Climate spectrum estimation in the presence of timescale errors
Mudelsee, M.; Scholz, D.; Röthlisberger, Regine; Fleitmann, D.; Mangini, A.; Wolff, Eric W.. 2009 Climate spectrum estimation in the presence of timescale errors. Nonlinear Processes in Geophysics, 16 (1). 43-56. 10.5194/npg-16-43-2009Before downloading, please read NORA policies.
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We introduce an algorithm (called REDFITmc2) for spectrum estimation in the presence of timescale errors. It is based on the Lomb-Scargle periodogram for unevenly spaced time series, in combination with the Welch's Overlapped Segment Averaging procedure, bootstrap bias correction and persistence estimation. The timescale errors are modelled parametrically and included in the simulations for determining (1) the upper levels of the spectrum of the red-noise AR(1) alternative and (2) the uncertainty of the frequency of a spectral peak. Application of REDFITmc2 to ice core and stalagmite records of palaeoclimate allowed a more realistic evaluation of spectral peaks than when ignoring this source of uncertainty. The results support qualitatively the intuition that stronger effects on the spectrum estimate (decreased detectability and increased frequency uncertainty) occur for higher frequencies. The surplus information brought by algorithm REDFITmc2 is that those effects are quantified. Regarding timescale construction, not only the fixpoints, dating errors and the functional form of the age-depth model play a role. Also the joint distribution of all time points (serial correlation, stratigraphic order) determines spectrum estimation.
|Programmes:||BAS Programmes > Global Science in the Antarctic Context (2005-2009) > Climate and Chemistry - Forcings and Phasings in the Earth System|
|NORA Subject Terms:||Meteorology and Climatology
|Date made live:||08 Nov 2010 14:17|
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