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Thomas Felis - One of the best experts on this subject based on the ideXlab platform.
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Distinct modes of East Asian Winter Monsoon documented by a southern Red Sea Coral Record
Journal of Geophysical Research: Oceans, 2014Co-Authors: Monica Ionita, Gerrit Lohmann, Norel Rimbu, Thomas Felis, Jürgen PätzoldAbstract:The large-scale boreal winter climatic patterns associated with interannual variability in a Coral oxygen isotope (δ18O) Record from the southern Red Sea covering most of the last century are investigated. From the early 1930s to the early 1960s, the winter Coral δ18O Record, reflecting temperature and salinity variations in southern Red Sea surface waters, is associated with global (or large scale) sea surface temperature (SST) and 850 mb geopotential height (Z850) anomalies which project on the corresponding patterns associated with the El Nino-Southern Oscillation (ENSO). In contrast, since the early 1960s the winter Coral δ18O Record is related to a Z850 pattern that reflects the ENSO-independent part of the East Asian Winter Monsoon (EAWM), which includes the Siberian High, the East Asian through, and the East Asian upper-tropospheric Jet. Our results indicate a weakening of the ENSO control on interannual temperature/salinity variations in southern Red Sea surface waters in the early 1960s, due to the warming of the Indian Ocean, and suggest that information about the nonstationarity in the relationship between ENSO and two distinct modes of EAWM can be documented in southern Red Sea Coral δ18O Records.
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Long-term variability in the stable carbon isotopic composition of Porites Corals at the northern Gulf of Aqaba, Red Sea
Palaeogeography Palaeoclimatology Palaeoecology, 2013Co-Authors: Saber Al-rousan, Thomas FelisAbstract:Abstract To study long-term variations in surface ocean δ13C, we investigated Coral skeletal δ13C Records of 20 colonies of the shallow-water Coral Porites spp. from the northern Gulf of Aqaba and the northern Red Sea. The Coral colonies represent different water depths, a wide range of different periods (Last Interglacial, Holocene, the last centuries, the last decades), and various growth rates. Records from modern and fossil Corals show irregular seasonal cycles, attributed mainly to the seasonal cycle of light. No attenuation in the amplitude of the seasonal skeletal δ13C cycle with depth is evident, and no significant correlation between mean annual Coral δ13C and water depth was observed in the modern Corals. The mean Coral extension rates show no clear relationship with mean skeletal δ13C values. The average skeletal δ13C value of modern Corals was − 2.74 ± 0.49‰, offset from both calcite and aragonite equilibrium values by about 5.22‰ and 6.26‰, respectively. Modern Corals reveal a clear trend toward lighter skeletal δ13C values since the year 1974. At longer timescales, the skeletal δ13C values from Last Interglacial and Holocene Corals and from Coral Records extending back to the mid- to late 18th century reveal much heavier δ13C values compared to values from 1960 to the present. The trend toward lighter skeletal δ13C values over the last decades can be attributed to changes in the δ13C of the dissolved inorganic carbon of the ambient seawater due to the addition of anthropogenically derived CO2 (13C Suess effect) to the atmosphere. Other factors such as the metabolic effects of Corals may account for the modulation of skeletal δ13C on shorter timescales. A centuries-long Coral Record from the northern Red Sea reveals a magnitude of decrease in skeletal δ13C comparable to global trends (1960–1990), whereas a centuries-long Coral Record from the northern Gulf of Aqaba indicates a larger decrease over the same period, probably due to local effects. In conclusion, the combined carbon isotope Records obtained from Porites spp. Corals from the northern Red Sea seem to be suited to provide information on long-term world-wide changes in atmospheric CO2.
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Pronounced interannual variability in tropical South Pacific temperatures during Heinrich Stadial 1
Nature Communications, 2012Co-Authors: Thomas Felis, Guy Cabioch, Ute Merkel, Ryuji Asami, Pierre Deschamps, Ed C. Hathorne, Martin Kölling, Edouard Bard, Nicolas Durand, Matthias PrangeAbstract:During the last glacial termination, the North Atlantic experienced a cold interval, but its impact on tropical climate variability is not clear. Here, a fossil Tahiti Coral Record shows that tropical sea surface temperature varied actively during this event, consistent with climate model simulations. The early last glacial termination was characterized by intense North Atlantic cooling and weak overturning circulation. This interval between ~18,000 and 14,600 years ago, known as Heinrich Stadial 1, was accompanied by a disruption of global climate and has been suggested as a key factor for the termination. However, the response of interannual climate variability in the tropical Pacific (El Niño-Southern Oscillation) to Heinrich Stadial 1 is poorly understood. Here we use Sr/Ca in a fossil Tahiti Coral to reconstruct tropical South Pacific sea surface temperature around 15,000 years ago at monthly resolution. Unlike today, interannual South Pacific sea surface temperature variability at typical El Niño-Southern Oscillation periods was pronounced at Tahiti. Our results indicate that the El Niño-Southern Oscillation was active during Heinrich Stadial 1, consistent with climate model simulations of enhanced El Niño-Southern Oscillation variability at that time. Furthermore, a greater El Niño-Southern Oscillation influence in the South Pacific during Heinrich Stadial 1 is suggested, resulting from a southward expansion or shift of El Niño-Southern Oscillation sea surface temperature anomalies.
