首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
1.
Håkan Grudd 《Climate Dynamics》2008,31(7-8):843-857
This paper presents updated tree-ring width (TRW) and maximum density (MXD) from Torneträsk in northern Sweden, now covering the period ad 500–2004. By including data from relatively young trees for the most recent period, a previously noted decline in recent MXD is eliminated. Non-climatological growth trends in the data are removed using Regional Curve Standardization (RCS), thus producing TRW and MXD chronologies with preserved low-frequency variability. The chronologies are calibrated using local and regional instrumental climate records. A bootstrapped response function analysis using regional climate data shows that tree growth is forced by April–August temperatures and that the regression weights for MXD are much stronger than for TRW. The robustness of the reconstruction equation is verified by independent temperature data and shows that 63–64% of the instrumental inter-annual variation is captured by the tree-ring data. This is a significant improvement compared to previously published reconstructions based on tree-ring data from Torneträsk. A divergence phenomenon around ad 1800, expressed as an increase in TRW that is not paralleled by temperature and MXD, is most likely an effect of major changes in the density of the pine population at this northern tree-line site. The bias introduced by this TRW phenomenon is assessed by producing a summer temperature reconstruction based on MXD exclusively. The new data show generally higher temperature estimates than previous reconstructions based on Torneträsk tree-ring data. The late-twentieth century, however, is not exceptionally warm in the new record: On decadal-to-centennial timescales, periods around ad 750, 1000, 1400, and 1750 were equally warm, or warmer. The 200-year long warm period centered on ad 1000 was significantly warmer than the late-twentieth century (p < 0.05) and is supported by other local and regional paleoclimate data. The new tree-ring evidence from Torneträsk suggests that this “Medieval Warm Period” in northern Fennoscandia was much warmer than previously recognized.  相似文献   

2.
利用2014年采自巴丹吉林沙漠西南缘的胡杨样本,建立了该地区胡杨树轮年表,选用相关函数法结合高台气象站历年逐月降水和温度(月平均气温、月平均最高气温、月平均最低气温、平均地温)等主要气候因子,分析巴丹吉林沙漠西南缘胡杨树轮对气候的响应;研究表明,黑泉乡胡杨树轮宽度标准化年表与生长季平均气温相关较好,具有明显的正相关关系。而生长季3-9月的平均气温与胡杨树轮宽度年表的相关高达0.629(P<0.0001),3-9月的平均气温可能是该地区胡杨树木径向生长的主要限制性因子且具有明确的树木生理学意义。  相似文献   

3.
We present a warm season (April–September) temperature reconstructionfor Asahikawa, north central Hokkaido, Japan for AD 1557–1990. The reconstruction, which accounts for 34% of the temperature variancefrom 1925–1990, is based on maximum latewood density data from Saghalinspruce (Picea glehnii) growing at timberline (1340–1390 m) at MountAsahidake, Hokkaido. We only present a high frequency (prewhitened or white noise) version of the reconstruction because there is an unexplained offset in the mean between the actual and estimated temperature data for an earlier period of overlap from 1891–1924. The coldest summer in the reconstruction is 1718, forwhich the estimated value is 12.89 ° C, nearly four standard deviations (SD) below the mean. A colder-than-average year is reconstructed for 1641 (13.30° C, nearly 3 SD below mean), following the eruption of Komagatake, Hokkaido which began in July, 1640. The Asahikawa density chronology, shows decadal modes of variation with statistically significant spectral peaks prior to around 1850. A tree-ring width chronology for this same site (AD 1532–1990) is in phase with a tree-ring width record from centralKamchatka prior to around 1850, but out of phase since that time. This pattern suggests, as has been hypothesized for temperature-sensitive tree-ring records from the eastern Pacific sector (Alaska and Patagonia), that a decadal mode of climate variation was more dominant in the Pacific sector prior to about 1850, after which a higher frequency (ENSO-type) mode may have become more pronounced, at least until recent decades. Additional data from the northwestern Pacific is needed to compare to these findings.  相似文献   

