Change in chemical composition of the annual snow layer: the effects of rain event and melting processes

The annual snow layer is an extremely dynamic portion of the cryosphere and can be defined as the snow accumulated and present on the ground during the year. The snow deposited and accumulated over the glaciers reflects the average atmospheric composition and preserves some information about the transport processes of atmospheric aerosol. In the polar region, the annual snow strata can be preserved and the snow accumulation from year to year then forms proxies for climate reconstructions. However, several processes can influence the annual signal in the accumulated snow. To better interpret the chemical signal in ice archive is crucial to investigate the effect of the surface melting and the effect of water percolation due to some atmospheric events such as rain. A daily sampling of the first meter of snowpack was carried out in the Austre Brøggerbreen glacier (Spitsbergen, Svalbard Islands) from 27th March to 31st May 2015. During the experiment a rain event occurred 16th to 17th of April while from the 15th of May the snow had an homogeneous thermal profile. The main aim of this experiment was to describe the daily physical and chemical changes of snowpack occurred during a rain event and when the melting phase is on-going. This is the first field experiment about the evolution of chemical composition of snowpack in a Svaldard glacier. The presented dataset is unique and help to clarify the behaviour of cations (K+, Ca2+, Na+, Mg2+) anions (Br-, I-, SO42-, NO3-, Cl-, MSA) and two carboxylic acids (C2-glycolic and C5-glutaric acids) in the snow pack during this melting period. Understanding the dynamic of ions during these specific events is mandatory to use these species as climatic proxies in the ice cores archive.