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Daniel A. Dixon

Daniel A. Dixon. Daniel A. Dixon 20 th Century Forcing of the Antarctic Atmosphere. Climate Change Institute Department of Earth Sciences University of Maine. ITASE Traverse Routes. US ITASE traversed over >10,000 km Drilled >40 ice cores.

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Daniel A. Dixon

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  1. Daniel A. Dixon Daniel A. Dixon20th Century Forcing of the Antarctic Atmosphere Climate Change Institute Department of Earth Sciences University of Maine ITASE Traverse Routes • US ITASE traversed over >10,000 km • Drilled >40 ice cores

  2. Daniel A. DixonUS ITASE Traverse Routes and Ice Core Sites ITASE Traverse Routes

  3. Daniel A. DixonIce Core Dating Accuracy US ITASE SO4 time series (2005-1800 A.D.) Tambora Pinatubo Agung Krakatau Cosiguina?

  4. Daniel A. DixonIce Core Proxy for SH Westerlies Seasonal mean pattern of 850mb zonal winds around Antarctica Correlation field (nssCa and 850mb zonal winds 1948-2000) Antarctic Oscillation (AAO) AAO is the dominant pattern of Southern Hemisphere atmospheric variability south of 20ºS (From Yan et al., 2005) Warming causing intensification of the Southern Hemisphere westerlies and contraction of the Antarctic circumpolar vortex nssCa (ppb)

  5. Daniel A. DixonMultiple Ice Core Non-Sea-Salt-Calcium Records

  6. nssCa Records Positively Correlated with NCEP Zonal Winds

  7. nssCa Records Positively Correlated with NCEP Zonal Winds Jan-Dec 850mb Zonal Wind Correlation with Annual Ice Core nssCa 00-1 00-3 00-4 01-1 01-2 CWA-D SDM-94 UP-C

  8. US ITASE Normalized nssCa Stack Plot Correlation between ~1950-1995 AAO (Thompson & Wallace, 2000) & normalized 2.5yr nssCa stack yields: r = 0.862 (>99.9% sig.)

  9. Daniel A. DixonRAMP DEM vs. Ice Core Site Elevation Grid Contours

  10. Daniel A. DixonRAMP DEM vs. Ice Core Site Elevation Grid Contours

  11. Daniel A. DixonnssCa Concentration Contours (1800-1995)

  12. Daniel A. DixonnssCa Spatio-Temporal Concentration Trends 1800 1850 1995 1905 1945

  13. Daniel A. Dixon Conclusions • nssCa concentration increases at multiple sites since ~1850 A.D. • Biggest increases occur in West Antarctica • Rate of nssCa increase increases ~1950! • nssCa spatial concentration maps… • Goal to create major-ion and trace-element concentration maps for entire continent

  14. Daniel A. Dixon Questions…

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