4.
Dendroclimatological sampling of Scots pine (Pinus sylvestris L.) has been made in the province of J?mtland, in the west-central Scandinavian mountains, since the 1970s. The tree-ring width (TRW) chronology spans several thousand years and has been used to reconstruct June?CAugust temperatures back to 1632 bc. A maximum latewood density (MXD) dataset, covering the period ad 1107?C1827 (with gap 1292?C1315) was presented in the 1980s by Fritz Schweingruber. Here we combine these historical MXD data with recently collected MXD data covering ad 1292?C2006 into a single reconstruction of April?CSeptember temperatures for the period ad 1107?C2006. Regional curve standardization (RCS) provides more low-frequency variability than ??non-RCS?? and stronger correlation with local seasonal temperatures (51% variance explained). The MXD chronology shows a stronger relationship with temperatures than the TRW data, but the two chronologies show similar multi-decadal variations back to ad 1500. According to the MXD chronology, the period since ad 1930 and around ad 1150?C1200 were the warmest during the last 900?years. Due to large uncertainties in the early part of the combined MXD chronology, it is not possible to conclude which period was the warmest. More sampling of trees growing near the tree-line is needed to further improve the MXD chronology.  相似文献   

5.
A millennium-long tree-ring width chronology of living and dead larch (Larix decidua Mill.) specimens from the Maritime French Alps was introduced 35?years ago. This record has been included in various large-scale temperature reconstructions, though recent analyses revealed only weak associations with regional summer temperatures. Calibration and verification trials against instrumental measurements were, however, limited by the original record’s early ending in 1974. Here we introduce an update of this widely considered chronology until 2007 and back into medieval times. A total of 297 new larch samples from high-elevation settings in the southern French Alps were included, and the combined 398 measurement series allowed effects of tree-ring detrending and chronology development to be explored. Comparisons with meteorological temperature, precipitation and drought indices revealed weak and temporally inconsistent climate sensitivity. To further place these local findings in a biogeographic context, we used >3,000 larch trees from 61 locations across the Alpine arc. This unique network approach confirmed fading temperature sensitivity with decreasing latitude, and thus questioned the overall reliability of ring width-based temperature reconstructions in the Mediterranean region. Our results further emphasize the pending need to develop chronologies from maximum latewood densities and stable isotope ratios across the lower latitudes, and to carefully evaluate ecological site conditions and methodological data restrictions prior to compiling local data into global networks.  相似文献   

6.
新疆伊犁乌孙山北坡树轮灰度年表的建立及气候意义   总被引：1，自引：0，他引：1  
利用2006年采自新疆伊犁乌孙山北坡3个采点的树轮样本,建立了树轮宽度年表,采用树轮图像分析法进一步建立了3种宽度年表和5种灰度年表。宽度年表对比发现,树木年轮对气候响应南疆强于北疆,北疆其它地方强于伊犁地区,而乌孙山北坡与伊犁其它地区比较,树轮宽度对气候的响应较敏感。树轮图像分析法建立的8种年表特征进行对比发现,恰依恰孜宽度年表对气候的响应最为强烈;而阿乌里亚乔克标准化灰度年表对气候的响应较好。相关分析表明,全轮灰度、早材灰度和最大灰度与4、5月气温相关较好。4月降水和实测宽度、全轮宽度以及早材宽度相关较好,而6月降水与全轮灰度和早材灰度相关较好。早材宽度对气候的响应强于晚材宽度;全轮灰度和早材灰度对气候的响应较好。利用树轮图像分析所得到的8个树轮参数年表可增加气候重建代用指标,提高气候重建的精度。  相似文献   

