Zhang, H.; Yuan, N.; Esper, J.; Werner, J.P.; Xoplaki, E.; Büntgen, U.; Treydte, K. & Luterbacher, J. (2015): <b>Modified climate with long term memory in tree ring proxies</b>. <i>Environmental Research Letters</i> <b>10</b>, 084020<br>DOI: <a href="http://dx.doi.org/10.1088/1748-9326/10/8/084020" target="_blank">http://dx.doi.org/10.1088/1748-9326/10/8/084020</a>.
Resource Description
Title:
Modified climate with long term memory in tree ring proxies
Long term memory (LTM) scaling behavior in worldwide tree-ring proxies and subsequent climate<br/>
reconstructions is analyzed for and compared with the memory structure inherent to instrumental<br/>
temperature and precipitation data. Detrended fluctuation analysis is employed to detect LTM, and its<br/>
scaling exponent ? is used to evaluate LTM. The results show that temperature and precipitation<br/>
reconstructions based on ringwidthmeasurements (mean ? = 0.8) containmorememory than<br/>
records based onmaximumlatewood density (mean ? = 0.7). Both exceed thememory inherent to<br/>
regional instrumental data (? = 0.6 for temperature, ? = 0.5 for precipitation) in the time scales<br/>
ranging from1 year up to 50 years.We comparememory-free (? = 0.5) pseudo-instrumental<br/>
precipitation datawith pseudo-reconstructed precipitation datawith LTM (? > 0.5), and demonstrate<br/>
the biasing influences ofLTMon climate reconstructions. Wecall for attention to statistical<br/>
analysis with regard to the variability of proxy-based chronologies or reconstructions, particularly<br/>
with respect to the contained (i) trends, (ii) past warm/cold period and wet/dry periods; and (iii)<br/>
extreme events.
Keywords:
| climate reconstructions | tree-ring width | maximum latewood density | frequency domains |
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