Pleistocene Nutrient, Thermocline, and Bottom Current Dynamics in the South Pacific Sector of the Western Pacific Warm Pool PDF Download
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Author: Jonathan Edward Lambert Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
I also identify a period between 100 and 60 ka during a potential reorganization of the upper water column in which variability in productivity occurs at a higher frequency than that of precession. Finally, while also related to ITCZ shifts, a nearby record closer to the equator is phase-lagged from Site U1486 - emphasizing the fine-scale regional differences in the drivers of primary productivity in the WPWP.
Author: Jonathan Edward Lambert Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
I also identify a period between 100 and 60 ka during a potential reorganization of the upper water column in which variability in productivity occurs at a higher frequency than that of precession. Finally, while also related to ITCZ shifts, a nearby record closer to the equator is phase-lagged from Site U1486 - emphasizing the fine-scale regional differences in the drivers of primary productivity in the WPWP.
Author: Patrick Anthony Rafter Publisher: ISBN: Category : Languages : en Pages : 117
Book Description
The tropical Pacific is a region where nutrient delivery, upper ocean dynamics, and global climate variability are tightly coupled. For example, the depth of the eastern equatorial Pacific (EEP) thermocline, for the most part, determines the delivery of the essential nutrient nitrate, but it is also a key aspect of an ocean-atmosphere feedback system responsible for global climate variability--the El Nino Southern Oscillation (ENSO). To provide a unique view of the upper ocean processes directly responsible for nutrient and climate dynamics in this region, I apply a single tracer--the ratio of 15N to 14N (hereafter "[delta]15N")--in modern seawater and sediment throughout the tropical Pacific. I find that the [delta]15N of nitrate is homogeneous throughout the tropical Pacific and is elevated by 2 / relative to the Southern and Atlantic Oceans by mixing with the denitrified waters of the eastern tropical Pacific. The results of this modern ocean survey are used to devise a new application of [delta]15N in eastern and western equatorial Pacific (WEP) sediments that provides a record of EEP nitrate consumption over the past 1,200,000 years. This record strongly suggests that the depth of the EEP thermocline--and therefore the upper ocean conditions driving the tropical climate system--has little to no response to high-latitude processes such as icesheet dynamics. Instead, as has been suggested by coupled ocean-atmosphere models, the east/west thermocline tilt responded primarily to changes in local seasonal insolation over thousands of years (a product of planetary axial precession). Some of the long-term changes in these deep-sea sediment [delta]15N records would seem to suggest an alteration of the original surface ocean signal, but additional [delta]15N measurements of sedimentary size fractions and components support the fidelity of bulk sedimentary [delta]15N as an archive of surface ocean nutrient cycling.
Author: Victoria Yuan Publisher: ISBN: 9780438249455 Category : Languages : en Pages : 60
Book Description
Tropical Pacific sea surface temperatures (SSTs) are a critical component of the global climate system with oceanic and atmospheric teleconnections through meridional and latitudinal heat transport. Understanding the climate drivers and dynamics of this region enables a better understanding of global climate. Orbital scale climate drivers for eastern and western Pacific SSTs have been studied; however, SSTs and thermocline structure have not been studied in the central equatorial Pacific (CEP). Studying temperature dynamics in the CEP upper water column can help determine which mechanisms control SST and thermocline structure and test previously proposed hypotheses. Here, I present CEP SST and subsurface temperature records from the Line Islands (ML1208-17PC) that span the last 380,000 years. Using two species of foraminifera, G. ruber and G. tumida, I respectively generated Mg/Ca based SST and subsurface temperature records and compared them to published records from the equatorial Pacific. This comparison indicates an expanded west pacific warm pool (WPWP) during interglacial periods but no expansion of the eastern Pacific cold tongue during glacial periods. Based on the thermocline depth proxy, the thermocline was deeper in glacial periods and shallower in interglacial periods. Cross-spectral analysis demonstrates which climate drivers are the likely forcings for CEP SST and thermocline behavior. The CEP SSTs are distinct from those to the east or the west as they are not directly driven by CO2 or insolation at orbital frequencies; instead, the CEP SST record is linked to subsurface temperature at eccentricity and obliquity bands. However, changes in thermocline conditions at the CEP are potentially driven by CO2 and Antarctic temperature changes. This study agrees and supports previous studies that indicate deeper thermocline depths in glacials and shallower depths in interglacials.
Author: Miriam Jones Publisher: Frontiers Media SA ISBN: 2889633373 Category : Languages : en Pages : 208
Book Description
The vast area of the North Pacific, spanning ~55˚ longitude, represents a challenge for documenting and understanding the geologic history of ocean, atmosphere, and terrestrial environmental change. Nevertheless, its importance for many issues, including our fundamental understanding of ocean and atmospheric circulation patterns and teleconnections with natural modes of climate variability through time, has led to a steady rise in the numbers of study sites and proxy types. By bringing together a wide range of proxies and timescales that examine the impacts of paleoclimate on ecosystems, water, carbon, and humans, and interactions between marine and terrestrial processes, this Research Topic contributes to an improved understanding of the region’s significance at global, hemispheric, and regional scales.
Author: Publisher: ISBN: Category : Languages : en Pages : 5
Book Description
A source of instability in the western Pacific warm pool is shown to be due to sea surface elevation variations caused by changes in the zonal sea-surface temperature (SST) gradient and the changes in the Pacific Ocean basin length in relation to the warm pool latitudinal location. The variation of the sea-surface elevation is measured by using the thermocline depth response calculated from a two-layer ocean. The warm pool is shown to be barely at equilibrium during the boreal late winter and early spring by comparing the measured thermocline at 110°W, 0°E with the calculated thermocline depth. Based on this analysis, a failure or reversal of the climatological zonal winds are apparently not a necessary precursor for the instability of the warm pool and initiation of a warm event. A warm event can be initiated by an increase in the size of the warm pool and/or an increase in zonal SST differences during the boreal/winter spring. This mechanism could be an alternate mechanism for El-Nino Southern Oscillation (ENSO) dynamics to that postulated by Bjeknes (1969).
Author: Jonathan Edward Lambert
Author: Jonathan Edward Lambert
Author: Patrick Anthony Rafter
Author: Victoria Yuan
Author: Miriam Jones
Author: 
Author: 毛特立
Author: Rebecca Sprague Robinson
Author: Martina Hollstein
Author: Jennifer L. Massoll
Author: Petra Simonne Dekens