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Pacific Decadal Oscillation documented in a Coral Record of North Pacific winter temperature since 1873
Geophysical Research Letters, 2010Co-Authors: Thomas Felis, Norel Rimbu, Atsushi Suzuki, Henning Kuhnert, Hodaka KawahataAbstract:[1] The Pacific Decadal Oscillation (PDO), the leading mode of sea surface temperature (SST) anomalies in the extratropical North Pacific Ocean, has widespread impacts on precipitation in the Americas and marine fisheries in the North Pacific. However, marine proxy Records with a temporal resolution that resolves interannual to interdecadal SST variability in the extratropical North Pacific are extremely rare. Here we demonstrate that the winter Sr/Ca and U/Ca Records of an annually-banded reef Coral from the Ogasawara Islands in the western subtropical North Pacific are significantly correlated with the instrumental winter PDO index over the last century. The reconstruction of the PDO is further improved by combining the Coral data with an existing eastern mid-latitude North Pacific growth ring Record of geoduck clams. The spatial correlations of this combined index with global climate fields suggest that SST proxy Records from these locations provide potential for PDO reconstructions further back in time.
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winter and summer climate patterns in the european middle east during recent centuries as documented in a northern red sea Coral Record
The Holocene, 2006Co-Authors: Norel Rimbu, Gerrit Lohmann, Thomas Felis, Jurgen PaatzoldAbstract:The Ras Umm Sidd Coral 6180 Record from the northern Red Sea is the northernmost centuries long Coral time series that is currently available in seasonal resolution (AD 1750-1995). Here we investigate climate patterns associated with the Coral 6180 time series separately for boreal winter and summer, using instrumental and reconstructed climate fields for the European-Middle East region. The winter Coral 6180 Record is associated with dominant modes of sea-level pressure, temperature and precipitation variability in the European-Middle East region, which reflect the Arctic Oscillation/North Atlantic Oscillation (AO/ NAO) phenomenon. The summer Coral 6180 Record is associated with an atmospheric pattern having its main centre of action over southwestern Scandinavia/northern Great Britain. The connection between these large-scale atmospheric circulation patterns and the Coral time series was stable during the past 250 years. During winter, eastern Mediterranean/Middle East climate, as reflected in the Coral...
Thomas P. Guilderson - One of the best experts on this subject based on the ideXlab platform.
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surface water processes in the indonesian throughflow as documented by a high resolution Coral δ14c Record
Journal of Geophysical Research, 2008Co-Authors: Thomas P. Guilderson, Stewart FallonAbstract:[1] To explore the seasonal to decadal variability in surface water masses that contribute to the Indonesian throughflow, we have generated a 115-year bimonthly Coral-based radiocarbon time series from a Coral in the Makassar Straits. In the pre-bomb (pre-1955) era from 1890 to 1954, the radiocarbon time series occasionally displays a small seasonal signal (10–15‰). After 1954 the radiocarbon Record increases rapidly, in response to the increased atmospheric 14C content caused by nuclear weapons testing. From 1957 to 1986 the Record displays clear seasonal variability from 15 to 60‰ and the post-bomb peak (163 per mil) occurred in 1974. The seasonal cycle of radiocarbon can be attributed to variations of surface waters passing through the South Makassar Strait. Southern Makassar is under the influence of the Northwest Monsoon, which is responsible for the high austral summer radiocarbon (North Pacific waters) and the Southeast Monsoon that flushes back a mixture of low (South Pacific and upwelling altered) radiocarbon water from the Banda Sea. The Coral Record also shows a significant 14C peak in 1955 due to the bomb-14C water advected into this region from nuclear weapons tests in the Marshall Islands in 1954.
