Seasonal variations of glaciochemical, isotopic and stratigraphic properties in Siple Dome (Antarctica) surface snow

Six snow-pit records recovered from Siple Dome, West Antarctica, during 1994 are used to study seasonal variations in chemical (major ion and H2O2), isotopic (deuterium) and physical stratigraphic properties during the 1988-94 period. Comparison of delta D measurements and satellite-derived brightness temperature for the Siple Dome area suggests that most seasonal delta D maxima occur within +/-4 weeks of each 1 January. Several other chemical species (H2O2, non-sea-salt (nss) SO42-, methanesulfonic acid and NO3-) show coeval peaks with delta D, together providing an accurate method for identifying summer accumulation. Sea-salt-derived species generally peak during winter/spring, but episodic input is noted throughout some years. No reliable seasonal signal is identified in species with continental sources (nssCa(2+), nssMg(2+)), NH4+ or nssCl(-). Visible strata such as large depth-hoar layers (>5 cm) are associated with summer accumulation and its metamorphosis, but smaller hear layers and crusts are more difficult to interpret. A multi-parameter approach is found to provide the most accurate dating of these snow-pit records, and is used to determine annual laver thicknesses at each site. Significant spatial accumulation variability exists on an annual basis, but mean accumulation in the sampled 10 km(2) grid for the 1988-94 period is fairly uniform.