scholarly journals Blue Intensity based experiments for reconstructing North Pacific temperatures along the Gulf of Alaska

2017 ◽  
Author(s):  
Rob Wilson ◽  
Rosanne D'Arrigo ◽  
Laia Andreu-Hayles ◽  
Rose Oelkers ◽  
Greg Wiles ◽  
...  
Keyword(s):  
Tree Ring ◽  
North Pacific ◽  
Large Scale ◽  
Ring Width ◽  
Gulf Of Alaska ◽  
Cool Period ◽  
Latewood Density ◽  
Ocean Atmosphere ◽  
Blue Intensity

Abstract. Climate in the Gulf of Alaska (GOA) reflects large-scale ocean-atmosphere variability of the North Pacific climate system. Ring-width (RW) records from the GOA have yielded a valuable long-term perspective for North Pacific changes on decadal to longer time scales in prior studies, but express a broad winter to late summer seasonal response. Similar to the highly climate-sensitive maximum latewood density (MXD) proxy, the Blue Intensity (BI) parameter has recently been shown to correlate well with year-to-year warm-season temperatures for a number of sites at northern latitudes. Since BI records are much less expensive and labor intensive to generate than MXD, such data hold great potential value for future tree-ring studies in the GOA and other regions at mid-to-high latitudes. Here we highlight the potential for improving tree-ring based reconstructions using combinations of RW and BI-related parameters (latewood BI (LWB) and delta BI (DB)) from an experimental sub-set of samples from eight mountain hemlock (Tsuga mertensiana) sites along the GOA. This is the first such study for the hemlock genus using BI data. We find that using either LWB or DB can improve the amount of explained temperature variance by > 10 % compared to RW alone although the optimal target season changes to June–September, which may have implications for studying ocean-atmosphere variability in the region. However, one challenge in building these BI records is that resin extraction did not remove colour differences between the heartwood and sapwood, so long term trend biases, expressed as relatively warm temperatures in the 18th century, were noted when using the LWB data. Using DB appeared to overcome these trend biases resulting in a reconstruction expressing 18th–19th century temperatures ca. 0.5 °C cooler than the 20th/21st centuries. This cool period agrees well with previous dendroclimatic studies and the glacial advance record in the region. Continuing BI measurement in the GOA region must focus on sampling more trees per site (> 20) and more sites to overcome site specific factors effecting climate response while sub-fossil material will extend the reflectance records back over 1000 years. DB appears to capture long term secular trends that agree with other proxy archives in the region but great care is needed when implementing different detrending options. Finally, more experimentation is needed to assess the utility of DB for different conifer species around the Northern Hemisphere.

scholarly journals Experiments based on blue intensity for reconstructing North Pacific temperatures along the Gulf of Alaska

2017 ◽  
Vol 13 (8) ◽  
pp. 1007-1022 ◽  
Author(s):  
Rob Wilson ◽  
Rosanne D'Arrigo ◽  
Laia Andreu-Hayles ◽  
Rose Oelkers ◽  
Greg Wiles ◽  
...  
Keyword(s):  
Tree Ring ◽  
North Pacific ◽  
Ring Width ◽  
Gulf Of Alaska ◽  
Climate Response ◽  
Cool Period ◽  
Climate Signal ◽  
Latewood Density ◽  
Blue Intensity

Abstract. Ring-width (RW) records from the Gulf of Alaska (GOA) have yielded a valuable long-term perspective for North Pacific changes on decadal to longer timescales in prior studies but contain a broad winter to late summer seasonal climate response. Similar to the highly climate-sensitive maximum latewood density (MXD) proxy, the blue intensity (BI) parameter has recently been shown to correlate well with year-to-year warm-season temperatures for a number of sites at northern latitudes. Since BI records are much less labour intensive and expensive to generate than MXD, such data hold great potential value for future tree-ring studies in the GOA and other regions in mid- to high latitudes. Here we explore the potential for improving tree-ring-based reconstructions using combinations of RW- and BI-related parameters (latewood BI and delta BI) from an experimental subset of samples at eight mountain hemlock (Tsuga mertensiana) sites along the GOA. This is the first study for the hemlock genus using BI data. We find that using either inverted latewood BI (LWBinv) or delta BI (DB) can improve the amount of explained temperature variance by > 10 % compared to RW alone, although the optimal target season shrinks to June–September, which may have implications for studying ocean–atmosphere variability in the region. One challenge in building these BI records is that resin extraction did not remove colour differences between the heartwood and sapwood; thus, long term trend biases, expressed as relatively warm temperatures in the 18th century, were noted when using the LWBinv data. Using DB appeared to overcome these trend biases, resulting in a reconstruction expressing 18th–19th century temperatures ca. 0.5 °C cooler than the 20th–21st centuries. This cool period agrees well with previous dendroclimatic studies and the glacial advance record in the region. Continuing BI measurement in the GOA region must focus on sampling and measuring more trees per site (> 20) and compiling more sites to overcome site-specific factors affecting climate response and using subfossil material to extend the record. Although LWBinv captures the inter-annual climate signal more strongly than DB, DB appears to better capture long-term secular trends that agree with other proxy archives in the region. Great care is needed, however, when implementing different detrending options and more experimentation is necessary to assess the utility of DB for different conifer species around the Northern Hemisphere.

