Response of the Current Climate to Land‐Ocean Contrasts in Parameterized Cumulus Entrainment
- Department of Atmospheric and Oceanic Sciences McGill University Montréal QC Canada
- Program in Atmospheric and Oceanic Sciences Princeton University Princeton NJ USA
Cumulus entrainment substantially regulates the earth's climate but remains poorly constrained in global climate models. Recent studies have shown that cumulus bulk entrainment (or dilution) is particularly sensitive to continentality, with the entrainment rate in simulated maritime cumuli nearly double that of continental cumuli. This study examines the impacts of such land–ocean entrainment contrasts on the current climate using 21‐year simulations with the Geophysical Fluid Dynamics Laboratory's High‐Resolution Atmospheric Model (HIRAM). In response to a 25% reduction in the HIRAM entrainment parameter c 0 over land, precipitation over tropical land regions increases by up to 40%. Along with directly facilitating enhanced convective precipitation, this c 0 reduction induces an increase in soil moisture, which may contribute to a further enhancement of convective precipitation over land. A 25% c 0 reduction over the oceans leads to more widespread modifications of convection patterns, with the strongest signal in the tropical Pacific. Deep convection shifts upstream (eastward) there, inducing enhanced large‐scale ascent over the central Pacific with compensating subsidence and reduced humidity and precipitation over the western Pacific (WP). Land–ocean variations in c 0 project onto the Pacific Walker circulation, with the 25% land reduction strengthening it by 4% and the 25% ocean reduction weakening it by 14%. These changes are driven by variations in convective and large‐scale stratiform heating over the Pacific. While reduced c 0 over land enhances diabatic heating in the Maritime Continent to strengthen the Walker circulation, reduced c 0 over the oceans decreases diabatic heating in the WP to weaken the Walker circulation.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE; USDOE Office of Science (SC), Biological and Environmental Research (BER)
- Grant/Contract Number:
- SC0020083
- OSTI ID:
- 2315722
- Alternate ID(s):
- OSTI ID: 2322385
- Journal Information:
- Journal of Advances in Modeling Earth Systems, Journal Name: Journal of Advances in Modeling Earth Systems Journal Issue: 3 Vol. 16; ISSN 1942-2466
- Publisher:
- American Geophysical Union (AGU)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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