A Sub-Seasonal Trace Chemical Ice Core Record from Piz Zupo, Swiss Alps

The NCCR Climate program `Varves, Ice cores, and Tree rings -- Archives with annual resolution (VITA)' aims to compare proxy climate records from trees, lakes, peat bogs and glaciers within the Engadine region, South-East Switzerland. The focus of this work is the ice core component of the VITA project. In March 2002 a 43 m ice core was extracted from the saddle between Piz Zupo and Piz Argient (46^o22'6.9''N, 9^o55'44.0''E, ∼3900 m asl). High-resolution sampling of the ice core was conducted (sample length 5-8~cm) and the samples analysed by ion chromatography for sodium, ammonium, potassium, magnesium, calcium, fluoride, acetate, formate, methanesulphonate, chloride, nitrate, sulphate and oxalate. Dating of the ice core was performed using the ammonium ion, which shows the most pronounced seasonal variations in Alpine ice cores with elevated levels during spring and summer. Counting these seasonal cycles, the Piz Zupo ice core spans an 11-year period from 1991-2001 with an uncertainty of ±1 year. Here we present a detailed examination of this record including (i) sub-seasonal variations of the chemical species, (ii) comparison of the chemical and meteorological records from the surrounding area, and (iii) identification of Saharan dust events and their spatial variability using various data sources.