ACP Atmospheric Chemistry and Physics ACP Atmos. Chem. Phys. 1680-7324 Copernicus Publications Göttingen, Germany 10.5194/acp-14-9343-2014 Evaluation of IASI-derived dust aerosol characteristics over the tropical belt Capelle V. https://orcid.org/0000-0002-9912-3742 1 Chédin A. 1 Siméon M. 1 Tsamalis C. 1 2 Pierangelo C. 3 Pondrom M. 1 Crevoisier C. 1 Crepeau L. 1 Scott N. A. 1 Laboratoire de Météorologie Dynamique, UMR8539, CNRS/IPSL, Ecole Polytechnique, Palaiseau, France UK MetOffice, Exeter, UK Centre National d'Etudes Spatiales, Toulouse, France 10 09 2014 14 17 9343 9362 Copyright: © 2014 V. Capelle et al. 2014 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/14/9343/2014/acp-14-9343-2014.html The full text article is available as a PDF file from https://acp.copernicus.org/articles/14/9343/2014/acp-14-9343-2014.pdf

IASI (Infrared Atmospheric Sounder Interferometer)-derived monthly mean infrared (10 μm) dust aerosol optical depth (AOD) and altitude are evaluated against ground-based Aerosol RObotic NETwork of sun photometers (AERONET) measurements of the 500 nm coarse-mode AOD and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) measurements of altitude at 38 AERONET sites (sea and land) within the tropical belt (30° N–30° S). The period covered extends from July 2007 to June 2013. The evaluation goes through the analysis of Taylor diagrams and box-and-whiskers plots, separating situations over oceanic regions and over land. For the AOD, such an evaluation raises the problem of the difference between the two spectral domains used: infrared for IASI and visible for AERONET. Consequently, the two measurements do not share the same metrics. For that reason, AERONET coarse-mode AOD is first "translated" into IASI-equivalent infrared AOD. This is done by the determination, site by site, of an infrared to visible AOD ratio. Because translating visible coarse-mode AOD into infrared AOD requires accurate knowledge of variables, such as the infrared refractive index or the particle size distribution, quantifying the bias between these two sources of AOD is not straightforward. This problem is detailed in this paper, in particular in Appendix A. For the sites over oceanic regions, the overall AOD temporal correlation comes to 0.86 for 786 items (IASI and AERONET monthly mean bins). The overall normalized standard deviation (i.e. ratio of the standard deviation of the test data (IASI) to that of the reference data (AERONET)) is 0.93, close to the desired value of 1. Over land, essentially desert, correlation is 0.74 for 619 items and the normalized standard deviation is 0.86. This slight but significant degradation over land most probably results from the greater complexity of the surface (heterogeneity, elevation) and, to a lesser extent, to the episodic presence of dust within the boundary layer (particularly for sites close to active sources) to which IASI, as any thermal infrared sounder, is poorly sensitive, unlike AERONET. Site by site, disparities appear that are principally due to either the insufficient number of AERONET observations throughout the period considered, to the complexity of the location leading to the mixing of several aerosol types (in