Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 10 5 2010 10.5194/acp-10-2287-2010 http://www.atmos-chem-phys.net/10/2287/2010/ http://www.atmos-chem-phys.net/10/2287/2010/acp-10-2287-2010.html http://www.atmos-chem-phys.net/10/2287/2010/acp-10-2287-2010.pdf 2287 2305 2010-03-05 Statistical properties of aerosol-cloud-precipitation interactions in South America T. A. Jones tjones@nsstc.uah.edu S. A. Christopher Earth System Science Center, UAHuntsville, Huntsville, AL, USA Department of Atmospheric Science, UAHuntsville, Huntsville, AL, USA Given the complex interaction between aerosol, cloud, and atmospheric properties, it is difficult to extract their individual effects to observed rainfall amount. This research uses principle component analysis (PCA) that combines Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol and cloud products, NCEP Reanalysis atmospheric products, and rainrate estimates from the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) to assess if aerosols affect warm rain processes. Data collected during September 2006 over the Amazon basin in South America during the biomass-burning season are used. The goal of this research is to combine these observations into a smaller number of variables through PCA with each new variable having a unique physical interpretation. In particular, we are concerned with PC variables whose weightings include aerosol optical thickness (AOT), as these may be an indicator of aerosol indirect effects. If they are indeed occurring, then PC values that include AOT should change as a function of rainrate. <br><br> To emphasize the advantage of PCA, changes in aerosol, cloud, and atmospheric observations are compared to rainrate. Comparing no-rain, rain, and heavy rain only (&gt;5 mm h^&minus;1) samples, we find that cloud thicknesses, humidity, and upward motion are all greater during rain and heavy rain conditions. However, no statistically significant difference in AOT exists between each sample, indicating that atmospheric conditions are more important to rainfall than aerosol concentrations as expected. If aerosols are affecting warm process clouds, it would be expected that stratiform precipitation would decrease as a function increasing aerosol concentration through either Twomey and/or semi-direct effects. PCA extracts the latter signal in a variable labeled PC2, which explains 15% of the total variance and is second in importance the variable (PC1) containing the broad atmospheric conditions. PC2 contains weightings showing that AOT is inversely proportional to low-level humidity and cloud optical thickness. Increasing AOT is also positively correlated with increasing low-level instability due to aerosol absorption. The nature of these weightings is strongly suggestive that PC2 is an indicator of the semi-direct effect with larger values associated with lower rainfall rates. PC weightings consistent with the Twomey effect (an anti-correlation between AOT and cloud droplet effective radius) are only present in higher order PC variables that explain less than 1% of the total variance, and do not vary significantly as a function of rainrate. If the Twomey effect is occurring, it is highly non-linear and/or being overshadowed by other processes. Using the raw variables alone, these determinations could not be made; thus, we are able to show the advantage of using advanced statistical techniques such as PCA for analysis of aerosols impacts on precipitation in South America. Ackerman, A. S., Toon, O. B., Stevens, D. E., Heymsfield, A. J., Ramanathan, V., and Welton, E. J.: Reduction of tropical cloudiness by soot, Science, 288, 1042–1047, 2000. Ackerman, A. S., Toon, O. B., Stevens, D. E., and Coakley Jr., J. A.: Enhancement of cloud cover and suppression of nocturnal drizzle in stratocumulus polluted by haze, Geophys. Res. Lett., 30, L1381, doi:10.1029/2002GL016634, 2003. Albrecht, B.: Aerosols, Cloud Microphysics, and Fractional Cloudiness, Science, 245, 1227–1230, 1989. Andreae, A., Rosenfeld, D., Artaxo, P., et al.: Smoking rain clouds over the Amazon, Science, 303, 1337–1342, 2004. Brenguier, J.