In:
Ocean Science, Copernicus GmbH, Vol. 19, No. 4 ( 2023-07-18), p. 1083-1106
Abstract:
Abstract. The Weddell Gyre plays an important role in the global climate
system by supplying heat to underneath the ice shelves and in the formation of deep and bottom water masses, which have been subject to widespread
warming over past decades. In this study, we investigate the re-distribution
of heat throughout the Weddell Gyre by diagnosing the terms of the heat
conservation equation for a 1000 m thick layer of water encompassing the
core of Warm Deep Water. The spatial distributions of the different advective
and diffusive terms in terms of heat tendencies are estimated using gridded
climatologies of temperature and velocity, obtained from Argo floats in the
Weddell Gyre from 2002 to 2016. While the results are somewhat noisy on the
grid scale and the representation of the effects of eddy mixing is highly
uncertain due to the need to parameterise them by means of turbulent diffusion,
the heat budget (i.e. the sum of all terms) closes (within the uncertainty
range) when integrated over the open inflow region in the southern limb,
whereas the interior circulation cell remains unbalanced. There is an
overall balance in the southern limb between the mean horizontal advection
and horizontal turbulent diffusion of heat, whereas the vertical terms
contribute comparatively little to the heat budget throughout the Weddell
Gyre. Heat convergence due to mean horizontal advection balances with
divergence due to horizontal turbulent diffusion in the open southern limb
of the Weddell Gyre. In contrast, heat divergence due to mean horizontal
advection is much weaker than convergence due to horizontal turbulent
diffusion in the interior circulation cell of the Weddell Gyre, due to large
values in the latter along the northern boundary due to large meridional
temperature gradients. Heat is advected into the Weddell Gyre along the
southern limb, some of which is turbulently diffused northwards into the
interior circulation cell, while some is likely turbulently diffused
southwards towards the shelf seas. This suggests that horizontal turbulent
diffusion plays a role in transporting heat both towards the gyre interior
where upwelling occurs and towards the ice shelves. Horizontal turbulent diffusion is also a mechanism by which heat can be transported
into the Weddell Gyre across the open northern boundary. Temporal deviations
from the mean terms are not included due to study limitations. In order to
appreciate the role of transient eddying processes, a continued effort to
increase the spatial and temporal coverage of observations in the eastern
Weddell Sea is required.
Type of Medium:
Online Resource
ISSN:
1812-0792
DOI:
10.5194/os-19-1083-2023
DOI:
10.5194/os-19-1083-2023-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2023
detail.hit.zdb_id:
2183769-7
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