the case of the Persian Gulf, for example), to surface heterogeneities (elevation, emissivity, etc.), or to the use of a single aerosol model (called "MITR"). Results using another aerosol model, with a different refractive index, are presented and discussed. Concerning altitude over oceanic regions, correlation is 0.70 for 853 items and the normalized standard deviation is 0.92. A systematic bias of −0.4 km (IASI–CALIOP) is observed, with a standard deviation of 0.48 km. This result is satisfactory, considering the important differences between the two instruments (space–time coverage, definition of the altitude). Altitude results over land, essentially over deserts, are not satisfactory for a majority of sites. The smaller sensitivity of IASI to altitude compared to its sensitivity to AOD, added to the difficulties met for the determination of the AOD over land (surface heterogeneities), explain this result. Work is in progress to solve this difficulty. <br><br> We conclude that the present results demonstrate the usefulness of IASI data, which are planned to cover a long period of time, as an additional constraint to a better knowledge of the impact of aerosols on the climate system.

 European Commission MACC II - Monitoring Atmospheric Composition and Climate Interim Implementation (283576) References Amiridis, V., Wandinger, U., Marinou, E., Giannakaki, E., Tsekeri, A., Basart, S., Kazadzis, S., Gkikas, A., Taylor, M., Baldasano, J., and Ansmann, A.: Optimizing CALIPSO Saharan dust retrievals, Atmos. Chem. Phys., 13, 12089–12106, <a href="http://dx.doi.org/10.5194/acp-13-12089-2013">https://doi.org/10.5194/acp-13-12089-2013</a>, 2013. Balkanski, Y., Schulz, M., Claquin, T., and Guibert, S.: Reevaluation of Mineral aerosol radiative forcings suggests a better agreement with satellite and AERONET data, Atmos. Chem. Phys., 7, 81–95, <a href="http://dx.doi.org/10.5194/acp-7-81-2007">https://doi.org/10.5194/acp-7-81-2007</a>, 2007. Basart, S., Pérez, C., Cuevas, E., Baldasano, J. M., and Gobbi, G. P.: Aerosol characterization in Northern Africa, Northeastern Atlantic, Mediterranean Basin and Middle East from direct-sun AERONET observations, Atmos. Chem. Phys., 9, 8265–8282, <a href="http://dx.doi.org/10.5194/acp-9-8265-2009">https://doi.org/10.5194/acp-9-8265-2009</a>, 2009. Capelle, V., Chédin, A., Péquignot, E.,Schlüssel, P., Newman, S. M., and Scott, N. A.: Infrared continental surface emissivity spectra and skin temperature retrieved from IASI observations over the tropics, J. Appl. Meteor. Climatol., 51, 1164–1179, <a href="http://dx.doi.org/10.1175/JAMC-D-11-0145.1">https://doi.org/10.1175/JAMC-D-11-0145.1</a>, 2012. Chalon, G., Cayla, F., and Diebel, D.: IASI: An Advanced Sounder for Operational Meteorology, Proceedings of the 52nd Congress of IAF, Toulouse France, October, 2001. Chiapello, I., Bergametti, G., Gomes, L., Chatenet, B., Dulac, F., Pimenta, J., and Santos Suares, E.: An additional low layer transport of Sahelian and Saharan dust over the North-Eastern Tropical Atlantic, Geophys. Res. Lett., 22, 3191–3194, 1995. Chiapello, I., Moulin, C., and Prospero, J. M.: Understanding the long-term variability of African dust transport across the Atlantic