USF Libraries
USF Digital Collections

Extracting a climate signal from the skeletal geochemistry of the caribbean coral Siderastrea siderea

MISSING IMAGE

Material Information

Title:
Extracting a climate signal from the skeletal geochemistry of the caribbean coral Siderastrea siderea
Physical Description:
Book
Language:
English
Creator:
Maupin, Christopher Robert
Publisher:
University of South Florida
Place of Publication:
Tampa, Fla
Publication Date:

Subjects

Subjects / Keywords:
Coral geochemistry
Sr/Ca
Oxygen isotopes
Dry Tortugas
Paleoclimatology
Dissertations, Academic -- Marine Science -- Masters -- USF   ( lcsh )
Genre:
non-fiction   ( marcgt )

Notes

Abstract:
ABSTRACT: The first bimonthly resolved, paired δ¹⁸O and Sr/Ca time series from the slow-growing, tropical western Atlantic coral, Siderastrea siderea, from the Dry Tortugas, Florida has been generated and used to document that robust proxy climate records can be produced from this heretofore underutilized massive coral. The coral time series contains a 20-year long calibration window (1973-1992) for both δ¹⁸O and Sr/Ca and a 73-year long verification window (1900-1972) for Sr/Ca. These time series permits both the quantification of the relationship between coral δ18O-SST and Sr/Ca-SST using an augmented, 1ʻ x 1ʻ gridded SST record and the assessment of the stability of the proxy relationships over time. Both coral geochemical records are highly correlated with the augmented instrumental SST record through the calibration period and Sr/Ca remains highly correlated through the verification period both at the bimonthly (r = -0.97) and annual average level (r = -0.72). Additionally, both coral δ¹⁸O and Sr/Ca are highly reproducible within the same core, and Sr/Ca exhibits no extension-related vital effects. Sr/Ca-SST anomalies are also significantly correlated to the augmented SST anomalies, despite the removal of the serial autocorrelation. The skill of this proxy demonstrates its potential as a continuously growing, long-lived recorder of climate variability for the tropical Atlantic and Intra-American Seas. The relatively slow extension rate of the coral (~5 mm yr-1 during the 20th century) also suggests the potential for long records of climate variability (~200 years) of the region to be extracted from even modest-sized colonies (~1 m in height). The results of this study are important because relatively few century-long, sub-annually resolved time series of climate variability from massive Atlantic corals have been published, despite the significance of the tropical Atlantic climate modes of variability.
Thesis:
Thesis (M.S.)--University of South Florida, 2008.
Bibliography:
Includes bibliographical references.
System Details:
Mode of access: World Wide Web.
System Details:
System requirements: World Wide Web browser and PDF reader.
Statement of Responsibility:
by Christopher Robert Maupin.
General Note:
Title from PDF of title page.
General Note:
Document formatted into pages; contains 60 pages.

Record Information

Source Institution:
University of South Florida Library
Holding Location:
University of South Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 001994150
oclc - 317403753
usfldc doi - E14-SFE0002433
usfldc handle - e14.2433
System ID:
SFS0026750:00001


This item is only available as the following downloads:


Full Text
xml version 1.0 encoding UTF-8 standalone no
record xmlns http:www.loc.govMARC21slim xmlns:xsi http:www.w3.org2001XMLSchema-instance xsi:schemaLocation http:www.loc.govstandardsmarcxmlschemaMARC21slim.xsd
leader nam 2200397Ka 4500
controlfield tag 001 001994150
005 20090330125647.0
007 cr mnu|||uuuuu
008 090330s2008 flu s 000 0 eng d
datafield ind1 8 ind2 024
subfield code a E14-SFE0002433
035
(OCoLC)317403753
040
FHM
c FHM
049
FHMM
066
(S
090
GC11.2 (Online)
1 100
Maupin, Christopher Robert.
0 245
Extracting a climate signal from the skeletal geochemistry of the caribbean coral Siderastrea siderea
h [electronic resource] /
by Christopher Robert Maupin.
260
[Tampa, Fla] :
b University of South Florida,
2008.
500
Title from PDF of title page.
Document formatted into pages; contains 60 pages.
502
Thesis (M.S.)--University of South Florida, 2008.
504
Includes bibliographical references.
516
Text (Electronic thesis) in PDF format.
538
Mode of access: World Wide Web.
System requirements: World Wide Web browser and PDF reader.
590
Advisor: David Hollander, Ph.D.
3 520
ABSTRACT: The first bimonthly resolved, paired O and Sr/Ca time series from the slow-growing, tropical western Atlantic coral, Siderastrea siderea, from the Dry Tortugas, Florida has been generated and used to document that robust proxy climate records can be produced from this heretofore underutilized massive coral. The coral time series contains a 20-year long calibration window (1973-1992) for both O and Sr/Ca and a 73-year long verification window (1900-1972) for Sr/Ca. These time series permits both the quantification of the relationship between coral 18O-SST and Sr/Ca-SST using an augmented, 1 x 1 gridded SST record and the assessment of the stability of the proxy relationships over time. Both coral geochemical records are highly correlated with the augmented instrumental SST record through the calibration period and Sr/Ca remains highly correlated through the verification period both at the bimonthly (r = -0.97) and annual average level (r = -0.72). Additionally, both coral O and Sr/Ca are highly reproducible within the same core, and Sr/Ca exhibits no extension-related vital effects. Sr/Ca-SST anomalies are also significantly correlated to the augmented SST anomalies, despite the removal of the serial autocorrelation. The skill of this proxy demonstrates its potential as a continuously growing, long-lived recorder of climate variability for the tropical Atlantic and Intra-American Seas. The relatively slow extension rate of the coral (~5 mm yr-1 during the 20th century) also suggests the potential for long records of climate variability (~200 years) of the region to be extracted from even modest-sized colonies (~1 m in height). The results of this study are important because relatively few century-long, sub-annually resolved time series of climate variability from massive Atlantic corals have been published, despite the significance of the tropical Atlantic climate modes of variability.
653
Coral geochemistry
Sr/Ca
Oxygen isotopes
Dry Tortugas
Paleoclimatology
690
Dissertations, Academic
z USF
x Marine Science
Masters.
773
t USF Electronic Theses and Dissertations.
4 856
u http://digital.lib.usf.edu/?e14.2433



PAGE 1

Extracting a Climate Signal from the Skeletal Geochemistry of the Caribbean Coral Siderastrea siderea by Christopher Robert Maupin A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science College of Marine Science University of South Florida Major Professor: David H. Hollander, Ph.D. Terrence M. Quinn, Ph.D. Eugene A. Shinn, Ph.D. Al Hine, Ph.D. Date of Approval February 24, 2008 Keywords: coral geochemistry, Sr/Ca, oxygen isotopes, Dry Tortugas, paleoclimatology, paleoceanography Copyright 2008, Chris Maupin

PAGE 2

i Table of Contents List of Figures.iii Abstract....v Introduction..1 Background and Methods Climate Setting.....5 Western Hemisphere Warm Pool. Atlantic Warm Pool......... Gulf of Mexico.... Dry Tortugas........7 Coral Sampling....8 Elemental and Isotopic Analyses. Data Analysis.10 Results Sampling Resolution and Reproducibility Skeletal Sr/Ca Geochemistry and Extension Rate.12 Calibration of Geochemistry with SST......13 Verification of Proxy Skill.....15 Discussion..16 Vital Effects....

PAGE 3

ii Removal of SST Annual Cycle......16 Capture of Regional Climate Variability........17 Conclusions Literature Cited..33 Appendices Appendix 1: Calculation of 18 O sw and 18 O sw anomalies..39 Appendix 2: Carbon Isotopic Variations...43 Appendix 3: Bimonthly Calibration Interval Data ..... Appendix 4: Bimonthly Verification Interval Data...51

PAGE 4

iii List of Figures Figure 1: Monthly SST variations from the 1 x 1 HadISST1 gridded product and in situ DRYF1 data sets (SEAKEYS/CMAN) plotted with the augmented data set generated from the relationship between the HadISST1 and in situ records Figure 2: Plot of sea-surface temperature and sea-surface salinity variations retrieved in the Dry Tortugas by the SEAKEYS/CMAN program.20 Figure 3: X-radiographs of the top two slabs of the 93DRYSS-1 core.....21 Figure 4: Age-modeled, bimonthly interpolated geochemical variations from 19731992 Figure 5: Effect of increasing sampling resolution from 0.75 mm sample -1 (ca. 6 samples yr -1 ) to 0.25 mm sample -1 (ca. 18 samples yr -1 ) on the amplitude of the coral Sr/Ca signal over 3 annual cycles Figure 6: Values of Sr/Ca and 18 O from two parallel paths, sampled ~2 cm apart on a slab of the 93DRYSS-1 core..25 Figure 7: Calibration interval (a) Sr/Ca plotted with 18 O and (b) with bimonthlyaveraged augmented SST... Figure 8: Calibrationand verification-interval time series of: bimonthly-averaged augmented SST data, age modeled, bimonthly-interpolated Sr/Ca variations, annual extension rate for the 93DRYSS1 coral along drilling transects....... Figure 9: Annual average augmented SST plotted with annual average Sr/Ca-SST

PAGE 5

iv estimations.28 Figure 10: Running correlations between annual average Sr/Ca and annual average extension rate values along sampling transects.29 Figure 11: Plot of time series of both bimonthly augmented SST data and age-modeled, bimonthly-interpolated Sr/Ca-SST anomalies, compared to highlight common variance despite removal of annual cycle serial correlation..30 Figure 12: Plot of annually averaged 20 th century GOM and Sr/Ca-based Dry Tortugas SST data sets..31

PAGE 6

v Abstract The first bimonthly resolved, paired 18 O and Sr/Ca time series from the slowgrowing, tropical western Atlantic coral, Siderastrea siderea from the Dry Tortugas, Florida has been generated and used to document that robust proxy climate records can be produced from this heretofore underutilized massive coral. The coral time series contains a 20-year long calibration window (1973-1992) for both 18 O and Sr/Ca and a 73-year long verification window (1900-1972) for Sr/Ca. These time series permits both the quantification of the relationship between coral 18 O-SST and Sr/Ca-SST using an augmented, 1 x 1 gridded SST record and the assessment of the stability of the proxy relationships over time. Both coral geochemical records are highly correlated with the augmented instrumental SST record through the calibration period and Sr/Ca remains highly correlated through the verification period both at the bimonthly ( r = -0.97) and annual average level ( r = -0.72). Additionally, both coral 18 O and Sr/Ca are highly reproducible within the same core, and Sr/Ca exhibits no extension-related vital effects. Sr/Ca-SST anomalies are also significantly correlated to the augmented SST anomalies, despite the removal of the serial autocorrelation. The skill of this proxy demonstrates its potential as a continuously growing, long-lived recorder of climate variability for the tropical Atlantic and Intra-American Seas. The relatively slow extension rate of the coral (~5 mm yr -1 during the 20th century) also suggests the potential for long records of climate variability (~200 years) of the region to be extracted from even modest-sized

PAGE 7

vi colonies (~1 m in height). The results of this study are important because relatively few century-long, sub-annually resolved time series of climate variability from massive Atlantic corals have been published, despite the significance of the tropical Atlantic climate modes of variability.

