Surface atmospheric forcing as the driver of long-term pathways and timescales of ocean ventilation
<p>The ocean takes up 93 <span class="inline-formula">%</span> of the excess heat in the climate system and approximately a quarter of the anthropogenic carbon via air–sea fluxes. Ocean ventilation and subduction are key processes that regulate the transport of water (and...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-07-01
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| Series: | Ocean Science |
| Online Access: | https://os.copernicus.org/articles/17/935/2021/os-17-935-2021.pdf |
| Summary: | <p>The ocean takes up 93 <span class="inline-formula">%</span> of the excess heat in the climate system and
approximately a quarter of the anthropogenic carbon via air–sea fluxes. Ocean
ventilation and subduction are key processes that regulate the transport of
water (and associated properties) from the surface mixed layer, which is in
contact with the atmosphere, to the ocean's interior, which is isolated from
the atmosphere for a timescale set by the large-scale circulation. Utilising
numerical simulations with an ocean–sea-ice model using the NEMO (Nucleus for
European Modelling of the Ocean) framework, we
assess where the ocean subducts water and, thus, takes up properties from the
atmosphere; how ocean currents transport and redistribute these properties over time;
and how, where, and when these properties are ventilated. Here, the strength and patterns
of the net uptake of water and associated properties are analysed by including
simulated seawater vintage dyes that are passive tracers released annually
into the ocean surface layers between 1958 and 2017. The dyes' distribution is
shown to capture years of strong and weak convection at deep and mode water
formation sites in both hemispheres, especially when compared to observations
in the North Atlantic subpolar gyre. Using this approach, relevant to any
passive tracer in the ocean, we can evaluate the regional and depth
distribution of the tracers, and determine their variability on interannual to
multidecadal timescales. We highlight the key role of variations in the subduction
rate driven by changes in surface atmospheric forcing in setting the different
sizes of the long-term inventory of the dyes released in different years and
the evolution of their distribution. This suggests forecasting potential for
determining how the distribution of passive tracers will evolve, from having
prior knowledge of mixed-layer properties, with implications for the uptake
and storage of anthropogenic heat and carbon in the ocean.</p> |
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| ISSN: | 1812-0784 1812-0792 |