Arabian Sea Surface Temperature Pattern Reconstructions ----------------------------------------------------------------------- World Data Center for Paleoclimatology, Boulder and NOAA Paleoclimatology Program ----------------------------------------------------------------------- NOTE: PLEASE CITE CONTRIBUTORS WHEN USING THIS DATA!!!!! NAME OF DATA SET: Arabian Sea Surface Temperature Pattern Reconstructions LAST UPDATE: 5/2006 (Original receipt by WDC Paleo) CONTRIBUTOR: Kristina Dahl, University of California, San Diego. IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2006-049 SUGGESTED DATA CITATION: Dahl, K.A. and D.W. Oppo. 2006. Arabian Sea Surface Temperature Pattern Reconstructions. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2006-049. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCE: Dahl, K.A. and D.W. Oppo. 2006. Sea surface temperature pattern reconstructions in the Arabian Sea. Paleoceanography, v. 21, PA1014, doi:10.1029/2005PA001162. ABSTRACT: Sea surface temperature (SST) and seawater d18O (d18Ow) were reconstructed in a suite of sediment cores from throughout the Arabian Sea for four distinct time intervals (0 ka, 8 ka, 15 ka, and 20 ka) with the aim of understanding the history of the Indian Monsoon and the climate of the Arabian Sea region. This was accomplished through the use of paired Mg/Ca and d18O measurements of the planktonic foraminifer Globigerinoides ruber. By analyzing basin-wide changes and changes in cross-basinal gradients, we assess both monsoonal and regional-scale climate changes. SST was colder than present for the majority of sites within all three paleotime slices. Furthermore, both the Indian Monsoon and the regional Arabian Sea mean climate have varied substantially over the past 20 kyr. The 20 ka and 15 ka time slices exhibit average negative temperature anomalies of 2.5–3.5C attributable, in part, to the influences of glacial atmospheric CO2 concentrations and large continental ice sheets. The elimination of the cross-basinal SST gradient during these two time slices likely reflects a decrease in summer monsoon and an increase in winter monsoon strength. Changes in d18Ow that are smaller than the d18O signal due to global ice volume reflect decreased evaporation and increased winter monsoon mixing. SSTs throughout the Arabian Sea were still cooler than present by an average of 1.4C in the 8 ka time slice. These cool SSTs, along with lower d18Ow throughout the basin, are attributed to stronger than modern summer and winter monsoons and increased runoff and precipitation. The results of this study underscore the importance of taking a spatial approach to the reconstruction of processes such as monsoon upwelling. GEOGRAPHIC REGION: Arabian Sea PERIOD OF RECORD: 20 KYrBP - present FUNDING SOURCES: Analyses were funded by National Science Foundation (USA) SGER grant OCE03-34598. Funding was also provided by a Schlanger Ocean Drilling Program Fellowship (to K.A.D.) and NSF grant OCE02-20776 (to D.W.O.). DESCRIPTION: These data come from cores throughout the Arabian Sea. We measured d18O, shell weight, and Mg/Ca of G. ruber for four distinct time horizons within the core. Forams were subjected to a full oxidative and reductive cleaning prior to Mg/Ca analysis, as per Boyle and Keigwin (1985) and subsequent revisions. Mg/Ca was converted to SST using the shell weight-dependent calibration of Rosenthal and Lohmann (2002). SST and d18O were used to calculate the d18O of seawater using Mulitza et al. (2003) calibration for G. ruber. DATA: 1. Sample Locations Table 1. Locations of Sediment Samples Used in This Study Cruise Core Time Slices Latitude Longitude Water Depth,m Sample Depth, cm below sea floor SO28 