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Subtropical-tropical pathways of spiciness anomalies and their impact on equatorial Pacific temperature



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  • Journal Title:
    Climate Dynamics
  • Personal Author:
  • NOAA Program & Office:
  • Description:
    Understanding mechanisms of tropical Pacific decadal variability (TPDV) is of high importance for differentiating between natural climate variability and human induced climate change as this region sustains strong global teleconnections. Here, we use an ocean general circulation model along with a Lagrangian tracer simulator to investigate the advection of density compensated temperature anomalies (“spiciness mechanism”) as a potential contributor to TPDV during the 1980–2016 period. Consistent with observations, we find the primary regions of spiciness generation in the eastern subtropics of each hemisphere. Our results indicate that 75% of the equatorial subsurface water originates in the subtropics, of which two thirds come from the Southern hemisphere. We further show two prominent cases where remotely generated spiciness anomalies are advected to the equatorial Pacific, impacting subsurface temperature. The relative contribution of Northern versus Southern Hemisphere prominence and/or interior versus western boundary pathways depends on the specific event. The anomalously warm case largely results from advection via the Southern hemisphere interior (65%), while the anomalously cold case largely results from advection via the Northern hemisphere western boundary (48%). The relatively slow travel times from the subtropics to the equator (> 4 years) suggests that these spiciness anomalies underpin a potentially predictable contribution to TPDV. However, not all decadal peaks in equatorial spiciness can be explained by remotely generated spiciness anomalies. In those cases, we propose that spiciness anomalies are generated in the equatorial zone through changes in the proportion of Northern/Southern hemisphere source waters due to their different mean spiciness distribution.
  • Keywords:
  • Source:
    Clim Dyn 56, 1131–1144 (2021)
  • DOI:
  • Document Type:
    Journal Article
  • Place as Subject:
    Pacific Ocean
  • Rights Information:
    Accepted Manuscript
  • Rights Statement:
    The NOAA IR provides access to this content under the authority of the government's retained license to distribute publications and data resulting from federal funding. While users may legally access this content, the copyright owners retain rights that govern the reproduction, redistribution, and re-use of this work. The user is solely responsible for complying with applicable copyright law.
  • Compliance:
    Submitted
  • Main Document Checksum:
    urn:sha-512:ad358f6e92f08d4e527b59243e92848b0078221b374f4164ab1920fed141c07a4c8d625949fcbd5c5e98c63c5a174bcca01faa1d30b433b92e1c72ceac079596
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  • File Type:
    Filetype[PDF - 3.69 MB ]
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