Meridional Asymmetry in Recent Decadal Sea‐Level Trends in the Subtropical Pacific Ocean. Issue 6 (24th March 2021)

• Record Type: Journal Article
• Authors: Schloesser, F.; Thompson, P. R.; Piecuch, C. G.
• Is Part Of: Geophysical research letters. Volume 48:Issue 6(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-03-24
• Subjects: Pacific heat content trends -- Pacific sea level trends -- thermosteric sea level -- wind driven circulation; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2020GL091959
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Recent sea surface height (SSH) trends in the South Pacific are substantially greater than trends in the North Pacific. Here, we use the Estimating the Climate and Circulation of the Ocean Version 4 Release 4 ocean state estimate and the Ocean Reanalysis System 5 to identify the forcing and mechanisms underlying that meridional asymmetry during 2005–2015. Thermosteric contributions dominate the spatial structure in Pacific SSH trends, but contributions from local surface heat fluxes are small. Wind stress trends drive a spin‐up of the South Pacific subtropical gyre and a northward shift of the North Pacific subtropical gyre. A reduced gravity model forced with reanalysis winds qualitatively reproduces the meridional seesaw in sea level, suggesting that asymmetric trends in subtropical wind stress drive a cross‐equatorial heat transport. A reversal in forcing associated with this process could impact near‐term rates of coastal sea‐level change, particularly in Pacific Island communities. Plain Language Summary: Recent sea‐surface‐height trends in the South Pacific are substantially greater than trends in the North Pacific. Here, we use the Estimating the Climate and Circulation of the Ocean Version 4 Release 4 ocean state estimate and the Ocean Reanalysis System 5 to identify the forcing and mechanisms underlying that meridional asymmetry during 2005–2015. We show that the anomalous sea‐level trends are associated with a cross‐equatorial transport and Southern Hemisphere accumulation of heat in response to changes in wind forcing. Key Points: Sea‐level trends during 2005–2015 exhibited a meridional asymmetry in the subtropical Pacific Ocean This behavior is qualitatively reproduced by a reduced gravity model forced by surface wind stress Results suggest an important role for anomalous cross‐equatorial Pacific meridional heat flux