7.
Development of long tree-ring records is an important task in paleoclimate studies. Here we presented a five-century long reconstruction of summer (June to August) temperature based on a tree ring-width chronology of Picea brachytyla var. complanata originating from the Hengduan Mountains of China. Climate-growth response analysis showed that summer temperature was the main climatic factor limiting tree-ring growth in the study area. The reconstructed summer temperature accounted for 47.6% of the variance in actual temperature during their common period A.D. 1958–2002. Analysis of the temperature reconstruction showed that major warm periods occurred in the A.D. 1710s–1750s, 1850s, 1920s–1950s and 1990s to present, whereas cold intervals occurred in the A.D. 1630s–1680s, 1790s–1800s, 1860s–1880s and 1950s–1980s, respectively. The low-frequency variation of the reconstruction agreed fairly well with tree-ring reconstructed temperature from nearby regions and with records of glacier fluctuations in the surrounding high mountains, suggesting that our reconstructed summer temperature was reliable, and could aid in the evaluation of regional climate variability.  相似文献   

8.
Until recently, there have been very few tree-ring studies in southeast China due largely to the scarcity of old trees and the complexity of relationships between tree growth and climate in subtropical regions of China. Recent studies on the conifers in southeast China revealed that tree ring-based climate reconstructions are feasible. Here, we describe a reconstruction (AD 1850–2009) of November–February maximum temperatures for Changting, Fujian, southeast China based on tree ring width data of Pinus massiniana which considerably extends the available climatic information. Calibration and verification statistics for the period 1956–2009 show a high level of skill and account for a significant portion of the observed variance (32.9%) irrespective of which period is used to develop or verify the regression model. Split sample validation supports our use of a reconstruction model based on the full period of reliable observational data (1956–2009). Warm periods occurred during 1854–1859, 1868–1880, 1885–1899, 1906–1914, 1920–1943, 1964–1975 and 1994–present; while the periods of AD 1850–1853, 1860–1867, 1881–1884, 1900–1907, 1915–1919, 1944–1963 and 1976–1993 were relatively cold. The climate correlation analyses with gridded temperature dataset and SST revealed that our season temperature reconstruction contains the strong large-scale climate signals. Our results suggest that some warm winters of Changting are coincident with El Ni?o events over the past 150?years. In addition, several severely cold winters coincide with major volcanic eruptions.  相似文献   

9.
Changes in maximum spring and summer temperature are expected to have impacts on plant phenology and the occurrence of forest fires. Homogenised instrumental records of maximum spring and summer temperature are available in northern France for the past century, as well as documentary records of grape harvest dates and forest fire frequencies. Here we provide a new proxy of seasonal climate obtained by the analysis of latewood tree ring cellulose isotopic composition (δ18O, δ13C and δD), from 15 living oak trees (Quercus petraea) sampled in the Fontainebleau forest, near Paris. For the past 30 years, we have conducted a study on the inter-tree (for oxygen isotopes) and inter-station (for oxygen and hydrogen) isotopic variability. Multiple linear regression statistical analyses are used to assess the response function of documentary and tree-ring isotopic records to a variety of climatic and hydrological parameters. This calibration study highlights the correlation between latewood tree-ring δ18O and δ13C, grape harvest dates and numbers of forest fire starts with maximum growing season (April to September) temperature, showing the potential of multiple proxy reconstructions to assess the past fluctuations of this parameter prior to the instrumental period.  相似文献   

10.
The Mediterranean region has been identified as a global warming hotspot, where future climate impacts are expected to have significant consequences on societal and ecosystem well-being. To put ongoing trends of summer climate into the context of past natural variability, we reconstructed climate from maximum latewood density (MXD) measurements of Pinus heldreichii (1521–2010) and latewood width (LWW) of Pinus nigra (1617–2010) on Mt. Olympus, Greece. Previous research in the northeastern Mediterranean has primarily focused on inter-annual variability, omitting any low-frequency trends. The present study utilizes methods capable of retaining climatically driven long-term behavior of tree growth. The LWW chronology corresponds closely to early summer moisture variability (May–July, r = 0.65, p < 0.001, 1950–2010), whereas the MXD-chronology relates mainly to late summer warmth (July–September, r = 0.64, p < 0.001; 1899–2010). The chronologies show opposing patterns of decadal variability over the twentieth century (r = ?0.68, p < 0.001) and confirm the importance of the summer North Atlantic Oscillation (sNAO) for summer climate in the northeastern Mediterranean, with positive sNAO phases inducing cold anomalies and enhanced cloudiness and precipitation. The combined reconstructions document the late twentieth—early twenty-first century warming and drying trend, but indicate generally drier early summer and cooler late summer conditions in the period ~1700–1900 CE. Our findings suggest a potential decoupling between twentieth century atmospheric circulation patterns and pre-industrial climate variability. Furthermore, the range of natural climate variability stretches beyond summer moisture availability observed in recent decades and thus lends credibility to the significant drying trends projected for this region in current Earth System Model simulations.  相似文献   