PAGE 8

1 1. Introduction In recent years, coral-based Sr/Caand 18 O-derived records of climate variability from the tropical Pacific have become numerous and spatially extensive (see recent summary of Correge 2006). Such records have considerably furthered understanding of the El Nio-Southern Oscillation (ENSO) in the tropical Pacific, and have also expanded the possibilities of using corals as climate archives [ Gagan, et al. 1998; Gagan, et al. 2004; Kilbourne, et al. 2004a; Kilbourne, et al. 2004b]. In particular, the validity of Sr/Ca as a paleotemperature tracer in the commonly used proxy genus of the region, Porites has been tested and verified with statistical rigor [ Lough 2004; Quinn and Sampson 2002; Stephans, et al. 2004]. However, a comparably robust proxy species of coral is needed to generate continuous, multi-century records of climate variability in the tropical North Atlantic, Caribbean and Gulf of Mexico regions, where there are currently no continuous, subannually-resolved records of sea surface conditions [ Hetzinger, et al. 2006]. Such records are needed to extend instrumental records and allow further interpretation of important modes of climate variability, such as Western Hemisphere Warm Pool variability, ENSO teleconnections, and the so-called Atlantic Multidecadal Oscillation [ Delworth and Mann 2000; Gray, et al. 2004; Kerr 2005; Knight, et al. 2006; Mann 2001; Wang 2006b; Wang and Enfield 2001b, 2003b; Wang, et al. 2006b] The massive Atlantic coral species Montastraea spp. has been previously singled out and investigated for their ability to act as a proxy species for generation of Sr/Caand 18 O-based records of tropical Atlantic and Caribbean climate, as they are continuously growing, long-lived, widely distributed throughout the region and exhibit clear annual density banding for external chronological control [ Leder, et al. 1996; Smith, et al.

PAGE 9

2 2006; Swart, et al. 1996]. However, multiple studies have concluded that there may be additional forcing unrelated to SST which affect the skeletal Sr/Ca of Montastraea and whose origins continue to remain unclear [ Smith, et al. 2006; Swart, et al. 2002]. Smith et al. [2006] demonstrated that there may be up to ~0.25 mmol/mol difference between the Sr/Ca of a thecal wall and adjacent exothecal dissepiments in M. faveolata from the Florida Keys. This variability is not only greater than the range of the reported instrumental error ( 0.016 mmol/mol), but a Sr/Ca of 0.25 mmol/mol corresponds to a SST of ~ 9C, using the Sr/Ca-SST relationship produced for the same coral by Smith et al [2006]. This ~9C SST is ~30% greater than the amplitude of the entire seasonal SST cycle at Looe Key (6.9 C) averaged over the period of 1961 2002 [ Smith, et al. 2006] The primary sampling strategy employed thus far to avoid any signal contamination from heterogeneous or time-transgressive skeletal elements in Montastraea has been to exclusively targeting the thecal wall of the corallite [ Leder, et al. 1996; Smith, et al. 2006; Swart, et al. 2002], although workers have admitted that such inclusions may be impossible to avoid using millimeter-scale sampling [ Smith, et al. 2006; Swart, et al. 2002] Recent work done by Cohen and Thorrold [2007] on a slow growing (<5 mm yr -1 ) colony of Montastraea franksii utilized laser ablation inductively coupled plasma mass spectrometry to discretely sample nighttime-deposited centers of calcification (COCs) at a temporal resolution of ~5 days sample -1 The resulting data, along with coeval data from colonies of Diploria labyrinthiformis, yielded a reproducible equation relating Sr/Ca to SST with a slope ~3 times as large as those previously published for these same species [ Cohen and Thorrold 2007] This increase in slope was attributed to the

PAGE 10

3 avoidance of measuring Sr/Ca ratios in daytime calcification or thickening deposits of ambiguous age and temperature sensitivity. While such a study is commendable for progress in understanding temperature dependence of Sr/Ca in COCs, the tremendous number of analyses that would be required to generate continuous multi-centennial climate records of interest makes the method impractical as a sampling strategy for reconstructing modes of climate variability. A 5day sampling interval represents a >508% increase in the number of analyses required per year from the commonplace monthly resolution of mm-scale sampling, and a 200 year time series would require a minimum of 14.6 x 10 3 individual analyses. Such a strategy also fails to address the critical need of many paleoclimate workers to reconstruct sea surface conditions through the paired analysis of 18 O and Sr/Ca from powdered, homogenized sample material. The challenge of extracting multi-centennial climate records from massive Atlantic corals using mm-scale sampling techniques is approached here by investigating a new potential proxy species of coral, Siderastrea siderea The coral S. siderea is a massive slow-growing (< 1 cm yr -1 ) species commonly found in shallow Caribbean, tropical West Atlantic and Gulf of Mexico waters. Colonies are often > 1 m across and exhibit cerioid corallites 3-4.5 mm in diameter with thickened septo-costae forming poorly-defined, dense corallite walls [ Veron 2000] This species remains largely unexplored with regard to its ability to yield climate records through trace element and isotopic variations. No previous work has been published examining skeletal Sr/Ca variations and their potential relationship to temperature. Studies of stable isotopic variations within the skeleton have concluded that

PAGE 11

4 the species may have use as paleo-environmental recorder [ Gischler and Oschmann 2005; Guzman and Tudhope 1998]. Guzman and Tudhope [1998] examined isotopic variations in the skeletons of multiple colonies of S. siderea from Panama over a 14 month period and found significant inter-colony differences in mean 18 O over the study period, indicating that care must be taken if using multiple colonies to generate a continuous 18 O record or when comparing modern and fossil coral 18 O values. Gischler and Oschmann [2005] presented a continuous 18 O record from S. siderea from near the southern Belize coast spanning 1870-1999 with a maximum sampling resolution of 8 samples yr -1 The authors concluded that the 18 O record exhibits significant correlations with the SST as extracted from the GISST 2.3b gridded SST product (Rayner et al., 1996), but may also be significantly influenced by rainfall and riverine discharge. Here we attempt to develop a new high-resolution climate archive for the tropical West Atlantic and Intra-American Seas by demonstrating that reproducible, bimonthlyresolved Sr/Ca and 18 O measurements in S. siderea are capable of robust reconstruction of SST variability within a 20-year calibration window, and extending the Sr/Ca time series to include a 73-year verification interval of SST reconstruction.

PAGE 12

5 2. Background and Methods 2.1. Climate Setting 2.1.1. Western Hemisphere Warm Pool The Western Hemisphere Warm Pool (WHWP) is defined as the region of surface water spanning the tropical North Atlantic (TNA), Caribbean Sea, Gulf of Mexico (GOM), and Eastern North Pacific (ENP) bounded by the 28.5 C isotherm [ Wang and Enfield 2001a]. This pool of water undergoes a strong annual cycle in spatial extent, disappearing completely during the boreal winter, and first occurring in the ENP during the boreal spring, spreading through the Gulf of Mexico and Caribbean Sea during the boreal summer, and reaching eastward into the TNA during its peak in the late boreal summer and early fall [ Wang and Enfield 2001a]. Interannual variability is significant in both the extent and intensity of the warm pool evolution. Wang and Enfield [2001] defined a WHWP intensity index as the average SST within the region from 7 N N and 110 W-150 W. Additionally, the WHWP intensity index is well correlated with the size of the warm pool, allowing reconstructions of one to make inferences regarding the other [ Wang and Enfield 2001a]. Potential forcing and feedbacks involving the WHWP are only beginning to be understood in detail [ Wang 2006a; Wang and Enfield 2001a, 2003a; Wang, et al. 2006a]. It has been recognized as the primary oceanic heating source driving Western Hemisphere Walker, and therefore Hadley cell, circulation, particularly during the boreal spring following an ENSO-warm phase winter, whereby an anomalously large and intense warm pool may develop as tropospheric circulation bridges ENSO warm event SST anomalies with the WHWP [ Wang and Enfield 2003a]. The hypothesized

PAGE 13

6 mechanism that maintains the anomalously intense warm pool into the summer is one of ocean-atmosphere feedback, where increased cloudiness from warm SST-based convection limits the escape of long-wave radiation from the sea surface [ Wang and Enfield 2003a]. It is also likely that abnormally large and warm WHWP events can intensify South Pacific subtropical Hadley cell circulation, acting to return more neutral or normal phase ENSO conditions [ Wang and Enfield 2003a]. However, not all ENSO warm events in the instrumental records were followed by anomalously warm or large WHWP events, and further studies, and perhaps climate reconstructions to augment the instrumental record, are necessary to understand why [ Wang and Enfield 2003a]. 2.1.2. Atlantic Warm Pool The Atlantic Warm Pool (AWP) is the part of the WHWP consisting of the GOM, Caribbean Sea and the western tropical North Atlantic [ Wang, et al. 2006b]. The AWP, like the WHWP as a whole, undergoes a large seasonal cycle with considerable interannual variability in both size and warming intensity [ Wang, et al. 2006b]. Wang et al. [2006b] found that this interannual variability has far-reaching climate effects, influencing rainfall amounts in the central and eastern United States, southwestern US Monsoon region and tropic Western Hemisphere, and regulating tropospheric windshear in the Atlantic hurricane main development region (MDR). New model data coupled with instrumental observation has suggested that these effects are controlled by the size and strength of the AWP warming; an anomalously large AWP corresponds to a weakened North Atlantic subtropical high (NASH) and anomalous westerly sea level pressure (SLP) gradients, thereby reducing the strength of low level jets supplying moisture to the central United States, as well as reducing tropospheric vertical wind shear

PAGE 14

7 in the Atlantic Basin hurricane MDR, making conditions more favorable for summer cyclogenesis [ Wang and Lee 2007; Wang, et al. 2008]. 2.1.3. Gulf of Mexico The GOM makes up a large component of the Intra-American Seas (IAS) and the WHWP/AWP and is a major contributor to the moisture budget for the central and eastern United States. The IAS is the source of more than one third of the moisture transported into the contiguous United States during summer months [ Mestas-Nunez, et al. 2005]. The mechanism for this seasonal transport consists of evaporation and transport by easterly trade wind, and, ultimately, low-level jets that move across the IAS and onto the continental United States. The Great Plains low-level jet (GPLLJ) supplies summertime moisture to the central United States East of the Rocky Mountains through northward flow from the GOM and into the Great Plains region, while the Caribbean low level jet (CLLJ) provides moisture to the broader eastern GOM region [ Mestas-Nunez and Enfield 2007; Mestas-Nunez, et al. 2005]. 2.2. Dry Tortugas The Dry Tortugas are a series of modern and relict coral reef and sand shoal features adjacent to the southwest Florida continental margin and the Straits of Florida [ Mallinson, et al. 2003]. Hydrographic features are dominated by the Florida Current and the local formation and persistence of large (100-200 km in diameter) cyclonic eddies that control surface circulation in the Dry Tortugas region [ Fratantoni, et al. 1998]. The quasi-stationary, closed-circulation cold-core eddies may remain stationary in the region for up to 100 days before being interrupted by cold-core frontal perturbations

