Shallow cumulus rooted in photosynthesis
Article first published online: 7 MAR 2014
©2014. American Geophysical Union. All Rights Reserved.
Geophysical Research Letters
Volume 41, Issue 5, pages 1796–1802, 16 March 2014
How to Cite
2014), Shallow cumulus rooted in photosynthesis, Geophys. Res. Lett., 41, 1796–1802, doi:10.1002/2014GL059279., , , and (
- Issue published online: 2 APR 2014
- Article first published online: 7 MAR 2014
- Accepted manuscript online: 15 FEB 2014 05:05AM EST
- Manuscript Accepted: 10 FEB 2014
- Manuscript Revised: 9 FEB 2014
- Manuscript Received: 17 JAN 2014
- shallow cumulus;
- land-atmosphere interaction
We study the interactions between plant evapotranspiration, controlled by photosynthesis (C3 and C4 grasses), and moist thermals responsible for the formation of shallow cumulus clouds (SCu). Our findings are based on a series of systematic numerical experiments at fine spatial and temporal scales using large eddy simulations explicitly coupled to a plant-physiology model. The shading provided by SCu leads to strong spatial variability in photosynthesis and the surface energy balance. This in turn results in SCu characterized by less extreme and less skewed values of liquid water path. The larger water use efficiency of C4 grass leads to two opposite effects that influence boundary layer clouds: more vigorous and deeper thermals due to the larger buoyancy surface flux (positive effect) characterized by less moisture content (negative). We find that under these midlatitude and well-watered soil conditions, SCu are characterized by a larger cloud cover and liquid water path over C4 grass fields.