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PRE-BOMB RADIOCARBON VARIABILITY INFERRED FROM A KENYAN Coral Record
Radiocarbon, 2002Co-Authors: N. S. Grumet, Thomas P. Guilderson, Robert B. DunbarAbstract:We report results from AMS radiocarbon measurements (∆14C) in Corals recovered off the coast of Kenya. Bimonthly samples which span the pre-bomb era average -51‰ (±3.7; n=43), when age and Suess effect are corrected, and over the time of interest (1946-1954) do not exhibit any discernible seasonality. Relative to regional pre-bomb ∆14C values in the western Indian Ocean, our results indicate 14C enrichment off the coast of Kenya. Furthermore, the absence of a distinct subannual ∆14C signal suggests that open and coastal upwelling is negligible off the coast of Kenya. Unlike pre-bomb values south of the equator near Seychelles and Madagascar, our pre-bomb value are enriched by more than 10‰. The enrichment of pre-bomb Kenyan ∆14C values relative to sites around Mauritius, northern Madagascar and Seychelles, suggest that the influence of depleted ∆14C water transported in the SEC is limited to regions south of 3 to 4°S. INTRODUCTION The intimate relationship between the Indian Ocean and the atmosphere is revealed in the seasonal reversal of the Indian-Asian monsoons. The monsoons develop primarily as a response to the large thermal gradients between the Asian continent and the Indian Ocean. During the Northern-Hemi- sphere winter, a high-pressure cell develops over the Asian land mass and contributes to the creation of the Northeast (NE) monsoon; the extremely cold and dry air masses over land force air from the northeast to the southwest and drive surface ocean circulation counter-clockwise in the northern Indian Ocean. In contrast, during the Northern-Hemisphere summer, the Asian land mass becomes very warm and a low-pressure cell develops and forms the Southwest (SW) monsoon. Strong south- westerly flow in the lower troposphere brings substantial amount of moisture to India and releases it as precipitation from June to September. The influence of the monsoons on the Indian Ocean is seen in the reversals of the surface circulation and in the hydrological conditions of the surface waters to 10-20°S. The northern and equatorial Indian Ocean circulation is especially complex with large seasonal variations and reversals in major current systems. For example, as a response to prevailing southwesterly flow in the lower tropo- sphere during the SW monsoon, a northward flowing Somali Current (SC) is strongly developed as a continuation of the South Equatorial Current (SEC) and East African Coast Current (EACC) (Figure 1a). Recognized as the western boundary current that causes structural readjustment in the baroclinicity down to 1000 m, the SC is responsible for strong upwelling along the northern coasts of Somali and Oman and the development of the Southern Gyre (SG) and Great Whirl (GW) during the SW monsoon (Luther 1999). Surface water flow is predominantly in an eastward direction. In contrast, during the NE monsoon, northeasterly winds develop causing surface waters north of the equator to flow to the west or southwest comprising the North Equatorial Current (NEC) north of the equator and at the equator, south-flowing water off the coast of Somalia together with the northflow- ing EACC feed the Equatorial Counter Current (ECC), which moves eastward across the Indian Ocean between 0° and 8°S (Figure 1b) (Schott and McCreary 2001). The complex oceanography in the northern and equatorial Indian Ocean, briefly described above, is responsible for regional differences in the strength and amount of upwelling of subsurface water. As
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Southwest subtropical pacific surface water radiocarbon in a high-resolution Coral Record
Radiocarbon, 2000Co-Authors: Thomas P. Guilderson, Daniel P. Schrag, Michaele Kashgarian, Ethan A. Goddard, Gerard M. Wellington, Braddock K. LinsleyAbstract:We have generated a high-resolution Coral 6,14(: Record from the southwest subtropical Pacific spanning the last 50 yr. Prebomb (1950-1956) 6,t4C values average -52%0. Values begin to increase in 1957, reaching a maximum in the early 1970s, about 10 yr after the atmospheric peale There is a consistent 10-15%0 seasonal cycle whose relationship with vertical mixing evol ves as a consequence of the penetration of the bomb transient into subsurface waters. Comparison of this Record with that simulated in an ocean general circulation model highlights the difficulty in modeling vertical exchange processes.
