Recent changes in climate in the far western equatorial Pacific and their relationship to the Southern Oscillation; oxygen isotope records from massive corals, Papua New Guinea

1995 ◽  
Vol 136 (3-4) ◽  
pp. 575-590 ◽  
Author(s):  
A.W. Tudhope ◽  
G.B. Shimmield ◽  
C.P. Chilcott ◽  
M. Jebb ◽  
A.E. Fallick ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Papua New Guinea ◽  
Southern Oscillation ◽  
New Guinea ◽  
Equatorial Pacific ◽  
Western Equatorial Pacific

scholarly journals Half-precessional cycle of thermocline temperature in the western equatorial Pacific and its bihemispheric dynamics

2020 ◽  
Vol 117 (13) ◽  
pp. 7044-7051
Author(s):  
Zhimin Jian ◽  
Yue Wang ◽  
Haowen Dang ◽  
David W. Lea ◽  
Zhengyu Liu ◽  
...  
Keyword(s):  
Climate Change ◽  
Southern Oscillation ◽  
Decisive Role ◽  
Equatorial Pacific ◽  
The Pacific ◽  
Equatorial Thermocline ◽  
Western Equatorial Pacific ◽  
Tightly Coupled ◽  
Interannual Climate Variability

The El Niño−Southern Oscillation (ENSO), which is tightly coupled to the equatorial thermocline in the Pacific, is the dominant source of interannual climate variability, but its long-term evolution in response to climate change remains highly uncertain. This study uses Mg/Ca in planktonic foraminiferal shells to reconstruct sea surface and thermocline water temperatures (SST and TWT) for the past 142 ky in a western equatorial Pacific (WEP) core MD01-2386. Unlike the dominant 100-ky glacial−interglacial cycle recorded by SST and δ18O, which echoes the pattern seen in other WEP sites, the upper ocean thermal gradient shows a clear half-precessional (9.4 ky or 12.7 ky) cycle as indicated by the reconstructed and simulated temperature (ΔT) and δ18O differences between the surface and thermocline waters. This phenomenon is attributed to the interplay of subtropical-to-tropical thermocline anomalies forced by the antiphased meridional insolation gradients in the two hemispheres at the precessional band. In particular, the TWT shows greater variability than SST, and dominates the ΔT changes which couple with the west−east SST difference in the equatorial Pacific at the half-precessional band, implying a decisive role of the tropical thermocline in orbital-scale climate change.

Fluctuations in Terrestrial–Marine Environments in the Western Equatorial Pacific during the Late Pleistocene

2002 ◽  
Vol 57 (1) ◽  
pp. 71-81 ◽  
Author(s):  
Hodaka Kawahata ◽  
Rena Maeda ◽  
Hideaki Ohshima
Keyword(s):  
Late Pleistocene ◽  
Accumulation Rate ◽  
Global Climate ◽  
New Guinea ◽  
Equatorial Pacific ◽  
Pollen Record ◽  
Western Equatorial Pacific ◽  
Large Heat ◽  
Pollen And Spores ◽  
Marine Environmental

AbstractLarge heat storage capacity in the western equatorial Pacific has played an important role in modulating global climate. The fluctuation in pollen and spore abundances, together with organic matter (OM) and lithogenics sedimentation, was investigated to reconstruct terrestrial and marine environmental change around New Guinea during the Late Pleistocene. Although appreciable contribution from Indonesian Maritime Continent was expected, the majority of the pollen and spore grains found in core C4402 was transported from New Guinea. Fern spores accounted for 70% (46–90%) of the total pollens and spores. Positive correlation between lithogenic content and the relative abundance of fern spores suggests that lithogenics could be derived from coastal lowland.The mass accumulation rate (MAR) of pollen and spores varied from 44 to 7,031×10−3 grains cm−2 yr−1 with maxima in oxygen isotope stages (OIS) 2, 3, 4, and around the OIS 4/5 boundary. Less rainfall during glacial times generally enhanced transport of pollen by wind to Site C4402. Their scavenging from the water column was promoted by high activity of the biological pump. Pollen record from core C4402 suggests that lower montane group vegetation was dominant relative to lowland vegetation and upper and mid-montane group during glacial times. Although appreciable contribution by terrestrial OM is expected from high correlation of MAR between organic carbon (OC) and pollen and spores, fairly low COrganic/N ratios and δ13C values (around −20‰) of OM demonstrate that OM in core C4402 is mainly of marine origin.

Upper-Ocean Circulation Anomalies of the Western Equatorial Pacific Observed in 2016 Summer

2020 ◽  
Author(s):  
Yilong Lyu
Keyword(s):  
Ocean Circulation ◽  
Rossby Waves ◽  
New Guinea ◽  
Equatorial Pacific ◽  
Eastern Pacific ◽  
Boreal Summer ◽  
Western Boundary ◽  
Easterly Wind ◽  
Western Equatorial Pacific ◽  
Circulation Anomalies

