The GFDL‐CM4X Climate Model Hierarchy, Part I: Model Description and Thermal Properties
Journal
Journal of Advances in Modeling Earth Systems
Journal Volume
17
Journal Issue
10
ISSN
1942-2466
1942-2466
Date Issued
2025-10
Author(s)
Griffies, Stephen M.
Adcroft, Alistair
Beadling, Rebecca L.
Bushuk, Mitchell
Drake, Henri F.
Dussin, Raphael
Hallberg, Robert W.
Hurlin, William J.
Khatri, Hemant
Krasting, John P.
Lobo, Matthew
MacGilchrist, Graeme A.
Reichl, Brandon G.
Sane, Aakash
Sergienko, Olga
Sonnewald, Maike
Steinberg, Jacob M.
Tesdal, Jan‐Erik
Thomas, Matthew
Turner, Katherine E.
Ward, Marshall L.
Winton, Michael
Zadeh, Niki
Zanna, Laure
Zhang, Rong
Zhang, Wenda
Zhao, Ming
Abstract
We present the GFDL-CM4X (Geophysical Fluid Dynamics Laboratory Climate Model version 4X) coupled climate model hierarchy. The primary application for CM4X is to investigate ocean and sea ice physics as part of a realistic coupled Earth climate model. CM4X utilizes an updated MOM6 (Modular Ocean Model version 6) ocean physics package relative to CM4.0, and there are two members of the hierarchy: one that uses a horizontal grid spacing of (Formula presented.) (referred to as CM4X-p25) and the other that uses a (Formula presented.) grid (CM4X-p125). CM4X also refines its atmospheric grid from the nominally 100 km (cubed sphere C96) of CM4.0–50 km (C192). Finally, CM4X simplifies the land model to allow for a more focused study of the role of ocean changes to global mean climate. CM4X-p125 reaches a global ocean area mean heat flux imbalance of (Formula presented.) within (Formula presented.) years in a pre-industrial simulation, and retains that thermally equilibrated state over the subsequent centuries. This 1850 thermal equilibrium is characterized by roughly (Formula presented.) less ocean heat than present-day, which corresponds to estimates for anthropogenic ocean heat uptake between 1870 and present-day. CM4X-p25 approaches its thermal equilibrium only after more than 1000 years, at which time its ocean has roughly (Formula presented.) more heat than its early 21st century ocean initial state. Furthermore, the root-mean-square sea surface temperature bias for historical simulations is roughly 20% smaller in CM4X-p125 relative to CM4X-p25 (and CM4.0). We offer the mesoscale dominance hypothesis for why CM4X-p125 shows such favorable thermal equilibration properties.
Subjects
Climate change
Climate models
Earth (planet)
Earth system models
Oceanography
Personnel
Thermal modeling
Thermodynamic properties
Coupled climate model
Earth's climate
Geophysical fluid dynamics laboratories
Model description
Model hierarchy
Modular Ocean Model
Ocean physics
Property
Thermal
Thermal-equilibrium
climate modeling
Earth
geophysical method
global ocean
heat flux
sea surface temperature
simulation
thermal power
Sea ice
Publisher
American Geophysical Union (AGU)
Type
journal article