Transitions in the mesoscale cellular organization of closed cell marine stratiform clouds
Abstract
A machine-learning algorithm has been applied to level-2 MODIS imagery to classify the cellular organization of stratiform clouds in the marine boundary layer (MBL). This algorithm separates clouds into three categories of mesoscale cellular convection (MCC): open, closed, and disorganized. This study uses over 160,000 isobaric MBL trajectories generated in the eastern subtropical ocean basins between 2003-2011 to assess which meteorological and cloud variables are most associated with transitions from closed MCC into open or disorganized MCC over 24 hours. Significant differences are seen between sets of trajectories that stay closed, transition from closed to open, or transition from closed to disorganized MCC. Compared to a set of trajectories that remains closed MCC over 24 hours, trajectories that transition from closed to open MCC are associated with stronger surface winds, heavier rain rates, and fewer cloud droplets initially. Trajectories that transition from closed to disorganized MCC originate in deeper boundary layers under a weaker trade inversion and a drier and more weakly subsiding overlying atmosphere. Taken together, these results suggest that cloud processes within the MBL control the closed to open MCC transitions, while the closed to disorganized MCC transitions are driven more by surrounding meteorology.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMA127...07E
- Keywords:
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- 3307 Boundary layer processes;
- ATMOSPHERIC PROCESSES;
- 3311 Clouds and aerosols;
- ATMOSPHERIC PROCESSES;
- 3323 Large eddy simulation;
- ATMOSPHERIC PROCESSES;
- 3365 Subgrid-scale (SGS) parameterization;
- ATMOSPHERIC PROCESSES