Implementation of a Boundary Layer Heat Flux Parameterization Into the Regional Atmospheric Modeling System (RAMS) and its Effects on Regional Carbon Budgets
Estimates of regional carbon budgets depend upon the depth of the planetary boundary layer. Overshooting thermals that entrain free tropospheric air down into the boundary layer modify the characteristics and depth of the lower layer through the insertion of energy and mass. This alters the surface energy budget by changing the bowen ratio and thereby altering the vegetative response and the surface boundary conditions. Although overshooting thermals are important in the physical world, their effects are neglected in most regional models. We have included a parameterization to include the effects of boundary layer entrainment into a coupled ecosystem-atmosphere model (SiB-RAMS). The parameterization is based on a downward heat flux at the top of the boundary layer that is proportional to the heat flux at the surface. Results with the parameterization show that the boundary layer simulated is deeper, warmer, and drier than when the parameterization is turned off. These results alter the vegetative stress factors thereby changing the carbon flux from the surface. The combination of this and the deeper boundary layer change the concentration of carbon dioxide in the boundary layer.
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- 0428 Carbon cycling (4806);
- 3307 Boundary layer processes