PAGE 15

8 in the Loop Current, which migrate southward along the Loop Current edge adjacent to the West Florida Shelf [ Fratantoni, et al. 1998] Sea surface temperature (SST) data used for the calibration and verification intervals of the Sr/Ca record were extracted from the HADISST1 gridded data set at the 1 x 1 grid box of 24-25N and 82-83W [ Rayner, et al. 2003]. These data were corrected using an ordinary least squares (OLS) regression relationship between the HadISST1 gridded data product and a local SEAKEYS/C-MAN station (DRYF1) time series of SST from the Dry Tortugas National Park with a short, incomplete temporal (1992-2003) window [ Smith, et al. 2006] The corrected data are hereafter referred to as an augmented instrumental data set (Figure 1). Mean annual SST from the DRYF1 time series for 1995 and 1998-2001 was 26.07 C ( 0.38 C, 1 # ) with an average annual cycle of 9.04 C ( 1.10 C, 1 # ). The warmest and coolest annual temperatures occur during August and February, respectively. Sea surface salinity (SSS) data available from the SEAKEYS program for the Dry Tortugas from 1993-2000 reveal a mean SSS of 35.6 ( 1.42, 1 # ), with more saline values tending to occur during boreal spring and summer months, and fresher values occurring during boreal fall and winter (Figure 2). 2.3. Coral Sampling A colony of S. siderea >1 m in height, growing in the Dry Tortugas, immediately southeast of Long Key (~24N, 82W), was cored along the axis of maximum growth in the summer of 1993. This core, hereafter referred to as 93DRYSS1, was cut lengthwise into 0.5 cm-thick slabs and x-radiographed (Figure 3). The coral slabs were mounted to a computer-aided triaxial sampling platform and samples for paired elemental and isotopic analyses were milled out of the coral thecal wall using a 1.4

PAGE 16

9 mm dental drill bit along continuous paths. Corallite walls most parallel to the lengthwise axis of the slabs were thought to promote the least time-transgressive sampling paths and were selected for sampling. One sample was drilled every 0.75 mm of linear skeletal extension, corresponding to approximately 6-8 samples per year of skeletal extension as estimated by the existence of annual cycles in the resulting geochemical data. The width and depth of the sample transects were 2 mm and ~1.5 mm, respectively. An additional sampling path, 4.575 cm in length, was drilled at an arbitrary location down-core parallel to the initial path in order to assess geochemical reproducibility within the core. A second additional sampling path near the core top was drilled at an interval of 0.25 mm of extension per sample in order to assess the effect of multiple sampling resolutions on the geochemical signal. 2.4. Elemental and Isotopic Analyses Analyses of Sr/Ca were performed by dissolving ~100-300 g of drilled coral powder in a volume of 2% HNO 3 appropriate to dilute the Ca concentration of the sample to ~20 ppm. Measurements of sample Sr/Ca ratios were made using a Perkin-Elmer 4300 Dual View Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) housed at the Paleoceanography, Paleoclimatology and Biogeochemistry (PPB) Laboratory of the University of South Florida College of Marine Science. The Sr/Ca of a gravimetrically prepared standard solution (IGS) was measured between each dissolved coral sample in order to correct sample Sr/Ca for instrumental drift and noise [ Schrag 1999]. The average corrected precision of the IGS standard was 0.015 mmol/mol, based on batches of 7 consecutive measurements ( 1 # n = 278 corrected values ) performed at

PAGE 17

10 the beginning and end of each 50 samples measured per instrument run containing 93DRYSS samples. A second standard consisting of homogenized powder from a Porites lutea coral dissolved in 2% HNO 3 was analyzed for Sr/Ca between every fifth sample analyzed. The average precision of this second standard within instrument runs containing 93DRYSS-1 samples was 0.015 mmol/mol (1 # n = 277). Stable isotopic analyses of oxygen and carbon were performed by dissolution of powdered samples in phosphoric acid at 70 C in a Kiel III automated carbonate preparation device connected to a ThermoFinnigan Delta PlusXL gas-source dual-inlet stable isotope ratio monitoring mass spectrometer, also housed at the PPB Laboratory. All resulting isotope values are reported in delta notation relative to the VPDB isotopic standard. Analyses of the isotopic standard NBS-19 were measured within sample runs to monitor instrumental precision at a ratio of 3 standard to 20 sample measurements. The resulting average precision of this standard was 0.06 for 18 O and 0.03 for 13 C (1 # n = 20 measurements of NBS-19). 2.5. Data Analysis The x-radiographs of the coral slabs show none of the clear annual density band couplets that are often observed in other species of coral [ Alibert and McCulloch 1997; Cohen, et al. 2004; Smith, et al. 2006] Hence, geochemical variations with depth were converted to variations in time by maximizing agreement between the Sr/Ca (inverted) and augmented SST data sets, both of which exhibit clear annual cycles, using the Analyseries program [ Paillard, et al. 1996] Age-modeled data were then evenly sampled at bimonthly resolution, resulting in a bimonthly-resolved coral 18 O and 13 C time-series spanning 1973 through 1992 (Figure 4) and a Sr/Ca time-series spanning

PAGE 18

11 1900-1992. The origin of 13 C variations in coral skeletons is ambiguous [e.g., [ Swart, et al. 1996; Swart, et al. 2005] and will not be discussed further. The remaining two geochemical time series were directly compared to the augmented SST data, which were averaged from monthly to bimonthly to match the coral data. Extension rates were calculated at a maximum resolution of 0.75 mm (sampling resolution) based on the age model prior to interpolation into an even time step. The first 20 years (1973-1992) of the coral Sr/Ca and 18 O time series were regressed against the bimonthly augmented SST data set in order to yield equations relating Sr/Ca and 18 O to SST. The resulting Sr/Ca equation was used to predict bimonthly and mean annual SST from the geochemical time series, allowing assessment of the skill of the Sr/Ca thermometer in this coral over a 73-year verification window. Given the time-averaging sampling method employed here (continuous routing of 1 sample representing 2 months of time at constant extension rate), which likely results in a minimum estimate of the Sr/Ca-SST slope. The veracity of this statement is tested in the next section by the results of the sampling resolution experiment.

PAGE 19

12 3. Results 3.1 Sampling Resolution and Reproducibility The effect of increasing sampling resolution from 0.75 mm sample -1 (ca. 6 samples yr -1 ) to 0.25 mm sample -1 (ca. 18 samples yr -1 ) on the amplitude of the geochemical signal recovered over 3 annual cycles is negligible (Figure 5). The mean amplitude of Sr/Ca values over the 3 years sampled is 0.303 mmol/mol at 0.75 mm sample -1 and 0.332 mmol/mol at 0.25 mm sample -1 values that agree within 2 # of instrumental precision for Sr/Ca measurements. The geochemistry of contemporaneous drill paths reveals a high level of reproducibility between respective variables (Figure 6). The mean Sr/Ca values for the two parallel paths are 9.008 0.003 ( # ) and 8.992 0.003 ( # ) mmol/mol, and the mean 18 O values are .24 0.01 ( # ) and .25 0.01 ( # ) The average absolute difference between the geochemical values in the parallel paths, 0.027 mmol/mol for Sr/Ca and 0.11 for 18 O, are within 2 # of the analytical precision for either variable (Sr/Ca: 0.030 mmol/mol, 18 O: 0.12 ). 3.2 Skeletal Sr/Ca Geochemistry and Extension Rate The average annual amplitude and overall mean Sr/Ca values for the entire 93year time series are 0.2664 0.046 (1 # ) mmol/mol and 8.999 0.103 (1 # ) mmol/mol respectively. The record exhibits a long-term trend manifested as a 0.032 mmol/mol decrease in Sr/Ca from 1900-1993. The average annual extension rate, estimated from skeletal geochemistry, is 4.94 0.73 (1 # ) mm yr -1 over the entire time series. The lowest and highest observed annual extension rates were 3 mm yr -1 and 6 mm yr -1 respectively.

PAGE 20

13 3.3 Calibration of geochemistry with SST The maximum likelihood estimator regression equations were developed for the relationships between bimonthly Sr/Ca-SST and 18 O-SST (Figure 7) for the calibration period from 1973-1992 and are given below: Sr/Ca = 10.008 (.13) 0.039 (.005)*[SST]; r = -0.96, n = 120 (1) 18 O = 0.247 (.47) 0.138 (.018)*[SST]; r = -0.92, n = 120 (2) The slope for the Sr/Ca equation is within the span of published slopes for Montastraea spp. from the Florida Keys, which range from .023 to .047 mmol/mol C -1 [ Smith, et al. 2006; Swart, et al. 2002] and another slow growing coral, Diploria labyrinthiformis from Bermuda, which range from .0359 to .0436 mmol/mol C -1 for multiple colonies [ Goodkin, et al. 2007]. The slope reported here is lower than the slopes found for a single Diploria strigosa colony from Guadalupe, which range from .041 to .042 mmol/mol C -1 [ Hetzinger, et al. 2006]. Slopes for published equations relating 18 O to SST for Montastraea spp. from the Florida Keys range from .085 to .22 C -1 [ Leder, et al. 1996; Smith, et al. 2006], and range from .184 to .196 C -1 for D. strigosa from Guadalupe [ Hetzinger, et al. 2006] and the slope of .138 C -1 found here is comparatively and significantly lower. Results of Leder et al. [1996] suggest that sampling rates of less than 50 samples yr -1 may be responsible for the relatively lower than predicted 18 O-SST slope, as is found here. However, the sampling resolution experimental results of this study, suggest that little change in the geochemical signal range results from sample resolution changes from 6 to 18 samples/year.

PAGE 21

14 The influences of seasonal changes in local 18 O sw such as from increased summertime evaporation (increased 18 O sw ) and a decrease in evaporation minus precipitation (E-P) and precipitation from frontal boundaries during winter (decreased 18 O sw ), may serve to reduce the observed slope by dampening the annual cycle of SSTdriven 18 O as recorded by the coral ( 18 O aragonite ), as coral 18 O is a function of both temperature and the 18 O sw composition of seawater [ Correge 2006] This hypothesis is supported by the short, in situ time series of salinity data from the short Dry Tortugas, which tends to show more saline (enriched 18 O sw ) values during warmer months and freshening (depleted 18 O sw ) values during cooler months, an annual cycle that would oppose the SST-driven annual cycle of 18 O aragonite The average absolute difference between bimonthly-interpolated augmented SST and Sr/Ca-estimated SST data during the calibration interval is 0.65 0.55 (1 # ) C, whereas the average absolute difference between bimonthly-interpolated augmented SST and 18 O-estimated SST data is 0.97 0.75 (1 # ) C. A further confirmation of the robustness of the proxies is agreement they share with each other (Figure 7b). The 18 O thermometer in coral-derived carbonates is a widely accepted and utilized, thermodynamically constrained proxy for the temperature of aragonite growth [ Correge 2006; Leder, et al. 1996] and the large annual cycle in SST would be expected to drive a large annual cycle in coral 18 O, barring large, rapid, local changes in 18 O sw which would thoroughly obfuscate the isotope temperature signal in the coral record. The annual cycle in the 18 O record, as well as the high correlation between 18 O and the instrumental record lends evidence to this, and the degree to which paired Sr/Ca and 18 O measurements agree ( r = 0.91, r = 0.44 with average annual cycle

PAGE 22

15 removed) lends further credence to the idea that Sr/Ca ratios of the coral skeleton are being forced by the temperature of aragonite precipitation, and that such a signal is extractible using the methods employed here. 3.4 Verification of proxy skill There is no independent, in situ SST data set available to verify the skill of the proxy-SST relationships. Instead, the 1900-1972 portion of the augmented SST data set is used here to observe the ability of the calibrations and geochemical data to hind-cast SST at both the bimonthly (Figure 8) and annual average resolution (Figure 9). The average absolute difference between bimonthly-interpolated augmented SST and Sr/Caestimated SST data during the verification interval is 0.56 0.49 (1 # ) C. The average absolute difference between annually averaged augmented SST and annually averaged Sr/Ca-estimated SST during the verification interval is 0.27 0.25 (1 # ) C. The entire 93-year annual average records exhibit an average absolute difference of 0.27 0.25 (1 # ) C for Sr/Ca-SST relative to the annual average augmented SST.

