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Abstract. We evaluate a range of blue intensity (BI) tree-ringparameters in eight conifer species (12 sites) from Tasmania and New Zealandfor their dendroclimatic potential, and as surrogate wood anatomicalproxies. Using a dataset of ca. 10–15 trees per site, we measured earlywoodmaximum blue intensity (EWB), latewood minimum blue intensity (LWB), and theassociated delta blue intensity (DB) parameter for dendrochronologicalanalysis. No resin extraction was performed, impacting low-frequency trends.Therefore, we focused only on the high-frequency signal by detrending alltree-ring and climate data using a 20-year cubic smoothing spline. All BIparameters express low relative variance and weak signal strength comparedto ring width. Correlation analysis and principal component regressionexperiments identified a weak and variable climate response for mostring-width chronologies. However, for most sites, the EWB data, despite weaksignal strength, expressed strong coherence with summer temperatures.Significant correlations for LWB were also noted, but the sign of therelationship for most species is opposite to that reported for all coniferspecies in the Northern Hemisphere. DB results were mixed but performedbetter for the Tasmanian sites when combined through principal componentregression methods than for New Zealand. Using the fullmulti-species/parameter network, excellent summer temperature calibrationwas identified for both Tasmania and New Zealand ranging from 52 % to78 % explained variance for split periods (1901–1950/1951–1995), withequally robust independent validation (coefficient of efficiency = 0.41 to0.77). Comparison of the Tasmanian BI reconstruction with a quantitativewood anatomical (QWA) reconstruction shows that these parameters recordessentially the same strong high-frequency summer temperature signal.Despite these excellent results, a substantial challenge exists with thecapture of potential secular-scale climate trends. Although DB, band-pass,and other signal processing methods may help with this issue, substantiallymore experimentation is needed in conjunction with comparative analysis withring density and QWA measurements. 

ABSTRACT In 2018 Pearson et al. published a new sequence of annual radiocarbon ( 14 C) data derived from oak ( Quercus sp.) trees from Northern Ireland and bristlecone pine ( Pinus longaeva ) from North America across the period 1700–1500 BC. The study indicated that the more highly resolved shape of an annually based calibration dataset could improve the accuracy of 14 C calibration during this period. This finding had implications for the controversial dating of the eruption of Thera in the Eastern Mediterranean. To test for interlaboratory variation and improve the robustness of the annual dataset for calibration purposes, we have generated a replicate sequence from the same Irish oaks at ETH Zürich. These data are compatible with the Irish oak 14 C dataset previously produced at the University of Arizona and are used (along with additional data) to examine inter-tree and interlaboratory variation in multiyear annual 14 C time-series. The results raise questions about regional 14 C offsets at different scales and demonstrate the potential of annually resolved 14 C for refining subdecadal and larger scale features for calibration, solar reconstruction, and multiproxy synchronization.