Microphysical and radiative properties of inhomogeneous stratocumulus: Observations and model simulations

Detailed microphysical observations made from aircraft during the Atlantic Stratocumulus Transition Experiment are used to examine the optical properties of marine stratocumulus. Special attention is given to the relationship between the droplet size distribution (droplet-number concentration, effective radius, and liquid-water content) and the optical extinction parameter. The extinction parameter calculated with measurements from the forward-scattering spectrometer probe (FSSP) differs only slightly from the extinction parameter obtained from the total droplet spectrum (measured with two optical probes, FSSP and 260X). In contrast, the results for the effective radius and the liquid-water content show differences up to 40% between the two spectra. A Monte Carlo radiative-transfer model is initialized with optical properties calculated from the observed microphysics. Monte Carlo simulations of radiative fluxes are in good agreement with observations for well-mixed boundary-layer cloud fields.

[1]  A. Slingo,et al.  A field study of nocturnal stratocumulus; III. High resolution radiative and microphysical observations , 1982 .

[2]  P. J. Jonker,et al.  Microphysical and Turbulent Structure of Nocturnal Stratocumulus as Observed during ASTEX , 1995 .

[3]  S. Caughey,et al.  A field study of nocturnal stratocumulus II Turbulence structure and entrainment , 1982 .

[4]  P. Duynkerke,et al.  Observed Lagrangian transition of stratocumulus into cumulus during ASTEX : Mean state and turbulence structure , 1997 .

[5]  H. V. Hulst.  Light Scattering by Small Particles , 1957 .

[6]  B. Albrecht,et al.  Surface‐based remote sensing of the observed and the Adiabatic liquid water content of stratocumulus clouds , 1990 .

[7]  J. P. Taylor,et al.  Measurements of Cloud Susceptibility , 1994 .

[8]  A. J. Drummond,et al.  Standard Values for the Solar Constant and its Spectral Components , 1971 .

[9]  G. Mie.  Beiträge zur Optik trüber Medien, speziell kolloidaler Metallösungen , 1908 .

[10]  David P. Duda,et al.  Microphysical and Radiative Properties of Marine Stratocumulus from Tethered Balloon Measurements , 1991 .

[11]  Jonathan P. Taylor.  Measurements of the radiative and microphysical properties of stratocumulus over the South Atlantic and around the British Isles , 1994 .

[12]  Howard W. Barker,et al.  Solar Radiative Transfer Through Clouds Possessing Isotropic Variable Extinction Coefficient , 1992 .

[13]  C. Bretherton,et al.  The Atlantic Stratocumulus Transition Experiment - ASTEX , 1995 .

[14]  C. Bretherton,et al.  Cloudiness and Marine Boundary Layer Dynamics in the ASTEX Lagrangian Experiments. Part II: Cloudiness, Drizzle, Surface Fluxes, and Entrainment , 1995 .

[15]  G. M. Hale,et al.  Optical Constants of Water in the 200-nm to 200-microm Wavelength Region. , 1973, Applied optics.

[16]  R. Rockafellar.  The multiplier method of Hestenes and Powell applied to convex programming , 1973 .

[17]  Graeme L. Stephens,et al.  The Parameterization of Radiation for Numerical Weather Prediction and Climate Models , 1984 .

[18]  S. Nicholls,et al.  An observational study of the structure of stratiform cloud sheets: Part I. Structure , 1986 .

[19]  Si-Chee Tsay,et al.  On the cloud absorption anomaly , 1990 .

[20]  R. Rogers,et al.  A short course in cloud physics , 1976 .

[21]  D. W. Johnson,et al.  The Measurement and Parameterization of Effective Radius of Droplets in Warm Stratocumulus Clouds , 1994 .

[22]  S. Klein,et al.  The Seasonal Cycle of Low Stratiform Clouds , 1993 .

[23]  S. Nicholls.  The dynamics of stratocumulus: Aircraft observations and comparisons with a mixed layer model , 1984 .

[24]  Y. Yung,et al.  Atmospheric Radiation: Theoretical Basis , 1989 .

[25]  A. Korolev,et al.  In situ measurements of effective diameter and effective droplet number concentration , 1999 .

[26]  J. Hovenier,et al.  The adding method for multiple scattering calculations of polarized light , 1987 .

[27]  Robert F. Cahalan,et al.  The albedo of fractal stratocumulus clouds , 1994 .

[28]  Graeme L. Stephens,et al.  Aircraft Observations of the Radiative and Microphysical Properties of Stratocumulus and Cumulus Cloud Fields , 1987 .

[29]  A. Slingo,et al.  Aircraft observations of marine stratocumulus during JASIN , 1982 .

[30]  C. Bohren,et al.  An introduction to atmospheric radiation , 1981 .

[31]  D. Randall,et al.  Mission to planet Earth: Role of clouds and radiation in climate , 1995 .

[32]  A. Slingo.  A GCM Parameterization for the Shortwave Radiative Properties of Water Clouds , 1989 .

[33]  A. Slingo,et al.  On the shortwave radiative properties of stratiform water clouds , 1982 .

[34]  S. D. Roode,et al.  Dynamics of cumulus rising into stratocumulus as observed during the first ‘Lagrangian’ experiment of ASTEX , 1996 .

[35]  Jonathan P. Taylor,et al.  The radiative properties of inhomogeneous boundary layer cloud: Observations and modelling , 1996 .

[36]  João Paulo Ramos Teixeira,et al.  Intercomparison of Three- and one-Dimensional Model Simulations and Aircraft Observations of Stratocumulus , 1999 .