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1.
RECONSTRUCTING MIDDLE-TIBET CLIMATE DURING THE LAST 600 YEARS BY DENDROCLIMATOLOGICAL METHOD* 
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下载免费PDF全文 Based on four tree-ring chronologies which was analyscd with appropriate collection and accurate dating in the middle Tibetan Plateau,an essential procedure on reconstruction of past climate has been pointed out in this paper.First,the response function of each dendrochronology has been built and used to estimate how ring-width growth responds to variations in monthly climatic change.Second,the climate factors which could be produced with different tree-ring series have been selected.Then,the transfer function equation,including a new set of orthogonal variables,can be used to reconstruct local past temperature or precipitation.It should be emphasized that prior growth has been considered in the relationship between climate factor and tree-ring chronology,Besides,some different periods for calibration and verification have been divided.And some statistics and other kinds of proxy data have been adopted as test approaches.As a result,the variations of air temperature during the last 600 years and precipitation during the last 340 years were reconstructed by combining the same types of tree-ring series in the middle Tibet. 相似文献
2.
Site-aspect influence on climate sensitivity over time of a high-altitude Pinus cembra tree-ring network 总被引：1，自引：0，他引：1
Giovanni Leonelli Manuela Pelfini Giovanna Battipaglia Paolo Cherubini 《Climatic change》2009,96(1-2):185-201
Recently a divergence between tree-ring parameters from temperature-limited environments and temperature records has been observed worldwide but comprehensive explanations are still lacking. From a dendroclimatic analysis performed on a high-altitude tree-ring network of Pinus cembra (L.) in the Central Italian Alps we found that site aspect influences non-stationary growth-climate relationships over time. A general increasing divergence between ring width and the summer temperature record (J–A) has been observed especially for chronologies from SW-facing slopes, whereas chronologies from N-facing sites showed stable relationships over time. The monthly analysis revealed that the decrease in sensitivity was mostly accounted for by the changes in the relationships with June temperature (decreasing correlations especially for S- and W-facing site chronologies), whereas trees from N-facing sites showed an increasing sensitivity to July temperatures. Our data suggest that at high altitudes, low temperatures at the beginning of the growing season no longer limit growth. We also found that our temperature-sensitive trees did not linearly respond in radial growth to the extreme heat event of summer 2003, and formed an annual ring of average width, resulting in a strong divergence from the temperature record. Our findings underline the importance of site ecology for tree-ring based climate reconstructions using temperature-sensitive ring-width chronologies, and may help in solving the ‘divergence problem’. 相似文献
3.
Decreasing teleconnections with inter-site distance in monthly climatic data and tree-ring width networks in a mountainous Alpine area 总被引：3，自引：0，他引：3
C. Rolland 《Theoretical and Applied Climatology》2002,71(1-2):63-75
Summary The similarities in time series recorded at sites which are distant from each other are called teleconnections. In this paper,
the loss of such correlations with inter-site distance was investigated for both climatic and dendrochronological data sets,
with 70 tree-ring chronologies. A dense network of weather stations was studied in the southeastern French Alps, covering
complex climatic gradients over three departments. 78 sites with precipitation data (with a total of 48 756 monthly values),
and 48 stations that recorded temperature (with 20 722 monthly mean values) were analysed. In the same area, four coniferous
species (mountain pine and stone pine, European larch and Norway spruce) provided 37 ring-width chronologies for high elevation
sites near the timberline. Both silver fir and Norway spruce provided a second tree-ring chronology network for 33 different
sites at lower elevations.
The teleconnections between precipitation series were found to be higher than those observed for temperature over short distances,
but the maximum threshold distance was lower (193 km) compared to a positive correlation distance that exceeds 500 km for
temperature. The maximum temperatures had stronger teleconnections than minimum values (522 km versus 476 km), since the latter
are linked more with other site factors, such as slope, exposure and local topography.
As expected, the tree-ring chronologies showed weaker teleconnections than the climatic series, with a threshold distance
of 374 km obtained for all high elevation forests. The coniferous species with high intra-specific teleconnections over large
distances were, in decreasing importance, Pinus uncinata (> 500 km), Picea abies (477 km), Pinus cembra (over 254 km) and Larix decidua (over 189 km only). The two former species showed the highest intra-specific correlations (with mean correlation R=0.625 and 0.666). The dendrochronological teleconnections were found to have a extent lesser for trees species that depend
on rainfall (such as larch, and stone pine). They are enhanced, however, for temperature sensitive species such as spruce
and mountain pine (a drought resistant tree). Therefore, these two latter conifers appear to be especially suitable for climatic
reconstruction over large distances in mountainous areas. However, teleconnections within silver fir (Abies alba) and spruce chronologies were sharply reduced (over 131 km and 135 km) in lower elevation forests, underlining the interest
of timberline forests for dendroclimatology.
A better knowledge of the spatial correlations in climatic series and ring-width data may enable the optimisation of weather
station networks. It may also permit a better choice of weather stations used for dendroclimatology, either for tree-ring
and climate relationship calibration or for climate reconstructions. In dendrochronology, wood dating also requires the knowledge
of to what extent remote ring-width chronologies can be used.
Received September 11, 2000 Revised March 26, 2001 相似文献
4.
