5. What is the influence of major atmospheric circulation systems (e.g., ENSO) and oceanic circulation on the moisture flux over the Ross Sea Embayment region?
   Snow and ice stratigraphy reveals regional characteristics of change in snow accumulation at several sites in Antarctica (Gow, 1961, 1963; Giovinetto and Schwerdtfeger, 1966; Yamada et al., 1978; Petit et al., 1982; Morgan et al., 1991). In the studies where such data have been compared to existing meteorological records, intriguing correlations have been developed which provide insight into major patterns of atmospheric and oceanic circulation. Examples include: positive correlations between sea ice cover in the Orcadas Island area and South Pole snow accumulation (Fletcher, 1969); possible relationships between South Pole, Dome C and Wilkes snow accumulation and sea level pressure fluctuations over the 40-50oS latitudinal zone (Enomoto, 1991); and major atmospheric circulation system influences on Antarctic climate (e.g., Bromwich and Robasky, 1993; Stearns et al., 1993, Cullather et al., 1997).
   
   US ITASE ice core investigations have already been used to develop proxies for several of these major atmospheric features including ENSO and major atmospheric systems such as the Amundsen Sea Low and the East Antarctic High (e.g., Bromwich et al., 1999; Kreutz et al., 2000; Meyerson et. al., in review, Mayewski et al., 2004b, 2004c; Souney et al., 2002). Ice core investigations in the Taylor Dome to South Pole region should provide proxies for the potential influence of major moisture-bearing air masses and katabatic flow in this region.
   
6. How does climate (e.g., temperature, accumulation rate, atmospheric circulation) vary over the region of the Ross Sea Embayment on seasonal, inter-annual, decadal and centennial scales, and what are the controls on this variability?
   Considerable evidence exists for short-term annual- to decadal-scale variability throughout the Antarctic from a variety of records including: decadal and greater productivity cycles in Antarctic Peninsula sediments (Leventer et al., 1997); changes in snow accumulation related to changes in atmospheric circulation (Enomoto, 1991); and annual-scale and greater variations in atmospheric circulation (Hogan et al., 1982; White and Peterson, 1996; Kreutz et al., 2000; Mayewski et al., 2001, 2004c In addition, rapid disintegration of ice shelf regions in West Antarctica has been linked to atmospheric warming (e.g., Vaughan and Doake, 1996).
   
   US ITASE ice core records provide proxies for temperature, accumulation rate, sea ice, and atmospheric circulation that will reveal the spatial and temporal scale of climate variability in this region and have been used to demonstrate potential controls on climate variability (Mayewski et al., in review).
   
7. What is the frequency, magnitude and effect of extreme climate events recorded over the region of the Ross Sea Embayment?
   As noted earlier in this proposal the rapid climate change events recorded throughout the last 110,000 years of the Greenland ice core record are also recorded in Antarctica. The relationship between these events is, however, not well understood and will be a major focus of the deep ice core activities for US and European deep ice coring activities. Increasing evidence shows that Antarctica holds a unique and important record of regional to global scale extreme climate events (US ITASE Members; Mayewski, 2003).
   
   Results covering the instrumental era suggest marked changes in moisture convergence over West Antarctica are synchronous with the portions of the Southern Oscillation record (Cullather et al., 1997). Differences in pressure patterns between normal and ENSO years (Cullather et al., 1997) reveal marked differences that could be extended back through time if related to changes in ice core parameters. Promising results come from the ice core-based ENSO record developed by Legrand and Feniet-Saigne (1991) and Meyerson et al. (2002) and changes in ice core chemistry related to deepening of Antarctic low pressure systems (eg., Kreutz et. al., 2000 and Reusch et al., 1999; Souney et al., 2002; Mayewski et al., 2001, in press 2004c).
8. What is the impact of anthropogenic activity (e.g., ozone depletion, pollutants) on the climate and atmospheric chemistry of Antarctica?
   The Antarctic continent and surrounding sea ice not only influence global climate but also appear to be sensitive to small environmental changes and, hence, could provide early indications of global change (Manabe and Stouffer, 1979). While clear indications of the industrially derived pollutants recognized in Greenland ice cores appear to be lacking in Antarctica, we have little basis in Antarctica for assessing subtle onset of such changes. Since such changes may be expected first be seen as increases in background concentration and/or shifts in input timing, it is important to develop a high-resolution record of the chemistry and dynamics of recent Antarctic climate.
   
9. How much has biogeochemical cycling of S, N, O and C, as recorded over Antarctica, varied over the last several hundred years?
   Changes in climate and the chemistry of the atmosphere over Antarctica could have major effects on biogeochemical cycling and climate (Mayewski et al., in review) thereby causing complex feedbacks. For example, the impact of changes in UV radiation related to ozone depletion could affect marine productivity with consequent changes in the emissions of marine biogenic gases that impact global atmospheric chemistry and climate. Changes in marine biological productivity can be assessed through the measurement of S species (e.g., MS, non seasalt sulfate) in US ITASE ice cores.
   
10. What properties of ice control radar reflections?
    The stronger radar reflections thus far interpreted from US ITASE are responses to changes in density and chemistry (e.g., Arcone et al., in press; Spikes et al., in press). The next generation of high-resolution radars already has superior noise suppression yielding better penetration. By comparing ice core records that penetrate radar traverses US ITASE has demonstrated that some of the radar reflectors represent layers of known age. Known age reflectors have now been traced across much of the US ITASE route in West Antarctica, allowing estimates of accumulation rate to be extended over the same range. In addition by utilizing 100-MHz profiles of the top 80 m of ice sheets it may be possible to reveal evidence of Holocene warming periods (density) or changes in atmospheric circulation and climate (chemistry).
    
11. Additional opportunities offered by the US ITASE 2005-2007 traverse include:

1. Interpretation of satellite data.
   Ground-based traverses have the capability to investigate the causes of unusual features observed in satellite imagery. In addition, surface data collected during ground-based traverses will be valuable calibration data for ICESat and CryoSat (laser and radar altimeter) measurements.
2. Operational base for new projects.
   1. The proposed traverse could offer access for glacial geology and bedrock geology teams to make several visits to sites that would normally require major logistic support.
   2. US ITASE could provide a logistic platform for testing new instrumentation such as NASA’s autonomous polar vehicle (F. Carsey, JPL) and ice core sampling not routinely included in ice coring programs (e.g., biological materials).
   3. Logistics developments and route characterization may be of value for future OPP planning of science and logistics.
   4. Collaborative efforts between US ITASE and several other research activities.
      US ITASE cooperates with all of the other ITASE national projects. The Taylor Dome to South Pole traverse provides complimentary results for the proposed Australian ITASE traverse (Casey to Dome C), the Italian ITASE traverse (Terra Nova Bay to Dome C), and the French ITASE traverse (Dumont d’Urville to Dome).

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