11.
基于2014年采自柴达木盆地南缘格尔木地区的胡杨树轮样本,采用三种不同去趋势方法(样条函数法、负指数拟合和区域曲线去趋势方法)建立树轮标准化序列,结合格尔木气象站气候资料,分析不同去趋势方法下胡杨径向生长对气候的响应。研究表明,利用区域去趋势方法建立的树轮年表包含有较多的气候环境信息,胡杨树轮年表与逐月气候因子相关表明,树轮年表对降水响应不显著,与生长季的平均气温和平均最高气温有较好的相关性,最高相关系数达0.411(p0.01),格尔木胡杨树轮的区域去趋势年表与组合相关的6—10月平均最高气温相关性最好,生长季的平均最高气温对胡杨径向生长有一定的限制作用并具有树木生理学意义。用区域曲线去趋势方法得出的格尔木胡杨树轮年表对气候的响应最好。  相似文献   

12.
For the first time we present a multi-proxy data set for the Russian Altai, consisting of Siberian larch tree-ring width (TRW), latewood density (MXD), δ13C and δ18O in cellulose chronologies obtained for the period 1779–2007 and cell wall thickness (CWT) for 1900–2008. All of these parameters agree well between each other in the high-frequency variability, while the low-frequency climate information shows systematic differences. The correlation analysis with temperature and precipitation data from the closest weather station and gridded data revealed that annual TRW, MXD, CWT, and δ13C data contain a strong summer temperature signal, while δ18O in cellulose represents a mixed summer and winter temperature and precipitation signal. The temperature and precipitation reconstructions from the Belukha ice core and Teletskoe lake sediments were used to investigate the correspondence of different independent proxies. Low frequency patterns in TRW and δ13C chronologies are consistent with temperature reconstructions from nearby Belukha ice core and Teletskoe lake sediments showing a pronounced warming trend in the last century. Their combination could be used for the regional temperature reconstruction. The long-term δ18O trend agrees with the precipitation reconstruction from the Teletskoe lake sediment indicating more humid conditions during the twentieth century. Therefore, these two proxies could be combined for the precipitation reconstruction.  相似文献   

13.
At present the most powerful tree-ring based climate reconstructions use high numbers of growth proxy series (ring width and density) to produce spatially smoothed estimates, such as average Northern Hemisphere summer temperatures. These single parameter reconstructions might be supplemented with regional climate reconstructions capable of capturing variability in more than one climate variable without lower replication compromising statistical quality, if multiple tree ring proxies were used. Pinus sylvestris and Pinus uncinata latewood density, width and δ13C series are presented from two sites in the French subalpine zone, east of Briançon. Where two proxies have the same dominant climate control their combination enhances that signal. Where proxies differ in dominant controlling climate variable, combining series allows access to bi-variable calibrations. Using this approach, multi-proxy reconstructions of both temperature and precipitation would better reflect complex synoptic variability in climate on spatially useful scales.  相似文献   

