Why is there is a persistent decrease in the amplitude of the seasonal cycle of atmospheric methane over the Arctic?
Abstract
Observed variations of atmospheric methane reflect changes in emissions and atmospheric chemistry and transport. A model is necessary to disentangle the competing processes that determine those variations. We focus our attention on Arctic sites where warming trends are projected to lead to increase methane emissions from thawing organic material. First, we spectrally decompose methane mole fraction data at Arctic stations to determine the dominant modes of observed variations. Using this method we will report annual growth rates at these sites but also changes in the amplitude of the seasonal cycle. We find, in particular, a robust and persistent decrease in the amplitude of the seasonal cycle that could be due to, for example, reduced midlatitude anthropogenic emissions being transported to Arctic latitudes and/or increased summertime Arctic emissions. To investigate this result and the importance of anthropogenic and wetland emissions, we use a global 3-D atmospheric chemistry transport model that takes into account changes in anthropogenic emissions. This allows us to investigate regional changes in the global context.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.A43P3366P
- Keywords:
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- 0315 Biosphere/atmosphere interactions;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0428 Carbon cycling;
- BIOGEOSCIENCESDE: 1605 Abrupt/rapid climate change;
- GLOBAL CHANGEDE: 1615 Biogeochemical cycles;
- processes;
- and modeling;
- GLOBAL CHANGE