250 years of accumulation, oxygen isotope and chemical records in a firn core from Princess Elizabeth Land, East Antarctica

Abstract

A 51.85-m firn core collected from site DT001 (accumulation rate 127 kgm -2 a -1 , mean annual temperature -33.1 o C) on Princess Elizabeth Land, East Antarctica, during the 1996-97 Chinese First Antarctic Inland Expedition has been analyzed for chemical composition and oxygen isotope ratio. A comparison between the seasonal variations of major ions was carried out in order to reduce the dating uncertainty, using the volcanic markers as time constrains. A deposition period of 251 years was determined. The calculated accumulation rates display an increasing trend before 1820, while after 1820, the trend of the accumulation is not obvious. Overall, temperature change in the region shows a slight increasing trend over the past 250 years. But, notably, a temperature decline of -2 o C is observed from 1860 to the present. This feature, at odds with the warming trend over the past century recorded in both hemispheres, likely reflects a regional characteristic related to the lack of a high latitude/low latitude link in the Southern Hemisphere circulation patterns. The results of the glaciochemical records of the firn core show that the mean concentrations of Cl -, Na + and Mg 2+ are similar to those reported from other sites in East Antarctica. However, the mean concentration of Ca 2+ is much higher than that reported from other regions, suggesting the influence of the strong local terrestrial sources in Princess Elizabeth Land. There is no evidence of a positive correlation between NO 3 -concentrations and solar activity (11-year solar cycle and solar cycle length), although solar proton events may account for some of the NO 3 -peak values in the record.

Application of visual stratigraphy from line-scan images to constrain chronology and melt features of a firn core from coastal Antarctica

“…Multiple and complementary methods are often used to establish more reliable ice core chronologies. When chronology for the past few centuries is established in coastal Antarctica, these methods are mainly a combination of annual layer counting, use of time markers and correlation with other dated time series, occasionally complemented with glaciological modelling (Stenni and others, 1999; Zhang and others, 2006; Thamban and others, 2013). High snow accumulation sites in the coastal region offer excellent opportunities to reconstruct sub-annual to annual climatic records by counting annual layers of stable water isotopes (Naik and others, 2010; Thamban and others, 2013; Philippe and others, 2016).…”