14.
Effects of global warming on radial growth were examined for the subalpine tree species Abies veitchii (1600–2200 m?a.s.l.), A. mariesii (2000–2500 m?a.s.l.) and Betula ermanii (1600–2500 m?a.s.l.) in central Japan, by using dendrochronological techniques. Chronologies of tree-ring widths were examined for the three species and of maximum latewood densities for the two Abies species at their upper and lower distribution limits (total 10 chronologies). We developed multiple regression models to reproduce these chronologies from the monthly mean temperature and sum of precipitation. Of the 10 chronologies, growth-climate relations could not be modeled for tree-ring width chronologies of the three species at their lower distribution limits because of low correlation. Annual mean temperature and annual sum of precipitation will increase about 3 °C and 100 mm, respectively, by 2100 in central Japan, according to 18 climatic change scenarios (6 general circulation models ×3 greenhouse gasses emission scenarios). We predicted tree-ring widths and maximum latewood densities by substituting 18 climatic change scenarios into the growth-climate models. Maximum latewood densities and tree-ring widths of A. mariesii at the upper and lower distribution limits increased by 2100. The rates of the increase tended to be greater for scenarios with more greenhouse gas emission. By contrast, maximum latewood densities of A. veitchii and tree-ring widths of B. ermanii were unchanged by 2100, irrespective of the three greenhouse gas emission scenarios. This study showed that radial growth of the three species responds differently to global warming and their responses are predictable by dendrochronological models.  相似文献   

15.
We present here the first statistically calibrated and verified tree-ring reconstruction of climate from continental Southeast Asia. The reconstructed variable is March–May (MAM) Palmer Drought Severity Index (PDSI) based on ring widths from 22 trees (42 radial cores) of rare and long-lived conifer, Fokienia hodginsii (Po Mu as locally called) from northern Vietnam. This is the first published tree ring chronology from Vietnam as well as the first for this species. Spanning 535 years, this is the longest cross-dated tree-ring series yet produced from continental Southeast Asia. Response analysis revealed that the annual growth of Fokienia at this site was mostly governed by soil moisture in the pre-monsoon season. The reconstruction passed the calibration-verification tests commonly used in dendroclimatology, and revealed two prominent periods of drought in the mid-eighteenth and late-nineteenth centuries. The former lasted nearly 30 years and was concurrent with a similar drought over northwestern Thailand inferred from teak rings, suggesting a “mega-drought” extending across Indochina in the eighteenth century. Both of our reconstructed droughts are consistent with the periods of warm sea surface temperature (SST) anomalies in the tropical Pacific. Spatial correlation analyses with global SST indicated that ENSO-like anomalies might play a role in modulating droughts over the region, with El Niño (warm) phases resulting in reduced rainfall. However, significant correlation was also seen with SST over the Indian Ocean and the north Pacific, suggesting that ENSO is not the only factor affecting the climate of the area. Spectral analyses revealed significant peaks in the range of 53.9–78.8 years as well as in the ENSO-variability range of 2.0 to 3.2 years.  相似文献   

16.
Summary We analyse the spatial representation of five previously published multi-century to millennial length dendroclimatological reconstructions of Fennoscandian summer temperatures. The reconstructions, ranging from local to regional scale, were based on either tree-ring width (TRW) or maximum latewood density (MXD) data or on a combination of the two. TRW chronologies are shown to provide reasonably good spatial information mainly for July temperatures, but a combination of TRW and MXD yields a better spatial representation for the whole summer season (June–August). A multiple-site reconstruction does not necessarily provide better spatial representation than a single site reconstruction, depending on the criterion for selecting data and also on the strength of the climate signal in the tree-ring data. In a new approach to analyse the potential for further developing Fennoscandian temperature reconstructions, we selected from a network of TRW and MXD chronologies those having the strongest temperature information a priori, to obtain a strong common climate signal suitable for a regional-scale reconstruction. Seven separate, but not independent, reconstructions based on progressively decreasing numbers of chronologies were created. We show that it is possible to improve the spatial representation of available reconstructions back to around AD 1700, giving high correlations (>0.7) with observed summer temperatures for nearly the whole of Fennoscandia, and even higher correlations (>0.85) over much of central-northern Fennoscandia. Further sampling of older trees (e.g. dry-dead and subfossil wood) would be needed to achieve the same high correlations prior to AD 1700. Our analysis suggests that it should be possible to select a few key sites for improving the reconstructions before AD 1700. Since tree-ring data from northern Fennoscandia are used in all available hemispheric-scale temperature reconstructions for the last millennium, there is also a potential for slightly improving the quality of the hemispheric-scale reconstructions, by including an improved reconstruction for Fennoscandia. However, adding new chronologies from previously unsampled regions would potentially improve hemispheric-scale temperature reconstructions more substantially. Authors’ addresses: Isabelle Gouirand, Anders Moberg, Department of Physical Geography and Quaternary Geology, Stockholm University, SE-106 91 Stockholm, Sweden; Hans W. Linderholm, Regional Climate Group, Department of Earth Sciences, G?teborg University, SE-405 30 G?teborg, Sweden; Barbara Wohlfarth, Department of Geology and Geochemistry, Stockholm University, SE-106 91 Stockholm, Sweden.  相似文献   

