Effects of observed horizontal inhomogeneities within cirrus clouds on solar radiative transfer

Nicole Buschmann, Greg M. McFarquhar, Andrew J. Heymsfield

Research output: Contribution to journalArticlepeer-review

Abstract

In situ microphysical and combined radar and radiometer measurements of 11 cirrus clouds from Central Equatorial Pacific Experiment (CEPEX), European Cloud and Radiation Experiment (EUCREX), investigation of Clouds by Ground-Based and Airborne Radar and Lidar (CARL), and First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment (FIRE) are used to investigate effects of horizontal cloud inhomogeneities on solar radiative transfer. A three-dimensional ray-tracing model (GRIMALDI), based on the Monte Carlo method, is used to calculate upward and downward flux densities and absorption for the spectral range from 0.38 to 4.0 μm. Radiative flux densities are calculated using the inhomogeneous clouds derived from the observations and for horizontally and vertically averaged homogeneous clouds. Horizontally averaged values of radiative flux densities and absorption for heterogeneous clouds can differ by up to 30% from those calculated for the homogeneous clouds for convectively induced tropical cirrus clouds. The midlatitude cases examined tended to be more homogeneous, and hence differences between radiative properties for the homogeneous and heterogeneous clouds did not exceed 10%. For cirrus clouds with mean optical thicknesses smaller than 5 and with relative variances of optical thickness smaller than 0.2, errors caused by the homogeneous assumption are smaller than ±10%.

Original languageEnglish (US)
Pages (from-to)AAC 9-1-AAC 9-9
JournalJournal of Geophysical Research: Atmospheres
Volume107
Issue number20
DOIs
StatePublished - 2002

Keywords

  • 0320 Atmospheric Composition and Structure: Cloud physics and chemistry
  • 1655 Global Change: Water cycles (1836)
  • 1694 Global Change: Instruments and techniques
  • 3359 Meteorology and Atmospheric Dynamics: Radiative processes
  • Cirrus clouds

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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