scholarly journals Improved dendroclimatic calibration using blue intensity in the southern Yukon

The Holocene ◽  
2019 ◽  
Vol 29 (11) ◽  
pp. 1817-1830 ◽  
Author(s):  
R Wilson ◽  
K Anchukaitis ◽  
L Andreu-Hayles ◽  
E Cook ◽  
R D’Arrigo ◽  
...  
Keyword(s):  
North America ◽  
Tree Ring ◽  
Picea Glauca ◽  
Ring Width ◽  
Gulf Of Alaska ◽  
Wood Properties ◽  
Temperature Sensitive ◽  
Latewood Density ◽  
June July ◽  
Blue Intensity

In 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.

Blue Intensity for dendroclimatology: The BC blues: A case study from British Columbia, Canada

The Holocene ◽  
2014 ◽  
Vol 24 (11) ◽  
pp. 1428-1438 ◽  
Author(s):  
Rob Wilson ◽  
Rohit Rao ◽  
Miloš Rydval ◽  
Cheryl Wood ◽  
Lars-Åke Larsson ◽  
...  
Keyword(s):  
British Columbia ◽  
Tree Ring ◽  
Large Scale ◽  
Ring Width ◽  
Frequency Information ◽  
Maximum Latewood Density ◽  
Latewood Density ◽  
Summer Temperatures ◽  
Two Parameters ◽  
Blue Intensity

Maximum latewood density (MXD) is a strong proxy of summer temperatures. Despite this, there is a paucity of long MXD chronologies in the Northern Hemisphere, which limits large-scale tree-ring-based reconstructions of past temperature which are dominated by ring-width (RW) data – a weaker temperature proxy at inter-annual time-scales. This paucity likely results from the relative expense of measuring MXD and the lack of laboratories with the facilities to measure it. Herein, we test the ability of a relatively new, less expensive, tree-ring parameter, Blue Intensity (BI), to act as a surrogate parameter for MXD. BI was measured on Engelmann spruce samples from British Columbia where MXD had previously been measured to allow direct comparison between the two parameters. Signal strength analyses indicate that 8 MXD series were needed to acquire a robust mean chronology while BI needed 14. Utilising different detrending methods and parameter choices (RW + MXD vs RW + BI), a suite of reconstruction variants was developed. The explained variance from the regression modelling (1901–1995) of May–August maximum temperatures ranged from 52% to 55%. Validation tests over the earlier 1870–1900 period could not statistically distinguish between the different variants, although spectral analysis identified more lower frequency information extant in the MXD-based reconstructions – although this result was sensitive to the detrending method used. Ultimately, despite the MXD-based reconstruction explaining slightly more of the climatic variance, statistically robust reconstructions of past summer temperatures were also derived using BI. These results suggest that there is great potential in utilising BI for dendroclimatology in place of MXD data. However, more experimentation is needed to understand (1) how well BI can capture centennial and lower frequency information and (2) what biases may result from wood discolouration, either from species showing a distinct heartwood/sapwood boundary or from partly decayed sub-fossil samples.

