RACORO continental boundary layer cloud investigations: 2. large-eddy simulations of cumulus clouds and evaluation with in situ and ground-based observations

Satoshi Endo, Ann M. Fridlind, Wuyin Lin, Andrew M. Vogelmann, Tami Toto, Andrews Ackerman, Greg M. McFarquhar, Robert C. Jackson, Haflidi H. Jonsson, Yangang Liu

Research output: Contribution to journalArticle

Abstract

A 60 h case study of continental boundary layer cumulus clouds is examined using two large-eddy simulation (LES) models. The case is based on observations obtained during the RACORO Campaign (Routine Atmospheric Radiation Measurement (ARM) Aerial Facility (AAF) Clouds with Low Optical Water Depths (CLOWD) Optical Radiative Observations) at the ARM Climate Research Facility’s Southern Great Plains site. The LES models are driven by continuous large-scale and surface forcings and are constrained by multimodal and temporally varying aerosol number size distribution profiles derived from aircraft observations. We compare simulated cloud macrophysical and microphysical properties with ground-based remote sensing and aircraft observations. The LES simulations capture the observed transitions of the evolving cumulus-topped boundary layers during the three daytime periods and generally reproduce variations of droplet number concentration with liquid water content (LWC), corresponding to the gradient between the cloud centers and cloud edges at given heights. The observed LWC values fall within the range of simulated values; the observed droplet number concentrations are commonly higher than simulated, but differences remain on par with potential estimation errors in the aircraft measurements. Sensitivity studies examine the influences of bin microphysics versus bulk microphysics, aerosol advection, supersaturation treatment, and aerosol hygroscopicity. Simulated macrophysical cloud properties are found to be insensitive in this nonprecipitating case, but microphysical properties are especially sensitive to bulk microphysics supersaturation treatment and aerosol hygroscopicity.

Original languageEnglish (US)
Pages (from-to)5993-6014
Number of pages22
JournalJournal of Geophysical Research
Volume120
Issue number12
DOIs
StatePublished - Jan 1 2015

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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    Endo, S., Fridlind, A. M., Lin, W., Vogelmann, A. M., Toto, T., Ackerman, A., McFarquhar, G. M., Jackson, R. C., Jonsson, H. H., & Liu, Y. (2015). RACORO continental boundary layer cloud investigations: 2. large-eddy simulations of cumulus clouds and evaluation with in situ and ground-based observations. Journal of Geophysical Research, 120(12), 5993-6014. https://doi.org/10.1002/2014JD022525