PAGE 23

16 4. Discussion 4.1 Vital effects Given the agreement and correlation between Sr/Ca and augmented SST time series at both the bimonthly and annual average resolution, the reproducibility between parallel paths, and the stability of the signal through the 20 th century, there is no reason to suspect that so-called vital or growth rate effects [ Cohen and McConnaughey 2003; Goodkin, et al. 2007] are significant drivers of Sr/Ca variability in this record. Based on the results of Cohen and McConnaughey (2003), which show decreased extension rates corresponding to relative enrichment in Sr/Ca values, one would expect to see a significant, persistent inverse relationship between annual average Sr/Ca and annual extension rate. The overall correlation between annual extension rate and annual average Sr/Ca is r = -0.14, which is insignificant at the 99% confidence level. However, given the limited resolution of our extension rate data (0.75 mm), we furthered our analysis by performing running correlations at different temporal scales to observe whether this overall insignificant inverse relationship remains throughout the last century of coral growth, and whether or not there are periods of strengthened covariance between the two variables. Figure 10 shows clearly that there is no systematic correlation between Sr/Ca and extension rate, and that the expected inverse relationship does not persist. 4.2 Removal of SST annual cycle The SST signal in the Dry Tortugas region and the Sr/Ca-SST signal from the coral time series both contain pronounced annual cycles, and each are forced to have a 0 phase difference from one another as a result of the age modeling process (see

PAGE 24

17 Background and Methods). The net effect is a lack of independence between the two bimonthly-resolved time series and therefore inflated covariance from serial correlation. Here the 93DRYSS-1 bimonthly Sr/Ca-SST is compared to the augmented bimonthly instrumental SST time series over the 20 th century in anomaly space, allowing the confirmation of a significant correlation between the two time series using independent data (Figure 11). Anomalies were calculated by removal of the mean bimonthly annual cycle from 1973-1992 for each time series from the entire 20 th century bimonthly record. The resulting correlation between the two time series at the bimonthly resolution is r = 0.56, which is significant at the 99% confidence level and indicative of common variability despite the lack of serial correlation. Disagreement between the two anomaly time series may be augmented by uncertainties in assigning time to coral core depth at sub-annual resolution. The relatively high correlation ( r = 0.72) between annual average Sr/Ca-SST and the annual average augmented SST time series further indicate that the Sr/Ca variations are driven by SST. The annual average time series are also independent of the serial correlation as the seasonal cycle is removed by averaging (as opposed to subtraction), but contains fewer degrees of freedom than the bimonthly anomaly time series comparison. The high degree of correlation between the two time series suggests that this proxy species can be utilized as an accurate indicator of climate variability on timescales as fine as interannual over intervals spanning multiple centuries. 4.3 Capture of regional climate variability The GOM, as a component of the AWP, is an important source of heat and moisture for the continental United States, and variability on interannual and

PAGE 25

18 multidecadal timescales has broad-reaching climate effects [ Mestas-Nunez and Enfield 2007; Mestas-Nunez, et al. 2005; Wang, et al. 2006b]. Therefore, the ability of a local, in situ proxy record of climate within the Gulf to reflect variability within the region as a whole is an important consideration when assessing the relevance of such records to the understanding of climate variability and change. In order to assess the correlation between the GOM regional SST and the local record Sr/Ca-SST record from the Dry Tortugas, SST data were extracted from the HadISST1 dataset for the GOM region, 24-28N and 84-96W [ Rayner, et al. 2003] for the 20 th century. The regional time series agrees well with the local, augmented SST data set over the interval from 1900-1992 ( r = 0.77), and similarly well with the local coral record on the annual average level ( r = 0.67) (Figure 12), suggesting that local, in situ coral records of SST variability from the Dry Tortugas have regional significance and can therefore be utilized in reconstructions of IAS or AWP thermal behavior on a variety of timescales, perhaps in concert with representative proxy records from other AWP components, such as the Caribbean and tropical West Atlantic.

PAGE 26

19 5. Conclusions Here we present time series geochemical variations from the coral S. siderea from which the following was concluded: Both Sr/Ca and 18 O variations are highly reproducible within the skeleton The Sr/Ca and 18 O variations agree well with augmented SST data from 19731992 ( r = 0.96 and r = 0.92, respectively), allowing calibration of geochemistry to SST. However, changing hydrologic conditions, which would oppose the annual cycle of 18 O in the coral, may influence the 18 O-SST slope Sr/Ca variations agree well with SST during the 20 th century in bimonthly ( r = 0.96), bimonthly anomaly ( r = 0.56), and annual average ( r = 0.72) SST space, indicating a relationship between SST and Sr/Ca that is stable long term. There appear to be no extension rate related vital effects present to obfuscate a climate signal. The coral record agrees well with regional scale GOM climate variability ( r = 0.67) This indicates that extracting geochemical data from S. siderea allows continuous, potentially multi-centennial, subannual coral-based hind-casting of SST variability in the Caribbean and tropical West Atlantic. The extension rate of the 93DRYSS-1 coral suggests that a 200-year-long continuous record of in situ SST variability in the Dry Tortugas could be extracted from the core from which these data were generated.

PAGE 27

20 18.0 20.0 22.0 24.0 26.0 28.0 30.0 32.0 1985 1990 1995 2000 2005 Monthly SEAKEYS/C-MAN (Station DRYF1) Gridded Product Augmented SST Record Monthly SST ( o C) Year Figure 1. Monthly SST variations from the 1 x 1 HadISST1 gridded product [ Rayner, et al. 2003] and in situ DRYF1 data sets (SEAKEYS/CMAN) plotted with the augmented data set generated from the relationship between the HadISST1 and in situ records. The in situ data exhibits consistently lower winter SSTs than the gridded product data set. Overall, there is excellent correlation between the HadISST and in situ data ( r = 0.98).

PAGE 28

21 18.0 20.0 22.0 24.0 26.0 28.0 30.0 32.0 1992 1994 1996 1998 2000 2002 2004 SST SST ( o C) Year A 28.0 30.0 32.0 34.0 36.0 38.0 1992 1994 1996 1998 2000 2002 2004 SSS SSS Year B Figure 2. Plot of sea-surface temperature (SST, A) and sea-surface salinity variations (SSS, B) retrieved in the Dry Tortugas by the SEAKEYS/CMAN program. Note that summer (warmer) months tend to correspond with more saline conditions, and winter (cooler) months tend to show freshening salinities. The large freshening excursion in 1998-1999 is likely due to biofouling [ Quinn pers. comm.].

PAGE 29

22 Figure 3. X-radiographs of the top two slabs of the 93DRYSS-1 core. Note the lack of regular, annual density banding, but also the presence of a clear, dense and wide, thecal walls, which present an ideal target for mm-scale sampling methods such as microdrilling.

PAGE 30

23 8.70 8.80 8.90 9.00 9.10 9.20 9.30 1975 1980 1985 1990 Bimonthly Sr/Ca Sr/Ca (mmol/mol) Year A -4.00 -3.50 -3.00 -2.50 Bimonthly 18 O ( vPDB) 18 O ( vPDB) B -2.00 -1.60 -1.20 -0.80 -0.40 0.00 Bimonthly 13 C ( vPDB) 1975 1980 1985 1990 13 C ( vPDB) C Year

PAGE 31

24 Figure 4. Age-modeled, bimonthly interpolated geochemical variations from 1973-1992. Error bars represent 1 # of the respective instrumental precision for each variable. Note the presence of clear, consistent annual cycles in all three variables.

PAGE 32

25 8.70 8.80 8.90 9.00 9.10 9.20 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14 0.25 mm/sample 0.75 mm/sample Sr/Ca (mmol/mol) Depth (mm) Depth (mm) Figure 5. Effect of increasing sampling resolution from 0.75 mm sample -1 (ca. 6 samples yr -1 ) to 0.25 mm sample -1 (ca. 18 samples yr -1 ) on the amplitude of the coral Sr/Ca signal over 3 annual cycles. The mean amplitude of Sr/Ca values over the 3 years sampled is 0.303 mmol/mol at 0.75 mm sample -1 and 0.332 mmol/mol at 0.25 mm sample -1 values that agree within 2 # of instrumental precision for Sr/Ca ( 0.030 mmol/mol).

PAGE 33

26 8.70 8.80 8.90 9.00 9.10 9.20 9.30 0 10 20 30 40 50 Sr/Ca (mmol/mol) Length Along Paths (mm) A -4.50 -4.00 -3.50 -3.00 -2.50 93DRYSS-1-2.1 93DRYSS-1-2.1_p2 0 10 20 30 40 50 18 O vPDB Length Along Paths (mm) B Figure 6. Values of (a) Sr/Ca and (b) 18 O from two parallel paths, sampled ~2 cm apart on a slab of the 93DRYSS-1 core. Path 93DRYSS-1-2.1 was aligned with path 93DRYSS-1-2.1_p2 using Sr/Ca data and the Analyseries program. There is excellent agreement between the parallel paths with respect to both geochemical variables (Sr/Ca: r = 0.97, 18 O: r = 0.95), and the average absolute difference between them (Sr/Ca: 0.027 mmol/mol, 18 O: 0.11 per mil) is within 2 # of the analytical precision for either variable (Sr/Ca: .030 mmol/mol, 18 O: .12 per mil; see error bars).

PAGE 34

27 -4.00 -3.80 -3.60 -3.40 -3.20 -3.00 -2.80 -2.60 -2.40 8.80 8.90 9.00 9.10 9.20 Bimonthly 18 O ( vPDB) Bimonthly Sr/Ca 1975 1980 1985 1990 Bimonthly 18 O ( vPDB) Bimonthly Sr/Ca (mmol/mol) Year A 18.0 20.0 22.0 24.0 26.0 28.0 30.0 8.80 8.90 9.00 9.10 9.20 Bimonthly SST Bimonthly Sr/Ca 1975 1980 1985 1990 Bimonthly SST ( o C) Bimonthly Sr/Ca (mmol/mol) Year B Figure 7. Calibration interval (a) Sr/Ca plotted with 18 O and (b) with bimonthlyaveraged augmented SST. Refer to text for regression equations. The high degree of correlation between each geochemical variable and the augmented instrumental SST, as well as the agreement between the two geochemical variables strongly suggests a common SST forcing.