Comparison between Blue Intensity (BI) and Maximum Latewood Density (MXD) tree-ring chronologies from the North American Boreal forests

2020 ◽  
Author(s):  
Laia Andreu-Hayles ◽  
Rosanne D'Arrigo ◽  
Rose Oelkers ◽  
Kevin Anchukaitis ◽  
Greg Wiles ◽  
...  
Keyword(s):  
High Resolution ◽  
North America ◽  
Tree Ring ◽  
Boreal Forests ◽  
Ring Width ◽  
Maximum Latewood Density ◽  
Latewood Density ◽  
Tree Ring Data ◽  
Summer Temperatures ◽  
Blue Intensity

<p>Tree ring-width (TRW) and Maximum Latewood Density (MXD) series have been largely used to develop high-resolution temperature reconstructions for the Northern Hemisphere. The divergence phenomenon, a weakening of the positive relationship between TRW and summer temperatures, has been observed particularly in northwestern North America chronologies. In contrast, MXD datasets have shown a more stable relationship with summer temperatures, but it is costly and labor-intensive to produce. Recently, methodological advances in image analyses have led to development of a less expensive and labor-intensive MXD proxy known as Blue Intensity (BI). Here, we compare 6 newly developed BI tree-ring chronologies of white spruce (<em>Picea glauca</em> [Moench] Voss) from high-latitude boreal forests in North America (Alaska in USA; Yukon and the Northwestern Territory in Canada), with MXD chronologies developed at the same sites. We assessed the quality of BI in relation to MXD based on mean correlation between trees, chronology reliability based on the Expressed Population Signal (EPS), spectral properties, and the strength and spatial extent of the temperature signal. Individual BI chronologies established significant correlations with summer temperatures showing a similar strength and spatial cover than MXD chronologies. Overall, the BI tree-ring data is emerging as a valuable proxy for generating high-resolution temperature spatial reconstructions over northwestern America.</p>

Temperature changes along the Gulf of Alaska and the Pacific Northwest coast modeled from coastal tree rings

1996 ◽  
Vol 26 (3) ◽  
pp. 474-481 ◽  
Author(s):  
Gregory C. Wiles ◽  
Rosanne D. D'Arrigo ◽  
Gordon C. Jacoby
Keyword(s):  
Pacific Northwest ◽  
Large Scale ◽  
Ring Width ◽  
Warm Season ◽  
Gulf Of Alaska ◽  
Maximum Latewood Density ◽  
Pacific Northwest Coast ◽  
Latewood Density ◽  
The Pacific ◽  
Temperature Records

Warm-season (April–September) temperature models based on a network of coastal ring-width and maximum latewood density tree-ring chronologies are the first reconstructions for coastal stations along the Gulf of Alaska and the Pacific Northwest. These well-verified temperature models are consistent with long climatic series from coastal stations and other proxy data from the Pacific coast. Cool summers during the 1850s and late 1800s in the Gulf of Alaska correspond to general glacier advance from the region. The Pacific Northwest reconstruction shows summer temperatures cooling in the early 1800s, coincident with a maximum of glacier activity in the coastal Olympic Mountains, Washington. The two warm-season temperature records show intervals when anomalies are opposite in sign, most notably during the 1850s, when cooling is inferred for the Gulf and warming is inferred for the Pacific Northwest. The records are coherent, however, during other intervals, with both showing cooling in the early 1800s and warming around 1870. The phase of these two records may reflect decadal changes in large-scale circulation in the northeastern Pacific. These land temperature reconstructions are strongly correlated with nearby sea surface temperatures, indicating large-scale oceanic–atmospheric influences.

Is temperature still the most limiting factor for growth in northern boreal forests?

The Holocene ◽  
2021 ◽  
pp. 095968362110116
Author(s):  
Jeroen DM Schreel
Keyword(s):  
Tree Ring ◽  
Boreal Forests ◽  
Ring Width ◽  
Temperature Fluctuations ◽  
Limiting Factor ◽  
Tree Ring Width ◽  
Climate Reconstructions ◽  
Latewood Density

Over the last few decades – at a range of northern sites – changes in tree-ring width and latewood density have not followed mean summertime temperature fluctuations. This discrepancy sharply contrasts an earlier correlation between those variables. As the origin of this inconsistency has not been fully deciphered, questions have emerged regarding the use of tree-ring width and latewood density as a proxy in dendrochronological climate reconstructions. I suggest that temperature is no longer the most limiting factor in certain boreal areas, which might explain the observed divergence.