as recorded in both Barbados surface concentrations and large-scale Total Ozone Mapping Spectrometer (TOMS) optical thickness, J. Geophys. Res., 110, D18S10, <a href="http://dx.doi.org/10.1029/2004JD005132">https://doi.org/10.1029/2004JD005132</a>, 2005. Claquin, T., Schulz, M., Balkanski, Y., and Boucher, O.: Uncertainties in assessing radiative forcing by mineral dust, Tellus B, 50, 491–505, 1998. De Souza-Machado, S., Strow, L. L., Motteler, H., and Hannon, S.: Infrared dust spectral signatures from AIRS, Geophys. Res. Lett., 33, L03801, <a href="http://dx.doi.org/10.1029/2005GL024364">https://doi.org/10.1029/2005GL024364</a>, 2006. Dey, S., Tripathi, S. N., Singh, R. P., and Holben, B. N.: Influence of dust storms on the aerosol optical properties over the Indo-Gangetic basin, J. Geophys. Res., 109, D20211, <a href="http://dx.doi.org/10.1029/2004JD004924">https://doi.org/10.1029/2004JD004924</a>, 2004. Di Biagio, C., Boucher, H., Caquineau, S., Chevaillier, S., Cuesta, J., and Formenti, P.: Variability of the infrared complex refractive index of African mineral dust: experimental estimation and implications for radiative transfer and satellite remote sensing, Atmos. Chem. Phys. Discuss., 14, 10597–10657, <a href="http://dx.doi.org/10.5194/acpd-14-10597-2014">https://doi.org/10.5194/acpd-14-10597-2014</a>, 2014. 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 1998–2000, J. Geophys. Res., 106, 28555–28566, 2001. Eck, T. F., Holben, B. N., Reid J. S., Sinyuk, A., Dubovik, O., Smimov, A., Giles, D., O'Neill, N. T., Tsay, S.-C., Ji, Q., Al Mandoos, A., Ramzan Khan, M., Reid, E. A., Schafer, J. S., Sorokine, M., Newcomb, W., and Slutsker, I.: Spatial and temporal variability of column-integrated aerosol optical properties in the southern Arabian Gulf and United Arab Emirates in summer, J. Geophys. Res., 113, D01204, <a href="http://dx.doi.org/10.1029/2007JD008944">https://doi.org/10.1029/2007JD008944</a>, 2008. Eck, T. F., Holben, B. N., Sinyuk, A., Pinker, R. T., Goloub, P., Chen, H., Chatenet, B., Li, Z., Singh, R. P., Tripathi, S. N., Reid, J. S., Giles, D. M., Dubovik, O., O'Neill, N. T., Smirnov, A., Wang, P., and Xia, X.: Climatological aspects of the optical properties of fine/coarse mode aerosol mixtures, J. Geophys. Res., 115, D19205, <a href="http://dx.doi.org/10.1029/2010JD014002">https://doi.org/10.1029/2010JD014002</a>, 2010. Formenti, P., Schütz, L., Balkanski, Y., Desboeufs, K., Ebert, M., Kandler, K., Petzold, A., Scheuvens, D., Weinbruch, S., and Zhang, D.: Recent progress in understanding physical and chemical properties of African and Asian mineral dust, Atmos. Chem. Phys., 11, 8231–8256, <a href="http://dx.doi.org/10.5194/acp-11-8231-2011">https://doi.org/10.5194/acp-11-8231-2011</a>, 2011. Forster, P., Ramaswamy, V., Artaxo, P., Berntsen, T., Betts, R., Fahey, D. W., Haywood, J., Lean, J., Lowe, D. C., Myhre, G., Nganga, J., Prinn, R., Raga, G., Schulz, M., and Van Dorland, R.: Radiative Forcing of Climate Change, in: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K. B., Tignor, M., and Miller, H. L., 129–234, Cambridge Univ. Press, Cambridge, UK and New York, NY, USA, 2007. Hansen, J., Sato, M., and Ruedy, R.: Radiative forcing