Time series of methane and carbon dioxide concentrations measured in subglacial air in a cave under the Isunnguate Sermia glacier, Western Greenland. The Isunnguata Sermia is a glacier fed by the Greenland Ice Sheet. The time series are of shorter duration, 1 to 7 hours, and cover a 4-day period from August 23rd - 26th 2016.In situ concentrations of methane and carbon dioxide of the subglacial air were measured using a portable greenhouse gas analyzer based on state-of-the-art cavity ring-down spectroscopy with a measurement precision of 3 ppb and 0.4 ppm for methane and carbon dioxide, respectively and a sampling frequency of 1 hz (GasScouter G4301, Picarro Inc., CA, USA). The analyzer was connected to a flux chamber via a PVC tube (4 meter).

Supplement to: Christiansen, Jesper Riis; Jørgensen, Christian Juncher (2018): First observation of direct methane emission to the atmosphere from the subglacial domain of the Greenland Ice Sheet. Scientific Reports, 8(1)