LES Simulations of Roll Clouds Observed During Mixed- Phase Arctic Cloud Experiment
نویسندگان
چکیده
Roll clouds and associated roll convection, are fairly common features of the atmospheric boundary layer. While these organized cumuliform clouds are found over many regions of the planet, they are quite ubiquitous near the edge of the polar ice sheets. In particular, during periods of off-ice flow, when cold polar air flows from the ice pack over the relatively warm ocean water, strong boundary layer convection develops along with frequent rolls. According to Brümmer and Pohlman (2000), most of the total cloud cover in the Arctic is due to roll clouds.
منابع مشابه
Simulations of Arctic mixed-phase clouds in forecasts with CAM3 and AM2 for M-PACE
[1] Simulations of mixed-phase clouds in forecasts with the NCAR Atmosphere Model version 3 (CAM3) and the GFDL Atmospheric Model version 2 (AM2) for the MixedPhase Arctic Cloud Experiment (M-PACE) are performed using analysis data from numerical weather prediction centers. CAM3 significantly underestimates the observed boundary layer mixed-phase cloud fraction and cannot realistically simulate...
متن کاملEvaluation of Mixed-Phase Cloud Parameterizations in Short-Range Weather Forecasts with CAM3 and AM2 for Mixed-Phase Arctic Cloud Experiment
Mixed-phase clouds dominate low-level Arctic clouds in cold seasons and have a significant impact on the surface energy budget. However, the treatment of mixed-phase clouds in most current climate models is crude because the detailed microphysical processes involved in mixed-phase clouds are not completely understood, primarily owe to the paucity of cloud observations in the past. Improving mix...
متن کاملEvaluation of Mixed-Phase Cloud Parametrizations in Short-Range Weather Forecasts with CAM3 and AM2 for Mixed-Phase Arctic Cloud Experiment
Mixed-phase clouds dominate low-level Arctic clouds in cold seasons and have a significant impact on the surface energy budget. However, the treatment of mixed-phase clouds in most current climate models is crude because the detailed microphysical processes involved in mixed-phase clouds are not completely understood, primarily owe to the paucity of cloud observations in the past. Improving mix...
متن کاملPossible roles of ice nucleation mode and ice nuclei depletion in the extended lifetime of Arctic mixedphase clouds
[1] The sensitivity of Arctic mixed phase clouds to the mode of ice particle nucleation is examined using a 1-D cloud model. It is shown that the lifetime of a simulated low-level Arctic mixed-phase stratus is highly sensitive to the number concentration of deposition/condensationfreezing nuclei, and much less sensitive to the number of contact nuclei. Simulations with prognostic ice nuclei con...
متن کاملMicrophysical Properties of Single and Mixed-Phase Arctic Clouds Derived from AERI Observations
A novel new approach to retrieve cloud microphysical properties from mixed-phase clouds is presented. This algorithm retrieves cloud optical depth, ice fraction, and the effective size of the water and ice particles from ground-based, high-resolution infrared radiance observations. The theoretical basis is that the absorption coefficient of ice is stronger than that of liquid water from 10 μm t...
متن کامل