Difference between revisions of "Climate Proxy"
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Observations of past climates are necessarily indirect. Hence, the main tool in the study of past climates involves climate '''proxies''' i.e. measurements in 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 these archives, each '''sensing''' a different aspect of the environment (sometimes, several aspects at once). | Observations of past climates are necessarily indirect. Hence, the main tool in the study of past climates involves climate '''proxies''' i.e. measurements in 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 these archives, each '''sensing''' a different aspect of the environment (sometimes, several aspects at once). | ||
| − | [http://one.geol.umd.edu/preprints/psm13.pdf Evans et al, | + | [http://one.geol.umd.edu/preprints/psm13.pdf Evans et al, (2013)] 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]] is often used sensor for temperature but depends also on salinity and pH [http://onlinelibrary.wiley.com/doi/10.1002/2015GC005844/abstract (Khider et al., 2015)]. Its temperature dependence is exponential (reference). It is thus a multivariate and nonlinear sensor. | ||
| − | - The | + | - 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^{18}O |
| − | + | - [[Observation]]s are made on archives. | |
| + | |||
| + | |||
| + | These components are individually modeled, and linked together within a [[Proxy System Model]] (e.g. []) | ||
Revision as of 17:35, 13 January 2016
Observations of past climates are necessarily indirect. Hence, the main tool in the study of past climates involves climate proxies i.e. measurements in 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 these archives, each sensing a different aspect of the environment (sometimes, several aspects at once).
Evans et al, (2013) 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 is often used sensor for temperature but depends also on salinity and pH (Khider et al., 2015). Its temperature dependence is exponential (reference). 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^{18}O
- Observations are made on archives.
These components are individually modeled, and linked together within a Proxy System Model (e.g. [])
