NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
RACORO Continental Boundary Layer Cloud Investigations: 3. Separation of Parameterization Biases in Single-Column Model CAM5 Simulations of Shallow CumulusClimatically important low-level clouds are commonly misrepresented in climate models. The FAst-physics System TEstbed and Research (FASTER) Project has constructed case studies from the Atmospheric Radiation Measurement Climate Research Facility's Southern Great Plain site during the RACORO aircraft campaign to facilitate research on model representation of boundary-layer clouds. This paper focuses on using the single-column Community Atmosphere Model version 5 (SCAM5) simulations of a multi-day continental shallow cumulus case to identify specific parameterization causes of low-cloud biases. Consistent model biases among the simulations driven by a set of alternative forcings suggest that uncertainty in the forcing plays only a relatively minor role. In-depth analysis reveals that the model's shallow cumulus convection scheme tends to significantly under-produce clouds during the times when shallow cumuli exist in the observations, while the deep convective and stratiform cloud schemes significantly over-produce low-level clouds throughout the day. The links between model biases and the underlying assumptions of the shallow cumulus scheme are further diagnosed with the aid of large-eddy simulations and aircraft measurements, and by suppressing the triggering of the deep convection scheme. It is found that the weak boundary layer turbulence simulated is directly responsible for the weak cumulus activity and the simulated boundary layer stratiform clouds. Increased vertical and temporal resolutions are shown to lead to stronger boundary layer turbulence and reduction of low-cloud biases.
Document ID
20160003594
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Lin, Wuyin
(Brookhaven National Lab. Upton, NY, United States)
Liu, Yangang
(Brookhaven National Lab. Upton, NY, United States)
Vogelmann, Andrew M.
(Brookhaven National Lab. Upton, NY, United States)
Fridlind, Ann
(NASA Goddard Inst. for Space Studies New York, NY United States)
Endo, Satoshi
(Brookhaven National Lab. Upton, NY, United States)
Song, Hua
(Brookhaven National Lab. Upton, NY, United States)
Feng, Sha
(California Univ. Los Angeles, CA, United States)
Toto, Tami
(Brookhaven National Lab. Upton, NY, United States)
Li, Zhijin
(California Univ. Los Angeles, CA, United States)
Zhang, Minghua
(Stony Brook Univ. Stony Brook, NY, United States)
Date Acquired
March 22, 2016
Publication Date
June 19, 2015
Publication Information
Publication: Journal of Geophysical Research: Atmospheres
Publisher: Wiley
Volume: 120
Issue: 12
Subject Category
Meteorology And Climatology
Report/Patent Number
GSFC-E-DAA-TN30576
Funding Number(s)
CONTRACT_GRANT: DE-SC0012704
WBS: WBS 281945.02.20.02.37
Distribution Limits
Public
Copyright
Other
Keywords
parameterization
atmospheric radiation
boundary layers

Available Downloads

There are no available downloads for this record.
No Preview Available