A Shallow Thermocline Bias in the Southern Tropical Pacific in CMIP5/6 Models Linked to Double-ITCZ Bias

Maya Samuels, Ori Adam*, Hezi Gildor

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

A basin-wide strong shallow bias in the thermocline of the southern tropical Pacific is found in an ensemble of models from the coupled model intercomparison project phases 5 and 6 (CMIP5/6). The bias is present in over 90% of models examined and is equally represented in CMIP5 and CMIP6 models. In contrast to observations, where the southern thermocline is far deeper than its northern counterpart, models have a hemispherically symmetric tropical thermocline. The shallow thermocline bias is closely linked to the well known double intertropical convergence zone (ITCZ) bias; more so for the physical thermocline (i.e., depth of maximal vertical thermal gradient) than the commonly used (Formula presented.) C isotherm thermocline proxy. A shallow thermocline bias is further found to be associated with climatic conditions including wider separation of double ITCZ peaks, a pronounced cold tongue, and a spurious south equatorial counter current.

Original languageAmerican English
Article numbere2021GL093818
JournalGeophysical Research Letters
Volume48
Issue number15
DOIs
StatePublished - 16 Aug 2021

Bibliographical note

Publisher Copyright:
© 2021. American Geophysical Union. All Rights Reserved.

Keywords

  • CMIP
  • cold tongue bias
  • double ITCZ bias
  • thermocline

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