PAGE 35

28 20 22 24 26 28 30 32 1900 1920 1940 1960 1980 Bimonthly SST ( o C) Year A 8.80 8.90 9.00 9.10 9.20 Sr/Ca (mmol/mol) B 2 3 4 5 6 7 8 1900 1920 1940 1960 1980 Annual Extension Rate (mm/yr) Year C Figure 8. Calibrationand verification-interval time series of (a): bimonthly-averaged augmented SST data, (b) age modeled, bimonthly-interpolated Sr/Ca variations, (c) annual extension rate for the 93DRYSS1 coral along drilling transects ( = 4.94 0.73 mm yr -1 1 # ). There is excellent agreement between bimonthly Sr/Ca and SST values ( r = -0.96, n = 561). The error bar in panel (b) represents average instrumental precision based on repeated measurements of a powdered, homogenized and dissolved standard of Porites lutea coral (.015 mmol/mol, ~0.40C, 1 # n = 277).

PAGE 36

29 24 25 26 27 28 Annual Average SST Annual Average Sr/Ca-SST 1900 1920 1940 1960 1980 Annual Average SST ( o C) Figure 9. Annual average augmented SST plotted with annual average Sr/Ca-SST estimations. Annual average Sr/Ca-SST agrees well ( r = 0.72, n = 93) with the annual average augmented SST, especially within the pre-1973 verification interval ( r = 0.76, n = 73). The error bar in each panel corresponds to the precision of the mean annual Sr/CaSST estimations, 0.28C (1 # # calculated from the instrumental precision and two degrees of freedom per year).

PAGE 37

30 -1.00 -0.50 0.00 0.50 1.00 1900 1920 1940 1960 1980 5 year running correlation 10 year running correlation 20 year running correlation Correlation Coefficient, r First Year of Correlation Figure 10. Running correlations between annual average Sr/Ca and annual average extension rate values along sampling transects. The overall correlation between annual extension rate and annual average Sr/Ca is r = -0.14, and there is no systematic relationship between extension rate and Sr/Ca at the annual average level. This suggests a lack of extension rate-related so-called vital effects in this coral colony.

PAGE 38

31 -4.00 -3.00 -2.00 -1.00 0.00 1.00 2.00 3.00 1900 1920 1940 1960 1980 Bimonthly Sr/Ca-SSTA Bimonthly SSTA Bimonthly SSTA ( o C) Year Figure 11. Plot of time series of both bimonthly augmented SST data and age-modeled, bimonthly-interpolated Sr/Ca-SST anomalies, compared to highlight common variance despite removal of annual cycle serial correlation. Anomalies were calculated by removal of the mean bimonthly annual cycle from 1973-1992 for each variable from the entire 20 th century bimonthly record. Correlation between the two time independent time series at the bimonthly resolution is r = 0.56, and is significant at the 99% confidence interval.

PAGE 39

32 -3.00 -2.00 -1.00 0.00 1.00 2.00 3.00 1900 1920 1940 1960 1980 Dry Tortugas Gulf of Mexico Year Figure 12. Plot of annually averaged 20 th century GOM and Sr/Ca-based Dry Tortugas SST data sets. Both time series were detrended and divided by their respective standard deviations to highlight similar patterns of interannual, decadal and multidecadal variability. Correlation between time series before detrending is r = 0.67, and correlation between the two detrended time series is r = 0.64, indicating that robust coral-based SST records from the Dry Tortugas from are well suited to provide information regarding regional climate variability.

PAGE 40

33 Literature Cited Alibert, C., and M. T. McCulloch (1997), Strontium/calcium ratios in modern Porites corals from the Great Barrier Reef as a proxy for sea surface temperature: Calibration of the thermometer and monitoring of ENSO, Paleoceanography 12 345. Cohen, A. L., and T. A. McConnaughey (2003), Geochemical perspectives on coral mineralization, in Biomineralization edited, p. 151, Mineralogical Soc America, Washington. Cohen, A. L., et al. (2004), How brain corals record climate: an integration of skeletal structure, growth and chemistry of Diploria labyrinthiformis from Bermuda, Mar. Ecol.-Prog. Ser. 271 147. Cohen, A. L., and S. R. Thorrold (2007), Recovery of temperature records from slowgrowing corals by fine scale sampling of skeletons, Geophys. Res. Lett. 34 Correge, T. (2006), Sea surface temperature and salinity reconstruction from coral geochemical tracers, Paleogeogr. Paleoclimatol. Paleoecol. 232 408. Delworth, T. L., and M. E. Mann (2000), Observed and simulated multidecadal variability in the Northern Hemisphere, Clim. Dyn. 16 661. Fratantoni, P. S., et al. (1998), The influence of loop current perturbations on the formation and evolution of Tortugas eddies in the southern Straits of Florida, Journal Of Geophysical Research-Oceans 103 24759. Gagan, M. K., et al. (1998), Temperature and surface-ocean water balance of the midHolocene tropical Western Pacific, Science 279 1014. Gagan, M. K., et al. (2004), Post-glacial evolution of the Indo-Pacific Warm Pool and El

PAGE 41

34 Nino-Southern Oscillation, Quat. Int. 118-19 127. Gischler, E., and W. Oschmann (2005), Historical climate variation in Belize (Central America) as recorded in scleractinian coral skeletons, Palaios 20 159. Goodkin, N. F., et al. (2007), A multicoral calibration method to approximate a universal equation relating Sr/Ca and growth rate to sea surface temperature, Paleoceanography 22 Gray, S. T., et al. (2004), A tree-ring based reconstruction of the Atlantic Multidecadal Oscillation since 1567 AD, Geophys. Res. Lett. 31 Guzman, H. M., and A. W. Tudhope (1998), Seasonal variation in skeletal extension rate and stable isotopic (C-13/C-12 and O-18/O-16) composition in response to several environmental variables in the Caribbean reef coral Siderastrea siderea, Mar. Ecol.-Prog. Ser. 166 109. Hetzinger, S., et al. (2006), Sr/Ca and delta O-18 in a fast-growing Diploria strigosa coral: Evaluation of a new climate archive for the tropical Atlantic, Geochem. Geophys. Geosyst. 7 Kerr, R. A. (2005), Climate change Atlantic climate pacemaker for millennia past, decades hence? Science 309 41. Kilbourne, K. H., et al. (2004a), A fossil coral perspective on western tropical Pacific climate similar to 350 ka, Paleoceanography 19 Kilbourne, K. H., et al. (2004b), El Nino-Southern Oscillation-related salinity variations recorded in the skeletal geochemistry of a Porites coral from Espiritu Santo, Vanuatu, Paleoceanography 19 Knight, J. R., et al. (2006), Climate impacts of the Atlantic Multidecadal Oscillation,

PAGE 42

35 Geophys. Res. Lett. 33 Leder, J. J., et al. (1996), The origin of variations in the isotopic record of scleractinian corals.1. Oxygen, Geochim Cosmochim. Acta 60 2857. Lough, J. M. (2004), A strategy to improve the contribution of coral data to highresolution paleoclimatology, Paleogeogr. Paleoclimatol. Paleoecol. 204 115. Mallinson, D., et al. (2003), Development of small carbonate banks on the south Florida platform margin: response to sea level and climate change, Mar. Geol. 199 45. Mann, M. E. (2001), Large-scale temperature patterns in past centuries: Implications for North American climate change, Hum. Ecol. Risk Assess. 7 1247. Mestas-Nunez, A. M., and D. B. Enfield (2007), Water vapor fluxes over the IntraAmericas Sea: Seasonal and interannual variability and associations with rainfall, J. Clim. 20 1910. Mestas-Nunez, A. M., et al. (2005), Uncertainties in estimating moisture fluxes over the Intra-Americas Sea, Journal Of Hydrometeorology 6 696. Paillard, D., et al. (1996), Macintosh Program Performs Time-Series Analysis, EOS Transactions 77 379. Quinn, T. M., and D. E. Sampson (2002), A multiproxy approach to reconstructing sea surface conditions using coral skeleton geochemistry, Paleoceanography 17 Rayner, N. A., et al. (2003), Global analyses of SST, sea ice and night marine air temperature since the late nineteenth century, Geophysical Research Letters 108 Schrag, D. P. (1999), Rapid analysis of high-precision Sr/Ca ratios in corals and other marine carbonates, Paleoceanography 14 97. Smith, J. M., et al. (2006), Reproducibility of geochemical and climatic signals in the

PAGE 43

36 Atlantic coral Montastraea faveolata, Paleoceanography 21 Stephans, C. L., et al. (2004), Assessing the reproducibility of coral-based climate records, Geophys. Res. Lett. 31 Swart, P. K., et al. (2002), A high-resolution calibration of Sr/Ca thermometry using the Caribbean coral Montastraea annularis, Geochem. Geophys. Geosyst. 3 Swart, P. K., et al. (1996), The origin of variations in the isotopic record of scleractinian corals.2. Carbon, Geochim Cosmochim. Acta 60 2871. Swart, P. K., et al. (2005), The isotopic composition of respired carbon dioxide in scleractinian corals: Implications for cycling of organic carbon in corals, Geochim. Cosmochim. Acta 69 1495. Veron, J. E. N. (2000), Corals of the World Australian Institute of Marine Science and CRR Qld Ltd, Townsville MC. Wang, C. (2006a), An overlooked feature of tropical climate: Inter-Pacific-Atlantic variability, Geophysical Research Letters 33 Wang, C., and D. B. Enfield (2001a), The tropical Western Hemisphere warm pool, Geophysical Research Letters 28 1635-1638. Wang, C., and D. B. Enfield (2003a), A further study of the tropical Western Hemisphere warm pool, Journal of Climate 16 1476-1493. Wang, C., et al. (2006a), Influences of the Atlantic Warm Pool on Western Hemisphere summer rainfall and Atlantic hurricanes, Journal of Climate 19 3011. Wang, C. Z. (2006b), An overlooked feature of tropical climate: Inter-Pacific-Atlantic variability, Geophys. Res. Lett. 33 Wang, C. Z., and D. B. Enfield (2001b), The tropical Western Hemisphere warm pool,

PAGE 44

37 Geophys. Res. Lett. 28 1635. Wang, C. Z., and D. B. Enfield (2003b), A further study of the tropical Western Hemisphere warm pool, J. Clim. 16 1476. Wang, C. Z., et al. (2006b), Influences of the Atlantic warm pool on western hemisphere summer rainfall and Atlantic hurricanes, J. Clim. 19 3011. Wang, C. Z., and S. K. Lee (2007), Atlantic warm pool, Caribbean low-level jet, and their potential impact on Atlantic hurricanes, Geophys. Res. Lett. 34 Wang, C. Z., et al. (2008), Climate Response to Anomalously Large and Small Atlantic Warm Pools during the Summer, J. Clim In Press

PAGE 45

38 Appendices

PAGE 46

39 Appendix 1: Calculation of 18 O sw and 18 O sw anomalies The 18 O of coralline aragonite is a function of both the SST of aragonite growth and the 18 O of seawater ( 18 O sw ), therefore changes in the 18 O sw in the Dry Tortugas region, induced by phenomena such as changes in E-P, salinity, and intrusion of floodwaters from the Mississippi, may impact the 18 O aragonite signal extracted from the 93DRYSS-1 core and consequently affect the interpretation of this signal [ Leder, et al. 1996; Correge 2006]. The following equation (Equation 2) published by Leder et al. [1996] relating 18 O aragonite 18 O sw and SST was used here to calculate the 18 O sw as recorded by this coral from 1973-1992: T( C) = 5.33 4.519 ( 0.19) ( 18 O aragonite 18 O sw ). (1.1) Both bimonthly Sr/Ca-SST and the bimonthly augmented SST data were used separately as the T( C) term. The resulting two time series show a similar pattern of variability as the short, in situ salinity time series from the SEAKEYS/C-MAN stations, with more saline, drier spring and summer months, and freshening, wetter fall and winter months, and agree well with one another ( r = 0.83, n = 120) (Figure 1.1a). The mean annual cycle from 1973-1992 was subtracted from the time series to yield bimonthly 18 O sw anomalies from both the Augmented-SSTand Sr/Ca-SST-derived data (Figure II.1b). These time series also agree significantly with one another (99% confidence interval, r = 0.47, n = 120) and both show interannual and decadal variability that merits further investigation. However, the equation used here to calculate 18 O sw was developed for used in Montastraea spp. not Siderastrea siderea A study which examines simultaneous temperature, 18 O aragonite of S. siderea and 18 O sw may be

PAGE 47

40 necessary to obtain a robust relationship for calculating 18 O sw from the coral geochemical data.