and climate response, J. Geophys. Res., 102, 6831–6864, <a href="http://dx.doi.org/10.1029/96JD03436">https://doi.org/10.1029/96JD03436</a>, 1997. Haywood, J. M. and Ramaswamy, V.: Global sensitivity studies of the direct radiative forcing due to anthropogenic sulfate and black carbon aerosols, J. Geophys. Res., 103, 6043–6058, <a href="http://dx.doi.org/10.1029/97JD03426">https://doi.org/10.1029/97JD03426</a>, 1998. Hess, M., Koepke, P., and Schult, I.: Optical Properties of Aerosols and Clouds: The software package OPAC, B. Am. Meteorol. Soc., 79, 831–844, 1998. Highwood, E., Haywood, J. M., Silverstone, M. D., Newman, S. M., and Taylor, J. P.: Radiative properties and direct effect of Saharan dust measured by the C-130 aircraft during Saharan Dust Experiment (SHADE), 2. Terrestrial spectrum, J. Geophys. Res., 108, 8578, <a href="http://dx.doi.org/10.1029/2002JD002 552">https://doi.org/10.1029/2002JD002 552</a>, 2003. 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. Huneeus, N., Schulz, M., Balkanski, Y., Griesfeller, J., Prospero, J., Kinne, S., Bauer, S., Boucher, O., Chin, M., Dentener, F., Diehl, T., Easter, R., Fillmore, D., Ghan, S., Ginoux, P., Grini, A., Horowitz, L., Koch, D., Krol, M. C., Landing, W., Liu, X., Mahowald, N., Miller, R., Morcrette, J.-J., Myhre, G., Penner, J., Perlwitz, J., Stier, P., Takemura, T., and Zender, C. S.: Global dust model intercomparison in AeroCom phase I, Atmos. Chem. Phys., 11, 7781–7816, <a href="http://dx.doi.org/10.5194/acp-11-7781-2011">https://doi.org/10.5194/acp-11-7781-2011</a>, 2011. Journet, E., Balkanski, Y., and Harrison, S. P.: A new data set of soil mineralogy for dust-cycle modeling, Atmos. Chem. Phys., 14, 3801–3816, <a href="http://dx.doi.org/10.5194/acp-14-3801-2014">https://doi.org/10.5194/acp-14-3801-2014</a>, 2014. Kalashnikova, O. V. and Kahn, R. A.: Mineral dust plume evolution over the Atlantic from MISR and MODIS aerosol retrievals, J. Geophys. Res., 113, D24204, <a href="http://dx.doi.org/10.1029/2008JD010083">https://doi.org/10.1029/2008JD010083</a>, 2008. Kaskaoutis, D. G., Kalapureddy, M. C. R., Krishna Moorthy, K., Devara, P. C. S., Nastos, P. T., Kosmopoulos, P. G., and Kambezidis, H. D.: Heterogeneity in pre-monsoon aerosol types over the Arabian Sea deduced from ship-borne measurements of spectral AODs, Atmos. Chem. Phys., 10, 4893–4908, <a href="http://dx.doi.org/10.5194/acp-10-4893-2010">https://doi.org/10.5194/acp-10-4893-2010</a>, 2010. Kaufman, Y. J., Tanre, D., Gordon, H. R., Nakajima, T., Lenoble, J., Frouin, R., Grassl, H., Hermann, B. M., King, M. D., and Teillet, P. M.: Passive remote sensing of tropospheric aerosol and atmospheric correction for the aerosol effect, J. Geophys. Res., 102, 16815–16830, <a href="http://dx.doi.org/10.1029/97JD01496">https://doi.org/10.1029/97JD01496</a>, 1997. Klüser, L., Martynenko, D., and Holzer-Popp, T.: Thermal infrared remote sensing of mineral dust over land and ocean: a spectral SVD based retrieval approach for IASI, Atmos. Meas. Tech., 4, 757–773, <a href="http://dx.doi.org/10.5194/amt-4-757-2011">https://doi.org/10.5194/amt-4-757-2011</a>, 2011. Klüser, L., Kleiber, P., Holzer-Popp, T., and Grassian, V. H.: Desert dust observation from space – Application of measured mineral component infrared extinction spectra, Atmos. Environ., 54, 419–427, 2012. Knippertz, P. and Todd, M. C.: Mineral dust aerosols over the Sahara: Meteorological controls on emission and transport and implications for modeling, Rev. Geophys., 50, RG1007, <a href="http://dx.doi.org/10.1029/2011RG000362">https://doi.org/10.1029/2011RG000362</a>, 2012. Kocha, C., Tulet, P., Lafore, J.