Snow accumulation rates at Concordia Station from stake farm observations

In this study, surface mass balance (SMB) is estimated from snow accumulation data collected in the nearby area of Concordia Station. Results from the Italian and French stake farms are jointly analyzed. The Italian stake farm is located ~800 m southwest of the Concordia Station and consists of 13 stakes; observations started at the end of 2010 with almost monthly sampling. Some measurements are also available for the 2006-2010 period from a previous stake farm which was located ~300 m east of the current site. The French stake farm is located ~2 km south of the base and consists of 50 stakes; observations started in 2004 with yearly sampling conducted during austral summer. Snow build-up measurements at individual stakes show a strong variability caused by the interaction of wind-driven snow with surface micro-relief. Over the period of common observations, the present Italian stake farm generally underestimates the snow accumulation with respect to the French one, except for three years in which an overestimation is observed. Over the 2011-2023 period, the mean yearly accumulation recorded by the Italian and French stake farms is 7.3±0.2 cm and 8.4±0.1 cm, respectively. Bootstrap simulation has been performed to: (i) assess the significance of the differences between the two datasets; (ii) evaluate the effect of the different size of the stake farms and their distance to the Station on the measurements. Comparison of the observations with reanalysis datasets (ERA5 and MERRA2) and regional models (RACMO, MAR) has been also performed, with the first ones providing the best agreement with the observations. The potential shadowing effect of the station has also been investigated by analyzing the wind direction during the snowfall events, suggesting that buildings may influence accumulation when they are upwind with respect to the stake farms. Additionally, two more stake farms, located 25 km north and south of Concordia Station, are also analyzed to study the accumulation gradient across Dome C, confirming previous results of a continentality effect. On average, yearly accumulation increases by 0.7±0.2 cm over the 50 km span between the southern and northern stake farms. Results should be valuable for validating SMB estimates obtained from reanalysis, regional climate models and remote-sensing data.