Impacts on Ocean Heat from Transient Mesoscale Eddies in a Hierarchy of Climate Models

Stephen Matthew Griffies1, Michael Winton1, Whit Anderson2, Rusty Benson3, Thomas L Delworth4, Carolina O. Dufour5, John P Dunne6, Paul Goddard7, Adele K Morrison8, Anthony John Rosati3, Andrew Thorne Wittenberg3, Jianjun Yin9 and Rong Zhang3, (1)Geophysical Fluid Dynamics Laboratory, Princeton, NJ, United States, (2)NOAA/GFDL, Princeton, NJ, United States, (3)NOAA/Geophysical Fluid Dynamics Laboratory, Princeton, United States, (4)Geophysical Fluid Dynamics Laboratory, Princeton, United States, (5)McGill University, Department of Atmospheric and Oceanic Sciences, Montréal, QC, Canada, (6)NOAA Geophysical Fluid Dynamics Laboratory, Princeton, United States, (7)University of Arizona, Tucson, United States, (8)Australian National University and Australian Centre for Excellence in Antarctic Science, Canberra, ACT, Australia, (9)The University of Arizona, Tucson, AZ, United States
Abstract:
We characterize impacts on heat in the ocean climate system from
transient ocean mesoscale eddies. Our tool is a suite of
centennial-scale 1990 radiatively forced numerical climate simulations
from three GFDL coupled models comprising the CM2-O model suite. CM2-O
models differ in their ocean resolution: CM2.6 uses a 1/10-degree
ocean grid, CM2.5 uses an intermediate grid with 1/4-degree, spacing,
and CM2-1deg uses a nominally 1-degree grid.

Analysis of the ocean heat budget reveals that mesoscale eddies act to
transport heat upward in a manner that partially compensates (or
offsets) for the downward heat transport from the time mean currents.
Stronger vertical eddy heat transport in CM2.6 relative to CM2.5
accounts for the significantly smaller temperature drift in CM2.6. The
mesoscale eddy parameterization used in CM2-1deg also imparts an
upward heat transport, yet it differs systematically from that found
in CM2.6. This analysis points to the fundamental role that ocean
mesoscale features play in transient ocean heat uptake. In general,
the more accurate simulation found in CM2.6 provides an argument for
either including a rich representation of the ocean mesoscale in model
simulations of the mean and transient climate, or for employing
parameterizations that faithfully reflect the role of eddies in both
lateral and vertical heat transport

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