Preprints
https://doi.org/10.5194/os-2021-31
https://doi.org/10.5194/os-2021-31

  12 Apr 2021

12 Apr 2021

Review status: a revised version of this preprint was accepted for the journal OS and is expected to appear here in due course.

Contribution of buoyancy fluxes to tropical Pacific sea level variability

Patrick Wagner, Markus Scheinert, and Claus W. Böning Patrick Wagner et al.
  • GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel Germany

Abstract. Regional anomalies of steric sea level are either due to redistribution of heat and freshwater anomalies or due to ocean-atmosphere buoyancy fluxes. Interannual to decadal variability in sea level across the tropical Pacific is mainly due to steric variations driven by wind stress anomalies. The importance of air--sea buoyancy fluxes is less clear. We use a global, eddy permitting ocean model and a series of sensitivity experiments with quasi-climatological momentum and buoyancy fluxes to identify the contribution of buoyancy fluxes for interannual to decadal sea level variability in the tropical Pacific. We find their contribution on interannual timescales to be strongest in the central tropical Pacific at around 10° latitude in both hemispheres and also relevant in the very east of the tropical domain. Buoyancy flux forced anomalies are in phase with variations driven by wind stress changes but their effect on the prevailing anomalies and the importance of heat and fresh water fluxes vary locally. In the eastern tropical basin interannual sea level variability is amplified by anomalous heat fluxes, while the importance of fresh water fluxes is small and neither has any impact on decadal timescales. In the western tropical Pacific the variability on interannual and decadal timescales is dampened by both, heat and freshwater fluxes. The mechanism involves westward propagating Rossby waves that are triggered during ENSO events by anomalous buoyancy fluxes in the central tropical Pacific and counteract the prevailing sea level anomalies once they reach the western part of the basin.

Patrick Wagner et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • AC1: 'Comment on os-2021-31', Patrick Wagner, 13 Apr 2021
  • RC1: 'Comment on os-2021-31', Anonymous Referee #1, 24 May 2021
    • AC2: 'Reply on RC1', Patrick Wagner, 25 Jun 2021
  • RC2: 'Comment on os-2021-31', Anonymous Referee #2, 08 Jun 2021
    • AC3: 'Reply on RC2', Patrick Wagner, 25 Jun 2021

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • AC1: 'Comment on os-2021-31', Patrick Wagner, 13 Apr 2021
  • RC1: 'Comment on os-2021-31', Anonymous Referee #1, 24 May 2021
    • AC2: 'Reply on RC1', Patrick Wagner, 25 Jun 2021
  • RC2: 'Comment on os-2021-31', Anonymous Referee #2, 08 Jun 2021
    • AC3: 'Reply on RC2', Patrick Wagner, 25 Jun 2021

Patrick Wagner et al.

Patrick Wagner et al.

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Short summary
We analyse the importance of local heat and freshwater fluxes for sea level variability in the tropical Pacific on interannual to decadal timescales by using a global ocean model. Our results suggest that they amplify sea level variability in the eastern part of the basin and dampen it in the central and western part of domain. We demonstrate that the oceanic response allows local sea level anomalies to propagate zonally which enables remote effects of local heat and freshwater fluxes.