Download or read book Centennial scale Sea Surface Temperature and Salinity Variability in the Florida Straits During the Early Holocene written by William Weinlein and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Previous studies showed that sea surface salinity (SSS) in the Florida Straits as well as Florida Current transport covaried with changes in North Atlantic climate over the past two millennia. However, little is known about earlier Holocene variability in the Florida Straits. Here, we combine Mg/Ca-paleothermometry and stable oxygen isotope measurements on the planktonic foraminifera Globigerinoides ruber (white variety) from Florida Straits sediment core KNR166-2 JPC 51 (24 degrees 24.70' N, 83 degrees 13.14'W, 198m deep) to reconstruct a high-resolution (~30 yr/sample) early to mid Holocene record of sea surface temperature and delta18OSW (a proxy for SSS) variability. We also measured Ba/Ca ratios in the same shell material as a proxy for riverine input into the Gulf of Mexico over the same time interval. After removing the influence of global delta18OSW change due to continental ice volume variability, we propose that early Holocene SSS enrichments were caused by increased evaporation/precipitation ratios in the Florida Straits associated with periods of reduced solar output, increased ice rafted debris in the North Atlantic and the development of more permanent El Nino-like conditions in the eastern equatorial Pacific. When considered with previous high-resolution reconstructions of early Holocene tropical atmospheric circulation changes, our results provide evidence that solar output variability over the Holocene had a significant impact on the global tropical hydrologic cycle over the last 10,000 years.

Download or read book Sub centennial Scale Climatic and Hydrologic Variability in the Gulf of Mexico During the Early Holocene written by Jenna Meredith LoDico and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Sediment core MD02-2550 from Orca Basin located in the northern Gulf of Mexico (GOM) provides a high-resolution early Holocene record of climatic and hydrologic changes from approximately 10.5 to 7 thousand calendar years before present (ka). Paired analyses of Mg/Ca and oxygen isotopes on the planktonic foraminifer Globigerinoides ruber (white variety, 250-355 microns) sampled at approximately 20 remove a comment year resolution were used to generate proxy records of sea surface temperature (SST) and an oxygen isotope record of seawater in the GOM. The Mg/Ca-SST record contains an overall1.5 degree C warming trend from 10.5 to 7 ka that appears to track the intensity of the annual insolation cycle and six temperature oscillations (0.5-2 degree C), the frequency of which are consistent with those found in records of solar variability. The GOM oxygen isotope record contains six approximately 0.5 per mil oscillations from 10.5 to 7 ka that bear some resemblance to regional hydrologic records from Haiti and the Cariaco Basin, plus a -0.8 per mil excursion that may be associated with the "8.2 ka event" recorded in Greenland air temperatures. The GOM oxygen isotope record, if interpreted as a salinity proxy, suggest large salinity fluctuations (greater than 2 psu) reflecting changes in evaporation-precipitation (E-P) and Mississippi River input to the GOM. Percent Globigerinoides sacculifer records from three cores in the GOM exhibit remarkably coherent changes, suggesting episodic centennial-scale incursions of Caribbean waters. Spectral analysis of the Mg/Ca-SST and the GOM oxygen isotope record time series indicate that surface water conditions may be influenced by solar variations because they share significant periods of variability with atmospheric delta 14C near 700, 200, and 80-70 years. Our results add to the growing body of evidence that the sub-tropics were characterized by significant decadal to centennial-scale climatic and hydrologic variability during the early Holocene.

Download or read book Principles of Paleoclimatology written by Thomas M. Cronin and published by Columbia University Press. This book was released on 1999 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using the geologic records of ocean and lake sediment, ice cores, corals, and other natural archives, Principles of Paleoclimatology describes the history of the Earth's climate--the ice age cycles, sea level changes, volcanic activity, changes in atmosphere and solar radiation--and the resulting, sometimes catastrophic, biotic responses.