<p>Mooring measurements at ~140°E in the western equatorial Pacific documented greatly intensified eastward subsurface currents, which largely represents the nascent Equatorial Undercurrent (EUC), to ~67 cm s<sup>-1</sup> in boreal summer of 2016. The eastward currents occupied the entire upper 500 m, with the westward surface currents nearly diminished. Similar variations were also observed during previous El Niño events, as suggested by historical in-situ data. Further analysis combining satellite and reanalysis data reveals that the eastward currents observed at ~140°E are a component of an anomalous counterclockwise circulation straddling the equator, with westward current anomalies retroflecting near the western boundary and feeding southeastward current anomalies along New Guinea coast. A 1.5-layer reduced-gravity ocean (RGO) model is able to crudely reproduce these variations, and a hierarchy of sensitivity experiments are performed to understand the underlying dynamics. The observed circulation anomalies are largely the delayed ocean response to the strong equatorial wind anomalies over the central-to-eastern Pacific basin emerging in the mature stage of El Niño (September-April). Downwelling equatorial Rossby waves are generated by the reflection of equatorial Kelvin waves and easterly wind anomalies in the eastern Pacific. Upon reaching western Pacific, the Southern Hemisphere lobe of Rossby waves encounter the slanted New Guinea island and deflects equatorward, establishing a local sea surface height maximum near the equator and leading to the detour of westward currents flowing from the Pacific interior. Additional experiments with edited western boundary geometry confirm the importance of topography in regulating the structure of this cross-equatorial anomalous circulation.</p>

Anomalous Upper-Ocean Circulation of the Western Equatorial Pacific following El Niño Events

2020 ◽  
Vol 50 (11) ◽  
pp. 3353-3373
Author(s):  
Yilong Lyu ◽  
Yuanlong Li ◽  
Jianing Wang ◽  
Jing Duan ◽  
Xiaohui Tang ◽  
...  
Keyword(s):  
El Niño ◽  
Rossby Waves ◽  
El Nino ◽  
New Guinea ◽  
Equatorial Pacific ◽  
Eastern Pacific ◽  
Western Boundary ◽  
Western Equatorial Pacific ◽  
Anomalous Circulation ◽  
El Niño Events

AbstractMooring measurements at ~140°E in the western equatorial Pacific Ocean documented greatly intensified eastward subsurface currents, which largely represent the nascent Equatorial Undercurrent, to ~67 cm s−1 in boreal summer of 2016. The eastward currents occupied the entire upper 500 m while the westward surface currents nearly disappeared. Historical in situ data observed similar variations after most El Niño events. Further analysis combining satellite and reanalysis data reveals that the eastward currents observed at ~140°E are a component of an anomalous counterclockwise circulation straddling the equator, with westward current anomalies retroflecting near the western boundary and feeding southeastward current anomalies along the New Guinea coast. A 1.5-layer reduced-gravity ocean model is able to crudely reproduce these variations, and a hierarchy of sensitivity experiments is performed to understand the underlying dynamics. The anomalous circulation is largely the delayed ocean response to equatorial wind anomalies over the central-to-eastern Pacific basin emerging in the mature stage of El Niño. Downwelling Rossby waves are generated by the reflection of equatorial Kelvin waves and easterly winds in the eastern Pacific. Upon reaching the western Pacific, the southern lobes of Rossby waves encounter the slanted New Guinea island and deflect to the equator, establishing a local sea surface height maximum and leading to the detour of westward currents flowing from the Pacific interior. Additional experiments with edited western boundary geometry confirm the importance of topography in regulating the structure of this cross-equatorial anomalous circulation.

scholarly journals High interstadial sea levels over the past 420ka from Huon terraces (Papua New Guinea)

2021 ◽  
Author(s):  
Gino de Gelder ◽  
Laurent Husson ◽  
Anne-Morwenn Pastier ◽  
David Fernández-Blanco ◽  
Tamara Pico ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Sea Level ◽  
Papua New Guinea ◽  
New Guinea ◽  
Deformation Pattern ◽  
Glacial Cycle ◽  
Sea Levels ◽  
Global Mean Sea Level ◽  
Global Sea Level ◽  
Geological Constraints

The history of sea level across the Quaternary is essential for assessing past and future climate and geodynamics. Global sea-level reconstructions are typically derived from oxygen isotope curves, but require calibration with geological constraints that are particularly scarce prior to the last glacial cycle (>130 ka). The exceptionally well-preserved coral reef terrace sequence in the Huon Peninsula (Papua New Guinea) may provide such constraints up to ~420 ka, but has never been analysed in its full extent, or with high-resolution topographic data. Here we apply novel geometric approaches to show that the terrace sequence deformation pattern can be approximated by a northward tectonic tilt, and estimate relative sea-level (RSL) for 31 Late Pleistocene periods, including several periods for which no other RSL data exists elsewhere. Supported by reef modelling, these estimates suggest that global mean sea-level curves derived from oxygen isotopes systematically underestimate interstadial sea-level elevations, by up to ~20m. We propose that this discrepancy is either an effect of incorrect oxygen isotope curve calibrations, or that some short-lived sea-level variations are simply not recorded in oxygen isotope ratios.

Time Scale of the Wisconsin/Holocene Transition: Oxygen Isotope Record in the Western Equatorial Pacific

1987 ◽  
Vol 28 (2) ◽  
pp. 295-306 ◽  
Author(s):  
W. H. Berger ◽  
J. S. Killingley ◽  
E. Vincent
Keyword(s):  
Oxygen Isotope ◽  
Time Scale ◽  
Late Onset ◽  
Equatorial Pacific ◽  
The West ◽  
Oxygen Isotope Record ◽  
Western Equatorial Pacific ◽  
Isotope Record ◽  
Radiocarbon Data

AbstractAn evaluation of both published and new oxygen isotope and radiocarbon data from the west equatorial Pacific (7 box cores, 2 piston cores, 2 gravity cores) indicates that there was no significant input of meltwater to the ocean before 14,000 14C yr B.P. This finding is in conflict with various early deglaciation scenarios suggested several years ago on the basis of Wisconsin/Holocene transition records from the Atlantic, but agrees with late-onset scenarios proposed more recently, both for Pacific and Atlantic deglaciation records.

Sign in / Sign up

Export Citation Format

Share Document