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| Titel |
Multiscale Dynamics of ENSO Impacts on Coral Proxy Environments: Towards Improving Reconstruction Accuracy |
| VerfasserIn |
Samantha Stevenson, Brian Powell, Mark Merrifield, Kim Cobb, David Noone, Jesse Nusbaumer |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250114025
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| Publikation (Nr.) |
 EGU/EGU2015-14277.pdf |
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| Zusammenfassung |
| Oxygen isotope (δ18O) records from tropical coral skeletons are widely used for
reconstructing the El Niño/ Southern Oscillation (ENSO). However, data limitations have
prevented detailed investigation of the dynamical connection between ENSO variability
and δ18O anomalies near sites used for reconstructions, potentially creating large
uncertainties. To address this issue, a new, isotope-enabled version of the Regional Ocean
Modeling System ("isoROMS") has been developed to simulate seawater oxygen
isotope anomalies during historical El Niño and La Niña events at a variety of spatial
scales. isoROMS is forced with 20th century (1979-2009) boundary conditions
and surface fluxes, in addition to precipitation δ18O from the newly developed
isotope-enabled Community Atmosphere Model (iCAM5); it thus functions as an
approximate ’reanalysis’ of seawater δ18O over the satellite era. The balance of surface and
advective/diffusive processes during central and eastern Pacific El Niño events
is investigated at sites throughout the tropical Pacific, in order to understand the
mechanisms governing the magnitude of individual δ18O excursions in existing proxy
records. Budget analysis shows that in many cases impacts on δ18O take place
primarily through advective changes, rather than surface fluxes as previously thought.
Additionally, mesoscale processes such as tropical instability waves significantly affect
temperature and δ18O in some locations, and their importance varies with ENSO
phase; this suggests that rectification of such high-frequency variability into the
proxy signal may affect estimates of overall ENSO variance. Implications for ENSO
estimates using ’pseudoproxy’ conversions from instrumental data are discussed. |
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