This dataset contains two items: 1) firn air measurements of H2 from Megadunes, Antarctica. 2) atmospheric surface flask air measurements of H2 from NOAA GML, CSIRO, and AGAGE from 1991-2003 adjusted to a common calibration scale.   

Firn air was sampled at the Megadunes site in central Antarctica  (80.78 °S, 124.49 °E, Alt: 2,283 m) Antarctica during January of 2004.  A 3” diameter hole was bored to a depth of 70 m using an ice core drill. Drilling was paused at 15 unique depths so that firn air could be sampled. The sampling method was similar to techniques from previous published firn air studies. The hole was sealed above each sampling depth with an inflatable rubber packer to prevent contamination from the modern atmosphere. A waste air intake was positioned directly below the rubber packer. The waste air intake was separated from the sample air intake by a stainless-steel baffle with a 2 ¾” diameter. Air was pumped from the waste air intake 3x faster than from the sample air intake to ensure that no air that had been in contact with the rubber packer was sampled. 34 2 L glass flasks with Teflon seals were filled for analysis by the NOAA/GML ESRL Carbon Cycle group.

Details are given in the following manuscript:

J.D. Patterson, M. Aydin, A.M. Crotwell, G. Pétron, J.P. Severinghaus, P.B. Krummel, R.L. Langenfelds, and E.S. Saltzman

H₂ in Antarctic firn air: atmospheric reconstructions and implications for anthropogenic emissions, PNAS, 10.1073/pnas.2103335118, 2021.

The firn air samples were analyzed for H₂ at NOAA/GML using gas chromatography with a mercuric oxide reduction gas analyzer (HgO-RGA). Relative measurement uncertainty is estimated at ±2%. The H₂ measurements are reported as dry air mole fraction (ppb=nmol H₂ mol^-1 air). The measurements were corrected for calibration drift, detector non-linearity, and gravitational fractionation.