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  • 1
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    PANGAEA
    In:  Supplement to: Makou, Mathhew C; Oppo, Delia W; Curry, William B (2010): South Atlantic intermediate water mass geometry for the last glacial maximum from foraminiferal Cd/Ca. Paleoceanography, 25(4), PA4101, https://doi.org/10.1029/2010PA001962
    Publication Date: 2020-01-17
    Description: Paleoceanographic studies using benthic foraminiferal Cd as a nutrient tracer have provided a robust means of reconstructing glacial Atlantic Ocean water mass geometry, but a paucity of data from the South Atlantic above 1200 m has limited investigation of Antarctic Intermediate Water (AAIW) configuration and formation. A new Cd depth profile from Brazil margin sediments suggests that AAIW penetrated northward at 1100 m to at least 27°S in the glacial Atlantic. It exhibited substantially reduced d13Cas values, confirming preliminary evidence that this AAIW was unique to the glacial Atlantic and that it formed differently than today, with less atmospheric contact.
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 2
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    PANGAEA
    In:  Supplement to: Lynch-Stieglitz, Jean; Curry, William B; Slowey, Niall C (1999): A geostrophic transport estimate for the Florida Current from the oxygen isotope composition of benthic foraminifera. Paleoceanography, 14(3), 360-373, https://doi.org/10.1029/1999PA900001
    Publication Date: 2020-01-17
    Description: We present a new method for the quantitative reconstruction of upper ocean flows for during times in the past. For the warm (T〉5°C) surface ocean, density can be accurately reconstructed from calcite precipitated in equilibrium with seawater, as both of these properties increase with decreasing temperature and increasing salinity. Vertical density profiles can be reconstructed from the oxygen isotopic composition of benthic foraminifera. The net volume transport between two vertical density profiles can be calculated using the geostrophic method. Using benthic foraminifera from surface sediment samples from either side of the Florida Straits (Florida Keys and Little Bahama Bank), we reconstruct two vertical density profiles and calculate a volume transport of 32 Sv using this method. This agrees well with estimates from physical oceanographic methods of 30-32 Sv for the mean annual volume transport. We explore the sensitivity of this technique to various changes in the relationship between temperature and salinity as well as salinity and the oxygen isotopic composition of seawater.
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 3
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    PANGAEA
    In:  Supplement to: Lynch-Stieglitz, Jean; Schmidt, Matthew W; Curry, William B (2011): Evidence from the Florida Straits for Younger Dryas ocean circulation changes. Paleoceanography, 26(1), PA1205, https://doi.org/10.1029/2010PA002032
    Publication Date: 2020-01-17
    Description: The waters passing through the Florida Straits today reflect both the western portion of the wind-driven subtropical gyre and the northward flow of the upper waters which cross the equator, compensating North Atlantic Deep Water export as part of the large-scale Atlantic meridional overturning circulation. It has been postulated from various lines of evidence that the overturning circulation was weaker during the Younger Dryas cold event of the last deglaciation. We show here that the contrast in the oxygen isotopic composition of benthic foraminiferal tests across the Florida Current is reduced during the Younger Dryas. This most likely reflects a decrease in the density gradient across the channel and a decrease in the vertical shear of the Florida Current. This reduced shear is consistent with the postulated reduction in the Atlantic meridional overturning circulation. We find that the onset of this change in density structure and flow at the start of the Younger Dryas is very abrupt, occurring in less than 70 years.
    Type: Dataset
    Format: text/tab-separated-values, 350 data points
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  • 4
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    PANGAEA
    In:  Supplement to: Marchitto, Thomas M; Oppo, Delia W; Curry, William B (2002): Paired benthic foraminiferal Cd/Ca and Zn/Ca evidence for a greatly increased presence of Southern Ocean Water in the glacial North Atlantic. Paleoceanography, 17(3), 10-1-10-18, https://doi.org/10.1029/2000PA000598
    Publication Date: 2020-01-17
    Description: Benthic foraminiferal d13C and Cd/Ca studies suggest that deep Atlantic circulation during the Last Glacial Maximum was very different from today, with high-nutrient (low d13C, high Cd) deep Southern Ocean Water (SOW) penetrating far into the North Atlantic. However, if some glacial d13C values are biased by productivity artifacts and/or air-sea exchange processes, then the existing d13C data may be consistent with the continual dominance of North Atlantic Deep Water (NADW). Cibicidoides wuellerstorfi Cd/Ca results presented here indicate that the glacial North Atlantic was strongly enriched in dissolved Cd below ~2500 m depth. If NADW formation was still vigorous relative to SOW formation, these data could be explained by either increased preformed nutrient levels in the high-latitude North Atlantic or by increased organic matter remineralization within lower NADW. High glacial Zn/Ca values in the same samples, however, are best explained by a substantially increased mixing with Zn-rich SOW. The cause was most likely a partial replacement of NADW by less dense Glacial North Atlantic Intermediate Water. This reorganization also lowered deep North Atlantic [CO3]2- concentrations by perhaps 10 to 15 µmol/kg.