-L., Pawlowska, H., and Schuller, L.: Cloud microphysical and radiative properties for parameterization and satellite monitoring of the indirect effect of aerosol on climate, J. Geophys. Res., 108(D15), 8632, doi:10.1029/2002JD002682, 2003. DeMott, P. J., Sassen, K., Poellot, M. R., Baumgardner, D., Rodgers, D. C., Brooks, S. D., Prenni, A. J., and Kreidenweis, S. M.: African dust aerosols as atmospheric ice nuclei, Geophys. Res. Lett., 30, 1732, doi:10.1029/2003GL017410, 2003. Feingold, G.: Modeling of the first indirect effect: Analysis of measurement requirements, Geophys. Res. Lett., 30(6), 1997, doi:10.1029/2003GL017967, 2003. Feingold, G., Eberhard, W. L., Veron, D. E., and Previdi, M.: First measurements of the Twomey indirect effect using ground-based remote sensors, Geophys. Res. Lett., 30(6), 1287, doi:10.1029/2003GL016633, 2003. Han, Q. Y., Rossow, W. B., and Lacis, A. A.: Near-global survey of effective droplet radii in liquid water clouds using ISCCP data, J. Climate, 7, 465–497, 1994. Han, Q., Rossow, W. B., Chou, J., and Welch, R. M.: Global survey of the relationships of cloud albedo and liquid water path with droplet size using ISCCP., J. Climate, 11, 1516–1528, 1998. Hanson, J., Sato, M., and Ruedy, R.: Radiative forcing and climate response, J. Geophys. Res., 102, 6831–6864, 1997. Iguchi, T., Kozu, T., Meneghini, R., Awaka, J., and Okamoto, K.: Rain-profiling algorithm for the TRMM precipitation radar, J. App. Meteorol., 39, 2038–2052, 2000. Jeong, M.-J., Li, Z., Andrews, E., and Tsay, S.-C.: Effect of aerosol humidification on the column aerosol optical thickness over the Atmospheric Radiation Measurement Southern Great Plains site, J. Geophys. Res., 112, D10202, doi:10.1029/2006JD007176, 2007. Johnson, B. T., Shine, K. P., and Forster, P. M.: The semi-direct aerosol effect: Impact of absorbing aerosols on marine stratocumulus, Q. J. Roy. Meteorol. Soc., 130, 1407–1422, 2004. Jones, T. A., McGrath, K. M., and Snow, J. T.: Association Between NSSL Mesocyclone Detection Algorithm detected vortices and tornadoes, Wea. Forecasting, 19, 872–890, 2004. Jones, T. A. and Christopher, S. A.: Seasonal variation in satellite derived effects of aerosols on clouds in the Arabian Sea, J. Geophys. Res., 113, D09207, doi:10.1029/2007JD009118, 2008. Kalnay, E., Kanamitus, M., Kitsler, R., et al.: The NCEP/NCAR 40-year reanalysis project, B. Am. Meteorol. Soc., 77, 437–471, 1996. Kaufman, Y. J. and Fraser, R. S.: The effect of smoke particles on clouds and climate forcing, Science, 277, 1636–1639, 1997. Kaufman, Y. J., Koren, I., Remer, L. A., Rosenfeld, D., and Rudich, Y.: The effect of smoke, dust, and pollution, aerosol on shallow cloud development over the Atlantic Ocean, Proc. Natl. Acad. Sci., 102(32), 11207–11212, 2005a. Khain, A. P., Rosenfeld, D., and Pokrovsky, A.: Aerosol impact on the dynamics and microphysics of convective clouds, Q. J. Roy. Meteorol. Soc., 131, 2639–2663, 2005. Koren, I., Kaufman, Y. J., Remer, L. A., Rosenfeld, D., and Rudich, Y.: Aerosol invigoration and restructuring of Atlantic convective clouds, Geophys. Res. Lett., 32(14), L14828, doi:10.1029/2005GL023187, 2005. Koren, I., Remer, L. A., Kaufman, Y. J., Rudich, Y., and Martins, J. V.: On the twilight zone between clouds and aerosols, Geophys. Res. Lett., 34, L08805, doi:10.1029/2007GL029253, 