# Saharan dust fluxes over the last 22 ka in the Bahamas and central tropical Atlantic #----------------------------------------------------------------------- # World Data Center for Paleoclimatology, Boulder # and # NOAA Paleoclimatology Program #----------------------------------------------------------------------- # NOTE: Please cite original publication, online resource and date accessed when using this data. # If there is no publication information, please cite Investigator, title, online resource and date accessed. # # Description/Documentation lines begin with # # Data lines have no # # # Online_Resource: https://www.ncdc.noaa.gov/paleo/study/20775 # Online_Resource: http://www1.ncdc.noaa.gov/pub/data/paleo/paleocean/by_contributor/williams2016/williams2016-100-103ggc-iso.txt # # Archive: Paleoceanography # # Parameter_Keywords: radiogenic isotope, geochemistry #--------------------------------------- # Contribution_Date # Date: 2016-11-16 #--------------------------------------- # Title # Study_Name: Saharan dust fluxes over the last 22 ka in the Bahamas and central tropical Atlantic #--------------------------------------- # Investigators # Investigators: Williams, Ross H.; McGee, David; Kinsley, Christopher W.; Ridley, David A.; Hu, Shineng; Fedorov, Alexey; Tal, Irit; Murray, Richard W.; deMenocal, Peter B. #--------------------------------------- # Description and Notes # Description: Dust fluxes spanning the last 22 ka determined by Th-normalization in cores in the Bahamas and central tropical Atlantic # Provided Keywords: Saharan dust; Bahamas; North Atlantic; Th-normalization; Last Glacial Maximum; African Humid Period; Holocene #--------------------------------------- # Publication # Authors: R.H. Williams, D. McGee, D.A. Ridley, C.W. Kinsley, S. Hu, A. Fedorov, I. Tal, R. Murray, and P.B. deMenocal # Published_Date_or_Year: 2016 # Published_Title: Glacial to Holocene changes in trans-Atlantic Saharan dust transport and dust-climate feedbacks # Journal_Name: Science Advances # Volume: 2 # Edition: # Issue: # Pages: # Report Number: # DOI: 10.1126/sciadv.1600445 # Online_Resource: # Full_Citation: # Abstract: Saharan mineral dust exported over the tropical North Atlantic is thought to have significant impacts on regional climate and ecosystems, but limited data exists documenting past changes in long-range dust transport. This data gap limits investigations of the role of Saharan dust in past climate change, in particular during the early Holocene, when climate models consistently underestimate the intensification of the West African monsoon documented by paleorecords. Here we present reconstructions of African dust deposition in sediments from the Bahamas and the tropical North Atlantic spanning the last 23,000 years. Both sites show early Holocene dust fluxes 40-50% lower than recent values and maximum dust fluxes during the deglaciation, demonstrating strong agreement with records from the northwest African margin. These quantitative estimates of trans-Atlantic dust transport offer important constraints on past changes in dust-related radiative and biogeochemical impacts. Using idealized climate model experiments to investigate the response to reductions in Saharan dust's radiative forcing over the tropical North Atlantic, we find that small (0.15 °C) dust-related increases in regional sea surface temperatures are sufficient to cause significant northward shifts in the Atlantic Intertropical Convergence Zone, increased precipitation in the western Sahel and Sahara, and reductions in easterly and northeasterly winds over dust source regions. Our results suggest that the amplifying feedback of dust on sea surface temperatures and regional climate may be significant, and that accurate simulation of dust's radiative effects is likely essential to improving model representations of past and future precipitation