17.
位于西昆仑山北坡的叶尔羌河是塔里木河的三大源流之一,该流域山区分布的雪岭云杉为过去气候变化研究提供了理想的载体。本文建立了叶尔羌河流域4个雪岭云杉树轮宽度年表和区域合成年表,探讨了树轮年表对叶城气象站气温、降水等气候要素的响应特征。结果表明雪岭云杉树轮年表具有较高平均敏感度、缺轮率和序列间相关系数,年表的质量较高。区域合成年表与叶城站上年6月至当年5月降水量相关系数为0.393,与当年3—9月平均最低气温相关系数为0.624。一阶差相关分析表明,树轮年表与最低气温的高频变化特征并不一致,二者较高的正相关主要是由于温度升高趋势的贡献。树轮年表与乌恰站上年7月至当年4月降水量相关系数为0.535。西昆仑山北坡雪岭云杉树轮年表与周边对水分敏感的树轮气候记录对比表明,其低频变化趋势以及缺年集中出现的年份均具有较好的一致性。由于气候干旱、下垫面条件恶劣,位于叶尔羌河流域的西昆仑山北坡雪岭云杉树木径向生长的限制因子仍然为水分条件,而非气温。  相似文献   

18.
利用树轮资料重建1751-2005年崆峒山地区夏季温度变化   总被引：4，自引：0，他引：4  
利用采自崆峒山区的66根油松树轮样芯,建立了采样点的标准年表、差值年表和自回归标准化年表。相关分析表明,标准年表与当年夏季均温有显著的相关性,通过建立回归方程,重建了1751-2005年崆峒山地区夏季温度序列。结果表明,自1751年以来,研究区存在3个高温期（1786-1847年、1894-1937年、1987-2004年）和3个低温期（1764-1785年、1852-1893年、1952-1986年）。与Nino3指数、南方涛动指数（SOI）和太阳黑子数等对比表明,崆峒山地区对全球大尺度气候变化及太阳活动都有较好的响应。  相似文献   

19.
The dendrochronological use of the parameter maximum density (MXD) in Pinus Sylvestris L., at high latitudes, has provided valuable insights into past summer temperature variations. Few long MXD chronologies, from climatically coherent regions, exist today, with the exception being in northern Europe. Five, 500-year-long, Fennoscandian, MXD chronologies were compared with regard to their common variability and climate sensitivity. They were used to test Signal-free standardization techniques, to improve inferences of low-frequency temperature variations. Climate analysis showed that, in accordance with previous studies on MXD in Fennoscandia, the summer temperature signal is robust (R 2?>?50 %) and reliable over this climatically coherent region. A combination of Individual standardization and regional curve standardization is recommended to refine long-term variability from these MXD chronologies and relieve problems arising from low replication and standardization end-effects.  相似文献   

20.
利用采自川西高原金川情人海沟的云杉树轮样本,分析了树轮宽度与气候要素的关系。结果表明：树轮宽度指数与金川气象站6月平均气温具有显著的正相关关系。利用标准化树轮宽度指数重建了该区域1713—2010年6月平均气温序列,交叉检验及各项检验的参数表明重建方程是稳定可靠的。近298年来川西金川6月平均气温为18.2℃,经历了3个暖期和4个冷期。暖期时段为1825—1839、1854—1892和1951—1961年;冷期时段为1792—1804、1842—1853、1864—1893和1911—1924年。周期分析结果表明,重建序列存在2～3、7～8、20～30、32～64和70～130 a的变化周期。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号