Scipediacontent: Scipediacontent moved page Draft Content 239072190 to Trudinger et al 2013a

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Scipediacontent moved page Draft Content 239072190 to Trudinger et al 2013a

Scipediacontent: Created page with " == Abstract == Firn air transport models are used to interpret measurements of the composition of air in firn and bubbles trapped in ice in order to reconstruct past atmosph..."

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Created page with " == Abstract == Firn air transport models are used to interpret measurements of the composition of air in firn and bubbles trapped in ice in order to reconstruct past atmosph..."

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== Abstract ==

Firn air transport models are used to interpret measurements of the composition of air in firn and bubbles trapped in ice in order to reconstruct past atmospheric composition. The diffusivity profile in the firn is usually calibrated by comparing modelled and measured concentrations for tracers with known atmospheric history. However, in most cases this is an under-determined inverse problem, often with multiple solutions giving an adequate fit to the data (this is known as equifinality). Here we describe a method to estimate the firn diffusivity profile that allows multiple solutions to be identified, in order to quantify the uncertainty in diffusivity due to equifinality. We then look at how well different combinations of tracers constrain the firn diffusivity profile. Tracers with rapid atmospheric variations like CH3CCl3, HFCs and 14CO2 are most useful for constraining molecular diffusivity, while &delta:15N2 is useful for constraining parameters related to convective mixing near the surface. When errors in the observations are small and Gaussian, three carefully selected tracers are able to constrain the molecular diffusivity profile well with minimal equifinality. However, with realistic data errors or additional processes to constrain, there is benefit to including as many tracers as possible to reduce the uncertainties. We calculate CO2 age distributions and their spectral widths with uncertainties for five firn sites (NEEM, DE08-2, DSSW20K, South Pole 1995 and South Pole 2001) with quite different characteristics and tracers available for calibration. We recommend moving away from the use of a firn model with one calibrated parameter set to infer atmospheric histories, and instead suggest using multiple parameter sets, preferably with multiple representations of uncertain processes, to assist in quantification of the uncertainties.

Document type: Article

== Full document ==
<pdf>Media:Draft_Content_239072190-beopen343-9788-document.pdf</pdf>

== Original document ==

The different versions of the original document can be found in:

* [http://dx.doi.org/10.5194/acp-13-1485-2013 http://dx.doi.org/10.5194/acp-13-1485-2013] under the license http://creativecommons.org/licenses/by/3.0/

* [http://hdl.handle.net/11591/410561 http://hdl.handle.net/11591/410561] under the license https://creativecommons.org/licenses/by/3.0

* [https://eprints.keele.ac.uk/4836/1/2013Trudinger_How%20well%20do%20different%20tracers%20constrain%20the%20firn%20diffusivity%20profile.pdf https://eprints.keele.ac.uk/4836/1/2013Trudinger_How%20well%20do%20different%20tracers%20constrain%20the%20firn%20diffusivity%20profile.pdf]

* [https://www.atmos-chem-phys.net/13/1485/2013/acp-13-1485-2013.pdf https://www.atmos-chem-phys.net/13/1485/2013/acp-13-1485-2013.pdf] under the license http://creativecommons.org/licenses/by/3.0/

* [http://www.atmos-chem-phys.net/13/1485/2013/acp-13-1485-2013.pdf http://www.atmos-chem-phys.net/13/1485/2013/acp-13-1485-2013.pdf],
: [https://doaj.org/toc/1680-7316 https://doaj.org/toc/1680-7316],
: [https://doaj.org/toc/1680-7324 https://doaj.org/toc/1680-7324] under the license cc-by

* [https://acp.copernicus.org/articles/13/1485/2013/acp-13-1485-2013.pdf https://acp.copernicus.org/articles/13/1485/2013/acp-13-1485-2013.pdf],
: [http://dx.doi.org/10.5194/acp-13-1485-2013 http://dx.doi.org/10.5194/acp-13-1485-2013]

* [https://ir.library.oregonstate.edu/downloads/zk51vj23q https://ir.library.oregonstate.edu/downloads/zk51vj23q],
: [http://ui.adsabs.harvard.edu/abs/2013ACP....13.1485T/abstract http://ui.adsabs.harvard.edu/abs/2013ACP....13.1485T/abstract],
: [https://ir.library.oregonstate.edu/xmlui/handle/1957/38025 https://ir.library.oregonstate.edu/xmlui/handle/1957/38025],
: [https://www.atmos-chem-phys.net/13/1485/2013/acp-13-1485-2013-relations.html https://www.atmos-chem-phys.net/13/1485/2013/acp-13-1485-2013-relations.html],
: [https://acp.copernicus.org/preprints/12/17773/2012/acpd-12-17773-2012.pdf https://acp.copernicus.org/preprints/12/17773/2012/acpd-12-17773-2012.pdf],
: [https://noa.gwlb.de/receive/cop_mods_00050242 https://noa.gwlb.de/receive/cop_mods_00050242],
: [https://academic.microsoft.com/#/detail/2033540758 https://academic.microsoft.com/#/detail/2033540758] under the license https://creativecommons.org/licenses/by/3.0/

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Scipediacontent: Scipediacontent moved page Draft Content 239072190 to Trudinger et al 2013a

Scipediacontent: Created page with " == Abstract == Firn air transport models are used to interpret measurements of the composition of air in firn and bubbles trapped in ice in order to reconstruct past atmosph..."