2007. Koren, I., Martins, J. V., Remer, L. A., and Afargan, H.: Smoke invigoration versus inhibition of clouds over the Amazon, Science, 321, 946–949, 2008. Kummerow C., Simpson, J., Thiele, O., et al.: The status of the Tropical Rainfall Measuring Mission (TRMM) after two years in orbit, J. Appl. Meteorol., 39, 1965–1982, 2000. Lin, J. C., Matsui, T., Pielke Sr., R. A., and Kummerow, C.: Effects of biomass burning derived aerosols on precipitation and clouds in the Amazon Basin: a satellite-based empirical study, J. Geophys. Res., 111, D19204, doi:10.1029/2005JD006884, 2006. Loeb, N. G. and Manalo-Smith, N.: Top-of-atmosphere direct radiative effect of aerosols over global oceans from merged CERES and MODIS observations, J. Climate, 18, 3506–3526, 2005. Lohmann, U. and Feichter, J.: Global indirect aerosol effects: a review, Atmos. Chem. Phys., 5, 715–737, 2005. Lohmann, U. and Lesins, G.: Comparing continental and oceanic cloud susceptibilities to aerosols, Geophys. Res. Lett., 30(15), 1791, doi:10.1029/2003GL017828, 2003. Mauger, G. S. and Norris, J. R.: Meteorological bias in satellite estimates of aerosol-cloud relationships, Geophys. Res. Lett., 34, L16824, doi:10.1029/2007GL029952, 2007. Marshak, A., Wen, G., Coakley, J. A., Remer, L. A., Loeb, N. G., and Cahalan, R. F.: A simple model for the cloud adjacency effect and the apparent bluing of aerosols near clouds, J. Geophys. Res., 113, D14S17, doi:10.1029/2007JD009196, 2008. Martins, J. A., Silva Dias, M. A. F., Gonçalves, F. L. T.: Impact of biomass burning aerosols on precipitation in the Amazon: A modeling case study, J. Geophys. Res., 114, D02207, doi:10.1029/2007JD009587, 2009. Matsui, T., Masunaga, H., Kreidenweis, S. M., Pielke Sr., R. A., Tao, W.-K., Chin, M., and Kaufman, Y. J.: Satellite based assessment of marine low cloud variability associated with aerosol, atmospheric stability, and the diurnal cycle, J. Geophys. Res., 111, D17204, doi:10.1029/2005JD006097, 2006. Minnis, P., Young, D. F., Sun-Mack, S., Heck, P. W., Doelling, D. R., and Trepte, Q.: CERES Cloud Property Retrievals from Imagers on TRMM, Terra, and Aqua., Proc. SPIE 10th International Symposium on Remote Sensing: Conference on Remote Sensing of Clouds and the Atmosphere VII, Barcelona, Spain, 8–12 September, 37–48, 2003. Morisette, J. T., Giglio, L., Csiszar, I., Setzer, A., Schroeder, W., Morton, D., and Justice, C. O.: Validation of MODIS active fire detection products derived from two algorithms, Earth Interactions, 9, 1–23, 2005. Nakajima, T., King, M. D., and Spinhirne, J. D.: Determination of the optical thickness and effective particle radius of clouds from reflected solar radiation measurements. Part II: Marine strato-cumulus observations, J. Atmos. Sci., 48, 728–750, 1991. Nicholson, S. E., Some, B., McCollum,~J., et al.: Validation of TRMM and other rainfall estimates with a high-density gauge dataset for West Africa. Part II: Validation of TRMM rainfall products, J. Appl. Meteorol., 42, 1355–1368, 2003. Peng, Y., Lohmann, U., Leaitch, R., Banic, C., and Couture, M.: The cloud albedo-cloud droplet effective radius relationship for clean and polluted clouds from RACE and FIRE.ACE, J. Geophys. Res., 107(D11), 4106, doi:10.1029/2000JD000281, 2002. Penner, J. E., Dong, X., and Chen, Y.: Observational evidence of a change in radiative forcing due to the indirect aerosol effect, Nature, 427, 231–234, 2004. Platnick, S., King, M. D., Ackerman, S. A., Menzel, W. P., Baum, B. A., Riédi, J. C., and Frey, R. A.: The MODIS Cloud Products: Algorithms and Examples from Terra, IEEE Trans. Geosci. Rem. Sens., 41, 459–473, 2003. Quaas, J., Boucher, O., and Breon, F.