-P., and Flamant, C.: The importance of the diurnal cycle of Aerosol Optical Depth in West Africa, Geophys. Res. Lett., 40, 785–790, <a href="http://dx.doi.org/10.1002/grl.50143">https://doi.org/10.1002/grl.50143</a>, 2013. Koepke, P., Hess, M., Schult, I., and Shettle, E. P.: Global aerosol data set, Rep. No. 243, Max-Planck Institut für Meteorologie, Hamburg, Germany, 44 pp., 1997. Legrand, M, Bertrand, J. J., Desbois, M., Menenger L., and Fouquart, Y.: The potential of infrared satellite data for the retrieval of saharan-dust optical depth over Africa, J. Appl. Meteorol., 28–24, 309–319, <a href="http://dx.doi.org/10.1175/15200450">https://doi.org/10.1175/15200450</a>, 1989. Léon, J.-F. and Legrand, M.: Mineral dust sources in the surroundings of the north Indian Ocean, Geophys. Res. Lett., 30, 1309, <a href="http://dx.doi.org/10.1029/2002GL016690">https://doi.org/10.1029/2002GL016690</a>, 2003. Ma, X., Bartlett, K., Harmon, K., and Yu, F.: Comparison of AOD between CALIPSO and MODIS: significant differences over major dust and biomass burning regions, Atmos. Meas. Tech., 6, 2391–2401, <a href="http://dx.doi.org/10.5194/amt-6-2391-2013">https://doi.org/10.5194/amt-6-2391-2013</a>, 2013. Maher, B. A., Prospero, J. M., Mackie, D., Gaiero, D., Hesse, P. P., and Balkanski, Y.: Global connections between aeolian dust, climate and ocean biogeochemistry at the present day and at the last glacial maximum, Earth-Sci. Rev., 99, 61–97, <a href="http://dx.doi.org/10.1016/j.earscirev.2009.12.001">https://doi.org/10.1016/j.earscirev.2009.12.001</a>, 2010. Mahowald, N. M., Kloster, S., Engelstaedter, S., Moore, J. K., Mukhopadhyay, S., McConnell, J. R., Albani, S., Doney, S. C., Bhattacharya, A., Curran, M. A. J., Flanner, M. G., Hoffman, F. M., Lawrence, D. M., Lindsay, K., Mayewski, P. A., Neff, J., Rothenberg, D., Thomas, E., Thornton, P. E., and Zender, C. S.: Observed 20th century desert dust variability: impact on climate and biogeochemistry, Atmos. Chem. Phys., 10, 10875–10893, <a href="http://dx.doi.org/10.5194/acp-10-10875-2010">https://doi.org/10.5194/acp-10-10875-2010</a>, 2010. Markowicz, K. M., Flatau, P. J., Vogelmann, A. M., Quinn, P. M., and Welton, E.: Influence of relative humidity on aerosol radiative forcing: An ACE-Asia experiment perspective. J. Geophys. Res., 108, 8662, <a href="http://dx.doi.org/10.1029/2002JD003066">https://doi.org/10.1029/2002JD003066</a>, 2003. Mishchenko, M. I., Travis, L. D., and Lacis, A. A.: Scattering, Absorption, and Emission of Light by Small Particles, Cambridge University Press, Cambridge, 2002. Müller, D., Lee, K.