Formulation of Subgrid Variability and Boundary-Layer Cloud Cover in Large-Scale Models
Abstract
This report describes work on the Oregon State University (OSU) atmospheric boundary-layer (ABL) model under AFOSR Grant NO. F49620-96-1-0058. This model was developed to provide ABL and land-surface parameterization schemes for large-scale numerical weather prediction models. We address five classes of model development and testing: (1) A simple two-source canopy model is proposed which accounts for canopy sparseness and turbulent mixing between the surface and canopy, and directly between the surface and air above the canopy. (2) Using updated land-surface and ABL parameterizations, a case study investigates land-surface and ABL simulations without land-surface/ABL interaction (decoupled mode), then coupled land-surface/ABL simulations where more complicated interactions and feedbacks are possible, including the formation and interaction with ABL clouds. (3) The model is used to test how different ocean surface flux forcings interact to determine marine ABL structure and development. (4) The ABL fractional cloud cover formulation is updated using a more computationally efficient tophat distribution of specific humidity rather than the previous Gaussian distribution of relative humidity. (5) The land-surface scheme is tested using different observational data sets to assess model performance in calculating surface fluxes and soil processes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 28, 1999
- Accession Number
- ADA360481
Entities
People
- A. A. Holtslag
- G. Levy
- L. Mahrt
- M. Ek
- Shi Chang
Organizations
- Oregon State University