Download or read book Tropical North Atlantic Hydrologic Cycle Variability in the Florida Straits During the Last Ice Age written by Theodore Them and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abrupt, millennial-scale climate oscillations, known as Dansgaard-Oeschger (D-O) cycles, characterized the climate system during the last ice age. Proxy evidence suggests these climate oscillations resulted in global-scale reorganizations in the hydrological cycle. For this study, Mg/Ca-paleothermometry and stable isotope measurements were combined on the planktonic foraminifera Globigerinoides ruber (white variety) from Florida Straits sediment core KNR166-2 JPC26 (24*19.61'N, 83*15.14'W; 546 m depth) to reconstruct a high-resolution record of sea surface temperature and delta18OSW (a proxy for upper water column salinity) during Marine Isotope Stages 2 and 3 from 20-35.45 ka BP. As additional proxies for upper water column salinity change, Ba/Ca ratios in G. ruber were also measured to determine the relative contribution of local riverine input on the delta18OSW record and a faunal abundance count record of the planktonic foraminifera N. dutertrei abundance was developed. These results show that rapid upper water column salinity changes occurred across D-O events in the Florida Straits, coeval with climate change in the high-latitude North Atlantic. Furthermore, the G. ruber Ba/Ca record suggests that riverine-derived meltwater from the Gulf of Mexico did not significantly impact surface salinity in the Florida current, calling into question the role of Mississippi River discharge on Atlantic Meridional Overturning Circulation (AMOC) during MIS 2 and 3. Instead, the most likely cause of MIS 2 and 3 salinity changes in the Florida Straits were variations in the strength and position of the Intertropical Convergence Zone. Finally, the timing of surface salinity change was compared with the benthic delta18OC record from the same core. A recent study showed that benthic delta18OC changes on the Florida Margin can be combined with contemporaneous records from the Bahamas Margin to reconstruct Florida Current transport related to AMOC variability. These results show that atmospheric circulation changes lead AMOC changes on the transition out of cold stadial events, suggesting the trigger for these abrupt climate events may reside in the tropics rather than in the high-latitude North Atlantic as previously thought.

Download or read book Surface ocean Variability in the Northern Gulf of Mexico During the Late Holocene written by Kaustubh Ramesh Thirumalai and published by . This book was released on 2016 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: The surface waters of the Gulf of Mexico (GOM) are a major moisture source for North America and play an important role in modulating the hydroclimate of the region. Predictions of future changes in surface-ocean variability in the GOM and hydroclimatic changes in response to greenhouse gas forcing must be placed in context of past changes. However, the instrumental record of sea-surface temperature (SST) and salinity (SSS) observations in the GOM is too brief to examine climate variability on multidecadal-to-centennial timescales; thus, proxy records of SST and SSS variability as encoded in marine sedimentary archives must be used to extract information about climate change on these timescales. In this work, I produce a near-decadal-resolution record of SST and SSS variability in the northern GOM over the last 4,400 years. These paleo-records are based on the measurement of the stable isotopic and trace metal composition of planktic foraminifer Globigerinoides ruber (White) shells in a suite of multicores from the Garrison Basin, northern GOM (26° 40.19'N,93° 55.22'W). The fidelity of this proxy is assessed by performing geochemical measurements on in-situ samples from a nearby sediment trap and by performing statistical data-model comparisons with a foraminiferal forward model that can simulate different calcification depth habitats and seasonal productivity. Next, I construct a computational algorithm that characterizes uncertainty in foraminiferal reconstructions including age, analytical, calibration, ecological, sampling, and preservation errors. The utility of this algorithm is shown by applying it to several previously published records. It is also used to place the new Garrison Basin SST and SSS reconstructions in a quantitative uncertainty framework. I diagnose the controls of multidecadal-to-centennial-scale SST and SSS variability in the GOM (and establish its relationship with Atlantic Ocean circulation) by performing correlation analyses using observations, reanalysis datasets, and transient models. Several other marine and terrestrial proxy records spanning the last millennium are synthesized to document a coordinated linkage between Atlantic Ocean circulation and Western Hemisphere precipitation. This work hypothesizes that a century-scale linkage between ocean circulation and precipitation variability occurred over the last millennium, and perhaps the late Holocene, thereby providing a new perspective on long-term climate change.

