Dating of the GV7 East Antarctic ice core by high-resolution chemical records and focus on the accumulation rate variability in the last millennium

Abstract. Ice core dating is the first step for a correct interpretation of climatic and environmental changes. In this work, we release uppermost 197 m 250 deep GV7(B) ice (drill site, 70∘41′ S, 158∘52′ E; 1950 a.s.l. in Oates Land, East Antarctica) with sub-annual resolution. Chemical records NO3-, MSA (methanesulfonic acid), non-sea-salt SO42- (nssSO42-), sea-salt ions water stable isotopes (δ18O) were studied as candidates due to their seasonal pattern. Different procedures tested but nssSO42- record proved be most reliable on short- long-term scales, so it was chosen annual layer counting along whole core. The constrained by using volcanic signatures from historically known events tie points, thus providing an accurate age–depth relationship period 1179–2009 CE. achievement complete age scale allowed us calculate mean accumulation rate throughout analyzed core, yielding annually resolved history snow site last millennium. A small yet consistent rise (Tr = 1.6, p<0.001) found 830 years starting around mid-18th century.