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Radiocarbon variability in the western equatorial Pacific inferred from a high‐resolution Coral Record from Nauru Island
Journal of Geophysical Research: Oceans, 1998Co-Authors: Thomas P. Guilderson, Daniel P. Schrag, Michaele Kashgarian, John SouthonAbstract:We have generated a high resolution Coral {Delta}{sup 14}C Record spanning the last 50 years to document the seasonal and interannual redistribution of surface waters in the western tropical Pacific. Prebomb (1947{endash}1956) {Delta}{sup 14}C values average {minus}63{per_thousand} and have a total range of 30{per_thousand}. Values begin to increase in 1957, reaching a maximum of 137{per_thousand} in mid-1983. Large interannual variability of up to 80{per_thousand} closely follows the El Ni{tilde n}o-Southern Oscillation (ENSO). During each ENSO warm phase, {Delta}{sup 14}C values begin to increase, reflecting the reduction of low-{sup 14}C water upwelling in the east and the invasion of subtropical water into the western equatorial tropical Pacific. Maximum {Delta}{sup 14}C values are in phase or lag the corresponding sea surface temperature maxima in the eastern tropical Pacific, whereas the rapid return to more negative {Delta}{sup 14}C is in phase with eastern Pacific ENSO indices. The highest-amplitude excursions occur during the 1965/1966 and 1972/1973 events, when the {sup 14}C contrast is highest between the eastern Pacific and subtropics. The 1982/1983 El Ni{tilde n}o, although a larger ENSO event, has a lower {Delta}{sup 14}C amplitude, reflecting the penetration of bomb radiocarbon into the equatorial undercurrent and the reduced contrast in {Delta}{sup 14}C betweenmore » thermocline and subtropical surface waters at that time. This Coral Record demonstrates the potential for using similar radiocarbon time series for documenting variability in Pacific shallow circulation over interannual and decadal timescales. {copyright} 1998 American Geophysical Union« less
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radiocarbon variability in the western equatorial pacific inferred from a high resolution Coral Record from nauru island
Journal of Geophysical Research, 1998Co-Authors: Thomas P. Guilderson, Daniel P. Schrag, Michaele Kashgarian, John SouthonAbstract:We have generated a high resolution Coral {Delta}{sup 14}C Record spanning the last 50 years to document the seasonal and interannual redistribution of surface waters in the western tropical Pacific. Prebomb (1947{endash}1956) {Delta}{sup 14}C values average {minus}63{per_thousand} and have a total range of 30{per_thousand}. Values begin to increase in 1957, reaching a maximum of 137{per_thousand} in mid-1983. Large interannual variability of up to 80{per_thousand} closely follows the El Ni{tilde n}o-Southern Oscillation (ENSO). During each ENSO warm phase, {Delta}{sup 14}C values begin to increase, reflecting the reduction of low-{sup 14}C water upwelling in the east and the invasion of subtropical water into the western equatorial tropical Pacific. Maximum {Delta}{sup 14}C values are in phase or lag the corresponding sea surface temperature maxima in the eastern tropical Pacific, whereas the rapid return to more negative {Delta}{sup 14}C is in phase with eastern Pacific ENSO indices. The highest-amplitude excursions occur during the 1965/1966 and 1972/1973 events, when the {sup 14}C contrast is highest between the eastern Pacific and subtropics. The 1982/1983 El Ni{tilde n}o, although a larger ENSO event, has a lower {Delta}{sup 14}C amplitude, reflecting the penetration of bomb radiocarbon into the equatorial undercurrent and the reduced contrast in {Delta}{sup 14}C betweenmore » thermocline and subtropical surface waters at that time. This Coral Record demonstrates the potential for using similar radiocarbon time series for documenting variability in Pacific shallow circulation over interannual and decadal timescales. {copyright} 1998 American Geophysical Union« less
Chantal Alibert - One of the best experts on this subject based on the ideXlab platform.
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A 170‐year Sr/Ca and Ba/Ca Coral Record from the western Pacific warm pool: 2. A window into variability of the New Ireland Coastal Undercurrent
Journal of Geophysical Research, 2008Co-Authors: Chantal Alibert, Leslie KinsleyAbstract:[1] A Porites Coral from New Ireland (2.5°S, 150.5°E), at the heart of the Pacific warm pool, Records variations of Ba/Ca back to the early 1820s. The New Ireland Coastal Undercurrent, which flows along the north coast and transports high-nutrient thermocline waters, is thought to be the main source of the Ba enrichment observed in the Coral during El Nino. Between the 1850s and the 1960s, frequent large Ba peaks indicate that nutrients were available during both phases of El Nino–Southern Oscillation (ENSO). During La Nina, Ba could be advected along the South Equatorial Current. Also during this period, clusters of Ba/Ca peaks at nearly decadal timescale generally coincide with the return time of a strong El Nino, in accord with the high decadal variance of NINO3 sea surface temperatures. Ba enrichment in this Coral primarily reflects the stratification in the thermocline that controls vertical mixing. The Coral Records long-term changes in those properties affecting nutrients in surface waters, with reduced Ba after the 1960s, and even less between 1823 and 1850. These reductions are tentatively attributed to the high rate of warming at the end of the Dalton Minimum and since the mid-20th century. An ensuing weakening of the trade winds may have produced a more stratified equatorial thermocline, hindering the transport of Ba and nutrients from the undercurrent to the shallow coastal waters north of New Ireland.
