhayev, I., Liu, L., Lacis, A., Cairns, B., and Travis, L.: Toward unified satellite climatology of aerosol properties: What do fully compatible MODIS and MISR aerosol pixels tell us?, J. Quant. Spectrosc. Radiat. Transfer, 2009.

Molina, L. T., Madronich, S., Gaffney, J. S., Apel, E., de Foy, B., Fast, J., Ferrare, R., Herndon, S., Jimenez, J. L., Lamb, B., Osornio-Vargas, A. R., Russell, P., Schauer, J. J., Stevens, P. S., Volkamer, R., and Zavala, M.: An overview of the MILAGRO 2006 Campaign: Mexico City emissions and their transport and transformation, Atmos. Chem. Phys., 10, 8697–8760, <a href="http://dx.doi.org/10.5194/acp-10-8697-2010">https://doi.org/10.5194/acp-10-8697-2010</a>, 2010.

Mor{é}, J.: The Levenberg-Marquardt Algorithm: Implementation and Theory, in: Lecture Notes in Mathematics: Numerical Analysis, edited by Watson, G. A., Proceedings of the Biennial Conference Held at Dundee, Springer-Verlag, Berlin, Germany, 630, 105–116, 1977.

Paredes-Miranda, G., Arnott, W. P., Jimenez, J. L., Aiken, A. C., Gaffney, J. S., and Marley, N. A.: Primary and secondary contributions to aerosol light scattering and absorption in Mexico City during the MILAGRO 2006 campaign, Atmos. Chem. Phys., 9, 3721–3730, <a href="http://dx.doi.org/10.5194/acp-9-3721-2009">https://doi.org/10.5194/acp-9-3721-2009</a>, 2009.

Pilewskie, P., Pommier, J., Bergstrom, R., Gore, W., Howard, S., Rabbette, M., Schmid, B., Hobbs, P., and Tsay, S.: Solar spectral radiative forcing during the southern african regional science initiative, J. Geophys. Res, 108, 8486 <a href="http://dx.doi.org/10.1029/2002JD002411">https://doi.org/10.1029/2002JD002411</a>, 2003.

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, <a href="http://dx.doi.org/10.5194/acp-9-8159-2009">https://doi.org/10.5194/acp-9-8159-2009</a>, 2009.

Rogers, R. R., Hair, J. W., Hostetler, C. A., Ferrare, R. A., Obland, M. D., Cook, A. L., Harper, D. B., Burton, S. P., Shinozuka, Y., McNaughton, C. S., Clarke, A. D., Redemann, J., Russell, P. B., Livingston, J. M., and Kleinman, L. I.: NASA LaRC airborne high spectral resolution lidar aerosol measurements during MILAGRO: observations and validation, Atmos. Chem. Phys., 9, 4811–4826, <a href="http://dx.doi.org/10.5194/acp-9-4811-2009">https://doi.org/10.5194/acp-9-4811-2009</a>, 2009

Schmidt, K. S., Pilewskie, P., Bergstrom, R., Coddington, O., Redemann, J., Livingston, J., Russell, P., Bierwirth, E., Wendisch, M., Gore, W., Dubey, M. K., and Mazzoleni, C.: A new method for deriving aerosol solar radiative forcing and its first application within MILAGRO/INTEX-B, Atmos. Chem. Phys., 10, 7829–7843, <a href="http://dx.doi.org/10.5194/acp-10-7829-2010">https://doi.org/10.5194/acp-10-7829-2010</a>, 2010.

Schulz, M., Textor, C., Kinne, S., Balkanski, Y., Bauer, S., Berntsen, T., Berglen, T., Boucher, O., Dentener, F., Guibert, S., Isaksen, I. S. A., Iversen, T., Koch, D., Kirkevåg, A., Liu, X., Montanaro, V., Myhre, G., Penner, J. E., Pitari, G., Reddy, S., Seland, Ø., Stier, P., and Takemura, T.: Radiative forcing by aerosols as derived from the AeroCom present-day and pre-industrial simulations, Atmos. Chem. Phys., 6, 5225–5246, http://dx.doi.org/10.5194/acp-6-5225-2006https://doi.org/10.5194/acp-6-5225-2006, 2006.

Stohl, A., Forster, C., Frank, A., Seibert, P., and Wotawa, G.: Technical note: The Lagrangian particle dispersion model FLEXPART version 6.2, Atmos. Chem. Phys., 5, 2461–2474, <a href="http://dx.doi.org/10.5194/acp-5-2461-2005">https://doi.org/10.5194/acp-5-2461-2005</a>, 2005.

Sun, H., Biedermann, L., and Bond, T.: Color of brown carbon: A model for ultraviolet and visible light absorption by organic carbon aerosol, Geophys. Res. Lett., 34, L17813, <a href="http://dx.doi.org/10.1029/2007GL029797">https://doi.org/10.1029/2007GL029797</a>, 2007.

van de Hulst, H.: Light scattering by small particles, Dover Pubns, 1981.

Waquet, F., Cairns, B., Knobelspiesse, K., Chowdhary, J., Travis, L., Schmid, B., and Mishchenko, M.: Polarimetric remote sensing of aerosols over land, J. Geophys. Res, 114, D01206, <a href="http://dx.doi.org/10.1029/2008JD010619">https://doi.org/10.1029/2008JD010619</a>, 2009{a}.

Waquet, F., Riedi, J., Labonnote, L., Goloub, P., Cairns, B., Deuz{é}, J., and Tanr{é}, D.: Aerosol Remote Sensing over Clouds Using A-Train Observations, J. Atmos. Sci., 66, 2468–2480, 2009{b}.

Winker, D., Pelon, J., and McCormick, M.: The CALIPSO mission: Spaceborne lidar for observation of aerosols and clouds, Int. Society for Optical Engineering, 4893, 1–11, 2003.

Winker, D., Hostetler, C., Vaughan, M., and Omar, A.: CALIOP Algorithm Theoretical Basis Document, Part I, Tech. Rep. PC-SCI-202 Part I, NASA Langley Research Center, 2006.

Yu, X.-Y., Cary, R. A., and Laulainen, N. S.: Primary and secondary organic carbon downwind of Mexico City, Atmos. Chem. Phys., 9, 6793–6814, <a href="http://dx.doi.org/10.5194/acp-9-6793-2009">https://doi.org/10.5194/acp-9-6793-2009</a>, 2009.