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The water mass transformation framework and variability in hurricane activity

The water mass transformation framework and variability in hurricane activity
The water mass transformation framework and variability in hurricane activity
Hurricane activity has been higher since 1995 than in the 1970s and 1980s. This rise in activity has been linked to a warming Atlantic. In this study, we consider variability of the volume of water warmer than 26.5 ºC, considered widely to be the temperature threshold crucial to hurricane development. We find the depth of the 26.5 ºC isotherm better correlated with seasonal hurricane counts than SST in the early part of the Atlantic hurricane season in some regions. The volume of water transformed by surface heat fluxes to temperatures above 26.5 ºC is directly calculated using the Water Mass Transformation framework. This volume is compared with the year-to-year changes in the volume of water of this temperature to see how much of the volume can be explained using this calculation. In some years, there is notable correspondence between transformed and observed volume anomalies, but anomalies in other years must be largely associated with other processes, such as the divergence of horizontal heat transport associated with the AMOC. This technique provides evidence that, in a given year, coordinated physical mechanisms are responsible for the build-up of anomalous ocean heat; not only net surface heat exchange but also the convergence of horizontal heat transport from ocean currents, to provide fuel for larger numbers of intense hurricanes.
Atlantic, Hurricane, Surface heat flux, Warm water anomalies, Water mass transformation
0930-7575
961-972
Harris, Elizabeth
29d2058e-dd68-4f5e-995b-0748ff3ef10c
Marsh, Robert
702c2e7e-ac19-4019-abd9-a8614ab27717
Grist, Jeremy P
ffea99af-f811-436f-9bac-5b02ba6dc00f
McCarthy, Gerard D.
99241bcb-5667-469d-b7ae-4d308d516bd6
Harris, Elizabeth
29d2058e-dd68-4f5e-995b-0748ff3ef10c
Marsh, Robert
702c2e7e-ac19-4019-abd9-a8614ab27717
Grist, Jeremy P
ffea99af-f811-436f-9bac-5b02ba6dc00f
McCarthy, Gerard D.
99241bcb-5667-469d-b7ae-4d308d516bd6

Harris, Elizabeth, Marsh, Robert, Grist, Jeremy P and McCarthy, Gerard D. (2022) The water mass transformation framework and variability in hurricane activity. Climate Dynamics, 59 (3-4), 961-972. (doi:10.1007/s00382-022-06169-5).

Record type: Article

Abstract

Hurricane activity has been higher since 1995 than in the 1970s and 1980s. This rise in activity has been linked to a warming Atlantic. In this study, we consider variability of the volume of water warmer than 26.5 ºC, considered widely to be the temperature threshold crucial to hurricane development. We find the depth of the 26.5 ºC isotherm better correlated with seasonal hurricane counts than SST in the early part of the Atlantic hurricane season in some regions. The volume of water transformed by surface heat fluxes to temperatures above 26.5 ºC is directly calculated using the Water Mass Transformation framework. This volume is compared with the year-to-year changes in the volume of water of this temperature to see how much of the volume can be explained using this calculation. In some years, there is notable correspondence between transformed and observed volume anomalies, but anomalies in other years must be largely associated with other processes, such as the divergence of horizontal heat transport associated with the AMOC. This technique provides evidence that, in a given year, coordinated physical mechanisms are responsible for the build-up of anomalous ocean heat; not only net surface heat exchange but also the convergence of horizontal heat transport from ocean currents, to provide fuel for larger numbers of intense hurricanes.

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Published date: 13 April 2022
Additional Information: Funding Information: This analysis was possible due to the public availability of the NCEP/NCAR Reanalysis Monthly Means and Other Derived Variables data (https://psl.noaa.gov/data/gridded/data.ncep.reanalysis.derived.surfaceflux.html), the NCEP Global Ocean Data Assimilation System (GODAS) data (https://psl.noaa.gov/data/gridded/data.godas.html) and International Best Track Archive for Climate Stewardship (IBTrACS) data (https://www.ncdc.noaa.gov/ibtracs/index.php?name=ib-v4-access). We thank two anonymous reviewers for perceptive comments, helping us to substantially improve the manuscript. Publisher Copyright: © 2022, The Author(s).
Keywords: Atlantic, Hurricane, Surface heat flux, Warm water anomalies, Water mass transformation

Identifiers

Local EPrints ID: 470366
URI: http://eprints.soton.ac.uk/id/eprint/470366
ISSN: 0930-7575
PURE UUID: f2db75f3-746f-4c33-b3a8-cf4bce5654ca

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Date deposited: 07 Oct 2022 16:32
Last modified: 30 Oct 2023 01:33

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Contributors

Author: Robert Marsh
Author: Jeremy P Grist
Author: Gerard D. McCarthy

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