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McFarquhar et al. 2007

McFarquhar, G.M., G. Zhang, M.R. Poellot, G.L. Kok, R. McCoy, T. Tooman, A. Fridlind, and A.J. Heymsfield, 2007: Ice properties of single-layer stratocumulus during the Mixed-Phase Arctic Cloud Experiment (MPACE): Part I, Observations. J. Geophys. Res., 112, D24201, doi:10.1029/2007JD008633.

During the Department of Energy's Atmospheric Radiation Measurement Program's Mixed-Phase Arctic Cloud Experiment (MPACE) in fall 2004, the University of North Dakota Citation measured 53 profiles within single-layer stratus clouds by executing spiral ascents and descents over Barrow and Oliktok Point, Alaska, and by flying ramped ascents and descents between. Cloud phase was identified from an algorithm that uses voltage change from the Rosemount ice detector, the size distribution (SD) shape measured by the Forward Scattering Spectrometer Probe (FSSP), manual identification of particles imaged by the Cloud Particle Imager, the two-dimensional cloud probe (2DC) and the high volume precipitation sampler (HVPS). Size and mass distribution functions were derived using data from the FSSP, one-dimensional cloud probe, 2DC and HVPS in conjunction with total water content (TWC) measured by the Counterflow Virtual Impactor. With clouds defined as locations where TWC > 0.001 g/m³, there were a total of 513 30-s averaged SDs in single layer clouds, of which 71% were in mixed-phase parcels, 23% in ice-phase and 6% in liquid-phase. The mixed-phase parcels were dominated by contributions from liquid drops, with the liquid mass fraction f_l having averages and standard deviations of 0.89±0.18 with 75% of cases having f_l > 0.9.

For these single layer clouds, f_l increased with normalized cloud altitude z_n, defined as linearly increasing from 0 at cloud base to 1 at cloud top with f_l averaging 0.96±0.13 near zProgram's Mixed-Phase Arctic Cloud Experiment (MPACE) in fall 2004, the University of North Dakota Citation measured 53 profiles within single-layer stratus clouds by executing spiral ascents and descents over Barrow and Oliktok Point, Alaska, and by flying ramped ascents and descents between. Cloud phase was identified from an algorithm that uses voltage change from the Rosemount ice detector, the size distribution (SD) shape measured by the Forward Scattering Spectrometer Probe (FSSP), manual identification of particles imaged by the Cloud Particle Imager, the two-dimensional cloud probe (2DC) and the high volume precipitation sampler (HVPS). Size and mass distribution functions were derived using data from the FSSP, one-dimensional cloud probe, 2DC and HVPS in conjunction with total water content (TWC) measured by the Counterflow Virtual Impactor. With clouds defined as locations where TWC > 0.001 g/m³, there were a total of 513 30-s averaged SDs in single layer clouds, of which 71% were in mixed-phase parcels, 23% in ice-phase and 6% in liquid-phase. The mixed-phase parcels were dominated by contributions from liquid drops, with the liquid mass fraction f_l having averages and standard deviations of 0.89±0.18 with 75% of cases having f_l > 0.9 For these single layer clouds, f_l increased with normalized cloud altitude z_n, defined as linearly increasing from 0 at cloud base to 1 at cloud top with f_l averaging 0.96±0.13 near z_n=1 and .70±0.30 near z_n=0. The effective radius of water droplets rew increased with z_n, from an average of 6.9±1.8 µm near z_n=0 to 11.4±2.4 µm near z_n=1, whereas the effective radius of ice crystals rei (25.2±3.9 µm) was nearly independent of z_n. The averaged cloud droplet number concentration and concentrations of ice crystals with maximum dimensions greater than 53 µm were 43.6±30.5×103 L^-1 and 2.8±6.9 L^-1, 48 =0. The effective radius respectively, and nearly independent of z_n. In contrast to past measurements in mixed-phase clouds combined from many geographical locations where f_l increased with temperature, f_l decreased from -12 to -3°C as clouds typically consisted of a liquid topped layer with precipitating ice below.

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@article{mc05000n,
  author={McFarquhar, G. M. and Zhang, G. and Poellot, M. R. and Kok, G. L. and McCoy, R. and Tooman, T. and Fridlind, A. and Heymsfield, A. J.},
  title={Ice properties of single-layer stratocumulus during the Mixed-Phase Arctic Cloud Experiment (MPACE): Part I, Observations},
  year={2007},
  journal={Journal of Geophysical Research},
  volume={112},
  pages={D24201},
  doi={10.1029/2007JD008633},
}

TY  - JOUR
ID  - mc05000n
AU  - McFarquhar, G. M.
AU  - Zhang, G.
AU  - Poellot, M. R.
AU  - Kok, G. L.
AU  - McCoy, R.
AU  - Tooman, T.
AU  - Fridlind, A.
AU  - Heymsfield, A. J.
PY  - 2007
TI  - Ice properties of single-layer stratocumulus during the Mixed-Phase Arctic Cloud Experiment (MPACE): Part I, Observations
JA  - J. Geophys. Res.
JO  - Journal of Geophysical Research
VL  - 112
SP  - D24201
DO  - 10.1029/2007JD008633
ER  -

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