Atmospheric methane interpolar difference, four-box troposphere modeled sources, last glacial maximum and deglaciation, Greenland and Antarctica

• Main Authors: Benjamin Riddell-Young, Ed Brook
• Format: Dataset
• Language: unknown
• Published: Arctic Data Center 2023
• Subjects: Methane; Paleoclimate; Last Glacial Maximum; Deglaciation; Greenhouse Gases; Antarctica; Greenland; Antarctic; Antarc*; Greenland ice cores; Greenland Ice Sheet Project; ice core; Ice Sheet
• Online Access: https://doi.org/10.18739/A2222R75W

This dataset includes estimates of the atmospheric methane relative interpolar difference (rIPD) across the Last Glacial Maximum and Deglaciation. The rIPD was calculated using discrete, high-resolution methane measurements from the Western Antarctic Ice Sheet (WAIS) Divide, Northern Greenland Eemian (NEEM) and Greenland Ice Sheet Project Two (GISP2) ice cores. Two independent interpolar difference (IPD) records were determined: One using NEEM and WAIS and one using GISP2 and WAIS. The dataset includes rIPD values calculated using both Greenland methane data both corrected and uncorrected for excess methane (Lee et al., 2020). The rIPD was calculated by smoothing each methane record and synchronizing them to the WD2014 gas age scale. 1-sigma rIPD uncertainties are included. This dataset also includes the output of the four-box troposphere model used to interpret the rIPD. For both excess methane-corrected records, the model output and 1-sigma uncertainty is provided for northern extratropical (30N - 90N) and total tropical (30S - 30N) sources in teragrams per year (Tg yr-1). For the NEEM-derived rIPD, sections of the rIPD where atmospheric methane changed rapidly were deemed untrustworthy were removed from the dataset. Lee, J. E. et al. Excess methane in Greenland ice cores associated with high dust concentrations. Geochimica et cosmochimica acta 270, 409-430 (2020).