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a 170 year sr ca and ba ca Coral Record from the western pacific warm pool 2 a window into variability of the new ireland coastal undercurrent
Journal of Geophysical Research, 2008Co-Authors: Chantal Alibert, Leslie KinsleyAbstract:[1] A Porites Coral from New Ireland (2.5°S, 150.5°E), at the heart of the Pacific warm pool, Records variations of Ba/Ca back to the early 1820s. The New Ireland Coastal Undercurrent, which flows along the north coast and transports high-nutrient thermocline waters, is thought to be the main source of the Ba enrichment observed in the Coral during El Nino. Between the 1850s and the 1960s, frequent large Ba peaks indicate that nutrients were available during both phases of El Nino–Southern Oscillation (ENSO). During La Nina, Ba could be advected along the South Equatorial Current. Also during this period, clusters of Ba/Ca peaks at nearly decadal timescale generally coincide with the return time of a strong El Nino, in accord with the high decadal variance of NINO3 sea surface temperatures. Ba enrichment in this Coral primarily reflects the stratification in the thermocline that controls vertical mixing. The Coral Records long-term changes in those properties affecting nutrients in surface waters, with reduced Ba after the 1960s, and even less between 1823 and 1850. These reductions are tentatively attributed to the high rate of warming at the end of the Dalton Minimum and since the mid-20th century. An ensuing weakening of the trade winds may have produced a more stratified equatorial thermocline, hindering the transport of Ba and nutrients from the undercurrent to the shallow coastal waters north of New Ireland.
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A 170‐year Sr/Ca and Ba/Ca Coral Record from the western Pacific warm pool: 1. What can we learn from an unusual Coral Record?
Journal of Geophysical Research, 2008Co-Authors: Chantal Alibert, Leslie KinsleyAbstract:[1] A long-lived Porites Coral from New Ireland (2.5°S, 150.5°E), Papua New Guinea, has been analyzed for Sr/Ca and Ba/Ca by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). The top 50 years of the core are examined here and compared with instrumental sea surface temperatures (SSTs). For the small range of SST in the warm pool, Sr/Ca shows an unusually large response. The best estimate for the slope of a temperature calibration is –0.23 ± 0.03 mmol/mol per°C. This strong slope is partly a result of the high-resolution sampling, but is also due to additional biological mediation of the Sr/Ca ratios, which appears to be associated with seasonal changes of calcification rate, and limits the prediction skills of this proxy thermometer. High-density bands synchronous with high Sr/Ca ratios suggest that calcification may be enhanced by beneficial small amounts of nutrients available during El Nino. Transient Ba enrichment, synchronous with colder than average SST, is also observed during El Nino and attributed to the shoaling of the New Ireland Coastal Undercurrent. The high level of enrichment, in particular during upwelling triggered by westerly wind bursts, suggests an origin from both dissolved seawater and marine biological barium.
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a 170 year sr ca and ba ca Coral Record from the western pacific warm pool 1 what can we learn from an unusual Coral Record
Journal of Geophysical Research, 2008Co-Authors: Chantal Alibert, Leslie KinsleyAbstract:[1] A long-lived Porites Coral from New Ireland (2.5°S, 150.5°E), Papua New Guinea, has been analyzed for Sr/Ca and Ba/Ca by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). The top 50 years of the core are examined here and compared with instrumental sea surface temperatures (SSTs). For the small range of SST in the warm pool, Sr/Ca shows an unusually large response. The best estimate for the slope of a temperature calibration is –0.23 ± 0.03 mmol/mol per°C. This strong slope is partly a result of the high-resolution sampling, but is also due to additional biological mediation of the Sr/Ca ratios, which appears to be associated with seasonal changes of calcification rate, and limits the prediction skills of this proxy thermometer. High-density bands synchronous with high Sr/Ca ratios suggest that calcification may be enhanced by beneficial small amounts of nutrients available during El Nino. Transient Ba enrichment, synchronous with colder than average SST, is also observed during El Nino and attributed to the shoaling of the New Ireland Coastal Undercurrent. The high level of enrichment, in particular during upwelling triggered by westerly wind bursts, suggests an origin from both dissolved seawater and marine biological barium.