5KL 20 6deg. 39.80N 61deg. 8.00E 3335 30–33 SO28 11KL 0,8,15,20 5deg. 23.40N 60deg. 15.10E 3859 0–5/11–14/41–44/65–69 SO28 18KL 0,8,15,20 1deg. 54.00N 67deg. 20.50E 3035 0–10/17–21/33–37/43–47 SO42 15KL 8,20 14deg. 52.80N 64deg. 44.80E 3920 16–20/50–54 SO42 26KL 0,8,15,20 15deg. 30.90N 68deg. 45.60E 3776 0–5/15–19/78–82/103–107 SO42 36KL 0,8,15,20 17deg. 04.50N 69deg. 02.70E 2055 0–5/8–12/26–30/43–47 SO42 51KL 8,15,20 20deg. 57.90N 65deg. 33.50E 2644 28–32/78–82/130–134 SO42 57KL 0,8,15,20 20deg. 54.50N 63deg. 07.30E 3422 0–5/28–32/78–82/118–122 SO42 64KL 8,15,20 19deg. 4.60N 64deg. 41.00E 3281 8–12/58–62/96–100 SO42 70KL 8,15,20 17deg. 30.70N 61deg. 41.80E 3810 18–22/58–62/82–86 SO42 71KL 8,15 16deg. 14.20N 60deg. 15.30E 4029 38–40/70–74 SO42 74KL 0,8,15,20 14deg. 19.30N 57deg. 20.80E 3212 9–15/62–66/138–142/200–204 SO42 79KL 8,15 14deg. 19.30N 58deg. 19.60E 4351 38–42/79–83 SO42 82KL 8,15,20 12deg. 41.10N 58deg. 40.60E 4416 8–10/58–62/100–105 SO42 87KL 0,15,20 10deg. 30.10N 57deg. 44.20E 3773 0–5/94–98/118–122 SO90 39KG 0 24deg. 50.00N 65deg. 55.00E 704 0–2 SO130 211KG 0 24deg. 52.90N 63deg. 1.60E 691 0–2 SO130 282KG 0 23deg. 32.30N 65deg. 19.00E 988 0–1 SO130 285MC 0 23deg. 5.80N 66deg. 29.00E 778 0–1 IOE 105KK 15,20 11deg. 16.00N 53deg. 32.50E 3535 111–119/138–143 IOE 114KK 20 08deg. 00.50N 51deg. 12.80E 3843 137–141 IOE 143KK 0,20 01deg. 15.00N 44deg. 47.00E 1522 12–19/253–258 TN47 6GGC 0,8,15,20 17deg. 22.90N 58deg. 47.70E 3652 5–6/66–66.5/122–122.5/208–208.5 TN41 32MC 0 19deg. 30.10N 58deg. 28.10E 784 0–1 2. Isotope, Mg/Ca, SST data Column 1: Timeslice (KYrBP) Column 2: Core Column 3: d18O Column 4: Shell Weight (ug) Column 5: Mg/Ca (mmol/mol) Column 6: SST deg. C Column 7: d18O water (SMOW) Time Core d18O Shellwt Mg/Ca SST d18Ow(smow) 0 11KL -1.44 8.97 3.6 25 1.26 0 18KL -2.08 8.83 4.2 26.7 1 0 26KL -1.96 8.59 4.7 28.1 1.45 0 36KL -1.91 10.14 5.4 28.4 1.56 0 51KL -2.01 0 57KL -2.17 8.25 5.8 30.4 1.75 0 74KL -1.92 7.66 3.9 26.9 1.21 0 87KL -1.33 10.17 3.6 24.1 1.17 0 KK143 -2.31 11.32 4.5 25.7 0.55 0 6GGC -1.87 6.13 5.7 26.4 0.88 0 32MC -2.11 0 39KG -2.13 8.48 4.65 28.1 1 0 211KG -2.07 8.56 4.63 28 1.04 0 282KG -2.27 9.38 4.46 26.9 0.59 0 285MC -1.95 8.72 4.64 27.9 1.14 8 11KL -1.18 10.76 3.69 23.9 1.28 8 15KL -1.35 12.58 3.83 23.1 0.93 8 18KL -2.2 9.8 4.06 25.6 0.64 8 26KL -1.95 12.77 4.71 25.2 0.8 8 36KL -1.37 12.21 4.29 24.6 1.24 8 51KL -1.77 9.63 3.63 24.6 0.85 8 57KL -1.9 8 64KL -2.18 8.68 3.85 25.9 0.72 8 70KL -0.9 10.85 3.8 24.2 1.63 8 71KL -2.06 9.85 3.91 25.2 0.69 8 74KL -1.8 8.93 4.1 26.4 1.21 8 79KL -1.87 9.26 3.76 25.2 0.88 8 82KL -1.92 9 4.22 26.7 1.16 8 87KL -2.13 10 3.89 25.1 0.59 8 6GGC 0.74 9.3 3.62 24.8 -0.14 15 11KL -0.54 10.61 3.26 22.8 1.67 15 18KL -0.74 12.03 3.01 21 1.06 15 26KL -0.26 14.76 3.57 21.1 1.57 15 36KL -0.47 12.84 4.18 23.9 1.99 15 51KL 0.15 12.2 4.98 26.2 3.12 15 57KL -0.07 12.11 4.49 25.1 2.66 15 64KL -0.19 11.92 3.99 24 2.28 15 70KL -0.21 9.11 3.37 24.2 2.31 15 71KL -0.36 11.55 4.88 26.4 2.66 15 74KL -0.07 10.72 4.06 25 2.63 15 79KL -0.41 10 3.09 22.6 1.75 15 82KL -0.4 8.94 3.53 24.8 2.25 15 87KL -0.55 11.4 3.17 21.9 1.46 15 KK105 -1.17 9.67 4.02 25.6 1.67 15 6GGC 1.94 9.7 2.8 21.8 1.06 20 5KL -0.68 11 3.05 21.8 1.3 20 11KL -0.8 9.15 3.32 24 1.68 20 15KL -0.42 9.55 3.32 23.7 1.99 20 18KL -1.07 10.74 3.28 22.7 1.12 20 26KL -0.2 11 2.76 20.7 1.54 20 36KL -0.39 10.59 3.69 24.1 2.11 20 51KL 1.06 11.86 3.11 21.4 2.95 20 57KL -0.23 20 64KL -0.35 10.17 3.21 22.9 1.88 20 70KL -0.38 8.79 3.63 25.3 2.39 20 74KL -0.22 10.4 3.02 22.1 1.83 20 82KL -0.38 9.78 3.09 22.8 1.83 20 87KL -0.25 10.1 3 22.2 1.82 20 KK105 -1 8.66 3.76 25.7 1.86 20 KK114 -0.57 10.89 3.12 22.1 1.48 20 KK143 -0.43 9.89 3.27 23.3 1.89 20 6GGC 1.95 8.5 2.86 23 1.07