PAGE 48

41 0.50 1.00 1.50 2.00 2.50 1970 1975 1980 1985 1990 1995 Bimonthly 18 O w (), Augmented SST Bimonthly 18 O w (), Sr/Ca-SST Bimonthly 18 O w () Year A -0.60 -0.40 -0.20 0.00 0.20 0.40 0.60 1970 1975 1980 1985 1990 1995 Bimonthly 18 O w Anomaly (), Augmented SST Bimonthly 18 O w Anomaly (), Sr/Ca-SST Bimonthly 18 O w Anomaly () Year B Figure 1.1 (A) Time series of bimonthly 18 O sw calculated using both the Augmented SST (red) and Sr/Ca-SST (blue) estimations as the T( C) term in the Leder et al. [1996] equation. Note the character of the seasonal cycle, where more enriched (more depleted) 18 O sw values tend to occur in the Spring and Summer (Fall and Winter). (B) Time Series of bimonthly 18 O sw anomalies calculated by removal of mean seasonal cycle. Note interannual and decadal variability.

PAGE 49

42 Literature Cited Correge, T. (2006), Sea surface temperature and salinity reconstruction from coral geochemical tracers, Paleogeogr. Paleoclimatol. Paleoecol. 232 408. Leder, J. J., et al. (1996), The origin of variations in the isotopic record of scleractinian corals.1. Oxygen, Geochim Cosmochim. Acta 60 2857.

PAGE 50

43 Appendix 2: Carbon Isotopic Variations The 13 C value of coral aragonite in hermatypic coral species is traditionally thought to be primarily controlled by the photosynthesis/respiration (P/R) ratio of the zooxanthellate symbionts of the coral [ Swart, et al. 1996] This paradigm assumes a common dissolved inorganic carbon (DIC) pool for both the calcifying fluid as well as CO 2 diffusion for photosynthesis. As net insolation increases, P/R increases, preferentially using 12 C during photosynthetic isotopic fractionation, leaving the remaining DIC used for calcification relatively enriched in 13 C. Thus, insolation and 13 C would be positively correlated [ Cohen and McConnaughey 2003; Swart, et al. 2005] One way to examine the feasibility of solar insolation as a primary forcing is to determine the lead in the light proxy annual cycle phase relative to the temperature proxy annual cycle phase. Given the equation SST / t = Q net / C p h, where t is time, Q net is net heat flux (dominated by an annual cycle of insolation), is the average mixed layer density, and h is the ocean mixed layer depth, it is apparent that there should be a 90 or 3 month, phase lag between SST and insolation seasonal cycles, where the phase change in insolation precedes that of SST [ Wang and Enfield 2001] The 13 C and Sr/Ca from the 93 DRYSS-1 core both exhibit a clear seasonal cycle that persists throughout the time series spanning from 1973-1992 (Figure 2.1a). Lead-lag correlations between monthly-interpolated stable isotope data and Sr/Ca data reveal that peak correlation occurs between 2-4 months lead of the two annual cycles in the time series (Figure A.1b), implying that a seasonal cycle in insolation received by the coral may be a primary driver.

PAGE 51

44 Caution must be taken when considering these results. Coral calcification mechanisms are still largely unknown, especially with respect to inorganic carbon pools and pathways. In the inorganic model, 2H + are enzymatically exchanged for Ca 2+ within the calcifying fluid. This reduction of proton activity within the fluid raises the fluid pH and, consequently, the # fraction of CO 3 2in the DIC pool. This increase in CO 3 2activity raises the aragonite saturation state well above 1, allowing rapid spontaneous aragonite precipitation [ Cohen and McConnaughey 2003] This model raises two critical questions with respect to the origins of skeletal 13 C variations, the provenance of the carbon used in the DIC pool, and whether the DIC pool is actually shared between the demands of photosynthesis and skeletogenesis. Swart et al. [1996] found that in vitro incubations of M. faveolata yielded a surprising inverse correlation between the calculated P/R ratio of the corals and the 13 C of the skeletons, which is exactly the opposite of the expected result. One hypothesis is the notion of a kinetic vital effect, whereby during periods of rapid coral growth, such as in the spring, kinetic fractionation in the skeleton, preferentially using 13 C, would outpace the fractionation of the DIC pool towards higher 13 C values by photosynthesis, essentially developing a Rayleigh fractionation-type system, where as more of the DIC pool is used for calcification through time, the instantaneous 13 C value of the coral skeleton must become correspondingly depressed [ McConnaughey 1989a; 1989b; Swart, et al. 1996]. The second potential explanation for an inverse 13 C P/R relationship would be for the coral to have been using DIC in the form of respired carbon from zooxanthellaederived photosynthate, which would have depleted 13 C values that would then be

PAGE 52

45 reflected in the skeleton [ Erez 1978] If during periods of high photosynthesis and high calcification, carbonate becomes limiting due to some physical means, such as diffusion, the coral may then be forced to use carbon from an internal source such as photosynthate. Further complicating this scenario is the idea of coral mixotrophy: Swart et al. [1996] not only found isotopic offsets between coral zooxanthellae tissue and coral tissue, but the magnitude of offsets changed through time as well, suggesting changes in the organic carbon budget of the coral, with a varying dependence on zooxanthellae and allochthonous organic carbon sources. This would alter the isotopic composition of the DIC pool through time if any of the DIC pool originates from respired carbon. Regardless of the true explanation, it is clear that further understanding of the coral carbon budget as a function of time and environmental variables is necessary before concrete conclusions can be made about nature of skeletal variations in coral 13 C.

PAGE 53

46 8.70 8.80 8.90 9.00 9.10 9.20 9.30 -2.50 -2.00 -1.50 -1.00 -0.50 0.00 1975 1980 1985 1990 Bimonthly Sr/Ca Bimonthly 13 C ( vPDB) Bimonthly Sr/Ca Bimonthly 13 C ( vPDB) A -0.80 -0.60 -0.40 -0.20 0.00 0.20 0.40 0.60 0.80 -10 -8 -6 -4 -2 0 Correlation Lead (months) B Figure 2.1. (A) Sr/Ca (SST proxy) variations plotted with 13 C variations from 19731992, and (B) lead correlations between 13 C and Sr/Ca. Note the clear annual cycles in each geochemical variable, with seasonal enrichment of 13 C (increasing insolation) preceding decreasing Sr/Ca values (increasing SST) by a ~90 phase difference.

PAGE 54

47 Literature Cited Cohen, A. L., and T. A. McConnaughey (2003), Geochemical perspectives on coral mineralization, in Biomineralization edited, p. 151. Erez, J. (1978), Vital Effect On Stable-Isotope Composition Seen In Foraminifera And Coral Skeletons, Nature 273 199. McConnaughey, T. (1989a), C-13 And O-18 Isotopic Disequilibrium In Biological Carbonates.1. Patterns, Geochim. Cosmochim. Acta 53 151. McConnaughey, T. (1989b), C-13 And O-18 Isotopic Disequilibrium In Biological Carbonates.2. Invitro Simulation Of Kinetic Isotope Effects, Geochim. Cosmochim. Acta 53 163. Swart, P. K., et al. (1996), The origin of variations in the isotopic record of scleractinian corals.2. Carbon, Geochim Cosmochim. Acta 60 2871. Swart, P. K., et al. (2005), The isotopic composition of respired carbon dioxide in scleractinian corals: Implications for cycling of organic carbon in corals, Geochim. Cosmochim. Acta 69 1495. Wang, C. Z., and D. B. Enfield (2001), The tropical Western Hemisphere warm pool, Geophys. Res. Lett. 28 1635.

PAGE 55

48 Appendix 3: Bimonthly Calibration Interval Data Year Bimonthly Sr/Ca Bimonthly SST Bimonthly 18 O Bimonthly 13 C 1973.0833 9.12358 22.16 -2.8930 -0.8701 1973.2500 9.10190 23.36 -3.2722 -0.3155 1973.4167 8.95198 27.44 -3.5848 -0.5742 1973.5833 8.81161 30.03 -3.6915 -1.4093 1973.7500 8.84741 28.95 -3.5120 -1.5701 1973.9167 9.02653 24.95 -3.0646 -1.2978 1974.0833 9.08959 23.19 -2.9372 -1.0414 1974.2500 9.09840 23.67 -2.9225 -0.7952 1974.4167 8.94165 27.49 -3.4874 -0.3138 1974.5833 8.84191 29.64 -3.9466 -1.0266 1974.7500 8.90051 28.32 -3.7694 -1.5136 1974.9167 9.10542 24.38 -3.0509 -1.3138 1975.0833 9.11413 23.73 -2.9231 -1.1275 1975.2500 9.07145 24.61 -3.2726 -0.1470 1975.4167 8.88254 28.40 -3.7516 -0.6907 1975.5833 8.85256 30.04 -3.7485 -1.2763 1975.7500 8.88624 28.63 -3.6417 -1.4072 1975.9167 9.03610 24.78 -3.0478 -1.3419 1976.0833 9.19720 21.17 -2.8105 -1.1208 1976.2500 9.07911 23.84 -3.2154 -0.2156 1976.4167 8.93835 27.04 -3.7618 -0.5975 1976.5833 8.89343 29.54 -3.7477 -1.0748 1976.7500 8.89149 28.77 -3.5914 -1.5009 1976.9167 9.10128 24.06 -2.8755 -1.4912 1977.0833 9.21815 20.78 -2.5704 -0.7728 1977.2500 9.10903 23.41 -2.8992 -0.4690 1977.4167 8.95000 26.93 -3.3763 -0.3378 1977.5833 8.95000 29.81 -3.6050 -0.8503 1977.7500 8.94185 28.73 -3.6741 -1.1672 1977.9167 9.06214 24.72 -3.1002 -1.5509 1978.0833 9.15324 21.33 -2.8233 -1.3526 1978.2500 9.18453 21.99 -2.7192 -0.8294 1978.4167 8.91898 27.74 -3.5440 -0.6159 1978.5833 8.84710 29.75 -3.8756 -1.4319 1978.7500 8.89824 28.86 -3.7622 -1.8497 1978.9167 9.02789 25.68 -3.2022 -1.4808 1979.0833 9.06892 22.51 -2.9666 -1.1206 1979.2500 9.10996 23.47 -2.7310 -0.7603

