Signals and memory in tree-ring width and density data

Abstract

a b s t r a c tIt has been suggested that maximum latewood density (MXD) should be used instead of tree-ring width (TRW) data to reconstruct post-volcanic cooling effects. A thorough assessment of high frequency signals and potentially differing memory effects in long MXD and TRW chronologies, in response to large volcanic eruptions, is still missing, however. We here present a compilation of MXD and TRW chronologies from 11 sites in the Northern Hemisphere, covering the past 750+ years, and containing significant June-August temperature signals. Basic assessment of the data using Superposed Epoch Analysis reveals a temporally extended response in TRW, by 2-3 years, to large volcanic eruptions, though post-volcanic cooling patterns vary considerably within the Northern Hemisphere network. Comparison with instrumental temperature data demonstrates the TRW chronologies underestimate cold conditions associated with large volcanic eruptions, a bias that is mitigated in the MXD data. While species composition (pine, spruce, larch) has no detectable influence on the cooling patterns, trees from high latitude sites (>60 • N) indicate a stronger and delayed (1-2 years) response to large eruptions, compared to the lower latitude sites (<60 • N). These basic findings caution against using TRW data for quantitatively estimating post-volcanic cooling and for comparison against the simulated climate effects of volcanic eruptions in models.

Spatio-temporal variability of Arctic summer temperatures over the past two millennia: an overview of the last major climate anomalies

“…These records may require additional attention in future studies, as the level of high-versus low frequency variability is unusual compared to other proxy records and also instrumental measurements. Similar spectral characteristics were obtained for other tree-ring chronolo-595 gies in (Franke et al, 2013;Zhang et al, 2015;Esper et al, 2015;Büntgen et al, 2015). The memory properties in a number of proxy-based temperature reconstructions have been studied in (Østvand et al, 2014;Nilsen et al, 2016) using the power spectrum along with selected other techniques.…”

“…The latter comprises varved lacustrine sediments and ice core data. In contrast to the procedure 155 outlined by Luterbacher et al (2016) tree-ring width measurements are not treated differently from maximum latewood density data, although the spectral properties would in principle warrant this separation (Zhang et al, 2015;Esper et al, 2015;Büntgen et al, 2015).…”

Relationships between Wood Formation and Cambium Phenology on the Tibetan Plateau during 1960–2014

“…The different allocation strategies of absorbed carbon by a tree probably result in more complex relationships between wood formation and cambium phenology [7,49]. The variability of tree-ring width is also affected by the climate conditions during previous year(s) [50][51][52]. Consequently, weak relationships, or the lack of relationships between wood formation and cambium phenology at some of the composite sites is rational and coherent with our actual knowledge of tree-ring formation.…”

Temperature variability in the Iberian Range since 1602 inferred from tree-ring records

“…Thus, developing the 2-year memory IR2Tmax allowed us to maintain not only the low-frequency signal, highlighting the warm and cold phases, which may be explained by the high correlation with solar activity during 410 years (0.34, p < 0.001), but also the high-frequency signal, emphasizing the memory effects of the volcanic eruptions in TRW, already studied by Briffa et al (1998) and recently by Esper et al (2015b). According to the SEA (Fig.…”