Download or read book Integrated Analysis of Interglacial Climate Dynamics INTERDYNAMIC written by Michael Schulz and published by Springer. This book was released on 2014-11-20 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work addresses the following questions in the context of interglacial climate dynamics: (i) What are the amplitudes of natural climate variations on timescales of several years to millennia? (ii) Do abrupt changes in the large-scale circulation of the Atlantic Ocean occur in interglacials? (iii) Which biogeochemical feedback mechanisms control the natural limits of atmospheric concentrations of greenhouse gases and aerosols? (iv) Which linkages exist between climate and pre-industrial cultures? The work is based on an integrated approach in paleoclimate research, in which all available paleoclimate archives (terrestrial and marine as well as ice cores) are combined in order to yield a comprehensive and quantitative analysis of global environmental variations. Moreover, through a close linkage be-tween paleoclimate reconstructions and results from Earth-system models detailed insights into the dynamics of climate variations are gained.

Download or read book Orbital to Millennial scale Variability in Gulf of Mexico Sea Surface Temperature and Salinity During the Late Pleistocene written by Jessica L. Whitaker and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The initial rise in GOM SST at 132.1 ka of 2.9 °C is followed by a cold reversal of 1.5 °C at 130.4 ka for 2 ky and final increase to full interglacial warmth. The reversal in GOM SST is consonant with a pause in sea level rise and reduced NADW, suggesting a reduction in THC may have caused a global two-step deglaciation.

Download or read book Dynamics of Sea Temperature Variability on Florida s Reef Tract written by Lewis J Gramer and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Variability in 5- to 25-year records of hourly mean in situ sea temperature, ocean currents, and meteorology at diverse shallow-water habitats in the Florida reef tract (FRT) is analyzed. Tidal, diurnal, and annual periodicities generally dominate sea temperature variability, with strong variability apparent in the "weather band" of 3-42 d at one reef-flat site, and at the local inertial period at one offshore site near the shelf break. A statistically significant interannual warming trend is also observed at this one offshore site only. Significant covariability between sea temperature and coincident air temperature, wind speed, sea-surface temperature (SST) gradients, and incident radiation (light) is also found. However, this covariability itself varies with an annual period, and differs between sites with similar depths, apparently due to differences in seafloor slope. A coastal ocean reef heat budget is estimated from the hourly mean in situ sea temperature, meteorology, satellite SST, and reanalysis data for each site, together with a model of insolation absorption in the water column and heat exchange at the seafloor. A term for smaller-scale heat advection, the so-called horizontal convection (HC) or thermal siphon, previously observed at coral reefs elsewhere in the world, balances the heat budget. At six of the eight sites analyzed, the budget matches the long-term annual climatology of observed in situ sea temperature variability within estimated uncertainty, and matches full seasons at the two other sites. Budget results also match the observed daily sea temperature variability, with R2 > 0.3, root mean squared error

Download or read book Salinity and Temperature Variability in the Caribbean and the North Atlantic Gyre During the Last Three Ice Age Cycles on Millennial and Orbital Time Scales written by Matthew William Schmidt and published by . This book was released on 2005 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Ocean and Cryosphere in a Changing Climate written by Intergovernmental Panel on Climate Change (IPCC) and published by Cambridge University Press. This book was released on 2022-04-30 with total page 755 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for assessing the science related to climate change. It provides policymakers with regular assessments of the scientific basis of human-induced climate change, its impacts and future risks, and options for adaptation and mitigation. This IPCC Special Report on the Ocean and Cryosphere in a Changing Climate is the most comprehensive and up-to-date assessment of the observed and projected changes to the ocean and cryosphere and their associated impacts and risks, with a focus on resilience, risk management response options, and adaptation measures, considering both their potential and limitations. It brings together knowledge on physical and biogeochemical changes, the interplay with ecosystem changes, and the implications for human communities. It serves policymakers, decision makers, stakeholders, and all interested parties with unbiased, up-to-date, policy-relevant information. This title is also available as Open Access on Cambridge Core.

