The evolution of cloud field properties in shallow continental convective clouds
Abstract
Using routine large eddy simulation at a continental site in the US, we track cloud field properties such as size distributions, aspect ratios (depth vs. area and depth vs. perimeter), cloud fraction and scene albedo and relate their evolution to underlying convective processes such as entrainment, deepening, and consumption of convective available potential energy (CAPE). The cloud fields are shown to trace out a hysteresis curve in scene albedo vs. cloud fraction phase space, which is related to the asymmetry in the response of the boundary layer to daytime surface heating and how the clouds themselves respond to this asymmetry. We describe the system as a slow manifold defining the evolution of daytime convection, with fast cloud processes (deepening, entrainment, response to the local environment) 'slaved' to the slow manifold. Implications of the hysteresis for detection of aerosol-related cloud brightening are considered.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.A43A..01F
- Keywords:
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- 0320 Cloud physics and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 3322 Land/atmosphere interactions;
- ATMOSPHERIC PROCESSESDE: 0426 Biosphere/atmosphere interactions;
- BIOGEOSCIENCESDE: 4548 Ocean fog;
- OCEANOGRAPHY: PHYSICAL