Research ArticleCLIMATOLOGY

Dole effect as a measurement of the low-latitude hydrological cycle over the past 800 ka

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Science Advances  07 Oct 2020:
Vol. 6, no. 41, eaba4823
DOI: 10.1126/sciadv.aba4823
  • Fig. 1 Modern global monsoon domain and locations of paleoclimatological reconstructions.

    Monsoon domain (green) was defined by Wang and Ding (1). Blue and red lines indicate the mean position of the Intertropical Convergence Zone for August and February, respectively (solid for monsoon trough and dashed for trade wind convergence) (24). Blue (11) and red (this study) dots indicate δ18Osurf reconstructions used for the generation of a global stack. WAIS, West Antarctic Ice Sheet; EPICA, European Project for Ice Coring in Antarctica.

  • Fig. 2 Comparison of proxy records over the past 800 ka.

    (A) A global stack of δ18Osurf (blue, with ±1σ standard error) [this study, (11)] and the modeled δ18Osw (red) (10). (B) Normalized δ18Osurf and δ18Osw are obtained by the z-standard method, which are further used to calculate the difference. (C) A composite δ18Oatm record from Antarctic ice cores, including the WAIS Divide and the Siple Dome (50 to 0 ka BP) (2, 5), the Vostok (100 to 50 ka BP) (12), and the EPICA Dome C (800 to 100 ka BP) (1317). (D) Chinese stalagmite δ18O, compiled by Cheng et al. (18). (E) A compilation of Bornean stalagmite δ18O (1922). The duration of terminations I to V is marked by yellow bars. In (B) to (E), dashed lines indicate the linear regression of each proxy record over the past 430 ka.

  • Fig. 3 Comparison of two different estimates of the ΔDE.

    (A) The previous estimate of ΔDE (red) and precession (gray). (B) Eccentricity cycles. (C) The new estimate of ΔDE* (blue, with ±1σ standard error) and precession (gray). (D) The global stack of benthic foraminiferal δ18O (23). Eccentricity, obliquity, and precession are derived from Berger (41), which are further normalized to calculate the ETP (E + T-P). Cross-spectral analysis results of the ETP with the previous (E) and the new (F) estimate of ΔDE, respectively, over the past 800 ka. In (E) and (F), the spectrum of each record is presented with the 95% confidence level (dashed lines). Below, coherency spectra are indicated by gray-filled curves associated with the 95% Monte Carlo false-alarm level (black dashed lines). The time-series analysis was performed using the REDFIT program (46). The numbers denote primary orbital cycles.

  • Fig. 4 Comparison of the ΔDE*, Chinese stalagmite δ18O, and simulated rainfall changes.

    (A) The ΔDE* (blue, with ±1σ standard error) and Chinese stalagmite δ18O (orange, after adjusted for changes in δ18Osurf) (17). (B) Simulated terrestrial rainfall changes between 30°N and 30°S (annual mean, green) and July 21 daily insolation at 20°N (gray) (41). (C) Simulated terrestrial rainfall changes over 0 to 30°N (annual mean, red) and 0 to 30°S (annual mean, blue). Simulation results are from the experiment CCSM3_orb+ghg + ice (Materials and Methods), which are further fitted using the Savitzky-Golay algorithm with 15 points at second order. In (D) and (E), spectra of the 800-ka ΔDE*, the 640-ka Chinese stalagmite δ18O, and the 300-ka simulation output are presented with the 95% confidence level (dashed lines). Below, coherency spectra of their cross-spectral analysis are indicated by gray-filled curves associated with the 95% Monte Carlo false-alarm level (black dashed lines). The time-series analysis was performed using the REDFIT program (46). The numbers denote primary orbital cycles.

Supplementary Materials

  • Supplementary Materials

    Dole effect as a measurement of the low-latitude hydrological cycle over the past 800 ka

    Enqing Huang, Pinxian Wang, Yue Wang, Mi Yan, Jun Tian, Shihan Li, Wentao Ma

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