variations in North Africa. #--------------------------------------- # Funding_Agency # Funding_Agency_Name: NSF # Grant: OCE-1030784, OCE-09277247 #--------------------------------------- # Funding_Agency # Funding_Agency_Name: NASA # Grant: NN14AP38G #--------------------------------------- # Site Information # Site_Name: OCE205-2 100GGC and 103GGC # Location: Bahamas # Country: # Northernmost_Latitude: 26.0703 # Southernmost_Latitude: 26.0612 # Easternmost_Longitude: -78.0277 # Westernmost_Longitude: -78.05617 # Elevation: #--------------------------------------- # Data_Collection # Collection_Name: OCE205-2 100GGC-103GGC Isotopes Williams2016 # First_Year: 22248 # Last_Year: 288 # Time_Unit: cal yr BP # Core_Length: # Notes: Ages for cores OCE205-2 100GGC and 103GGC previously published by Came et al. (2003; 2008) #--------------------------------------- # Chronology_Information # Chronology: # Ages for cores OCE205-2 100GGC and 103GGC previously published by Came et al. (2003; 2008) # #--------------------------------------- # Variables # Data variables follow that are preceded by "##" in columns one and two. # Variables list, one per line, shortname-tab-longname components (9 components: what, material, error, units, seasonality, archive, detail, method, C or N for Character or Numeric data) ## core Core,,,unitless,,,,,C ## depth_cm Depth,,,cm,,,,,N ## age Age,,,calendar ka BP,,,,,N ## water_depth_m Depth of water column,,,m,,,,,N ## 232Th 232Th activity,detrital ,,dpm/g,,Paleoceanography,,instrument: inductively coupled plasma mass spectrometer,N ## 232Th_error 232Th activity,detrital ,one standard deviation margin of error,dpm/g,,Paleoceanography,,instrument: inductively coupled plasma mass spectrometer,N ## 230Th 230Th activity,detrital ,,dpm/g,,Paleoceanography,,instrument: inductively coupled plasma mass spectrometer,N ## 230Th_error 230Th activity,detrital ,one standard deviation margin of error,dpm/g,,Paleoceanography,,instrument: inductively coupled plasma mass spectrometer,N ## 238U 238U activity,detrital ,,dpm/g,,Paleoceanography,,instrument: inductively coupled plasma mass spectrometer,N ## 238U_error 238U activity,detrital ,one standard deviation margin of error,dpm/g,,Paleoceanography,,instrument: inductively coupled plasma mass spectrometer,N ## 230Th_norm 230Th normalized sediment flux,detrital ,,g/cm^2/ka,,Paleoceanography,assumes detrital U/Th activity ratio of 0.6 ± 0.1,instrument: inductively coupled plasma mass spectrometer,N ## 230Th_norm_error 231st normalized sediment flux,detrital ,one standard deviation margin of error,g/cm^2/ka,,Paleoceanography,,instrument: inductively coupled plasma mass spectrometer,N ## 232Th_conc 232Th concentration,detrital ,,µg/g,,Paleoceanography,,instrument: inductively coupled plasma mass spectrometer,N ## detrital_flux Dust flux,,,g/cm2/kyr,,Paleoceanography,assumes 232Th concentration of 13.7 ± 1.0 µg/g in dust,,N ## detrital_flux_error Dust flux,,one standard deviation margin of error,g/cm2/kyr,,Paleoceanography,,,N #------------------------ # Data # Data lines follow (have no #) # Data line format - tab-delimited text, variable short name as header # Missing Value: NA core depth_cm age water_depth_m 232Th 232Th_error 230Th 230Th_error 238U 238U_error 230Th_norm 230Th_norm_error 232Th_conc detrital_flux detrital_flux_error OCE205-2 103GGC 5.5 0.29 965 0.099 0.002 1.000 0.020 1.931 0.039 2.758 0.066 0.408 0.082 0.006 OCE205-2 103GGC 15.5 1.14 965 0.09 0.002 0.980 0.020 2.076 0.042 2.837 0.068 0.372 0.077 0.006 OCE205-2 103GGC 26.5 2.65 965 0.091 0.002 1.070 0.021 2.422 0.048 2.657 0.065 0.375 0.073 0.006 OCE205-2 103GGC 33.5 3.14 965 0.087 0.002 0.989 0.020 2.012 0.04 2.877 0.071 0.357 0.075 0.006 OCE205-2 103GGC 35.5 3.32 965 0.094 0.002 1.195 0.024 2.222 0.044 2.357 0.057 0.389 0.067 0.005 OCE205-2 103GGC 36 3.37 965 0.084 0.002 1.037 0.021 1.968 0.039 