• Cahalan, R. F., and J. H. Joseph, 1989: Fractal statistics of cloud fields. Mon. Wea. Rev.,117, 261–272.

  • Ellingson, R. G., 1982: On the effects of cumulus dimensions on longwave irradiance and heating rate calculations. J. Atmos. Sci.,39, 886–896.

  • Ellingson, R. G., and J. C. Gille, 1978: An infrared radiative transfer model. Part I: Model description and comparison of observations with calculations. J. Atmos. Sci.,35, 523–545.

  • Ellingson, R. G., and G. N. Serafino, 1984: Observations and calculations of aerosol heating over the Arabian Sea during MONEX. J. Atmos. Sci.,41, 875–889.

  • Ellingson, R. G., and W. J. Wiscombe, 1996: The spectral radiance experiment (SPECTRE): Project description and sample results. Bull. Amer. Meteor. Soc.,77, 1967–1985.

  • Ellingson, R. G., D. J. Yanuk, and A. Gruber, 1989: Effects of the choice of meteorological data on a radiation model simulation of the NOAA technique for estimating outgoing longwave radiation from satellite radiance observations. J. Climate,2, 761–765.

  • Guan, S., M. K. Yau, and R. Davies, 1997: The effects of longwave radiation in a small cumulus cloud. J. Atmos. Sci.,54, 2201–2214.

  • Han, D., 1996: Studies of longwave radiative transfer under broken cloud conditions: Cloud parameterizations and validations. Ph.D. dissertation, University of Maryland at College Park, 163 pp.

  • Han, D., and R. G. Ellingson, 1999: Cumulus cloud formulizations for longwave radiation calculations. J. Atmos. Sci.,56, 837–851.

  • Harshvardhan, and J. A. Weinman, 1982: Infrared radiative transfer through a regular array of cuboidal clouds. J. Atmos. Sci.,39, 431–439.

  • Killen, R., and R. G. Ellingson, 1994: The effect of shape and spatial distribution of cumulus clouds on longwave irradiance. J. Atmos. Sci.,51, 2123–2136.

  • Koehler, T., and J. Shields, 1990: Factors influencing the development of a short term CFARC prediction technique based on WSI imagery. Scripps Institution of Oceanography Marine Physical Laboratory Tech. Note 223, 16 pp. [Available from Marine Physical Laboratory, Scripps Institution of Oceanography, La Jolla, CA 92151-6400.].

  • Lee, F. Y. P., 1988: Statistical parameters of a cloud field. IRS’88: Current Problems in Atmospheric Radiation, J. Lenoble and J. Geleyn, Eds., A. Deepak, 91–94.

  • McClatchey, R. A., R. W. Fenn, J. E. A. Selby, F. E. Volz, and J. S. Goring, 1972: Optical properties of the atmosphere. Air Force Cambridge Research Laboratories Environmental Research Paper 411, 108 pp.

  • Naber, P. S., and J. A. Weinman, 1984: The angular distribution of infrared radiances emerging from broken fields of cumulus clouds. J. Geophys. Res.,89, 1249–1257.

  • Sengupta, S. K., R. M. Welch, M. S. Navar, T. A. Berendes, and D. W. Chen, 1990: Cumulus cloud field morphology and spatial patterns derived from high spatial resolution Landsat imagery. J. Appl. Meteor.,29, 1245–1267.

  • Slingo, J. M., 1980: A cloud parameterization scheme derived from GATE data for use with a numerical model. Quart. J. Roy. Meteor. Soc.,106, 747–770.

  • Slingo, J. M., 1987: The development and verification of a cloud prediction scheme for ECMWF model. Quart. J. Roy. Meteor. Soc.,113, 899–927.

  • Takara, E. E., and R. G. Ellingson, 1996: Scattering effects on longwave fluxes in broken cloud fields. J. Atmos. Sci.,53, 1464–1476.

  • Welch, R. M., K. S. Kuo, B. A. Wielicki, S. K. Sengupta, and L. Parker, 1988: Marine stratocumulus cloud fields off the coast of southern California observed using LANDSAT imagery. Part I:Structural characteristics. J. Appl. Meteor.,27, 341–362.

  • Zhu, T., J. Lee, R. C. Weger, and R. M. Welch, 1992: Clustering, randomness, and regularity in cloud fields: 2. Cumulus cloud fields. J. Geophys. Res.,97, 20 537–20 558.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 168 168 5
PDF Downloads 11 11 0

An Experimental Technique for Testing the Validity of Cumulus Cloud Parameterizations for Longwave Radiation Calculations

View More View Less
  • 1 Department of Meteorology, University of Maryland at College Park, College Park, Maryland
© Get Permissions Rent on DeepDyve
Restricted access

Abstract

Cumulus cloud bulk geometry, size, and spatial distributions have long been recognized as important factors for longwave radiative transfer under broken cloud conditions. Most current climate models, however, still ignore these factors and estimate the effects of broken cumulus clouds as the cloud amount–weighted average of clear and black-cloud overcast conditions, that is, the black plate approximation. Although several groups have adopted the simplicity of the black plate approximation and extended it to include the effects of cloud geometry, cloud size, and spatial distributions by defining an effective cloud fraction, the validity of these parameterizations has long been assumed because of inadequate measurements of the instantaneous atmospheric radiative properties. Now ground-based measurements at the Atmospheric Radiation Measurement Program southern Great Plains Cloud and Radiation Test Bed site allow the derivation of the effective cloud fraction, absolute cloud fraction, cloud aspect ratio, and many other variables characterizing cumulus clouds. Using an empirically determined sampling period of 10 min, several different parameterizations for effective cumulus cloud fraction were tested by comparing effective amounts derived from hemispheric flux observations with values predicted by the parameterizations. Within the range of data and among the models tested, the better results were obtained with the cuboidal model with exponential cloud size and spatial distributions, the random cylinder model, the regular cuboidal model, and the shifted-periodic array cuboidal model. However, there are few cases in the range of greatest sensitivity where model comparisons demonstrate larger disparity.

Corresponding author address: Dejiang Han, 5000 Philadelphia Way, Suite A, Lanham, MD 20706-4417.

dhan@integ.com

Abstract

Cumulus cloud bulk geometry, size, and spatial distributions have long been recognized as important factors for longwave radiative transfer under broken cloud conditions. Most current climate models, however, still ignore these factors and estimate the effects of broken cumulus clouds as the cloud amount–weighted average of clear and black-cloud overcast conditions, that is, the black plate approximation. Although several groups have adopted the simplicity of the black plate approximation and extended it to include the effects of cloud geometry, cloud size, and spatial distributions by defining an effective cloud fraction, the validity of these parameterizations has long been assumed because of inadequate measurements of the instantaneous atmospheric radiative properties. Now ground-based measurements at the Atmospheric Radiation Measurement Program southern Great Plains Cloud and Radiation Test Bed site allow the derivation of the effective cloud fraction, absolute cloud fraction, cloud aspect ratio, and many other variables characterizing cumulus clouds. Using an empirically determined sampling period of 10 min, several different parameterizations for effective cumulus cloud fraction were tested by comparing effective amounts derived from hemispheric flux observations with values predicted by the parameterizations. Within the range of data and among the models tested, the better results were obtained with the cuboidal model with exponential cloud size and spatial distributions, the random cylinder model, the regular cuboidal model, and the shifted-periodic array cuboidal model. However, there are few cases in the range of greatest sensitivity where model comparisons demonstrate larger disparity.

Corresponding author address: Dejiang Han, 5000 Philadelphia Way, Suite A, Lanham, MD 20706-4417.

dhan@integ.com

Save