Difference between revisions of "Climate Proxy"
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Observations of past climates are necessarily indirect. These observations are made on climate '''proxies''' in various geological (e.g. lake or marine sediments, living or fossil coral reefs, cave deposits), glaciological (ice cores or snow pits) or biological (trees) [[archive]]s. Many data streams can be collected from each archives, each '''sensing''' a different aspect of the environment (sometimes, several aspects at once). A paleoclimate dataset is almost always a [https://en.wikipedia.org/wiki/Time_series time series] of observations made on a proxy system. | Observations of past climates are necessarily indirect. These observations are made on climate '''proxies''' in various geological (e.g. lake or marine sediments, living or fossil coral reefs, cave deposits), glaciological (ice cores or snow pits) or biological (trees) [[archive]]s. Many data streams can be collected from each archives, each '''sensing''' a different aspect of the environment (sometimes, several aspects at once). A paleoclimate dataset is almost always a [https://en.wikipedia.org/wiki/Time_series time series] of observations made on a proxy system. | ||
| − | + | Evans et al. (2013) <ref name="evans2013"> Evans, M. N., Tolwinski-Ward, S. E., Thompson, D. M., & Anchukaitis, K. J. (2013). Applications of proxy system modeling in high resolution paleoclimatology. Quaternary Science Reviews, 76, 16-28. doi:10.1016/j.quascirev.2013.05.024 </ref> define a proxy system as comprised of three components: | |
| − | * The [[sensor]] comprises physical, chemical and/or biological components that react to environmental conditions. Sensors are often multivariate (i.e. sensitive to more than one environmental [[variable]]), seasonal and/or nonlinear or thresholded (record only part of the range of environmental conditions), or do so nonlinearly. For instance, [[Mg/Ca in foraminifera]] is often used sensor for temperature but depends also on salinity and deep-ocean carbonate saturation | + | * The [[sensor]] comprises physical, chemical and/or biological components that react to environmental conditions. Sensors are often multivariate (i.e. sensitive to more than one environmental [[variable]]), seasonal and/or nonlinear or thresholded (record only part of the range of environmental conditions), or do so nonlinearly. For instance, [[Mg/Ca in foraminifera]] is often used sensor for temperature but depends also on salinity and deep-ocean carbonate saturation <ref> Khider, D., Huerta, G., Jackson, C., Stott, L. D., & Emile-Geay, J. (2015). A Bayesian, multivariate calibration for Globigerinoides ruber Mg/Ca. Geochemistry Geophysics Geosystems, 16(9), 2916-2932. doi:10.1002/2015GC005844 </ref>. Its temperature dependence is exponential <ref> Anand, P., Elderfield, H., & Conte, M. H. (2003). Calibration of Mg/Ca thermometry in planktonic foraminifera from a sediment trap time series. Paleoceanography, 18(2), 1050. doi:10.1029/2002PA000846 </ref>. It is thus a multivariate and nonlinear sensor. |
| − | * The [[archive]] is the medium in which the response of a sensor to environmental forcing is recorded (Fig. 1). [Marine sediments] are a type of archive, on which many sensors may be measured (e.g. Mg/Ca, &delta^{ | + | * The [[archive]] is the medium in which the response of a sensor to environmental forcing is recorded (Fig. 1). [[Marine sediment | Marine sediments]] are a type of archive, on which many sensors may be measured (e.g. Mg/Ca, δ<sup>18</sup>O, <math> U_{37}^{k'} </math>, TEX86, δD) |
* [[observation]]s are made on archives, and involve several processes: | * [[observation]]s are made on archives, and involve several processes: | ||
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| − | These three major components may be individually modeled, and linked together within a [[Proxy System Model]] | + | These three major components may be individually modeled, and linked together within a [[Proxy System Model]] <ref name="evans2013" /> <ref> Dee, S., Emile-Geay, J., Evans, M. N., Allam, A., Steig, E. J., & Thompson, D. M. (2015). PRYSM: An open-source framework for PRoxy System Modeling, with applications to oxygen-isotope systems. Journal of Advances in Modeling Earth Systems, 7, 1220-1247. doi:10.1002/2015MS000447 |
| + | </ref>. Some sensors are common to multiple archives (e.g. δ<sup>18</sup>O), and all archives support more than one possible sensor. | ||
TABLE HERE | TABLE HERE | ||
--[[User:Julien|Julien]] ([[User talk:Julien|talk]]) 16:47, 13 January 2016 (PST) | --[[User:Julien|Julien]] ([[User talk:Julien|talk]]) 16:47, 13 January 2016 (PST) | ||
| + | |||
| + | ==References== | ||
| + | <references /> | ||
Revision as of 18:42, 15 January 2016
Observations of past climates are necessarily indirect. These observations are made on climate proxies in various geological (e.g. lake or marine sediments, living or fossil coral reefs, cave deposits), glaciological (ice cores or snow pits) or biological (trees) archives. Many data streams can be collected from each archives, each sensing a different aspect of the environment (sometimes, several aspects at once). A paleoclimate dataset is almost always a time series of observations made on a proxy system.
Evans et al. (2013) [1] define a proxy system as comprised of three components:
- The sensor comprises physical, chemical and/or biological components that react to environmental conditions. Sensors are often multivariate (i.e. sensitive to more than one environmental variable), seasonal and/or nonlinear or thresholded (record only part of the range of environmental conditions), or do so nonlinearly. For instance, Mg/Ca in foraminifera is often used sensor for temperature but depends also on salinity and deep-ocean carbonate saturation [2]. Its temperature dependence is exponential [3]. It is thus a multivariate and nonlinear sensor.
- The archive is the medium in which the response of a sensor to environmental forcing is recorded (Fig. 1). Marine sediments are a type of archive, on which many sensors may be measured (e.g. Mg/Ca, δ18O,
, TEX86, δD)
- observations are made on archives, and involve several processes:
- sampling is the process where the subsets of the archive are extracted, usually via coring or drilling.
- often, the observations are made on a purified, chemically transformed (.e.g leached) form of the sampled material
- what else?
These three major components may be individually modeled, and linked together within a Proxy System Model [1] [4]. Some sensors are common to multiple archives (e.g. δ18O), and all archives support more than one possible sensor.
TABLE HERE
--Julien (talk) 16:47, 13 January 2016 (PST)
References
- ↑ 1.0 1.1 Evans, M. N., Tolwinski-Ward, S. E., Thompson, D. M., & Anchukaitis, K. J. (2013). Applications of proxy system modeling in high resolution paleoclimatology. Quaternary Science Reviews, 76, 16-28. doi:10.1016/j.quascirev.2013.05.024
- ↑ Khider, D., Huerta, G., Jackson, C., Stott, L. D., & Emile-Geay, J. (2015). A Bayesian, multivariate calibration for Globigerinoides ruber Mg/Ca. Geochemistry Geophysics Geosystems, 16(9), 2916-2932. doi:10.1002/2015GC005844
- ↑ Anand, P., Elderfield, H., & Conte, M. H. (2003). Calibration of Mg/Ca thermometry in planktonic foraminifera from a sediment trap time series. Paleoceanography, 18(2), 1050. doi:10.1029/2002PA000846
- ↑ Dee, S., Emile-Geay, J., Evans, M. N., Allam, A., Steig, E. J., & Thompson, D. M. (2015). PRYSM: An open-source framework for PRoxy System Modeling, with applications to oxygen-isotope systems. Journal of Advances in Modeling Earth Systems, 7, 1220-1247. doi:10.1002/2015MS000447
