A Second-Order Bulk Boundary Layer Model. Revision
Abstract
Bulk mass flux models represent the large eddies that are primarily responsible for the turbulent fluxes in the planetary boundary layer as convective circulations, with an associated convective mass flux. In order for such models to be useful, it is necessary to determine the fractional area covered by rising motion in the convective circulations. This fraction can be used as an estimate of the cloud amount, under certain conditions. We have developed matching conditions that relate the convective mass flux to the ventilation and entrainment mass fluxes. These are based on conservation equations for the scalar means and variances in the entrainment and ventilation layer. Methods are presented to determine both the fractional area covered by rising motion and the convective mass flux. We also show how the requirement of variance balance can be used to relax the well mixed assumption. the vertical structures of the mean state and the turbulent fluxes are determined analytically. Several aspects of our simple model's formulation are evaluated usng results from large-eddy simulations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 06, 1992
- Accession Number
- ADA245828
Entities
People
- Chin-hoh Moeng
- David A. Randall
- Qingqiu Shao
Organizations
- Colorado State University