Victoria University Antarctic Research Expedition Science and Logistics Reports 2006-07: VUWAE 51
The main objective of ITASE is to determine the spatial climate variability across Antarctica over the last 200 years, and where possible further back in time. The focus of the New Zealand ITASE group (this proposal) is to provide information from the climate sensitive, low altitude, coastal sites (Fig.8). This will capture the climate signature of the troposphere, which represents a regional account on the Ross Sea climate. Our preceding research showed that while the direct ENSO influence warms the eastern Ross Sea (oceanic forcing), the indirect ENSO influence dominated in the western Ross Sea, leading to the observed cooling in McMurdo Sound Region (atmospheric forcing) (Bertler et al., 2004a; Bertler et al., 2005b). The comparison with data from other ITASE-nations will allow us to date relative phasing and signal migration velocities of these climate drivers across Antarctica.
Furthermore, the gas record will allow us to determine the role of CO2 and in rapid climate change events and the CO2 and methane source/sink fluxes of the Ross Sea. The isotopic page 14 fractionation of biogenic (terrestrial) material is –with the exception of C4 plants – enriched in the lighter 13C isotopes and carries therefore a different signature than ocean derived carbon, which shows no such enrichment (Indermühle et al., 1999; Sigman & Boyle, 2000). For this reason the change of isotopic ratio in CO2 and CH4 can be used to determine the change in sources of GHG concentration through time. This is particular important to determine the role of the oceans versus the atmosphere in rapid climate change (White, 1993; Stocker, 1998; Broecker, 2000; Schrag, 2000; Stocker, 2002; Broecker, 2003; Ferretti et al., 2005) and has the potential to detect influences of early human activities in the late Holocene (Ruddimann, 2003).
In conjunction with the US-ITASE traverse of our collaboration partners altitude and continentality gradients across the Trans Antarctic Mountains (TAM) can be established. Temperature and humidity gradients across the TAM are amongst the most extreme on the continent and exceed the latitudinal gradients by more than one order of magnitude. The correlation between the US-ITASE polar plateau traverse (Fig.8) and our data will allow determining the climatic influence of the mountain range and also the position of the Antarctic Vortex, the geographical boundary of tropospheric and stratospheric influence. The results of the NZ ITASE programme contributes directly to science aims of the International Partnership of Ice Coring Sciences (IPICS) and Antarctica in the Global Climate System (AGCS).