Research ArticleCLIMATOLOGY

Intertropical convergence zone variability in the Neotropics during the Common Era

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Science Advances  14 Feb 2020:
Vol. 6, no. 7, eaax3644
DOI: 10.1126/sciadv.aax3644
  • Fig. 1 Locations of Yok Balum Cave (magenta circle) and other records discussed in the text.

    The average annual northernmost (July) and southernmost (January) margins are also shown (yellow and blue bands, respectively).

  • Fig. 2 Age model and proxy comparison for stalagmite YOK-G.

    (A) U-series–based age model for speleothem YOK-G. The model was constructed using the COPRA algorithm (37), and the 2σ uncertainty limits are shown as green (top) and blue (bottom) curves. Individual sample ages (52 ages) and their errors are denoted as black bars. (B) δ13C and U concentration data for YOK-G. Note the inverted axis for U concentrations (brown line) compared with δ13C (black line). ppm, parts per million.

  • Fig. 3 Comparison between YOK-G δ13C and other rainfall proxy records at the northern and southern extents of the ITCZ.

    From north to south (A to C): (A) The JUX Cave (stalagmite JUX-MX) δ18O time series (light brown) from southwest Mexico (22). (B) Tzabnah Cave (Chaac stalagmite) δ18O time series (green line) from the northern Yucatan, Mexico (23). (C) Huagapo Cave δ18O time series (blue line) from the central Peruvian Andes (19). (D) Cariaco Basin Ti concentration record (purple) (4). Note that the Cariaco Ti axis is showing the opposite moisture trend (wet top). The best match for the full record is achieved between the two regions (C) that are located at the northern and southern margins of the ITCZ. Correlation statistics in each panel are for the time intervals indicated.

  • Fig. 4 Wavelet spectral analysis of high-resolution YOK-G δ13C data and detailed look at seasonal rainfall variability.

    (A) Wavelet spectral output of the high-resolution (0.25-year resolution) YOK-G δ13C data. (B) Difference in rainfall variability between the pre-ITCZ period and ITCZ period. Both segments were samples at the same, ~1.3-month, temporal resolution (small filled circles).

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/6/7/eaax3644/DC1

    Fig. S1. Location map.

    Fig. S2. Temperature and relative humidity data.

    Fig. S3. Results from duplicate analyses using Kiel and GasBench inlet systems.

    Fig. S4. δ13C versus rainy season (June to October) rainfall data.

    Fig. S5. Comparison between isotope data and growth rate.

    Fig. S6. δ18O and U concentration data for YOK-G.

    Fig. S7. Annual Oceanic Nino Index versus rainy season monthly average rainfall data.

    Table S1. Uranium-series chronology data.

  • Supplementary Materials

    The PDF file includes:

    • Fig. S1. Location map.
    • Fig. S2. Temperature and relative humidity data.
    • Fig. S3. Results from duplicate analyses using Kiel and GasBench inlet systems.
    • Fig. S4. δ13C versus rainy season (June to October) rainfall data.
    • Fig. S5. Comparison between isotope data and growth rate.
    • Fig. S6. δ18O and U concentration data for YOK-G.
    • Fig. S7. Annual Oceanic Nino Index versus rainy season monthly average rainfall data.

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    Other Supplementary Material for this manuscript includes the following:

    • Table S1 (Microsoft Excel format). Uranium-series chronology data.

    Files in this Data Supplement:

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