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High-resolution Coral Records of rare earth elements in coastal seawater: biogeochemical cycling and a new environmental proxy
Geochimica et Cosmochimica Acta, 2004Co-Authors: Timothy Wyndham, Malcolm T. Mcculloch, Stewart Fallon, Chantal AlibertAbstract:In this study we have used laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), to produce a high resolution Coral Record of rare earth elements (REE), Mn and Ba from coastal Porites Corals from the Great Barrier Reef of Australia. Validation of the LA-ICP-MS technique indicated that the method provides accurate and reproducible (RSD = 13–18%) analysis of low concentration REE in Corals (∼1 to 100 ppb). The REE composition in Coral samples was found to closely reflect that of the surrounding seawater and distribution coefficients of ∼1–2 indicated minimal fractionation of the series during incorporation into Coral carbonate. To explore the idea that Coral Records of REE can be used to investigate dissolved seawater composition, we analyzed two coastal Corals representing a total of ∼30 yr of growth, including a 10-yr overlapping period. Comparable results were obtained from the two samples, particularly in terms of elemental ratios (Nd/Yb) and the Ce anomaly. Based on this evidence and results from the determination of distribution coefficients, we suggest that useful Records of seawater REE composition can be obtained from Coral carbonates. When compared to the REE composition of a mid shelf Coral, coastal Corals showed a significant terrestrial influence, characterized by higher REE concentrations (greater than 10 times) and light REE enrichment. The REE composition of coastal seawater inferred from the Coral Record was dependent on seasonal factors and the influence of flood waters. REE fractionation displayed a strong seasonal cycle that correlated closely with Mn concentration. We suggest that higher Nd/Yb ratios and higher Mn concentrations in summer result from scavenging of heavy REE by particulate organic ligands and Mn reductive dissolution respectively, both processes displaying higher rates during periods of high primary productivity. The Ce anomaly also displayed a strong seasonal cycle showing an enhanced anomaly during summer and during flood events. This is consistent with the Ce anomaly being primarily controlled by the abundance of Ce oxidizing bacteria. Based on these arguments, we suggest that the Coral Record of dissolved REE and Mn may be regarded as a useful proxy for biological activity in coastal seawater.
Jürgen Pätzold - One of the best experts on this subject based on the ideXlab platform.
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Distinct modes of East Asian Winter Monsoon documented by a southern Red Sea Coral Record
Journal of Geophysical Research: Oceans, 2014Co-Authors: Monica Ionita, Gerrit Lohmann, Norel Rimbu, Thomas Felis, Jürgen PätzoldAbstract:The large-scale boreal winter climatic patterns associated with interannual variability in a Coral oxygen isotope (δ18O) Record from the southern Red Sea covering most of the last century are investigated. From the early 1930s to the early 1960s, the winter Coral δ18O Record, reflecting temperature and salinity variations in southern Red Sea surface waters, is associated with global (or large scale) sea surface temperature (SST) and 850 mb geopotential height (Z850) anomalies which project on the corresponding patterns associated with the El Nino-Southern Oscillation (ENSO). In contrast, since the early 1960s the winter Coral δ18O Record is related to a Z850 pattern that reflects the ENSO-independent part of the East Asian Winter Monsoon (EAWM), which includes the Siberian High, the East Asian through, and the East Asian upper-tropospheric Jet. Our results indicate a weakening of the ENSO control on interannual temperature/salinity variations in southern Red Sea surface waters in the early 1960s, due to the warming of the Indian Ocean, and suggest that information about the nonstationarity in the relationship between ENSO and two distinct modes of EAWM can be documented in southern Red Sea Coral δ18O Records.
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nao signature in a bermuda Coral sr ca Record
Geochemistry Geophysics Geosystems, 2005Co-Authors: Henning Kuhnert, Traute Cruger, Jürgen PätzoldAbstract:[1] We present a 55-year-long Record (1928–1982) of Sr/Ca in a Bermuda Coral (Diploria strigosa), which we use to reconstruct local twentieth century climate features. The clearest climate signal emerges for the late-year Sr/Ca. Although the Coral was collected in shallow water (12 m), the correlation with station data is highest for temperatures at 50 m depth (r = −0.70), suggesting that local temperatures at the collection site are not representative for the sea surface temperatures in the adjacent open ocean. The most striking feature of the Coral Record is the persistent and significant correlation (r = −0.50) with the North Atlantic Oscillation (NAO) index. Field correlations of fall Sr/Ca with the winter sea level pressure (SLP) show the typical spatial NAO pattern. The stable relationship with the NAO shows that Sr/Ca in Bermuda Corals is a suitable tool for the reconstruction of North Atlantic climate variability.
