AMTD Atmospheric Measurement Techniques Discussions AMTD 1867-8610 Copernicus GmbH Göttingen, Germany 10.5194/amtd-5-2795-2012 Implications of satellite swath width on global aerosol optical thickness statistics Colarco P. R. 1 Remer L. A. 2 Kahn R. A. 2 Levy R. C. 2 3 Welton E. J. 4 NASA Goddard Space Flight Center, Atmospheric Chemistry and Dymamics Laboratory (Code 614), USA NASA Goddard Space Flight Center, Climate and Radiation Laboratory (Code 613), USA Science Systems and Applications, Inc., USA NASA Goddard Space Flight Center, Mesoscale Atmospheric Processes Laboratory (Code 612), USA 12 04 2012 5 2 2795 2820 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-meas-tech-discuss.net/5/2795/2012/amtd-5-2795-2012.html The full text article is available as a PDF file from http://www.atmos-meas-tech-discuss.net/5/2795/2012/amtd-5-2795-2012.pdf

We assess the impact of swath width on the statistics of aerosol optical thickness (AOT) retrieved by satellite, as inferred from observations made by the Moderate Resolution Imaging Spectroradiometer (MODIS). Using collocated AERONET sun photometer observations we develop a correction to the MODIS data to account for calibration and algorithmic view angle dependency in the retrieved AOT. We sub-sample and correct the AOT data from the MODIS Aqua instrument along several candidate swaths of various widths for the years 2003–2011. We find that over ocean the global, annual mean AOT is within ± 0.01 of the full swath AOT for all of our sub-samples. Over land, however, most of our sub-samples are outside of this criterion range in the global, annual mean. Moreover, at smaller spatial and temporal scales we find wide deviation in the sub-sample AOT relative to the full swath over both land and ocean. In all, the sub-sample AOT is within ± 0.01 of the full swath value less than 25% of the time over land, and less than 50% of the time over ocean (less than 35% for all but the widest of our sub-sample swaths). These results suggest that future aerosol satellite missions having only narrow swath views may not sample the true AOT distribution sufficiently to reduce significantly the uncertainty in aerosol direct forcing of climate.

 References Anderson, T. L., Charlson, R. J., Bellouin, N., Boucher, O., Chin, M., Christopher, S. A., Haywood, J., Kaufman, Y. J., Kinne, S., Ogren, J. A., Remer, L. A., Takemura, T., Tanré, D., Torres, O., Trepte, C. R., Wielicki, B. A., Winker, D. M., and Yu, H. B.: An "A-Train" strategy for quantifying direct climate forcing by anthropogenic aerosols, B. Am. Meteorol. Soc., 86, 1795–1809, 2005. CCSP (US Climate Change Science Program) Synthesis and Assessment Product 2.3: Atmospheric Aerosol Properties and Climate Impacts, edited by: Chin, M., Kahn,~R., and Schwartz,~S., US Climate Change Science Program, Washington, DC, USA, 116~pp., 2009. Colarco,~P., Da Silva,~A., Chin,~M., and Diehl,~T.: Online simulations of global aerosol distributions in the NASA GEOS-4 model and comparisons to satellite and ground-based aerosol optical depth, J. Geophys. Res., 115, D14207, http://dx.doi.org/10.1029/2009JD012820doi:10.1029/2009JD012820, 2010. Diner, D. J., Ackerman, T. P., Anderson, T. L., Bösenberg, J., Braverman, A. J., Charlson, R. J., Collins, W. D., Davies, R., Holben, B. N., Hostetler, C. A., Kahn, R. A., Martonchik, J. V., Menzies, R. T., Miller, M. A., Ogren, J. A., Penner, J. E., Rasch, P. J., Schwartz, S. E., Seinfeld, J. H., Stephens, G. L., Torres, O., Travis, L. D., Wielicki, B. A., and Yu, B.: PARAGON: an integrated approach for characterizing aerosol climate impacts and environmental interactions, B. Am. Meteorol. Soc., 85, 1491–1501, http://dx.doi.org/10.1175/BAMS-85-10-1491doi:10.1175/BAMS-85-10-1491, 