A Process Study of Mixed-phase Arctic Stratus and Associated Aerosol Effects

Mikhail Ovchinnikov Pacific Northwest National Laboratory
Jiwen Fan Pacific Northwest National Laboratory
Alexei Korolev Environment Canada

Category: Aerosol-Cloud-Radiation Interactions

Working Group: Cloud-Aerosol-Precipitation Interaction

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Spectral bin microphysics model predicted (lines) and observed (diamonds) mean vertical profiles of mixed-phase cloud parameters (liquid, Ql, and ice; Qi, mass mixing ratios, droplet, Nd, and ice particles; Ni, number-mixing ratios, and liquid water condensate fraction) for Flight 31 on April 27, 2008. Shaded areas and horizontal lines indicate 15–85 percentile ranges for simulated and measured parameters, respectively. A good agreement in clouds suggests that the Bergeron-Findeisen process is reasonably reproduced in this simulation, while model underestimation of below-cloud ice (snow) water content indicates that the sedimentation rate may be overpredicted by this model configuration.

Comprehensive ISDAC measurements provide ample opportunities for evaluating and improving cloud models and parameterizations, particularly in simulating the mixed-phase cloud regime. The longevity on climatically important low-level Arctic stratus depends critically on cloud microphysics, which controls liquid-to-ice conversion and precipitation rates. We conduct high-resolution simulations of persistent mixed-phase stratus clouds observed over the sea ice on April 27, 2008 during ISDAC using a model with both spectral bin (SBM) and two-moment bulk liquid and ice microphysics. These simulations are compared and evaluated using aircraft measurements. Model parameters and corresponding process rates that result in a better agreement with observations are examined in detail. Aerosol effects on cloud micro- and macro-structure will also be discussed.

This poster will be displayed at ASR Science Team Meeting.