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| Robust estimation of background noise and signal detection in climatic time series |
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| Author(s): Mann ME, Lees JM |
| Source: CLIMATIC CHANGE Volume: 33 Issue: 3 Pages: 409-445 Published: JUL 1996 |
| Times Cited: 252 References: 57 |
| Abstract: We present a new technique for isolating climate signals in time series with a characteristic 'red' noise background which arises from temporal persistence. This background is estimated by a 'robust' procedure that, unlike conventional techniques, is largely unbiased by the presence of signals immersed in the noise. Making use of multiple-taper spectral analysis methods, the technique further provides for a distinction between purely harmonic (periodic) signals, and broader-band ('quasiperiodic') signals. The effectiveness of our signal detection procedure is demonstrated with synthetic examples that simulate a variety of possible periodic and quasiperiodic signals immersed in red noise. We apply our methodology to historical climate and paleoclimate time series examples. Analysis of a approximate to 3 million year sediment core reveals significant periodic components at known astronomical forcing periodicities and a significant quasiperiodic 100 year peak. Analysis of a roughly 1500 year tree-ring reconstruction of Scandinavian summer temperatures suggests significant quasiperiodic signals on a near-century timescale, an interdecadal 16-18 year timescale, within the interannual El Ninio/Southem Oscillation (ENSO) band, and on a quasibiennial timescale. Analysis of the 144 year record of Great Salt Lake monthly volume change reveals a significant broad band of significant interdecadal variability, ENSO-timescale peaks, an annual cycle and its harmonics. Focusing in detail on the historical estimated global-average surface temperature record, we find a highly significant secular trend relative to the estimated red noise background, and weakly significant quasiperiodic signals within the ENSO band. Decadal and quasibiennial signals are marginally significant in this series. |
| Document Type: Article |
| Language: English |
| Reprint Address: Mann, ME (reprint author), YALE UNIV, DEPT GEOL & GEOPHYS, POB 208109, NEW HAVEN, CT 06520 USA |
| Publisher: KLUWER ACADEMIC PUBL, SPUIBOULEVARD 50, PO BOX 17, 3300 AA DORDRECHT, NETHERLANDS |
| Subject Category: Environmental Sciences; Meteorology & Atmospheric Sciences |
| IDS Number: VB197 |
| ISSN: 0165-0009 |
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