2004. Hansen, J., Rossow, W., Carlson, B., Lacis, A., Travis, L., Del Genio, A., Fung, I., Cairns, B., Mishchenko, M., and Sato, M.: Low-cost long-term monitoring of global climate forgings and feedbacks, Clim. Change, 31, 247–271, 1995. Kahn,~R A.: Reducing the uncertainties in direct aerosol radiative forcing, Surv. Geophys., online first: http://dx.doi.org/10.1007/s10712-011-9153-zdoi:10.1007/s10712-011-9153-z, 2011. Kiehl,~J T.: Twentieth century climate model response and climate sensitivity, Geophys. Res. Lett., 34, L22710, http://dx.doi.org/10.1029/2007GL031383doi:10.1029/2007GL031383, 2007. Levy,~R C., Remer,~L A., and Dubovik,~O.: Global aerosol optical properties and application to moderate resolution imaging spectroradiometer aerosol retrieval over land, J. Geophys. Res., 112, D13210, http://dx.doi.org/10.1029/2006JD007815doi:10.1029/2006JD007815, 2007a. Levy,~R C., Remer,~L A., Mattoo,~S., Vermote,~E F., and Kaufman,~Y J.: Second-generation operational algorithm: retrieval of aerosol properties over land from inversion of moderate resolution imaging spectroradiometer spectral reflectance, J. Geophys. Res., 112, D13211, http://dx.doi.org/10.1029/2006JD007811doi:10.1029/2006JD007811, 2007b. Levy,~R C., Leptoukh,~G G., Kahn,~R., Zubko,~V., Gopalan,~A., and Rember,~L A.: A~critical look at deriving monthly aerosol optical depth from satellite data, IEEE T. Geosci. Remote Sens., 47, 2942–2956, http://dx.doi.org/10.1109/TGRS.2009.2013842doi:10.1109/TGRS.2009.2013842, 2009. Levy,~R C., Remer,~L A., Kleidman,~R G., Mattoo,~S., Ichoku,~C., Kahn,~R., and Eck,~T F.: Global evaluation of the Collection 5 MODIS dark-target aerosol products over land, Atmos. Chem. Phys., 10, 10399–10420, http://dx.doi.org/10.5194/acp-10-10399-2010doi:10.5194/acp-10-10399-2010, 2010. Loeb,~N G. and Su,~W.: Direct aerosol radiative forcing uncertainty based on a~radiative perturbation analysis, J. Climate, 23, 5288–5293, http://dx.doi.org/10.1175/2010JCLI3543.1doi:10.1175/2010JCLI3543.1, 2010. Mishchenko, M. I., Cairns, B., Hansen, J. E., Travis, L. D., Burg, R., Kaufman, Y. J., Martins, J. V., and Shettle, E. P.: Monitoring of aerosol forcing of climate from space: analysis of measurement requirements, J. Quant. Spectosc. Ra., 88, 149–161, http://dx.doi.org/10.1016/j.jqsrt.2004.03.030doi:10.1016/j.jqsrt.2004.03.030, 2004. Remer, L. A., Kaufman, Y. J., Tanré, D., Mattoo, S., Chu, D. A., Martins, J. V., Li, R.-R., Ichoku, C., Levy, R. C., Kleidman, R. G., Eck, T., Vermote, E., and Holben, B. N.: The MODIS aerosol algorithm, products, and validation, J. Atmos. Sci., 62, 947–973, 2005. Remer, L. A., Kleidman, R. G., Levy, R. C., Kaufman, Y. J., Tanré, D., Mattoo, S., Martins, J. V., Ichoku, C., Koren, I., Yu, H., and Holben, B. N.: Global aerosol climatology from the MODIS satellite sensors, J. Geophys. Res., 113, D14S07, http://dx.doi.org/10.1029/2007JD009661doi:10.1029/2007JD009661, 2008. Solomon,~S., Qin,~D., Manning,~M., Marquis,~M., Averyt,~K., Tignor,~M M B., Miller Jr.,~H L., and Chen,~Z.: Climate Change 2007: The Physical Sciences Basis, Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 996~pp., 2007. Tanre,~D., Herman,~M., and Kaufman,~Y.: Information on aerosol size distribution contained in solar reflected spectral radiances, J. Geophys. Res., 101, 19043–19060, 1996. Tanre,~D., Kaufman,~Y., Herman,~M., and Mattoo,~S.: Remote sensing of aerosol properties over oceans using the MODIS/EOS spectral radiances, J. Geophys. Res., 102, 16971–16988, 1997. Zhang,~J. and Reid,~J S.: MODIS aerosol product analysis for data assimilation: assessment of over-ocean level 2 aerosol optical thickness retrievals, J. Geophys. Res., 111, D22207, http://dx.doi.org/10.1029/2005JD006898doi:10.1029/2005JD006898, 2006.