An improvement in the treatment of the convectively detrained cloud water from the planetary boundary layer scheme in the NOAA's operational Global Forecast System (GFS)
Abstract
The behavior of the planetary boundary layer (PBL) scheme used in NOAA's operational Global Forecast System (GFS) is examined at the level of mixing processes using single-column model simulations of a convective PBL growth case. Results from the simulations show that the PBL scheme produces unphysical thermal tendencies due to the scheme's treatment of detrained cloud water from the moist nonlocal mixing in the scheme's eddy diffusivity and mass flux (EDMF) parameterization framework. To eliminate the unphysical thermal tendencies, a physically-based approach is proposed to improve the treatment of the detrained cloud water from the PBL scheme. The results from single-column and three-dimensional model simulations using this physically-based approach are analyzed to highlight the need to address the uncertainty in the partition of local and nonlocal mixing in PBL schemes based on the EDMF parameterization framework. As an example of how to address the uncertainty, additional sensitivity experiments show essential parameters in the improved GFS PBL scheme that can be optimized according to observations and/or large-eddy-simulation results.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.A52O1188B