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Coupled Aqua and Ridge Planets in the Community Earth System Model
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  • Xiaoning Wu,
  • Kevin A. Reed,
  • Christopher Lee Pitt Wolfe,
  • Gustavo Marques,
  • Scott Daniel Bachman,
  • Frank O. Bryan
Xiaoning Wu
Stony Brook University, Stony Brook University

Corresponding Author:[email protected]

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Kevin A. Reed
Stony Brook University, Stony Brook University
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Christopher Lee Pitt Wolfe
Stony Brook University, Stony Brook University
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Gustavo Marques
NCAR, NCAR
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Scott Daniel Bachman
NCAR, NCAR
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Frank O. Bryan
National Center for Atmospheric Research (UCAR), National Center for Atmospheric Research (UCAR)
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Abstract

Idealized models can reveal insights into Earth’s climate system by reducing its complexities. However, their potential is undermined by the scarcity of fully coupled idealized models with components comparable to contemporary, comprehensive Earth System Models. To fill this gap, we compare and contrast the climates of two idealized planets which build on the Simpler Models initiative of the Community Earth System Model (CESM). Using the fully coupled CESM, the Aqua configuration is ocean-covered except for two polar land caps, and the Ridge configuration has an additional pole-to-pole grid-cell-wide continent. Contrary to most sea surface temperature profiles assumed for atmosphere-only aquaplanet experiments with the thermal maximum on the equator, the coupled Aqua configuration is characterized by a global cold belt of wind-driven equatorial upwelling, analogous to the eastern Pacific cold tongue. The presence of the meridional boundary on Ridge introduces zonal asymmetry in thermal and circulation features, similar to the contrast between western and eastern Pacific. This zonal asymmetry leads to a distinct climate state from Aqua, cooled by ~2{degree sign}C via the radiative feedback of clouds and water vapor. The meridional boundary of Ridge is also crucial for producing a more Earth-like climate state compared to Aqua, including features of atmospheric and ocean circulation, the seasonal cycle of the Intertropical Convergence Zone, and the meridional heat transport. The mean climates of these two basic configurations provide a baseline for exploring other idealized ocean geometries, and their application for investigating various features and scale interactions in the coupled climate system.
Apr 2021Published in Journal of Advances in Modeling Earth Systems volume 13 issue 4. 10.1029/2020MS002418