ACPD Atmospheric Chemistry and Physics Discussions ACPD 1680-7375 Copernicus GmbH Göttingen, Germany 10.5194/acpd-10-23091-2010 Influence of convection and aerosol pollution on ice cloud particle effective radius Jiang J. H. 1 Su H. 1 Zhai C. 1 Massie S. T. 2 Schoeberl M. R. 3 Colarco P. R. 3 Platnick S. 3 Gu Y. 4 Liou K.-N. 4 Jet propulsion Laboratory, California Institute of Technology, Pasadena, California, USA National Center for Atmospheric Research, Boulder, Colorado, USA NASA Goddard Space Flight Center, Greenbelt, Maryland, USA Department of Atmospheric Sciences, University of California, Los Angeles, USA 07 10 2010 10 10 23091 23108 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-discuss.net/10/23091/2010/acpd-10-23091-2010.html The full text article is available as a PDF file from http://www.atmos-chem-phys-discuss.net/10/23091/2010/acpd-10-23091-2010.pdf

Satellite observations show that ice cloud effective radius (<i>r</i><sub>e</sub>) increases with ice water content (IWC) but decreases with aerosol optical thickness (AOT). Using least-squares fitting to the observed data, we obtain an analytical formula to describe the variations of <i>r</i><sub>e</sub> with IWC and AOT for several regions with distinct characteristics of <i>r</i><sub>e</sub>-IWC-AOT relationships. As IWC directly relates to convective strength and AOT represents aerosol loading, our empirical formula provides a means to quantify the relative roles of dynamics and aerosols in controlling <i>r</i><sub>e</sub> in different geographical regions, and to establish a framework for parameterization of aerosol effects on <i>r</i><sub>e</sub> in climate models.

 References Ackerman, A. C., Kirkpatrick, M. P., Stevens, D. E., and Toon, O. B.: The impact of humidity above stratiform clouds on indirect aerosol climate forcing, Nature, 432, 1014–1017, 2004. Albrecht, B. A.: Aerosols, cloud microphysics, and fractional cloudiness, Science, 245, 1227–1230, 1989. Evans, K. F. and Stephens, G. L.: Microwave radiative transfer through clouds composed of realistically shaped ice crystals. Part I: Single scattering properties, J. Atmos. Sci., 52, 2041–2057, 1995. Jiang, J. H., Su, H., Schoeberl, M., Massie, S. T., Colarco, P., Platnick, S., and Livesey, N.: Clean and polluted clouds: relationships among pollution, ice cloud and precipitation in South America, Geophys. Res. Lett., 35, L14804, doi:10.1029/2008GL034631, 2008. Jiang, J. H., Su, H., Massie, S. T., Colarco, P. R., Schoeberl, M. R., and Platnick, S.: Aerosol-CO relationship and aerosol effect on Ice cloud particle size: Analyses from Aura MLSand Aqua MODIS observations, J. Geophys. Res., 114, D20207, doi:10.1029/2009JD012421, 2009. Jiang, J. H., Su, H., Pawson, S., Liu, H. C., Read, W., Waters, J. W., Santee, M., Wu, D. L., Schwartz, M., Livesey, N., Lambert, A., Fuller, R., and Lee, J. N.: Five-year (2004–2009) Observations of Upper Tropospheric Water Vapor and Cloud Ice from MLS and Comparisons with GEOS-5 analyses, J. Geophys. Res. 115, D15103, doi:10.1029/2009JD013256, 2010. Lohmann, U. and Feichter, J.: Global indirect aerosol effects: a review, Atmos. Chem. Phys., 5, 715–737, doi:10.5194/acp-5-715-2005, 2005. McFarquhar, G. M. and Heymsfield, A. J.: Parameterization of tropical cirrus ice crystal size distributions and implications radiative transfer: Results from CEPEX, J. Atmos. Sci., 54, 2187–2200, 1997. Matrosov, S. Y., Orr, B. W., Kropfli, R. A., and Snider, J. B.: Retrieval of vertical profiles of cirrus cloud microphysical parameters from Doppler radar and infrared radiometer measurements, J. Appl. Meteor., 33, 617–626, 1994. Menon, S., Hansen, J., Nazarenko, L., and Luo, Y.: Climate Effects of Black Carbon Aerosols in China and India, Science, 27, 2250–2253, doi:10.1126/science.1075159, 2002. Mitchell, D. L., Macke, A., and Liu, Y.: Modeling cirrus clouds. Part I: Treatment of bimodal size spectra and case study analysis, J. Atmos. Sci., 53, 2952–2966, 1996. Penner, J. E., Andreae, M., Annegarn, H., Barrie, L., Feichter, J., Hegg, D., Jayaraman, A., Leaitch, R., Murphy, D., Nganga, J., and Pitari, G.: Chapter 5: Aerosols, their direct and indirect effects, in Climate Change 2001: The Scientific Basis, edited by: Houghton, H. T., Ding, Y., Griggs, D. J., et. al., Report to Intergovernmental Panel on Climate Change from the Scientific Assessment Working Group (WGI), 289–348, Cambridge University Press, 2006. Platnick, S.: Vertical photon transport in cloud remote sensing problems, J. Geosphys, Res., 105(D18), 22919–22935, 2000. Platt, C. M. R.: A parameterization of the visible extinction coefficient in terms of the ice/water content, J. Atmos. Sci., 48, 2083–2098, 1997. Sherwood, S. C.: Aerosols and ice particle size in tropical cumulonimbus, J. Clim, 15, 1051–1063, 2002. Su, H., Jiang, J. H., Liu, X., Penner, J. E., Read, W. G., Massie, S. T., Schoeberl, M. R., Colarco, P., Livesey, N. J., and Santee, M. L.: Enhanced Water Vapor Transport to the Stratosphere by Pollutants in Asia, J. Climate, in press, 2010. Twomey, S.: Atmospheric Aerosols, Elsevier Scientific, Amsterdam, 302~pp., 1977. Zhang, Z., Platnick, S., Yang, P., Heidinger, A. K., and Comstock, J. M.: Effects of ice particle size vertical inhomogeneity on the passive remote sensing of ice clouds, J. Geophys. Res., 115, D17203, doi:10.1029/2010JD013835, 2010.