-M.: Aerosol indirect effects in POLDER satellite data and the Laboratoire de Meteorologie Dynamique-Zoom (LMDZ) general circulation model, J. Geophys. Res., 109, D08205, doi:10.1029/2003JD004317, 2004. Quaas, J., Boucher, O., Bellouin, N., and Kinne, S.: Satellite-based estimate of the direct and indirect aerosol climate forcing, J. Geophys. Res., 113, D05204, doi:10.1029/2007JD008962, 2008. Ramana, M. V. and Ramanathan, V.: Abrupt transition from natural to anthropogenic aerosol radiative forcing: Observations at the ABC-Maldives Climate Observatory, J. Geophys. Res., 111, D20207, doi:10.1029/2006JD007063, 2006. Ramanathan, V., Crutzen, P. J., Kiehl, J. T., and Rosenfeld, D.: Aerosols, climate, and the hydrological cycle, Science, 294, 2119–2124, 2001. Reid, J. S., Hobbs, P. V., Ferek, R. J., Blake, D. R., Martins, J. V., Dunlap, M. R., and Liousse, C.: Physical, chemical, and optical properties of regional hazes dominated by smoke in Brazil, J. Geophys. Res., 103, 32059–32080, 1998. Reid, J. S., Hobbs, P. V., Rangno, A. L., and Hegg, D. A.: Relationships between cloud droplet effective radius, liquid water content, and droplet concentration for warm clouds in Brazil embedded in biomass smoke, J. Geophys. Res., 104(D6), 6145–6153, 1999. 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, 2009. Remer, L. A. and Kaufman, Y. J.: Aerosol direct radiative effect at the top of the atmosphere over cloud free ocean derived from four years of MODIS data, Atmos. Chem. Phys., 6, 237–253, 2006. Richman, M. B. and Gong, X.: Relationships between the definition of the hyperplane width to the fidelity of principal component loading patterns, J. Climate, 12, 1557–1576, 1999. Rosenfeld, D., Kaufman, Y. J., and Koren, I.: Switching cloud cover and dynamical regimes from open to closed Benard cells in response to the suppression of precipitation by aerosols, Atmos. Chem. Phys., 6, 2503–2511, 2006. Rosenfeld, D., Lohmann, U., Raga, G. B., O'Dowd, C. D., Kulmala, M., Fuzzi, S., Reissell, A., and Andreae, M. O.: Flood or drought: How do aerosols affect precipitation, Science, 321, 1309–1313, 2008. Schwartz, S. E., Harshvardhan, and Benkovitz, C. M.: Influence of anthropogenic aerosol on cloud optical depth and albedo shown by satellite measurements and chemical transport modeling, Proc. Nat. Acad. Sci. US, 99, 1784–1789, 2002. Teller, A. and Levin, Z.: The effects of aerosols on precipitation and dimensions of subtropical clouds: a sensitivity study using a numerical cloud model, Atmos. Chem. Phys., 6, 67–80, 2006. Turner, D. D., Vogelmann, A. M., and Austin, R. T.: Thin Liquid Water Clouds: Their Importance and Our Challenge, B. Am Meteorol. Soc, 88(2), 177–190, doi:10.1175/BAMS-88-2-177, 2007. Twomey, S. A.: The influence of pollution on the shortwave albedo of clouds, J. Atmos. Sci., 34, 1149–1152, 1977. Vaughan, M., Young, S., Winker, D., Powell, K., Omar, A., Liu, Z., Hu, Y., and Hostetler, C.: Fully automated analysis of space-based lidar data: an overview of the CALIPSO retrieval algorithms and data products, Proc. SPIE, 5575, pp. 16–30, 2004. Wen, G., Marshak, A., and Cahalan, R. F.: Impact of 3D Clouds on Clear Sky Reflectance and Aerosol Retrieval in a Biomass Burning Region of Brazil, IEEE Geo. Rem. Sens. Lett., 3, 169–172, 2006. Williams, E., Rosenfeld, D., Madden, N., et al.: Contrasting convective regimes over the Amazon: Implications for cloud electrification, J. Geophys. Res., 107, 8082, doi:10.1029/2001JD000380, 2002. Yuan, T., Li, Z., Chang, F. L., Vant-Hull, B., and Rosenfeld, D.: Increase of cloud droplet size with aerosol optical depth: An observation and modeling study, J. Geophys. Res., 113, D04201, doi:10.1029/2007JD008632, 2008. 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, doi:10.1029/2005JD006898, 2006.