Light-absorbing snow impurities: Nine years (2016–2024) of snowpack sampling close to Sonnblick Observatory, Austrian Alps

Abstract

We present chemical analysis data of the seasonal snow cover focusing on the light-absorbing snow impurities elemental carbon and mineral dust collected at a high-alpine glacier field close to Sonnblick Observatory. Sampling covered the whole winter accumulation periods between 2016 and 2024. The co-occurrence of mineral dust leads to an underestimation of elemental carbon quantified via thermal-optical analysis. To minimise the bias, we apply a linear laser correction, leading to a median increase in elemental carbon by 63 % for single samples and up to 8.3 % for entire snowpacks collected at the end of the accumulation period. Average concentrations for elemental carbon and water-insoluble organic carbon were 11.1±2.5 and 458±215 ng g⁻¹, respectively. Using the interference introduced by mineral dust, we identify mineral dust layers and find very good agreement with a complementary method based on calcium concentrations and the pH. Based on thermal-optical analysis and an average share of iron in mineral dust mass of 4 %, the approximated mineral dust input ranged up to 2100 mg m⁻². Results agree well with gravimetric results.