A Preliminary Reconstruction of Rainfall in North-Central China since A.D. 1600 from Tree-Ring Density and Width

1994 ◽  
Vol 42 (1) ◽  
pp. 88-99 ◽  
Author(s):  
Malcolm K. Hughes ◽  
Wu Xiangding ◽  
Shao Xuemei ◽  
Gregg M. Garfin
Keyword(s):  
Tree Ring ◽  
Spectral Power ◽  
Singular Spectrum Analysis ◽  
Ring Width ◽  
Central China ◽  
North Central ◽  
Ring Density ◽  
Maximum Latewood Density ◽  
Documentary Sources ◽  
Latewood Density

AbstractMay-June (MJ) and April-July (AJ) precipitation at Huashan in north-central China has been reconstructed for the period A.D. 1600 to 1988 using tree-ring density and width fromPinus armandii. MJ precipitation (based on ring width and maximum latewood density) calibrated and cross-validated against local instrumental data more strongly than AJ precipitation (based only on ring width). A major drought was reconstructed for the mid- and late 1920s, confirmed by local documentary sources. This drought (culminating in 1929) was the most severe of the 389-yr period for MJ and second most severe for AJ, after an event ending in 1683. Neither reconstruction shows much spectral power at frequencies lower than 1 in 10 yr, but both show concentrations of power between 2.1 and 2.7 yr and 3.5 to 9 yr. There are significant correlations between the two reconstructions and a regional dryness/wetness index (DW) based on documentary sources, particularly at high frequencies. These correlations are focused in the 7.6- to 7.3-, 3.8- to 3.6-, and 2.5-yr periods. Using singular spectrum analysis, quasiperiodic behavior with a period close to 7.2 yr was identified in the MJ precipitation reconstruction and in the DW index based on documents.

scholarly journals Long-term and large-scale epidemiology of Brucella infection in baleen whales and sperm whales in the western North Pacific and Antarctic Oceans

2016 ◽  
Vol 78 (9) ◽  
pp. 1457-1464 ◽  
Author(s):  
Kazue OHISHI ◽  
Takeharu BANDO ◽  
Erika ABE ◽  
Yasushi KAWAI ◽  
Yoshihiro FUJISE ◽  
...  
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Large Scale ◽  
Sperm Whales ◽  
Baleen Whales

scholarly journals Siberian tree-ring and stable isotope proxies as indicators of temperature and moisture changes after major stratospheric volcanic eruptions

2019 ◽  
Vol 15 (2) ◽  
pp. 685-700 ◽  
Author(s):  
Olga V. Churakova (Sidorova) ◽  
Marina V. Fonti ◽  
Matthias Saurer ◽  
Sébastien Guillet ◽  
Christophe Corona ◽  
...  
Keyword(s):  
Tree Ring ◽  
Global Climate ◽  
Sunshine Duration ◽  
Ring Width ◽  
Volcanic Eruptions ◽  
Climate Dynamics ◽  
Global Climate Models ◽  
Added Value ◽  
Latewood Density ◽  
The Impact

Abstract. Stratospheric volcanic eruptions have far-reaching impacts on global climate and society. Tree rings can provide valuable climatic information on these impacts across different spatial and temporal scales. To detect temperature and hydroclimatic changes after strong stratospheric Common Era (CE) volcanic eruptions for the last 1500 years (535 CE unknown, 540 CE unknown, 1257 CE Samalas, 1640 CE Parker, 1815 CE Tambora, and 1991 CE Pinatubo), we measured and analyzed tree-ring width (TRW), maximum latewood density (MXD), cell wall thickness (CWT), and δ13C and δ18O in tree-ring cellulose chronologies of climate-sensitive larch trees from three different Siberian regions (northeastern Yakutia – YAK, eastern Taimyr – TAY, and Russian Altai – ALT). All tree-ring proxies proved to encode a significant and specific climatic signal of the growing season. Our findings suggest that TRW, MXD, and CWT show strong negative summer air temperature anomalies in 536, 541–542, and 1258–1259 at all studied regions. Based on δ13C, 536 was extremely humid at YAK, as was 537–538 in TAY. No extreme hydroclimatic anomalies occurred in Siberia after the volcanic eruptions in 1640, 1815, and 1991, except for 1817 at ALT. The signal stored in δ18O indicated significantly lower summer sunshine duration in 542 and 1258–1259 at YAK and 536 at ALT. Our results show that trees growing at YAK and ALT mainly responded the first year after the eruptions, whereas at TAY, the growth response occurred after 2 years. The fact that differences exist in climate responses to volcanic eruptions – both in space and time – underlines the added value of a multiple tree-ring proxy assessment. As such, the various indicators used clearly help to provide a more realistic picture of the impact of volcanic eruption on past climate dynamics, which is fundamental for an improved understanding of climate dynamics, but also for the validation of global climate models.

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