Boundary Layer Parameterization for a Global Spectral Model
Final rept. 1 Oct 1987-30 Sep 1990
OREGON STATE UNIV CORVALLIS DEPT OF ATMOSPHERIC SCIENCES
Pagination or Media Count:
This reports describes work on the AFGL atmospheric boundary-layer model which was developed to provide turbulence parameterization schemes for a global spectral model. The research has led to new boundary-layer model developments, such as formulations for transport by clear air turbulence and transport due to topographically-forced gravity waves. The study of boundary- layer moisture regimes finds two asymptotic classes, drying and moistening, with the development of clouds found to be quite different for each class. A formulation for boundary-layer cloud cover is developed that includes important influences of turbulent scale and subgrid-mesoscale variations of relative humidity. The new surface roughness formulation allows the roughness length for momentum to be significantly larger than that for heat, accommodating recent observational evidence. An additional study examines the daytime evolution of the boundary-layer relative humidity and illustrates the complex interactions of the boundary layer, large-scale vertical motion and soil moisture.
- Atmospheric Physics