PAGE 56

49 1979.4167 8.93940 27.38 -3.5572 -0.3155 1979.5833 8.84282 29.93 -3.9142 -1.4180 1979.7500 8.92009 28.19 -3.6333 -1.6470 1979.9167 9.08562 23.99 -2.9453 -1.3431 1980.0833 9.11166 21.26 -2.8829 -1.0024 1980.2500 9.10053 23.25 -3.0523 -0.6852 1980.4167 8.92029 27.77 -3.6180 -0.5502 1980.5833 8.80337 30.08 -3.8853 -1.5968 1980.7500 8.85770 28.84 -3.8204 -1.8685 1980.9167 9.06522 24.83 -2.9994 -1.6662 1981.0833 9.20943 21.25 -2.5908 -1.2824 1981.2500 9.08840 23.13 -3.0376 -0.4973 1981.4167 8.94028 27.69 -3.9122 -1.0412 1981.5833 8.93052 29.97 -3.8790 -1.1379 1981.7500 8.92076 28.81 -3.8458 -1.2346 1981.9167 9.02455 24.54 -3.4696 -1.2900 1982.0833 9.16120 22.48 -2.8796 -1.2900 1982.2500 9.08663 24.01 -3.2399 -0.5093 1982.4167 8.93773 26.73 -3.7547 -0.6671 1982.5833 8.87566 29.88 -3.8483 -1.6030 1982.7500 8.87815 28.86 -3.6279 -1.5675 1982.9167 8.97267 25.17 -3.1445 -1.1692 1983.0833 9.15520 22.17 -2.8360 -0.9311 1983.2500 9.13444 22.38 -3.1026 -0.2312 1983.4167 8.94722 26.93 -3.7435 -0.3457 1983.5833 8.86682 29.81 -3.7612 -1.2475 1983.7500 8.89676 28.84 -3.5944 -1.3211 1983.9167 8.99359 25.32 -3.0841 -1.3327 1984.0833 9.13373 22.64 -2.8008 -0.5465 1984.2500 9.10680 22.97 -3.0854 -0.5874 1984.4167 8.97345 26.69 -3.4282 -0.7770 1984.5833 8.89795 28.78 -3.6310 -0.9849 1984.7500 8.94420 27.48 -3.2477 -1.2698 1984.9167 9.01713 24.70 -2.9096 -1.1377 1985.0833 9.11528 21.94 -2.8267 -0.7990 1985.2500 9.08816 23.17 -2.9049 -0.4133 1985.4167 9.04234 27.74 -3.5417 -0.7316 1985.5833 8.97269 29.31 -3.5550 -0.8928 1985.7500 8.96942 28.31 -3.5682 -1.0540 1985.9167 9.02331 25.14 -3.1213 -1.2768 1986.0833 9.11284 22.91 -2.8747 -0.7859 1986.2500 9.12119 23.12 -2.8784 -0.3871

PAGE 57

50 1986.4167 8.94930 26.94 -3.4747 -0.2184 1986.5833 8.84438 29.76 -3.7359 -1.0906 1986.7500 8.86172 29.13 -3.3113 -1.7733 1986.9167 8.99080 25.66 -2.9775 -1.7121 1987.0833 9.11439 22.56 -2.7314 -1.4027 1987.2500 9.08842 22.67 -2.9458 -0.3121 1987.4167 8.91962 26.99 -3.5347 -0.6389 1987.5833 8.87633 30.27 -3.7050 -1.6785 1987.7500 8.92182 28.95 -3.4224 -1.8352 1987.9167 9.04675 24.68 -3.1233 -1.5633 1988.0833 9.13460 21.75 -2.8998 -1.1866 1988.2500 9.15427 22.15 -2.8084 -0.7704 1988.4167 8.94451 26.54 -3.5028 -0.7698 1988.5833 8.84063 29.47 -3.5567 -0.9989 1988.7500 8.88650 28.11 -3.5988 -1.3301 1988.9167 9.01568 24.72 -3.1380 -1.7747 1989.0833 9.09455 22.84 -2.8455 -1.3857 1989.2500 9.07510 23.30 -2.7751 -0.8557 1989.4167 8.90718 27.29 -3.6556 -1.0177 1989.5833 8.79278 29.94 -3.8412 -1.7572 1989.7500 8.83513 28.74 -3.7024 -2.1903 1989.9167 9.01373 24.65 -2.9557 -1.8429 1990.0833 9.09750 22.82 -2.8798 -1.1731 1990.2500 9.06871 23.77 -3.1462 -0.3745 1990.4167 8.91453 27.40 -3.6189 -0.7727 1990.5833 8.85563 29.83 -3.7404 -1.8109 1990.7500 8.87151 29.35 -3.8856 -1.7852 1990.9167 9.01222 24.90 -3.1282 -1.6575 1991.0833 9.08365 23.07 -3.0328 -1.0197 1991.2500 9.05175 23.76 -3.2360 -0.5531 1991.4167 8.86888 27.72 -3.7664 -0.8124 1991.5833 8.79724 30.20 -3.9651 -1.6401 1991.7500 8.84169 28.91 -3.6810 -1.7957 1991.9167 9.01608 24.47 -2.9730 -1.6703 1992.0833 9.15464 22.18 -2.8568 -0.9308 1992.2500 9.08232 22.61 -3.2234 -1.0321 1992.4167 8.98326 26.17 -3.5945 -1.1457 1992.5833 8.82516 29.84 -3.8313 -1.4153 1992.7500 8.85990 28.57 -3.6835 -1.8669 1992.9167 9.05476 24.69 -3.0411 -1.6894

PAGE 58

51 Appendix 4: Bimonthly Verification Interval Data Year Bimonthly Sr/Ca Bimonthly SST 1900.0833 9.19302 21.49 1900.2500 9.11877 22.55 1900.4167 8.98669 27.02 1900.5833 8.87722 29.66 1900.7500 8.89551 28.64 1900.9167 9.06634 24.59 1901.0833 9.13757 22.05 1901.2500 9.11231 22.88 1901.4167 8.94557 26.89 1901.5833 8.88928 29.75 1901.7500 8.90360 28.13 1901.9167 9.04159 24.01 1902.0833 9.13639 21.97 1902.2500 9.12650 22.37 1902.4167 8.95190 26.47 1902.5833 8.88148 29.45 1902.7500 8.89096 28.47 1902.9167 9.08582 24.10 1903.0833 9.12938 21.89 1903.2500 9.10293 22.71 1903.4167 8.96275 26.67 1903.5833 8.91193 29.47 1903.7500 8.92028 28.10 1903.9167 9.05432 24.29 1904.0833 9.16875 21.44 1904.2500 9.13540 22.53 1904.4167 8.95621 26.62 1904.5833 8.90084 29.29 1904.7500 8.92338 28.19 1904.9167 9.07644 24.15 1905.0833 9.12340 21.31 1905.2500 9.15428 22.59 1905.4167 8.94660 26.90 1905.5833 8.82789 29.96 1905.7500 8.90097 28.84 1905.9167 9.05182 24.59 1906.0833 9.15775 21.67 1906.2500 9.14677 22.26 1906.4167 8.95255 26.54 1906.5833 8.84301 29.81

PAGE 59

52 1906.7500 8.90581 28.47 1906.9167 9.04978 24.53 1907.0833 9.16815 21.63 1907.2500 9.08776 23.20 1907.4167 8.94384 26.94 1907.5833 8.83827 29.37 1907.7500 8.89747 28.50 1907.9167 9.06444 24.18 1908.0833 9.11359 21.20 1908.2500 9.08935 23.09 1908.4167 8.96386 27.10 1908.5833 8.81488 29.45 1908.7500 8.91620 28.25 1908.9167 9.06593 24.33 1909.0833 9.13070 21.92 1909.2500 9.05615 23.03 1909.4167 8.95678 27.17 1909.5833 8.91766 29.49 1909.7500 8.91808 27.91 1909.9167 9.07679 23.79 1910.0833 9.19839 20.49 1910.2500 9.12579 21.41 1910.4167 9.00183 25.95 1910.5833 8.89473 29.08 1910.7500 8.91882 28.21 1910.9167 9.09855 23.29 1911.0833 9.20560 21.52 1911.2500 9.10562 22.88 1911.4167 8.96974 26.75 1911.5833 8.93404 29.59 1911.7500 8.93734 28.84 1911.9167 9.03466 25.01 1912.0833 9.10723 21.75 1912.2500 9.08455 23.84 1912.4167 8.94139 27.23 1912.5833 8.90955 29.33 1912.7500 8.89548 28.64 1912.9167 9.06176 24.50 1913.0833 9.11761 22.78 1913.2500 9.10524 23.28 1913.4167 8.98188 25.96 1913.5833 8.93008 28.83 1913.7500 8.96596 27.80 1913.9167 9.05886 23.80 1914.0833 9.09637 21.37

PAGE 60

53 1914.2500 9.12986 21.72 1914.4167 8.93373 26.94 1914.5833 8.92310 30.14 1914.7500 8.91248 28.64 1914.9167 9.05380 24.68 1915.0833 9.17032 21.61 1915.2500 9.09324 22.31 1915.4167 8.93077 27.38 1915.5833 8.88911 30.34 1915.7500 8.89338 29.15 1915.9167 9.07074 24.64 1916.0833 9.17782 22.09 1916.2500 9.15267 22.55 1916.4167 8.97897 26.44 1916.5833 8.80584 29.55 1916.7500 8.89880 28.63 1916.9167 9.07517 24.49 1917.0833 9.11484 22.41 1917.2500 9.10463 22.91 1917.4167 8.96275 26.56 1917.5833 8.88106 28.96 1917.7500 8.92079 27.71 1917.9167 9.09184 23.42 1918.0833 9.13226 21.76 1918.2500 9.05775 23.47 1918.4167 8.96493 27.04 1918.5833 8.88973 29.45 1918.7500 8.95365 28.09 1918.9167 9.08707 24.17 1919.0833 9.12098 21.67 1919.2500 9.16047 22.98 1919.4167 9.01203 26.53 1919.5833 8.91698 29.15 1919.7500 8.95964 28.35 1919.9167 9.09145 24.37 1920.0833 9.13843 21.42 1920.2500 9.07052 22.60 1920.4167 8.97306 27.01 1920.5833 8.88344 29.19 1920.7500 8.93695 28.24 1920.9167 9.10352 24.08 1921.0833 9.12960 22.07 1921.2500 9.08881 23.37 1921.4167 8.97658 26.67 1921.5833 8.83580 29.88

