Seasonal cycles of nonmethane hydrocarbons and methyl chloride, as derived from firn air from Dronning Maud Land, Antarctica

[1] This paper presents atmospheric concentrations of ethane, propane, acetylene, and methyl chloride, inferred from firn air by using a numerical one-dimensional firn diffusion model. The firn air was collected on the Antarctic plateau in Dronning Maud Land during the Norwegian Antarctic Research E...

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Bibliographic Details
Published in:Journal of Geophysical Research
Main Authors: Kaspers, K. A., van de Wal, R. S. W., de Gouw, J. A., Hofstede, C. M., van den Broeke, M. R., Reijmer, C. H., Veen, C. van der, Neubert, R. E. M., Meijer, H. A. J., Brenninkmeijer, C. A. M., Karlöf, L., Winther, J. G.
Format: Article in Journal/Newspaper
Language:English
Published: 2004
Subjects:
firn air
seasonal cycles
NMHC
methyl chloride
POLAR ICE CORES
EAST ANTARCTICA
GREENLAND
SUMMIT
TROPOSPHERE
SNOW
ATMOSPHERE
INCREASE
CLIMATE
MASS
Antarctic
Dronning Maud Land
East Antarctica
Greenland
Neumayer
New Zealand
South Pole
The Antarctic
Antarc*
Antarctica
Antarctica Journal
South pole
Online Access:https://hdl.handle.net/11370/0561e8ef-34b8-4128-862c-91673bd0ff84
https://research.rug.nl/en/publications/0561e8ef-34b8-4128-862c-91673bd0ff84
https://doi.org/10.1029/2004JD004629
https://pure.rug.nl/ws/files/67045709/kaspersetal2004c.pdf
Description
Summary:[1] This paper presents atmospheric concentrations of ethane, propane, acetylene, and methyl chloride, inferred from firn air by using a numerical one-dimensional firn diffusion model. The firn air was collected on the Antarctic plateau in Dronning Maud Land during the Norwegian Antarctic Research Expedition (NARE) 2000/2001. The influences of seasonal variations in temperature and pressure and the variation in accumulation rate were studied and are not negligible, but appear to cancel each other out if all variability is taken into account. This paper also demonstrates that firn air from the uppermost firn layer (30 m) can be used to derive seasonal cycles of these trace gases, without needing a year-round facility. These cycles display higher atmospheric mixing ratios during the Antarctic winter and lower atmospheric mixing ratios in summer. The cycles for the year 2000 show amplitudes of 140 +/- 25 ppt for ethane, 30 +/- 10 ppt for propane, 24 +/- 6 ppt for acetylene, and 40 +/- 20 ppt for methyl chloride. For ethane and propane the amplitudes and months of maximum atmospheric concentration (phase) are in reasonable agreement with year-round measurements at the South Pole and Baring Head (New Zealand). The amplitudes for methyl chloride and acetylene are significantly greater than seen in year-round measurements at the South Pole and at Neumayer (Antarctica), although the phase is in line. While biomass burning and removal by OH radicals can partially explain these large amplitudes, the exact cause still remains unclear for methyl chloride and acetylene.

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