Ice core glaciochemical records of late holocene climatic variability in West Antarctica.

摘要

The complex atmospheric and glaciological dynamics of West Antarctica make this region of particular interest in addressing the continent's cause and effect relationship in the global climate system, and for evaluating future global change scenarios. Ice core records from this region provide the resolution necessary to both improve our understanding of modern regional climate variability, and to reconstruct past changes in a number of climate components.; High-resolution (subannual to biannual) snow and ice core samples collected from two regions of West Antarctica, Siple Dome and Marie Byrd Land, were analyzed for water soluble major ion content. Examination of detailed surface snow data is used to determine seasonal chemical input timing, spatial variability, depositional and post-depositional processes, chemical sources, and transport pathways.; To develop quantitative relationships between temporal changes in ice core records and regional climatic conditions, Siple Dome glaciochemical data are correlated with meteorological observations, satellite sea ice data, and numerical modeling output. Results indicate that seasalt glaciochemistry at Siple Dome is a reliable proxy for changes in the Amundsen Sea Low pressure system. Multivariate time-series statistical investigation using high-resolution (subannual) chemical data suggests no significant trend in sea level pressure and atmospheric circulation strength over the past 110 years in the high-latitude South Pacific.; West Antarctic ice core glaciochemical records are correlated with other high-resolution climate proxy records to investigate climatic change over the last millennia. Comparison of Siple Dome and Central Greenland (GISP2) glaciochemical records reveals the synchronous onset of the Little Ice Age (LIA) in the polar South Pacific and North Atlantic. In these records, the LIA is recorded as a period of increased meridional wind strength beginning at {dollar}sim{dollar}1400 AD, and continuing to present in these two regions.; The research presented in this dissertation provides necessary baseline information for interpreting additional shallow and deep ice core records eventually recovered from West Antarctica. Such records will greatly advance our understanding of the high-latitude Southern Hemisphere climate system, as well as evaluate the past global extent, timing, and phasing of rapid climate change events.