000			02790nab a2200277 4500
003			OSt
005			20220823194117.0
007			cr aa aaaaa
008			220823b |||||||| |||| 00| 0 eng d
100			_aWilson, R _952490
245			_aImproved dendroclimatic calibration using blue intensity in the southern Yukon/
260			_bsage _c2019
300			_aVol 29, Issue 11, 2019 : (1817-1830 p.).
520			_aIn north-western North America, the so-called divergence problem (DP) is expressed in tree ring width (RW) as an unstable temperature signal in recent decades. Maximum latewood density (MXD), from the same region, shows minimal evidence of DP. While MXD is a superior proxy for summer temperatures, there are very few long MXD records from North America. Latewood blue intensity (LWB) measures similar wood properties as MXD, expresses a similar climate response, is much cheaper to generate and thereby could provide the means to profoundly expand the extant network of temperature sensitive tree-ring (TR) chronologies in North America. In this study, LWB is measured from 17 white spruce sites (Picea glauca) in south-western Yukon to test whether LWB is immune to the temporal calibration instabilities observed in RW. A number of detrending methodologies are examined. The strongest calibration results for both RW and LWB are consistently returned using age-dependent spline (ADS) detrending within the signal-free (SF) framework. RW data calibrate best with June–July maximum temperatures (Tmax), explaining up to 28% variance, but all models fail validation and residual analysis. In comparison, LWB calibrates strongly (explaining 43–51% of May–August Tmax) and validates well. The reconstruction extends to 1337 CE, but uncertainties increase substantially before the early 17th century because of low replication. RW-, MXD- and LWB-based summer temperature reconstructions from the Gulf of Alaska, the Wrangell Mountains and Northern Alaska display good agreement at multi-decadal and higher frequencies, but the Yukon LWB reconstruction appears potentially limited in its expression of centennial-scale variation. While LWB improves dendroclimatic calibration, future work must focus on suitably preserved sub-fossil material to increase replication prior to 1650 CE.
650			_aage-dependent spline, _952491
650			_a blue intensity, _952492
650			_asummer temperature reconstruction, _952493
650			_atree ring, _952494
650			_awhite spruce, _952495
650			_aYukon _952496
700			_aAnchukaitis, K _952497
700			_aAndreu-Hayles, L _952498
773	0		_012756 _916504 _dLondon: Sage Publication Ltd, 2019. _tHolocene/ _x09596836
856			_uhttps://doi.org/10.1177/0959683619862037
942			_2ddc _cART
999			_c12896 _d12896