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Detection of Climate Modes as Recorded in a Seasonal-resolution Coral Record Covering the Last 250 Years
The Climate in Historical Times, 2004Co-Authors: Norel Rimbu, Gerrit Lohmann, Thomas Felis, Jürgen PätzoldAbstract:The time series of oxygen isotopes (δ18O) from a northern Red Sea Coral is used to identify atmospheric circulation and sea surface temperature anomaly patterns related to interannual to decadal variability during different seasons of the year. We make use of seasonal resolution Coral data for the period 1751–1994 and various instrumental climate data sets. It is shown that during the winter season (January/February) the Coral δ18O variability at interannual time scales is related to a Northern Hemisphere atmospheric circulation mode similar to the Arctic Oscillation. Physically consistent large-scale sea surface temperature anomaly patterns are detected. In other seasons interannual Coral δ18O variability is related mainly to regional processes. The Arctic Oscillation appears to be the dominant atmospheric circulation pattern which controls decadal variability in this Coral Record during the winter season. We suggest that the δ18O signal of Corals from the northern Red Sea can be used to extract information on large-scale Northern Hemisphere atmospheric circulation regimes as well as regional processes associated with climate variability over Europe and the Middle East during the pre-instrumental period.
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Shift in ENSO Teleconnections Recorded by a Northern Red Sea Coral
Journal of Climate, 2003Co-Authors: Norel Rimbu, Gerrit Lohmann, Thomas Felis, Jürgen PätzoldAbstract:Abstract El Nino–Southern Oscillation (ENSO) teleconnections over Europe and the Middle East are evaluated using an oxygen isotope Coral time series from the northern Red Sea and various instrumental datasets. A shift in the correlation between the Nino-3 index and the Red Sea Coral Record in the 1970s is detected, and it is shown that this shift can be attributed to nonstationary circulation regimes and related ENSO teleconnections. It is found that positive anomalies of oxygen isotope in the Red Sea Coral Record from the middle 1930s to the late 1960s are associated with a strong Pacific–North Atlantic teleconnection accompanied by a weak Aleutian low, a more zonal flow at midlatitudes, and La Nina conditions in tropical Pacific. In contrast, positive anomalies of oxygen isotopes in the Red Sea Coral after the 1970s are related to El Nino conditions and weaker Pan-Pacific–Atlantic circulation regimes. Using the window correlation of the northern Red Sea Coral Record with two Coral Records from the tropi...
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Shift in ENSO teleconnections Recorded by a Red Sea Coral
2003Co-Authors: Norel Rimbu, Gerrit Lohmann, Thomas Felis, Jürgen PätzoldAbstract:El Nino-Southern Oscillation (ENSO) teleconnections over Europe and the Middle East are evaluated using an oxygen isotope Coral time series from the northern Red Sea and various instrumental data sets. We detect a shift in the correlation between the Nino3 index and the Red Sea Coral Record in 1970s and we show that this shift can be attributed to non-stationary circulation regimes and related ENSO teleconnections. We find that positive anomalies of oxygen isotope in the Red Sea Coral Record from mid-1930s to late 1960s are associated with a strong Pacific-North Atlantic teleconnection accompanied by a weak Aleutian Low, a more zonal flow at mid-latitudes, and La Nina conditions in tropical Pacific. In contrast, positive anomalous of oxygen isotopes in the Red Sea Coral after 1970s are related to El Nino conditions and weaker Pan-Pacific-Atlantic circulation regimes. Using the window correlation of the northern Red Sea Coral Record with two Coral Records from the tropical and subtropical Pacific, we find non-stationary relationships between the tropical Pacific and the European/Middle Eastern climate during the pre-instrumental period. Our results imply that the modulation of teleconnections at interdecadal time scales provides a limitation in the prediction and reconstruction of remote climate phenomena such as the ENSO impact over Europe.
Leslie Kinsley - One of the best experts on this subject based on the ideXlab platform.
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A 170‐year Sr/Ca and Ba/Ca Coral Record from the western Pacific warm pool: 2. A window into variability of the New Ireland Coastal Undercurrent
Journal of Geophysical Research, 2008Co-Authors: Chantal Alibert, Leslie KinsleyAbstract:[1] A Porites Coral from New Ireland (2.5°S, 150.5°E), at the heart of the Pacific warm pool, Records variations of Ba/Ca back to the early 1820s. The New Ireland Coastal Undercurrent, which flows along the north coast and transports high-nutrient thermocline waters, is thought to be the main source of the Ba enrichment observed in the Coral during El Nino. Between the 1850s and the 1960s, frequent large Ba peaks indicate that nutrients were available during both phases of El Nino–Southern Oscillation (ENSO). During La Nina, Ba could be advected along the South Equatorial Current. Also during this period, clusters of Ba/Ca peaks at nearly decadal timescale generally coincide with the return time of a strong El Nino, in accord with the high decadal variance of NINO3 sea surface temperatures. Ba enrichment in this Coral primarily reflects the stratification in the thermocline that controls vertical mixing. The Coral Records long-term changes in those properties affecting nutrients in surface waters, with reduced Ba after the 1960s, and even less between 1823 and 1850. These reductions are tentatively attributed to the high rate of warming at the end of the Dalton Minimum and since the mid-20th century. An ensuing weakening of the trade winds may have produced a more stratified equatorial thermocline, hindering the transport of Ba and nutrients from the undercurrent to the shallow coastal waters north of New Ireland.
