Speculation on the origin of sub-baseline excursions of CH4 at Cape Grim

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dc.contributor.authorLoh, ZMen_AU
dc.contributor.authorKrummel, PBen_AU
dc.contributor.authorGregory, RLen_AU
dc.contributor.authorSteele, LPen_AU
dc.contributor.authorStavert, ARen_AU
dc.contributor.authorSchoot, MVVDen_AU
dc.contributor.authorSpencer, DAen_AU
dc.contributor.authorMitrevski, Ben_AU
dc.contributor.authorThornton, DPen_AU
dc.contributor.authorGalbally, IEen_AU
dc.contributor.authorWard, JZen_AU
dc.contributor.authorSomerville, NTen_AU
dc.contributor.authorChambers, SDen_AU
dc.contributor.authorWilliams, AGen_AU
dc.date.accessioned2016-06-07T06:29:44Zen_AU
dc.date.available2016-06-07T06:29:44Zen_AU
dc.date.issued2016-01-01en_AU
dc.date.statistics2016-05-17en_AU
dc.description.abstractThe Advanced Global Atmospheric Gases Experiment (AGAGE) program has historically measured in situ methane (CH4 ) at Cape Grim via gas chromatography with flame ionization detection (GC-FID) in 40 minutely grab samples. By adding continuous, high precision in situ measurements of CH4 (Picarro cavity ring-down spectroscopy [CRDS]) at both Cape Grim, Tasmania, and Casey, Antarctica, a new feature has become apparent in the Cape Grim CH4 record. During the austral summer (December to February), the Cape Grim CH4 record periodically drops below baseline. For example, in Figure 1, a number of sustained episodes of depressed CH4 concentration can be seen below the baseline selected data shown in red. Notably, these episodes are also seen in the GC-FID record. In this presentation, we examine these sub-baseline excursions of CH4 . In conjunction with meteorology and a variety of other chemical species measured at Cape Grim, including radon, ozone, hydrogen and ethane, we speculate on a number of possible mechanisms that might be responsible for these dips in CH4 mixing ratio.en_AU
dc.identifier.citationLoh, Z. M., Krummel, P. B., Gregory, R. L., Steele, L. P., Stavert, A. R., Schoot, M. V. V. D., Spencer, D. A., Mitrevski, B., Thornton, D. P., Galbally, I. E., Ward, J. Z., Somerville, N. T., Chambers, S. D., & Williams, AG. (2016). Speculation on the origin of sub-baseline excursions of CH4 at Cape Grim. Paper presented at the 44th NOAA Global Monitoring Annual Conference, Boulder Colorado. Retrieved from http://www.esrl.noaa.gov/gmd/annualconference/agenda.phpen_AU
dc.identifier.conferenceenddate18 May 2016en_AU
dc.identifier.conferencename44th NOAA Global Monitoring Annual Conferenceen_AU
dc.identifier.conferenceplaceBoulder, Coloradoen_AU
dc.identifier.conferencestartdate17 May 2016en_AU
dc.identifier.govdoc6642en_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/6926en_AU
dc.identifier.urihttps://www.esrl.noaa.gov/gmd/publications/annual_meetings/2016/slides/13-Loh.pdfen_AU
dc.language.isoenen_AU
dc.publisherNOAA Earth System Research Laboratoryen_AU
dc.subjectOriginen_AU
dc.subjectHydrogenen_AU
dc.subjectEthaneen_AU
dc.subjectRadonen_AU
dc.subjectAllocationsen_AU
dc.subjectOzoneen_AU
dc.titleSpeculation on the origin of sub-baseline excursions of CH4 at Cape Grimen_AU
dc.typeConference Presentationen_AU
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