-H., Gasteiger, J., Tesche, M., Weinzierl, B., Kandler, K., Müller, T., Toledano, C., Otto, S., Althausen, D., and Ansmann, A.: Comparison of optical and microphysical properties of pure Saharan mineral dust observed with AERONET Sun photometer, Raman lidar, and in situ instruments during SAMUM 2006, J. Geophys. Res., 117, D07211, <a href="http://dx.doi.org/10.1029/2011JD016825">https://doi.org/10.1029/2011JD016825</a>, 2012. Myhre, G. and Stordal, F.: Global sensitivity experiments of the radiative forcing due to mineral aerosols, J. Geophys. Res., 106, 18193–18204, 2001. Omar, A. H., Winker D. M., Tackett J. L., Giles D. M., Kar J., Liu Z., Vaughan M. A., Powell K. A., and Trepte C. R.: CALIOP and AERONET aerosol optical depth comparisons: One size fits none, J. Geophys. Res.-Atmos., 118, 4748–4766, <a href="http://dx.doi.org/10.1002/jgrd.50330">https://doi.org/10.1002/jgrd.50330</a>, 2013. 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, <a href="http://dx.doi.org/10.1029/2002JD002975">https://doi.org/10.1029/2002JD002975</a>, 2003. Otto, S., de Reus, M., Trautmann, T., Thomas, A., Wendisch, M., and Borrmann, S.: Atmospheric radiative effects of an in situ measured Saharan dust plume and the role of large particles, Atmos. Chem. Phys., 7, 4887–4903, <a href="http://dx.doi.org/10.5194/acp-7-4887-2007">https://doi.org/10.5194/acp-7-4887-2007</a>, 2007. Peyridieu, S., Chédin, A., Tanré, D., Capelle, V., Pierangelo, C., Lamquin, N., and Armante, R.: Saharan dust infrared optical depth and altitude retrieved from AIRS: a focus over North Atlantic – comparison to MODIS and CALIPSO, Atmos. Chem. Phys., 10, 1953–1967, <a href="http://dx.doi.org/10.5194/acp-10-1953-2010">https://doi.org/10.5194/acp-10-1953-2010</a>, 2010. Peyridieu, S., Chédin, A., Capelle, V., Tsamalis, C., Pierangelo, C., Armante, R., Crevoisier, C., Crépeau, L., Siméon, M., Ducos, F., and Scott, N. A.: Characterisation of dust aerosols in the infrared from IASI and comparison with PARASOL, MODIS, MISR, CALIOP, and AERONET observations, Atmos. Chem. Phys., 13, 6065–6082, <a href="http://dx.doi.org/10.5194/acp-13-6065-2013">https://doi.org/10.5194/acp-13-6065-2013</a>, 2013. Pierangelo, C., Chédin, A., Heilliette, S., Jacquinet-Husson, N., and Armante, R.: Dust altitude and infrared optical depth from AIRS, Atmos. Chem. Phys., 4, 1813–1822, <a href="http://dx.doi.org/10.5194/acp-4-1813-2004">https://doi.org/10.5194/acp-4-1813-2004</a>, 2004. Pierangelo, C., Mishchenko, M., Balkanski, Y., and Chédin, A.: Retrieving the effective radius of Saharan dust coarse mode from AIRS, Geophys. Res. Lett., 32, L20813, <a href="http://dx.doi.org/10.1029/2005GL023425">https://doi.org/10.1029/2005GL023425</a>, 2005. Pierangelo, C.: in: Aerosol Remote Sensing, edited by: Lenoble, J., Remer, L., and Tanré, D., Chap. 9, Springer-Praxis Books: Environmental Sciences, 510 pp., ISBN-13: 9783642174407, 2013. Reid, J. S., Piketh, S. J., R. Kahn, R., Bruintjes, R. T., and Holben, B. N.: A Summary of First Year Activities of the United Arab Emirates Unified Aerosol Experiment: UAE2, Naval Research Laboratory report nb. NRL/MR/7534–05-8899, 150 pp., 2005. Reid, J. S., Piketh, S. J. , Walker, A. L. , Burger, R. P. , Ross, K. E. , Westphal, D. L. , Bruintjes, R. T. , Holben, B. N. , Hsu, N. C. , Jensen, T. L. , Kahn, R. A. , Kuciauskas, A. P. , Mandoos, A. Al, Mangoosh, A. Al , Miller, S. D. , Porter, J. N. , Reid, E. A., and