    Type: Dataset
    Format: text/tab-separated-values, 445 data points
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  • 5
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 499 data points
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  • 6
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    PANGAEA
    In:  Supplement to: Toomey, Michael R; Curry, William B; Donnelly, Jeffrey P; vam Hengstum, Peter J (2013): Reconstructing 7000 years of North Atlantic hurricane variability using deep-sea sediment cores from the western Great Bahama Bank. Paleoceanography, 28(1), 31-41, https://doi.org/10.1002/palo.20012
    Publication Date: 2020-01-17
    Description: Available overwash records from coastal barrier systems document significant variability in North Atlantic hurricane activity during the late Holocene. The same climate forcings that may have controlled cyclone activity over this interval (e.g., the West African Monsoon, El Niño-Southern Oscillation (ENSO)) show abrupt changes around 6000 yrs B.P., but most coastal sedimentary records do not span this time period. Establishing longer records is essential for understanding mid-Holocene patterns of storminess and their climatic drivers, which will lead to better forecasting of how climate change over the next century may affect tropical cyclone frequency and intensity. Storms are thought to be an important mechanism for transporting coarse sediment from shallow carbonate platforms to the deep-sea, and bank-edge sediments may offer an unexplored archive of long-term hurricane activity. Here, we develop this new approach, reconstructing more than 7000 years of North Atlantic hurricane variability using coarse-grained deposits in sediment cores from the leeward margin of the Great Bahama Bank. High energy event layers within the resulting archive are (1) broadly correlated throughout an offbank transect of multi-cores, (2) closely matched with historic hurricane events, and (3) synchronous with previous intervals of heightened North Atlantic hurricane activity in overwash reconstructions from Puerto Rico and elsewhere in the Bahamas. Lower storm frequency prior to 4400 yrs B.P. in our records suggests that precession and increased NH summer insolation may have greatly limited hurricane potential intensity, outweighing weakened ENSO and a stronger West African Monsoon-factors thought to be favorable for hurricane development.
    Type: Dataset
    Format: text/tab-separated-values, 112 data points
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  • 7
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    PANGAEA
    In:  Supplement to: Marchitto, Thomas M; Bryan, Sean P; Curry, William B; McCorkle, Daniel C (2007): Mg/Ca temperature calibration for the benthic foraminifer Cibicidoides pachyderma. Paleoceanography, 22(1), PA1203, https://doi.org/10.1029/2006PA001287
    Publication Date: 2020-01-17
    Description: The recent development of foraminiferal Mg/Ca as a paleotemperature proxy has enabled the extraction of global ice volume and local salinity from the more traditional paleotemperature proxy d18O. The benthic foraminiferal genus Cibicidoides is widely used in paleoceanographic reconstructions because of its epifaunal habitat and cosmopolitan distribution, and it has received early attention in Mg/Ca work. However, existing temperature calibrations for Cibicidoides rely heavily on C. pachyderma core top data from one location, Little Bahamas Bank, where authigenic processes and/or reworking may result in elevated warm water Mg/Ca values. Here we present new C. pachyderma Mg/Ca data from a series of 29 high-quality multicore tops collected in the Florida Straits, spanning a temperature range of 5.8-18.6°C. In contrast to previous calibrations, we find no evidence for a strongly exponential response to temperature. The data are best explained by a linear relationship, with a sensitivity of 0.12 mmol/mol per °C.
