Evaluation of a new mixed-phase cloud microphysics parameterization with CAM3 single-column model and M-PACE observations

摘要

Most global climate models generally prescribe the partitioning of condensed water into cloud droplets and cloud ice in mixed-phase clouds according to a temperature-dependent function, which affects modeled cloud phase, cloud lifetime and radiative properties. This study evaluates a new mixed-phase cloud microphysics parameterization ( for ice nucleation and water vapor deposition) against the Atmospheric Radiation Measurement (ARM) Mixed-phase Arctic Cloud Experiment (M-PACE) observations using the NCAR Community Atmospheric Model Version 3 (CAM3) single column model (SCAM). It is shown that SCAM with the new scheme produces a more realistic simulation of the cloud phase structure and the partitioning of condensed water into liquid droplets against observations during the M-PACE than the standard SCAM. A sensitivity test indicates that ice number concentration could play an important role in the simulated mixed-phase cloud microphysics, and therefore needs to be realistically represented in global climate models.