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

2. Daniel A. Dixon US ITASE Traverse Routes and Ice Core Sites ITASE Traverse Routes

3. US ITASE SO 4 time series (2005-1800 A.D.) PinatuboAgung Daniel A. Dixon Ice Core Dating Accuracy Cosiguina?Krakatau Tambora

4. Daniel A. Dixon Ice Core Proxy for SH Westerlies Warming causing intensification of the Southern Hemisphere westerlies and contraction of the Antarctic circumpolar vortex 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 nssCa (ppb) (From Yan et al., 2005)

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

6. nssCa Records Positively Correlated with NCEP Zonal Winds

7. 00-100-3 00-401-1 01-2CWA-DSDM-94UP-C nssCa Records Positively Correlated with NCEP Zonal Winds Jan-Dec 850mb Zonal Wind Correlation with Annual Ice Core nssCa

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

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

11. Daniel A. Dixon nssCa Concentration Contours (1800-1995)

12. Daniel A. Dixon nssCa Spatio-Temporal Concentration Trends 1800 1850 1905 19451995

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…