Snow collection occurred at five locations (2 on Canada Glacier and 3 on Commonwealth Glacier) co-located with ice cores and seasonal mass balance measurement locations (ablation stakes). However, this package only includes data from the subset of samples that have been analyzed. Snow samples were collected within several meters of ice core collections (these data are in an accompanying data package) and mass balance stakes. Samples were collected using a clean scoop and gloved hands and placed in a clean whirlpack. Upon collection, samples were placed in a cooler that was transported back to a field camp and stored at -20º C. Samples were later transported to the Crary Lab at McMurdo Station where they were melted and poured into a triple DI-washed polyethylene bottle and refrozen. Samples were then shipped back to Boulder, Colorado and stored at -20º C.The samples collected from Canada Glacier on 28 November 2016 were thawed at 4º C and analyzed by atomic absorption spectroscopy for Ca2+, Mg2+, K+, and Na+, and by ion chromatography (IC) for Cl-, NO3-, and SO4-.While the remaining samples have not yet been processed, additional notes regarding sample collection are provided here for reference.

• 28 November 2016, Canada Glacier: Snow was collected from snowfall that began on 21 November 2016. Total accumulation was approximately 6 inches. Some snow melt was observed on the glacier at the time of sampling, particularly in more sloped locations. Samples were collected integrating the entire depth of snow, approximately 3 inches.
• 6 December 2016, Canada Glacier: Additional snow samples were collected at the #52 and #54 ablation stakes (same as on 28 November 2016). Snow was crusty and had been redistributed as a result of a Foehn wind event that had occurred on 1 December 2016. More sediment was visible in the snow.
• 12 December 2016, Canada Glacier: Snow was collected from the #52 and #54 ablation stakes in depressions that had collected/maintained wind-blown snow.
• 13 December 2016, Commonwealth Glacier: Snow was collected from the #5, #6 and #10 ablation stakes. There was approximately 2 inches of snow on top of ice at the time of collection.