    Type: Dataset
    Format: text/tab-separated-values, 182 data points
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  • 8
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    PANGAEA
    In:  Supplement to: Lund, David C; Curry, William B (2006): Florida Current surface temperature and salinity variability during the last millennium. Paleoceanography, 21(2), PA2009, https://doi.org/10.1029/2005PA001218
    Publication Date: 2020-01-17
    Description: The salinity and temperature of the Florida Current are key parameters affecting the transport of heat into the North Atlantic, yet little is known about their variability on centennial timescales. Here we report replicated, high-resolution foraminiferal records of Florida Current surface hydrography for the last millennium from two coring sites, Dry Tortugas and the Great Bahama Bank. The oxygen isotopic composition of Florida Current surface water (d18Ow) near Dry Tortugas increased 0.4‰ during the course of the Little Ice Age (LIA) (~1200–1850 A.D.), equivalent to a salinity increase of 0.8–1.5. On the Great Bahama Bank, where surface waters are influenced by the North Atlantic subtropical gyre, d18Ow increased by 0.3‰ during the last 200 years. Although a portion (~0.1 per mil) of this shift may be an artifact of anthropogenically driven changes in surface water SumCO2, the remaining d18Ow signal implies a 0.4–1 increase in salinity after 200 years B.P. The simplest explanation of the d18Ow data is southward migration of the Atlantic Hadley circulation during the LIA. Scaling of the d18Ow records to salinity using the modern low-latitude d18Ow-S slope produces an unrealistic reversal in the salinity gradient between the two sites. Only if d18Ow is scaled to salinity using a high-latitude d18Ow-S slope can the records be reconciled. Variable atmospheric 14C paralleled Dry Tortugas d18Ow, suggesting that solar irradiance paced centennial-scale migration of the Inter-Tropical Convergence Zone and changes in Florida Current salinity during the last millennium.
    Type: Dataset
    Format: text/tab-separated-values, 48 data points
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  • 9
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    PANGAEA
    In:  Supplement to: Lynch-Stieglitz, Jean; Curry, William B; Lund, David C (2009): Florida Straits density structure and transport over the last 8000 years. Paleoceanography, 24(3), PA3209, https://doi.org/10.1029/2008PA001717
    Publication Date: 2020-01-17
    Description: The density structure across the Florida Straits is reconstructed for the last 8000 years from oxygen isotope measurements on foraminifera in sediment cores. The oxygen isotope measurements suggest that the density contrast across the Florida Current increased over this time period. The magnitude of this change corresponds to an increase in the geostrophic transport referenced to 800 m water depth of 4 sverdrups (Sv) over the last 8000 years. The spatial and seasonal distribution of incoming solar radiation due to changes in the Earth's orbit has caused systematic changes in the atmospheric circulation, including a southward migration of the Intertropical Convergence Zone over the last 8000 years. These changes in atmospheric circulation and the associated wind-driven currents of the upper ocean could readily account for a 4 Sv increase in the strength of the Florida Current. We see no evidence in our data for dramatic changes in the strength of the Atlantic Meridional Overturning Circulation over this time period.
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 10
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    PANGAEA
    In:  Supplement to: Came, Rosemarie E; Oppo, Delia W; Curry, William B (2003): Atlantic Ocean circulation during the Younger Dryas: Insights from a new Cd/Ca record from the western subtropical South Atlantic. Paleoceanography, 18(4), 1086, https://doi.org/10.1029/2003PA000888
    Publication Date: 2020-01-17
    Description: Benthic foraminiferal Cd/Ca from an intermediate depth, western South Atlantic core documents the history of southward penetration of North Atlantic Intermediate Water (NAIW). Cd seawater estimates (CdW) for the last glacial are consistent with the production of NAIW and its export into the South Atlantic. At ~14.5 ka concurrently with the onset of the Bølling-Allerød to Younger Dryas cooling, the NAIW contribution to the South Atlantic began to decrease, marking the transition from a glacial circulation pattern to a Younger Dryas circulation. High CdW in both the deep North Atlantic and the intermediate South Atlantic imply reduced export of deep and intermediate water during the Younger Dryas and a significant decrease in northward oceanic heat transport. A modern circulation was achieved at ~9 ka, concurrently with the establishment of Holocene warmth in the North Atlantic region, further supporting a close linkage between deepwater variability and North Atlantic climate.
    Type: Dataset
    Format: application/zip, 2 datasets
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