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Title: Vertical microphysical profiles of convective clouds as a tool for obtaining aerosol cloud-mediated climate forcings

Quantifying the aerosol/cloud-mediated radiative effect at a global scale requires simultaneous satellite retrievals of cloud condensation nuclei (CCN) concentrations and cloud base updraft velocities (Wb). Hitherto, the inability to do so has been a major cause of high uncertainty regarding anthropogenic aerosol/cloud-mediated radiative forcing. This can be addressed by the emerging capability of estimating CCN and Wb of boundary layer convective clouds from an operational polar orbiting weather satellite. Our methodology uses such clouds as an effective analog for CCN chambers. The cloud base supersaturation (S) is determined by Wb and the satellite-retrieved cloud base drop concentrations (Ndb), which is the same as CCN(S). Developing and validating this methodology was possible thanks to the ASR/ARM measurements of CCN and vertical updraft profiles. Validation against ground-based CCN instruments at the ARM sites in Oklahoma, Manaus, and onboard a ship in the northeast Pacific showed a retrieval accuracy of ±25% to ±30% for individual satellite overpasses. The methodology is presently limited to boundary layer not raining convective clouds of at least 1 km depth that are not obscured by upper layer clouds, including semitransparent cirrus. The limitation for small solar backscattering angles of <25º restricts the satellite coverage to ~25% of themore » world area in a single day. This methodology will likely allow overcoming the challenge of quantifying the aerosol indirect effect and facilitate a substantial reduction of the uncertainty in anthropogenic climate forcing.« less
  1. Hebrew Univ. of Jerusalem (Israel)
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Resource Type:
Technical Report
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Related Information: 1. Rosenfeld D., Wang H., and Rasch P. J., 2012: The roles of cloud drop effective radius and LWP in determining rain properties in marine stratocumulus. Geophys. Res. Lett., 39, L13801, doi:10.1029/2012GL052028, 2012.2. Creamean J. M., K. J. Suski, D. Rosenfeld, A. Cazorla, P. J. DeMott, R. C. Sullivan, A. B. White, F. M. Ralph, P. Minnis, J. M. Comstock, J. M. Tomlinson, and K. A. Prather, 2013: Dust and Biological Aerosols from the Sahara and Asia Influence Precipitation in the Western US. Science, Vol. 339 no. 6127 pp. 1572-1578. DOI: 10.1126/science.12272793. Daniel Rosenfeld, Rei Chemke, Paul DeMott, Ryan C. Sullivan, Roy Rasmussen, Frank McDonough, Jennifer Comstock, Beat Schmid, Jason Tomlinson, Haflidi Jonsson, Kaitlyn Suski, Alberto Cazorla, Kimberly Prather, 2013. The Common Occurrence of Highly Supercooled Drizzle and Rain near the Coastal Regions of the Western United States. JGR. DOI: 10.1002/jgrd.50529.4. Zhu Y., D. Rosenfeld, X. Yu, G. Liu, J. Dai, X. Xu, 2014: Satellite retrieval of convective cloud base temperature based on the NPP/VIIRS Imager. Geophys. Res. Lett., 41, doi:10.1002/2013GL058970.5. Rosenfeld D., B. Fischman, Youtong Zheng, T. Goren, D. Giguzin, 2014: Combined satellite and radar retrievals of drop concentration and CCN at convective cloud base. GRL, DOI:10.1002/2014GL0594536. Zheng, Y., Rosenfeld, D., and Li, Z., 2015: Satellite Inference of Thermals and Cloud-Base Updraft Speeds Based on Retrieved Surface and Cloud-Base Temperatures. J. Atmos. Sci., 72, 2411–2428. doi: Zheng Y., D. Rosenfeld, 2015: Linear relation between convective cloud base height and updrafts and application to satellite retrievals. GRL 2015. doi: 10.1002/2015GL064809
Research Org:
The Hebrew University of Jerusalem (Israel)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES; Cloud aerosol interactions