The sensitivity of Southeast Pacific heat distribution to local and remote changes in ocean properties

This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1175/JPO-D-19-0155.1.

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Authors

Dan Jones , Emma Joan Douglas Boland , Andrew Meijers, Gael Forget, Simon Josey, Jean-Baptiste Sallée, Emily Shuckburgh

Abstract

The Southern Ocean features ventilation pathways that transport surface waters into the subsurface thermocline on timescales of decades to centuries, sequestering anomalies of heat and carbon away from the atmosphere and thereby regulating the rate of surface warming. Despite its importance for climate sensitivity, the factors that control the distribution of heat along these pathways are not well understood. In this study, we use an observationally-constrained, physically consistent global ocean model to examine the sensitivity of heat distribution in the recently ventilated subsurface Pacific (RVP) sector of the Southern Ocean to changes in ocean temperature and salinity. First, we define the RVP using numerical passive tracer release experiments that highlight the ventilation pathways. Next, we use an ensemble of adjoint sensitivity experiments to quantify the sensitivity of the RVP heat content to changes in ocean temperature and salinity. In terms of sensitivities to surface ocean properties, we find that RVP heat content is most sensitive to anomalies along the Antarctic Circumpolar Current (ACC), upstream of the subduction hotspots. In terms of sensitivities to subsurface ocean properties, we find that RVP heat content is most sensitive to basin-scale changes in the subtropical Pacific Ocean, around the same latitudes as the RVP. Despite the localized nature of mode water subduction hotspots, changes in basin-scale density gradients are an important controlling factor on heat distribution in the Southeast Pacific.

DOI

https://doi.org/10.31223/osf.io/9sjha

Subjects

Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics

Keywords

Southern Ocean, Southeast Pacific, Adjoint modeling, Heat content, sensitivities

Dates

Published: 2019-07-16 13:51

Last Updated: 2020-01-11 12:38

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License

CC BY Attribution 4.0 International

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