PAGE 61

54 1921.7500 8.90237 28.51 1921.9167 9.04465 24.90 1922.0833 9.11947 22.45 1922.2500 9.13226 23.30 1922.4167 8.96298 26.86 1922.5833 8.85123 29.07 1922.7500 8.91426 28.32 1922.9167 9.06239 25.27 1923.0833 9.15674 22.50 1923.2500 9.14730 23.50 1923.4167 8.98260 26.98 1923.5833 8.86553 29.36 1923.7500 8.92558 28.16 1923.9167 9.07883 24.13 1924.0833 9.20306 21.65 1924.2500 9.12473 22.39 1924.4167 8.95612 27.26 1924.5833 8.87941 29.54 1924.7500 8.93687 28.26 1924.9167 9.10882 23.87 1925.0833 9.10786 22.73 1925.2500 9.10770 23.00 1925.4167 8.94526 27.16 1925.5833 8.89704 29.62 1925.7500 8.91231 29.23 1925.9167 9.07050 24.86 1926.0833 9.20048 21.88 1926.2500 9.12261 22.99 1926.4167 8.97288 26.88 1926.5833 8.90673 29.83 1926.7500 8.95341 28.62 1926.9167 9.07925 24.49 1927.0833 9.08282 21.97 1927.2500 9.08640 23.55 1927.4167 8.95403 27.70 1927.5833 8.84394 30.11 1927.7500 8.90672 28.86 1927.9167 9.08650 24.32 1928.0833 9.16057 21.51 1928.2500 9.13531 22.47 1928.4167 9.00510 26.62 1928.5833 8.85495 29.44 1928.7500 8.91581 28.55 1928.9167 9.08156 24.29 1929.0833 9.13445 22.16

PAGE 62

55 1929.2500 9.06317 23.91 1929.4167 8.96956 27.29 1929.5833 8.85791 28.90 1929.7500 8.92506 27.72 1929.9167 9.10312 24.95 1930.0833 9.20228 22.79 1930.2500 9.11629 23.11 1930.4167 8.95882 27.04 1930.5833 8.92563 29.61 1930.7500 8.91335 28.50 1930.9167 9.11107 24.00 1931.0833 9.25522 21.02 1931.2500 9.16159 21.77 1931.4167 9.00136 26.57 1931.5833 8.88328 29.49 1931.7500 8.87954 28.73 1931.9167 8.99205 25.12 1932.0833 9.05089 23.49 1932.2500 9.06099 23.30 1932.4167 8.93416 27.39 1932.5833 8.84933 29.93 1932.7500 8.93451 28.58 1932.9167 9.04188 24.77 1933.0833 9.13744 22.62 1933.2500 9.07904 23.63 1933.4167 8.91608 27.81 1933.5833 8.85670 29.89 1933.7500 8.89316 28.89 1933.9167 9.02213 24.69 1934.0833 9.13949 22.28 1934.2500 9.10025 23.15 1934.4167 8.95200 27.22 1934.5833 8.84724 29.93 1934.7500 8.88183 29.17 1934.9167 9.06273 24.51 1935.0833 9.06398 22.19 1935.2500 9.06523 23.39 1935.4167 8.98352 27.49 1935.5833 8.87811 29.80 1935.7500 8.90262 28.77 1935.9167 9.00655 24.54 1936.0833 9.10909 22.08 1936.2500 9.06391 22.62 1936.4167 8.95746 27.02 1936.5833 8.86841 29.88

PAGE 63

56 1936.7500 8.88621 29.41 1936.9167 9.01935 25.09 1937.0833 9.04396 23.50 1937.2500 9.06500 23.63 1937.4167 8.94007 27.43 1937.5833 8.82859 30.05 1937.7500 8.90259 29.08 1937.9167 9.06727 23.72 1938.0833 9.10962 21.89 1938.2500 9.05192 23.39 1938.4167 8.93855 27.72 1938.5833 8.86914 29.76 1938.7500 8.91439 28.49 1938.9167 9.02224 25.15 1939.0833 9.14529 22.88 1939.2500 9.07487 24.05 1939.4167 8.93155 27.86 1939.5833 8.84598 30.20 1939.7500 8.89091 29.27 1939.9167 9.05350 24.20 1940.0833 9.15446 21.12 1940.2500 9.07065 22.43 1940.4167 8.94034 27.42 1940.5833 8.84060 30.12 1940.7500 8.93491 28.12 1940.9167 9.05203 24.00 1941.0833 9.15945 21.40 1941.2500 9.05858 22.84 1941.4167 8.95142 27.02 1941.5833 8.89153 29.43 1941.7500 8.88059 29.20 1941.9167 9.03811 25.22 1942.0833 9.22644 22.08 1942.2500 9.11427 22.68 1942.4167 8.92984 27.68 1942.5833 8.84894 30.10 1942.7500 8.88752 28.78 1942.9167 9.01889 25.03 1943.0833 9.08254 22.69 1943.2500 9.06747 23.39 1943.4167 8.89856 28.05 1943.5833 8.82392 30.61 1943.7500 8.86698 29.03 1943.9167 9.00585 24.98 1944.0833 9.08903 22.70

PAGE 64

57 1944.2500 9.07534 23.90 1944.4167 8.92537 27.72 1944.5833 8.81461 30.65 1944.7500 8.85728 29.15 1944.9167 9.04804 24.68 1945.0833 9.10164 21.95 1945.2500 9.05438 24.66 1945.4167 8.91166 27.67 1945.5833 8.86622 30.21 1945.7500 8.85630 29.08 1945.9167 9.02659 25.27 1946.0833 9.18071 21.95 1946.2500 9.12747 23.40 1946.4167 8.93882 27.46 1946.5833 8.83927 29.28 1946.7500 8.87715 28.75 1946.9167 9.02615 25.41 1947.0833 9.08932 22.62 1947.2500 9.10557 23.20 1947.4167 8.91806 27.40 1947.5833 8.88343 29.86 1947.7500 8.89927 28.91 1947.9167 9.02654 25.24 1948.0833 9.13351 23.23 1948.2500 9.05922 24.26 1948.4167 8.92846 27.89 1948.5833 8.89418 29.81 1948.7500 8.89120 28.79 1948.9167 9.01827 25.41 1949.0833 9.08870 23.56 1949.2500 9.03245 24.41 1949.4167 8.91957 27.62 1949.5833 8.87955 29.57 1949.7500 8.90356 29.09 1949.9167 9.01828 24.83 1950.0833 9.08502 23.53 1950.2500 9.08709 23.40 1950.4167 8.93653 27.47 1950.5833 8.89730 29.54 1950.7500 8.90857 28.49 1950.9167 9.01964 24.44 1951.0833 9.17317 21.31 1951.2500 9.06943 23.02 1951.4167 8.93007 27.16 1951.5833 8.85763 30.34

PAGE 65

58 1951.7500 8.89629 29.35 1951.9167 9.02276 24.88 1952.0833 9.12905 22.50 1952.2500 9.05697 23.98 1952.4167 8.94702 27.61 1952.5833 8.88365 29.98 1952.7500 8.91099 28.85 1952.9167 9.01262 24.58 1953.0833 9.10547 22.20 1953.2500 9.03856 24.39 1953.4167 8.92339 27.78 1953.5833 8.90009 30.10 1953.7500 8.89287 28.68 1953.9167 9.01302 24.81 1954.0833 9.13343 22.54 1954.2500 9.04021 23.92 1954.4167 8.94448 27.59 1954.5833 8.87074 30.17 1954.7500 8.90677 28.50 1954.9167 9.03208 23.88 1955.0833 9.16278 22.18 1955.2500 9.06190 23.35 1955.4167 8.93991 27.21 1955.5833 8.89135 29.54 1955.7500 8.88529 28.81 1955.9167 8.99772 25.24 1956.0833 9.10765 22.26 1956.2500 9.11491 22.62 1956.4167 8.97272 27.25 1956.5833 8.85166 29.87 1956.7500 8.90081 28.42 1956.9167 9.01734 24.61 1957.0833 9.08934 23.00 1957.2500 9.05299 23.93 1957.4167 8.90754 28.01 1957.5833 8.88527 30.39 1957.7500 8.88045 29.00 1957.9167 9.06171 24.29 1958.0833 9.17996 19.85 1958.2500 9.13175 21.39 1958.4167 8.95528 27.10 1958.5833 8.82414 30.49 1958.7500 8.86530 29.71 1958.9167 8.99152 25.92 1959.0833 9.07785 23.00

PAGE 66

59 1959.2500 9.06748 23.52 1959.4167 8.94064 27.45 1959.5833 8.89497 29.80 1959.7500 8.89827 29.23 1959.9167 9.02491 24.99 1960.0833 9.14376 21.96 1960.2500 9.08179 23.34 1960.4167 8.95428 27.42 1960.5833 8.85938 30.27 1960.7500 8.88022 29.33 1960.9167 9.01252 25.30 1961.0833 9.12638 22.49 1961.2500 9.03779 24.54 1961.4167 8.94620 27.59 1961.5833 8.88298 29.67 1961.7500 8.92767 28.43 1961.9167 9.01995 25.66 1962.0833 9.08795 23.33 1962.2500 9.08410 23.30 1962.4167 8.95059 27.14 1962.5833 8.86013 30.95 1962.7500 8.89918 29.89 1962.9167 9.03156 24.80 1963.0833 9.07749 22.16 1963.2500 9.05299 24.24 1963.4167 8.92300 28.01 1963.5833 8.89233 30.37 1963.7500 8.93601 29.25 1963.9167 9.05418 24.02 1964.0833 9.16162 21.27 1964.2500 9.09786 23.49 1964.4167 9.00549 27.66 1964.5833 8.95666 30.00 1964.7500 8.92290 28.50 1964.9167 9.05336 24.92 1965.0833 9.12731 23.03 1965.2500 9.06128 23.64 1965.4167 8.96983 26.89 1965.5833 8.90574 29.49 1965.7500 8.91102 28.38 1965.9167 9.05007 25.05 1966.0833 9.10246 21.87 1966.2500 9.08199 22.66 1966.4167 8.98447 26.97 1966.5833 8.87370 29.74

PAGE 67

60 1966.7500 8.85047 29.25 1966.9167 9.01609 24.34 1967.0833 9.12656 22.16 1967.2500 9.04558 23.62 1967.4167 8.95205 27.49 1967.5833 8.90497 29.79 1967.7500 8.92280 28.71 1967.9167 9.05942 25.22 1968.0833 9.12902 22.92 1968.2500 9.10587 23.16 1968.4167 8.96582 27.59 1968.5833 8.88252 29.69 1968.7500 8.90359 29.09 1968.9167 9.03442 24.73 1969.0833 9.08121 22.29 1969.2500 9.04929 22.86 1969.4167 8.95137 28.10 1969.5833 8.83955 30.76 1969.7500 8.89486 28.74 1969.9167 9.04065 24.53 1970.0833 9.16247 21.41 1970.2500 9.10909 23.33 1970.4167 8.97048 27.16 1970.5833 8.84899 29.65 1970.7500 8.90195 28.97 1970.9167 9.02881 24.90 1971.0833 9.12255 23.24 1971.2500 9.13176 22.62 1971.4167 8.94678 27.38 1971.5833 8.85408 30.00 1971.7500 8.89838 28.84 1971.9167 9.00018 26.01 1972.0833 9.07939 24.09 1972.2500 9.06742 23.97 1972.4167 8.95849 27.54 1972.5833 8.88164 29.51 1972.7500 8.88421 29.19 1972.9167 9.01465 26.07