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 ngg-1, respectively, and ranged up to 86.3 and 3260 ngg-1 for single layers, respectively. Using the interference introduced by mineral dust, we identify mineral dust layers and find substantial agreement with a complementary method based on calcium concentrations and the pH. Based on thermal-optical analysis and an average iron fraction in mineral dust of 4 %, the approximated mineral dust concentrations ranged up to 25 µgg-1 in single layers. The approximated mineral dust input during the accumulation period agrees well with gravimetric results and ranged up to 2100 mgm-2.