Tsay, S. C.: An overview of UAE2 flight operations: Observations of summertime atmospheric thermodynamic and aerosol profiles of the southern Arabian Gulf, J. Geophys. Res., 113, D14213, <a href="http://dx.doi.org/10.1029/2007JD009435">https://doi.org/10.1029/2007JD009435</a>, 2008. Ryder, C. L., Highwood, E. J., Rosenberg, P. D., Trembath, J., Brooke, J. K., Bart, M., Dean, A., Crosier, J., Dorsey, J., Brindley, H., Banks, J., Marsham, J. H., McQuaid, J. B., Sodemann, H., and Washington, R.: Optical properties of Saharan dust aerosol and contribution from the coarse mode as measured during the Fennec 2011 aircraft campaign, Atmos. Chem. Phys., 13, 303–325, <a href="http://dx.doi.org/10.5194/acp-13-303-2013">https://doi.org/10.5194/acp-13-303-2013</a>, 2013. Scott, N. A. and Chédin, A.: A fast line-by-line method for atmospheric absorption computations: The Automatized Atmospheric Absorption Atlas, J. Appl. Meteor., 20, 802–812, 1981. Shao, Y., Wyrwoll, K., Chappell, A., Huang, J., Lin, Z., McTainsh, G. H., Mikami, M., Tanaka, T. Y., Wang, X., and Yoon, S.: Dust cycle: An emerging core theme in Earth system science, Aeolian Res., 2, 181–204, <a href="http://dx.doi.org/10.1016/j.aeolia.2011.02.001">https://doi.org/10.1016/j.aeolia.2011.02.001</a>, 2011. Singh, R. P., Dey, S., Tripathi, S. N., Tare, V., and Holben, B.: Variability of aerosol parameters over Kanpur, northern India, J. Geophys. Res., 109, D23206, <a href="http://dx.doi.org/10.1029/2004JD004966">https://doi.org/10.1029/2004JD004966</a>, 2004. Smirnov, A., Holben, B. N., Dubovik, O., O'Neill, N. T., Eck, T. F., Westphal, D. L., Goroch, A. K., Pietras, C., and Slutsker, I.: Atmospheric Aerosol Optical Properties in the Persian Gulf, J. Atm. Sci., 59, 620–634, 2002. Sokolik, I. N. and Toon, O. B.: Incorporation of mineralogical composition into models of the radiative properties of mineral aerosol from UV to IR wavelengths, J. Geophys. Res., 104, 9423–9444, 1999. Sokolik, I., Toon, O. B., and Bergstrom, R.W.: Modeling the radiative characteristics of airborne mineral aerosols at infrared wavelengths, J. Geophys. Res., 103, 8813–8826, 1998. Stamnes, K., Tsay, S.-C., Wiscombe, W., and Jayaweera, K.: Numerically stable algorithm for discrete ordinate-method radiative transfer in multiple scattering and emitting layered media, Appl. Optics, 27, 2502–2509, 1988. Tanré, D., Haywood, J., Pelon, J., Léon, J.-F., Chatenet, B., Formenti, P., Francis, P., Goloub, P., Highwood, E., and Myhre, G.: Measurement and modeling of the Saharan dust radiative impact: Overview of the Saharan Dust Experiment (SHADE), J. Geophys. Res., 108, 8574, <a href="http://dx.doi.org/10.1029/2002JD003273">https://doi.org/10.1029/2002JD003273</a>, 2003. Taylor, K. E.: Summarizing multiple aspects of model performance in a single diagram, J. Geophys. Res., 106, 7183–7192, 2001. Tesche, M., Wandinger, U., Ansmann, A., Althausen, D., Muller, D., and Omar, A. H.: Ground-based validation of CALIPSO observations of dust and smoke in the Cape Verde region, J. Geophys. Res. Atmos., 118, 2889–2902, <a href="http://dx.doi.org/10.1002/jgrd.50248">https://doi.org/10.1002/jgrd.50248</a>, 2013. Tsamalis, C., Chédin, A., Pelon, J., and Capelle, V.: The seasonal vertical distribution of the Saharan Air Layer and its modulation by the wind, Atmos. Chem. Phys., 13, 11235–11257, <a href="http://dx.doi.org/10.5194/acp-13-11235-2013">https://doi.org/10.5194/acp-13-11235-2013</a>, 2013. US Climate Change Science Program: Atmospheric aerosol properties and climate impacts, A report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research, edited b:y Chin, M., Kahn, R. A., and Schwartz, S. E., report, 128 pp., NASA, Washington, D. C., 2009. Vogelmann, A. M., Flatau, P. J., Szczodrak, M., Markowicz, K. M., and Minnett, P. J.: Observations of large aerosol infrared forcing at the surface, Geophys. Res. Lett., 30, 1655, <a href="http://dx.doi.org/10.1029/2002GL016829">https://doi.org/10.1029/2002GL016829</a>, 2003. Volz, F. E.: Infrared Refractive Index of Atmospheric Aerosol Substances, Appl. Opt., 11, 755–759, 1972. Volz, F. E.: Infrared optical constants ammonium sulfate, Sahara dust, volcanic pumace and flyash, Appl. Opt., 12, 564–568, 1973. Walters Sr., K. R. and Sjoberg, W. F.: The Persian Gulf Region, A Climatological Study, US Marine Corps, p. 62, available at: <a href="http://www.marines.mil/News/Publications/ELECTRONICLIBRARY/ ElectronicLibraryDisplay/tabid/13082/Article/127213/fmfrp-0-54.aspx">http://www.marines.mil/News/Publications/ELECTRONICLIBRARY/ ElectronicLibraryDisplay/tabid/13082/Article/127213/fmfrp-0-54.aspx</a>, 1990. Wang, S. H., Lin, N. H., Chou, M. D., Tsay, S. C., Welton, E. J., Hsu, N. C., Giles, D. M., Liu, G. R., and Holben, B. N.: Profiling transboundary aerosols over Taiwan and assessing their radiative effects, J. Geophys. Res., 115, D00K31, <a href="http://dx.doi.org/10.1029/2009JD013798">https://doi.org/10.1029/2009JD013798</a>, 2010. Winker, D., Hunt, W., and McGill, M.: Initial performance assessment of CALIOP, Geophys. Res. Lett., 34, L19803, <a href="http://dx.doi.org/10.1029/2007GL030135">https://doi.org/10.1029/2007GL030135</a>, 2007. Winker, D. M., Vaughan, M. A., Omar, A. H., Hu, Y., Powell,K. A., Liu, Z., Hunt, W. H., and Young, S. A.: Overview of the CALIPSO Mission and CALIOP Data Processing Algorithms, J. Atmos. Oceanic Technol., 26, 2310–2323, <a href="http://dx.doi.org/10.1175/2009JTECHA1281.1">https://doi.org/10.1175/2009JTECHA1281.1</a>, 2009. Winker, D. M., Pelon, J., Coakley Jr., J. A., Ackerman, S. A., Charlson, R. J., Colargo, P. R., Flamant, P., Fu, Q., Hoff, R. M., Kittaka, C., Kubar, T. L., Le Treut, H., McCormick, M. P., Mégie, G., Poole, L., Powell, K., Trepte, C., Vaughan, M. A., and Wielicki, B. A.: The CALIPSO Mission: A Global 3D View of Aerosols and Clouds, B. Am. Meteorol. Soc., 91, 1211–1229, <a href="http://dx.doi.org/10.1175/2010BAMS3009.1">https://doi.org/10.1175/2010BAMS3009.1</a>, 2010. Yu, H., Kaufman, Y. J., Chin, M., Feingold, G., Remer, L. A., Anderson, T. L., Balkanski, Y., Bellouin, N., Boucher, O., Christopher, S., DeCola, P., Kahn, R., Koch, D., Loeb, N., Reddy, M. S., Schulz, M., Takemura, T., and Zhou, M.: A review of measurement-based assessments of the aerosol direct radiative effect and forcing, Atmos. Chem. Phys., 6, 613–666, <a href="http://dx.doi.org/10.5194/acp-6-613-2006">https://doi.org/10.5194/acp-6-613-2006</a>, 2006.