Author: David Ericsson HunterPublisher:
ISBN:
Category :
Languages : en
Pages : 244
Book Description
Interannual and Decadal Climate Variability in Coral and Instrumental Records, with a Focus on the Western Indian Ocean
Author: David Ericsson HunterPublisher:
ISBN:
Category :
Languages : en
Pages : 244
Book Description
Coral Records of Central Tropical Pacific Sea-surface Temperature and Salinity Variability Over the 20th Century
Author: Intan Suci NurhatiPublisher:
ISBN:
Category : Climatic changes
Languages : en
Pages :
Book Description
Accurate forecasts of future regional temperature and rainfall patterns in many regions largely depend on characterizing anthropogenic trends in tropical Pacific climate. However, strong interannual to decadal-scale tropical Pacific climate variability, combined with sparse spatial and temporal coverage of instrumental climate datasets in this region, have obscured potential anthropogenic climate signals in the tropical Pacific. In this dissertation, I present sea-surface temperature (SST) and salinity proxy records that span over the 20th century using living corals from several islands in the central tropical Pacific. I reconstruct the SST proxy records via coral Sr/Ca, that are combined with coral oxygen isotopic (d18O) records to quantify changes in seawater d18O (hereafter d18Osw) as a proxy for salinity. Chapter 2 investigates the spatial and temporal character of SST and d18Osw-based salinity trends in the central tropical Pacific from 1972-1998, as revealed by corals from Palmyra (6°N, 162°W), Fanning (4°N, 159°W) and Christmas (2°N, 157°W) Islands. The late 20th century SST proxy records exhibit warming trends that are larger towards the equator, in line with a weakening of equatorial Pacific upwelling over this period. Freshening trends revealed by the salinity proxy records are larger at those sites most affected by the Inter-Tropical Convergence Zone (ITCZ), suggesting a strengthening and/or an equatorward shift of the ITCZ. Taken together, the late 20th century SST and salinity proxy records document warming and freshening trends that are consistent with a trend towards a weakened tropical Pacific zonal SST gradient under continued anthropogenic forcing. Chapter 3 characterizes the signatures of natural and anthropogenic variability in central tropical Pacific SST and d18Osw-based salinity over the course of 20th century using century-long coral proxy records from Palmyra. On interannual timescales, the SST proxy record from Palmyra tracks El Niño-Southern Oscillation (ENSO) variability. The salinity proxy record tracks eastern Pacific-centered ENSO events but is poorly correlated to central Pacific-centered ENSO events - the result of profound differences in precipitation and ocean advection that occur during the two types of ENSO. On decadal timescales, the coral SST proxy record is significantly correlated to the North Pacific Gyre Oscillation (NPGO), suggesting that strong dynamical links exist between the central tropical Pacific and the North Pacific. The salinity proxy record is significantly correlated to the Pacific Decadal Oscillation (PDO), but poorly correlated to the NPGO, suggesting that, as was the case with ENSO, these two modes of Pacific decadal climate variability have unique impacts on equatorial precipitation and ocean advection. However, the most striking feature of the salinity proxy record is a prominent late 20th century freshening trend that is likely related to anthropogenic climate change. Taken together, the coral data provide key constraints on tropical Pacific climate trends, and when used in combination with model simulations of 21st century climate, can be used to improve projections of regional climate in areas affected by tropical Pacific climate variability.
Global Change in the Holocene
Author: John BirksPublisher: Routledge
ISBN: 1444119176
Category : Science
Languages : en
Pages : 556
Book Description
The Holocene spans the 11,500 years since the end of the last Ice Age and has been a period of major global environmental change. However the rate of change has accelerated during the last hundred years, due largely to human impacts and this has led to a growing concern for the future of our environmental resources. Global Change in the Holocene demonstrates how reconstructing the record of past environmental change can provide us with essential knowledge about how our environment works and presents the reader with an informed viewpoint from which to project realistic future scenarios. The book brings together key techniques that are widely used in Holocene research, such as radiocarbon dating, dendrochronology and sediment analysis and offers a comprehensive analysis of various archives of environmental change including instrumental and documentary records, corals, lake sediments, glaciers and ice cores. This reference will be an informative and cutting-edge resource for all researchers in the fields of climate change, environmental science, geography, palaeoecology and archaeology.
Dissertation Abstracts International
Author: Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 806
Book Description
Pacific Climate Variability
Author: Sara C. SanchezPublisher:
ISBN:
Category :
Languages : en
Pages : 210
Book Description
This dissertation aims to understand the mechanisms and consequences of the low frequency "unforced" component of variability in the climate system using interannual and decadal variability as a platform to investigate phenomena thought to be sensitive to greenhouse gas emissions. To combat the lack of temporally extended instrumental observations, this dissertation relies on coral geochemistry and Earth System Models to identify the historical range of Pacific climate variability. Chapter 2 describes the analysis of a roughly 200 year-long coral record from Clarion Island, in the Revillagigedos Archipelago, Mexico. This record expresses substantial decadal variability in the oxygen isotopes, strongly coherent with other paleoproxies in the central equatorial Pacific and in Southern California, indicative of a coordinated system of ocean-atmospheric interaction. To best resolve the key processes involved, "forward models" are employed to interpret the decadal variability in the coral record. The third chapter complements the first by addressing a mechanism responsible for the modulation of decadal variability in the North Pacific; the Pacific Meridional Mode (PMM). The Community Earth System Model-Last Millennium Ensemble (CESM-LME) is used to estimate the historical range of PMM variability, highlighting the considerable power of natural variability within the system. I investigate the physical processes associated with adjustments in PMM variance, emphasizing that relatively small anomalies in the background state have a significant influence on PMM variability. Chapter 4 examines the roles of physical and biologically mediated processes on coral calcification from within an equatorial Pacific coral reef. Motivated by the biogeochemical implications of the previous sections, this work examines the manifestation of pH tracers in coral skeletal tissue across a network of diverse, monitored reef sites at Palmyra Atoll. Corals were analyzed for [delta]11B, trace metal, [delta]18O, and [delta]13C composition. Despite a narrow range in the pH of seawater, high variance in [delta]11B were observed between sites, and within single sites, suggesting that individual coral colonies have differential capacities to regulate pH variability and other environmental stressors.
The Agulhas Current
Author: Johann R.E. LutjeharmsPublisher: Springer Science & Business Media
ISBN: 3540372121
Category : Science
Languages : en
Pages : 334
Book Description
Based on the research findings of 60 years, the author describes the origins of the Agulhas Current, its behaviour, its influence on the adjacent continental shelf, its effect on local weather and its role in linking the Indian and Atlantic Oceans. The text is well-illustrated and includes asides on the history of research on the Current. An exhaustive bibliography gives easy access to present knowledge on this important current system.
Annual Report
Author: Scripps Institution of OceanographyPublisher:
ISBN:
Category : Ocean waves
Languages : en
Pages : 48
Book Description
Historical Climate Variability Reconstructed from Massive Coral Records in the Western Indian Ocean
Author: Jean Vincent Arnaud NicolasPublisher:
ISBN:
Category : Climatic changes
Languages : en
Pages : 0
Book Description
Explorations
Author: Decadal Climate Variability in the Western Tropical Atlantic and the Potential for Proxy Records from the Coral Siderastrea Siderea
Author: Nathalie E. G. SmithPublisher:
ISBN:
Category : Climatic changes
Languages : en
Pages : 200
Book Description