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| Titel |
A Multi-Proxy Perspective on Climate Variability in the Tropical Pacific over the Last Millennium |
| VerfasserIn |
Terrence Quinn, Jud Partin, Kaustubh Thirumalai, Kelly Hereid, Chris Maupin, Chuan-Chou Shen, Fred Taylor |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250099281
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| Publikation (Nr.) |
 EGU/EGU2014-15080.pdf |
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| Zusammenfassung |
| The southwest Pacific is a major source of tropical climate variability through heat and
moisture exchanges associated with the Western Pacific Warm Pool (WPWP) and the South
Pacific Convergence Zone (SPCZ). These variations are especially significant at the annual,
ENSO, and multi-decadal timescales. Climate proxy records from the tropical Pacific must be
used to extend records of SST, SSS, and rainfall variations into the pre-instrumental period.
We highlight our recent efforts to quantitatively understand tropical climate variability over
the last millennium using numerical simulations and climate proxy records (corals and
stalagmites), the latter of which overlap with, and extend beyond the instrumental
period.
We investigate the use of individual foraminiferal analyses (IFA) in assessing past ENSO
variability using numerical simulations. The simulation quantifies the sensitivity of IFA to
ENSO amplitude and seasonal cycle amplitude (or a combination of both) at different
locations in the tropical Pacific. Results indicate that IFA sensitivity towards ENSO is highest
at the central equatorial Pacific surface ocean and the eastern equatorial Pacific (EEP)
thermocline, whereas sensitivity towards the seasonal cycle is highest at the EEP surface
ocean.
We investigate tropical surface ocean variability using two recent coral-based climate
reconstructions: a 233 yr record from Misima Island, Papua New Guinea (10.6° S, 152.8°
E) and a 293 yr record from Olasana Island, Western Province, Solomon Islands (8.2° S,
157.2° E). The PNG coral record of monthly resolved δ18O and Sr/Ca variations spans the
interval ~1414-1645. This record indicates that the surface ocean in this region experienced
a small change in hydrologic balance with no change in temperature, extended
periods of quiescence in El Niño activity, and no change in average amplitudes of El
Niño events relative to signals captured in regional modern records. The Solomon
coral δ18O record (1716-2009) documents early 19th century El Niño events that
rival and exceed the largest instrumentally documented ENSO events at this site.
In addition, the Solomon record contains evidence of decadal and longer period
hydroclimate variability. Both of these coral proxy records from the WPWP suggest
that internal variability is responsible for the observed wide range of ENSO event
magnitudes.
We investigate tropical Pacific rainfall variability using two recent stalagmite-based
rainfall reconstructions: a 445 yr δ18O record from Espiritu Santo, Vanuatu (15.5°S, 167°E)
and a 595 yr δ18O record from Guadalcanal, Solomon Islands (9.4°S, 160°E). The Vanuatu
proxy rainfall record (1557-2003) is dominated by changes in stalagmite δ18O that are large
(~1o, quasi-periodic (~50 yr period), and generally abrupt (within 5–10 yr), which are not
correlated with solar forcing. The Solomon proxy rainfall record (1416-2011) displays
similar patterns of variability: stalagmite δ18O changes are large (~1.5o, quasi-periodic
(~12-60 yr period), and generally abrupt ( |
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