2.727 0.067 0.347 0.069 0.005 OCE205-2 103GGC 38.5 3.59 965 0.084 0.002 1.051 0.021 1.986 0.04 2.695 0.066 0.345 0.068 0.005 OCE205-2 103GGC 40.5 3.73 965 0.081 0.002 1.033 0.021 1.964 0.039 2.745 0.067 0.334 0.067 0.005 OCE205-2 103GGC 45 4.02 965 0.083 0.002 1.167 0.023 2.108 0.042 2.416 0.058 0.344 0.061 0.005 OCE205-2 103GGC 46.5 4.17 965 0.091 0.002 1.288 0.026 2.530 0.051 2.209 0.054 0.376 0.061 0.005 OCE205-2 103GGC 49.25 4.47 965 0.077 0.002 1.177 0.024 2.230 0.045 2.409 0.058 0.319 0.056 0.004 OCE205-2 103GGC 54 5.00 965 0.076 0.002 1.259 0.025 2.174 0.043 2.238 0.054 0.314 0.051 0.004 OCE205-2 103GGC 55.5 5.16 965 0.077 0.002 1.308 0.026 2.188 0.044 2.149 0.051 0.318 0.050 0.004 OCE205-2 103GGC 64.5 5.88 965 0.085 0.002 1.365 0.027 2.276 0.046 2.077 0.051 0.352 0.053 0.004 OCE205-2 103GGC 74.5 7.08 965 0.099 0.002 1.521 0.030 2.068 0.041 1.840 0.045 0.409 0.055 0.004 OCE205-2 103GGC 84.5 7.89 965 0.105 0.002 1.564 0.031 2.212 0.044 1.810 0.045 0.432 0.057 0.004 OCE205-2 103GGC 97 10.20 935 0.126 0.003 1.692 0.034 1.831 0.037 1.588 0.040 0.519 0.060 0.005 OCE205-2 103GGC 97.5 10.27 935 0.144 0.003 1.753 0.035 1.790 0.036 1.529 0.039 0.594 0.066 0.005 OCE205-2 103GGC 99.5 10.46 935 0.139 0.003 1.600 0.032 1.644 0.033 1.682 0.044 0.573 0.070 0.005 OCE205-2 103GGC 101.5 10.66 935 0.149 0.003 1.694 0.034 1.633 0.033 1.578 0.041 0.614 0.071 0.005 OCE205-2 103GGC 103.5 11.15 925 0.184 0.004 1.949 0.039 1.328 0.027 1.314 0.033 0.759 0.073 0.006 OCE205-2 103GGC 105.5 11.48 915 0.186 0.004 1.827 0.037 1.122 0.022 1.380 0.036 0.767 0.077 0.006 OCE205-2 103GGC 107.5 11.73 915 0.229 0.005 1.763 0.035 0.830 0.017 1.426 0.039 0.944 0.098 0.008 OCE205-2 103GGC 110.5 12.26 915 0.185 0.004 1.971 0.039 1.275 0.026 1.275 0.032 0.763 0.071 0.005 OCE205-2 103GGC 112.5 12.52 915 0.185 0.004 1.932 0.039 1.237 0.025 1.300 0.034 0.763 0.072 0.006 OCE205-2 103GGC 114.5 12.69 915 0.249 0.005 1.903 0.038 0.848 0.017 1.310 0.036 1.027 0.098 0.008 OCE205-2 103GGC 116.5 13.01 905 0.274 0.005 1.966 0.039 0.831 0.017 1.255 0.035 1.130 0.103 0.008 OCE205-2 103GGC 118.5 13.37 895 0.276 0.006 1.997 0.040 0.902 0.018 1.224 0.034 1.138 0.102 0.008 OCE205-2 103GGC 120.5 13.61 885 0.288 0.006 1.941 0.039 0.780 0.016 1.241 0.036 1.187 0.108 0.008 OCE205-2 103GGC 122.5 14.04 875 0.444 0.009 2.154 0.043 0.659 0.013 1.125 0.038 1.831 0.150 0.012 OCE205-2 103GGC 124.5 15.09 865 0.471 0.009 2.229 0.045 0.643 0.013 1.066 0.037 1.942 0.151 0.012 OCE205-2 103GGC 126.5 16.28 860 0.449 0.009 2.28 0.046 0.586 0.012 1.013 0.034 1.851 0.137 0.011 OCE205-2 103GGC 128.5 17.50 855 0.399 0.008 2.162 0.043 0.646 0.013 1.053 0.034 1.645 0.126 0.010 OCE205-2 103GGC 130.5 18.69 845 0.42 0.008 2.14 0.043 0.533 0.011 1.038 0.034 1.732 0.131 0.011 OCE205-2 103GGC 132.5 19.72 845 0.421 0.008 2.197 0.044 0.556 0.011 1.002 0.033 1.736 0.127 0.010 OCE205-2 103GGC 134.5 20.37 845 0.423 0.008 2.171 0.043 0.528 0.011 1.008 0.033 1.744 0.128 0.010 OCE205-2 103GGC 137.5 21.66 845 0.409 0.008 2.163 0.043 0.554 0.011 1.001 0.032 1.686 0.123 0.010 OCE205-2 103GGC 139.5 22.25 845 0.39 0.008 2.081 0.042 0.571 0.011 1.040 0.034 1.608 0.122 0.010 OCE205-2 100GGC 5.5 0.48 1057 0.140 0.003 1.333 0.027 1.661 0.033 2.272 0.055 0.578 0.096 0.007 OCE205-2 100GGC 15 1.40 1057 0.085 0.002 0.944 0.019 1.842 0.037 3.225 0.077 0.349 0.082 0.006 OCE205-2 100GGC 25 2.47 1057 0.090 0.002 1.043 0.021 2.459 0.049 2.986 0.073 0.37 0.081 0.006 OCE205-2 100GGC 35 3.26 1057 0.093 0.002 1.149 0.023 2.24 0.045 2.696 0.066 0.385 0.076 0.006 OCE205-2 100GGC 45 4.06 1057 0.083 0.002 1.212 0.024 2.081 0.042 2.532 0.06 0.341 0.063 0.005 OCE205-2 100GGC 54 4.83 1057 0.083 0.002 1.359 0.027 2.366 0.047 2.269 0.054 0.342 0.057 0.004 OCE205-2 100GGC 65 5.62 1057 0.083 0.002 1.350 0.027 2.286 0.046 2.296 0.056 0.341 0.057 0.004 OCE205-2 100GGC 114 12.73 1007 0.273 0.005 2.164 0.043 0.743 0.015 1.246 0.033 1.125 0.102 0.008