Download or read book Abrupt changes in early Holocene tropical sea surface temperature derived from coral records written by J. Warren Beck and published by . This book was released on 1997 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Early Holocene Decadal scale Ocean Variability Recorded in Gulf of California Laminated Sediments written by Jennifer Pike and published by . This book was released on 1997 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Quaternary Sedimentation in South Florida written by Paul Enos and published by Geological Society of America. This book was released on 1977 with total page 227 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Sources of Climate Variability in the Caribbean Sea written by Jennifer Wagner Whiteis and published by . This book was released on 2005 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Coastal Sea Surface Temperature Change in the East China Sea During the Late Holocene written by Anna Lee Fisher and published by . This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Coastal Sea Surface Temperature Change in the East China Sea During the Late Holocene" by Anna Lee, Fisher, 安宜, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Coastal sea surface temperatures were reconstructed using alkenone analyses on sediment core T08 collected from the Min-Zhe coastal mud area by gravity corer in 2011. The alkenone simplified U DEGREESK' 37 index has been widely recognised as one of the reliable ways for quantitative SST reconstruction. Sea surface temperatures were calculated using U DEGREESK' 37 for studying past coastal sea surface temperature change over the East China Sea during the Late Holocene. Results found span over the last 2300 years, and largely show a warm period. The alkenone U DEGREESK' 37-sea surface temperatures range from 28.15℃to 23.87℃. There are also noticeable cooling events recorded in the T08 core. Warm and cool periods show an apparent link to East Asia Monsoonal activities. During cooler periods, the East Asian winter monsoon strengthened as the East Asia summer monsoon weakened, and vice versa. However, spatial patterns could not be uncovered in this study as only one site was studied. More sites would need to be investigate in order to reveal more detailed spatial patterns of this region. DOI: 10.5353/th_b5677169 Subjects: Paleoclimatology - East China Sea Paleoclimatology - Holocene

Download or read book Late Holocene Climate Variability from Northern Gulf of Mexico Sediments written by Julie N. Richey and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Accurate reconstruction of natural climate variability over the past millennium is critical for predicting responses to future climate change. In order to improve on current understanding of climate variability in the sub-tropical North Atlantic region over the past millennium, a rigorous study of Gulf of Mexico (GOM) sea surface temperature (SST) variability was conducted using both inorganic (foraminiferal Mg/Ca) and molecular organic (TEX6) geochemical proxies. In addition to generating multiple high-resolution climate records, the uncertainties of the SST proxies are rigorously assessed. There are 3 major research questions addressed: (1) What was the magnitude of GOM SST variability during the past 1,000 years, particularly during large-scale climate events such as the Little Ice Age (LIA) and the Medieval Warm Period (MWP). (2) Is the SST signal reproducible within the same sediment core, among different northern GOM basins, and using different geochemical SST proxies? (3) What are the ecological controls on the paleothermometers used to reconstruct SST variability in the GOM? Can differences in the ecology (i.e. seasonal distribution, depth habitat, etc.) of distinct paleothermometers be exploited to gain insight into changes in upper water column structure or seasonality in the GOM during the LIA and MWP? The major findings include: (1) The magnitude of temperature variability in the GOM over the past millennium is much larger than that estimated from Northern Hemisphere temperature reconstructions. The MWP (1400-900 yrs BP) was characterized by SSTs in the GOM that were similar to the modern SST, while the LIA (400-150 yrs BP) was marked by a series of multidecadal intervals that were 2-2.5°C cooler than modern. (2) This LIA cooling was replicated in the Mg/Ca-SST records from three different well-dated northern GOM basins (Pigmy, Garrison and Fisk Basins), as well as in two different geochemical proxies. (3) It is determined that foraminiferal test size has a significant effect on shell geochemistry. Using core-top calibration, discrepancies in the seasonal/depth habitats between different planktonic Foraminifera, and between Foraminifera and Crenarchaeota are inferred. Downcore differences are used to make inferences about changes in GOM mixed layer depth and seasonality over the past millennium.

Download or read book Mesoscale Ocean Surface Temperature Variability written by Richard Grotjahn and published by . This book was released on 1975 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: