NUMERICAL MODELING OF ARCTIC MIXED-PHASE LAYERED CLOUDS
Open Access
- Author:
- Chen, Yaosheng
- Graduate Program:
- Meteorology and Atmospheric Science
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- April 30, 2018
- Committee Members:
- Johannes Verlinde, Dissertation Advisor/Co-Advisor
Johannes Verlinde, Committee Chair/Co-Chair
Eugene Edmund Clothiaux, Committee Member
Jerry Y Harrington, Committee Member
Kultegin Aydin, Outside Member
Marcelo Chamecki, Committee Member - Keywords:
- boundary-layer clouds
mesoscale dynamics
MMCR
North Slope Alaska
model evaluation - Abstract:
- Arctic mixed-phase clouds are often multi-layered. Different cloud layers interact through radiation as well as ice precipitation falling from upper layer clouds into the lower layer clouds. The evolution of an Arctic mixed-phase stratiform cloud under prescribed perturbations from an overlaying cloud in the form of downwelling longwave radiation and ice precipitation was simulated and documented. The perturbations created regions with heterogeneous properties in the horizontal direction within the lower level cloud, the consequence of which was the development of a mesoscale circulation that propagated the perturbations well beyond the location of the initial perturbed region. In a separate study, we forward modeled radar Doppler spectra based on a large-eddy simulation (LES) model simulation of a single layer Arctic mixed-phase cloud and compared the modeled quantities with those retrieved from the observations. We show that there was a significant contribution from the microphysical broadening to the cloud radar Doppler spectral width in Arctic mixed-phase clouds. LES simulations configured with different ice particle characteristics captured different aspects of the observations in the simulated case, where a mixture of ice particles of different properties were likely present. The dynamics of the LES simulations, characterized with the total turbulent kinetic energy dissipation rate, agreed fairly well with the values retrieved from the observations. Due to significant numerical dissipation in the model for the case evaluated here, the TKE dissipation rate from the subgrid-scale model did not represent the dissipation rate in the model.