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a 170 year sr ca and ba ca Coral Record from the western pacific warm pool 2 a window into variability of the new ireland coastal undercurrent
Journal of Geophysical Research, 2008Co-Authors: Chantal Alibert, Leslie KinsleyAbstract:[1] A Porites Coral from New Ireland (2.5°S, 150.5°E), at the heart of the Pacific warm pool, Records variations of Ba/Ca back to the early 1820s. The New Ireland Coastal Undercurrent, which flows along the north coast and transports high-nutrient thermocline waters, is thought to be the main source of the Ba enrichment observed in the Coral during El Nino. Between the 1850s and the 1960s, frequent large Ba peaks indicate that nutrients were available during both phases of El Nino–Southern Oscillation (ENSO). During La Nina, Ba could be advected along the South Equatorial Current. Also during this period, clusters of Ba/Ca peaks at nearly decadal timescale generally coincide with the return time of a strong El Nino, in accord with the high decadal variance of NINO3 sea surface temperatures. Ba enrichment in this Coral primarily reflects the stratification in the thermocline that controls vertical mixing. The Coral Records long-term changes in those properties affecting nutrients in surface waters, with reduced Ba after the 1960s, and even less between 1823 and 1850. These reductions are tentatively attributed to the high rate of warming at the end of the Dalton Minimum and since the mid-20th century. An ensuing weakening of the trade winds may have produced a more stratified equatorial thermocline, hindering the transport of Ba and nutrients from the undercurrent to the shallow coastal waters north of New Ireland.
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A 170‐year Sr/Ca and Ba/Ca Coral Record from the western Pacific warm pool: 1. What can we learn from an unusual Coral Record?
Journal of Geophysical Research, 2008Co-Authors: Chantal Alibert, Leslie KinsleyAbstract:[1] A long-lived Porites Coral from New Ireland (2.5°S, 150.5°E), Papua New Guinea, has been analyzed for Sr/Ca and Ba/Ca by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). The top 50 years of the core are examined here and compared with instrumental sea surface temperatures (SSTs). For the small range of SST in the warm pool, Sr/Ca shows an unusually large response. The best estimate for the slope of a temperature calibration is –0.23 ± 0.03 mmol/mol per°C. This strong slope is partly a result of the high-resolution sampling, but is also due to additional biological mediation of the Sr/Ca ratios, which appears to be associated with seasonal changes of calcification rate, and limits the prediction skills of this proxy thermometer. High-density bands synchronous with high Sr/Ca ratios suggest that calcification may be enhanced by beneficial small amounts of nutrients available during El Nino. Transient Ba enrichment, synchronous with colder than average SST, is also observed during El Nino and attributed to the shoaling of the New Ireland Coastal Undercurrent. The high level of enrichment, in particular during upwelling triggered by westerly wind bursts, suggests an origin from both dissolved seawater and marine biological barium.
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a 170 year sr ca and ba ca Coral Record from the western pacific warm pool 1 what can we learn from an unusual Coral Record
Journal of Geophysical Research, 2008Co-Authors: Chantal Alibert, Leslie KinsleyAbstract:[1] A long-lived Porites Coral from New Ireland (2.5°S, 150.5°E), Papua New Guinea, has been analyzed for Sr/Ca and Ba/Ca by laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). The top 50 years of the core are examined here and compared with instrumental sea surface temperatures (SSTs). For the small range of SST in the warm pool, Sr/Ca shows an unusually large response. The best estimate for the slope of a temperature calibration is –0.23 ± 0.03 mmol/mol per°C. This strong slope is partly a result of the high-resolution sampling, but is also due to additional biological mediation of the Sr/Ca ratios, which appears to be associated with seasonal changes of calcification rate, and limits the prediction skills of this proxy thermometer. High-density bands synchronous with high Sr/Ca ratios suggest that calcification may be enhanced by beneficial small amounts of nutrients available during El Nino. Transient Ba enrichment, synchronous with colder than average SST, is also observed during El Nino and attributed to the shoaling of the New Ireland Coastal Undercurrent. The high level of enrichment, in particular during upwelling triggered by westerly wind bursts, suggests an origin from both dissolved seawater and marine biological barium.