David R. Easterling 《Climatic change》1999,41(3-4):615-634
As the debate on potential climate change continues, it is becoming increasingly clear that the main concerns to the general public are the potential impacts of a change in the climate on societal and biophysical systems. In order to address these concerns researchers need realistic, plausible scenarios of climate change suitable for use in impacts analysis. It is the purpose of this paper to present a downscaling method useful for developing these types of scenarios that are grounded in both General Circulation Model simulations of climate change, and in situ station data. Free atmosphere variables for four gridpoints over the Missouri, Iowa, Nebraska, Kansas (MINK) region from both control and transient simulations from the GFDL General Circulation Model were used with thirty years of nearby station data to generate surface maximum and minimum air temperatures and precipitation. The free atmosphere variables were first subject to a principal components analysis with the principal component (PC) scores used in a multiple regression to relate the upper-air variables to surface temperature and precipitation. Coefficients from the regression on station data were then used with PC scores from the model simulations to generate maximum and minimum temperature and precipitation. The statistical distributions of the downscaled temperatures and precipitation for the control run are compared with those from the observed station data. Results for the transient run are then examined. Lastly, annual time series of temperature for the downscaling results show less warming over the period of the transient simulation than the time series produced directly from the model. 相似文献
5.
天山巩乃斯河源区树轮年表特征 总被引：4，自引：0，他引：4
利用树轮资料建立了天山巩乃斯河源区5个树轮采点的宽度年表,并对各采点的标准化年表进行特征分析。结果表明：巩乃斯林场5个采点年表的平均敏感度都较低,这与该区的降水丰富、土壤层较厚、坡度较小有关。阿尔先沟、东站、南站A、南站显著水平达到0.01的自相关分别达到9阶、6阶、5阶和6阶,反映该区气候对树木生长影响的＂滞后效应＂非常明显。巩乃斯林缘采点的标准化年表在5个采点中平均敏感度最高、一阶自相关最小,样本对总体的代表性、信噪比、第一主成分方差都为最高,表明该年表的质量最好。标准化年表与新源站月气象资料的相关分析发现,年表与生长季及其前期的降水呈正相关,而与夏季平均最高气温呈显著负相关关系,其相关时段也具有明显的生理学意义。巩乃斯林缘采点的标准化年表所含的气候信息最为丰富,与新源气象站上年7月至当年4月的降水相关系数达0.62,而其余4个点记录更多的记录了低频气候信息,年表经5点平滑处理后与月气象资料相关明显增大。 相似文献
6.
Temperature variability over the past millennium inferred from Northwestern Alaska tree rings 总被引：3，自引：0，他引：3
Rosanne D’Arrigo Erika Mashig David Frank Rob Wilson Gordon Jacoby 《Climate Dynamics》2005,24(2-3):227-236
We describe a new tree-ring width data set of 14 white spruce chronologies for the Seward Peninsula (SP), Alaska, based on living and subfossil wood dating from 1358 to 2001 AD. A composite chronology derived from these data correlates positively and significantly with summer temperatures at Nome from 1910 to 1970, after which there is some loss of positive temperature response. There is inferred cooling during periods within the Little Ice Age (LIA) from the early to middle 1600s and late 1700s to middle 1800s; and warming from the middle 1600s to early 1700s. We also present a larger composite data set covering 978–2001 AD, utilizing the SP ring-width data in combination with archaeological wood measurements and other recent collections from northwestern Alaska. The Regional Curve Standardization (RCS) method was employed to maximize potential low-frequency information in this data set. The RCS chronology shows intervals of persistent above-average growth around the time of the Medieval Warm Period (MWP) early in the millennium, which are comparable to growth levels in recent centuries. There is a more sustained cold interval during the LIA inferred from the RCS record as compared to the SP ring-width series. The chronologies correlate significantly with Bering and Chukchi Sea sea surface temperatures and with the Pacific Decadal Oscillation index. These atmosphere–ocean linkages probably account for the differences between these records and large-scale reconstructions of Arctic and Northern Hemisphere temperatures based largely on continental interior proxy data. 相似文献
7.
采用青海两个树木年轮年表重建局地过去降水的初步分析 总被引：3，自引：1，他引：3
本文依据青海乌兰、班玛两个经过精确定年的树木年轮年表，通过响应函数计算，求得逐月的气候因素对轮宽生长的贡献。在贡献显著的时区内，经由相关计算确立最佳重建时段，选取预报因子，再用逐步回归方法建立方程来重建过去气候。分析表明在重建时段内的两地降水变化，均有明显的多雨期和少雨期，同时存在显著的周期现象。 相似文献
8.
Biases existing in the lateral boundary conditions (LBCs) influence climate simulations in regional climate models (RCMs). Correcting the biases in global climate model (GCM)-produced LBCs before running RCMs was proposed in previous studies as a possible way to reduce the GCM-related model dependence of future climate projections using RCMs. In this study the ICTP Regional Climate Model Version 4 (RegCM4) is used to investigate the impact of LBC bias correction on projected future changes of regional climate in West Africa. To accomplish this, two types of present versus future simulations are conducted using RegCM4: a control type where both the present and future LBCs are derived directly from the GCM output (as is done in most regional climate downscaling studies); an experiment type where the present-day LBCs are from reanalysis data and future LBCs are derived by combining the reanalysis data and the GCM-projected LBC changes. For each type of simulations, three different sets of LBCs are experimented on: 6-hourly synoptic forcing directly from the reanalysis or GCM, 6-hourly data interpolated from monthly climatology (without diurnal cycle), and 6-hourly data interpolated from the month-specific climatology of diurnal cycles. It is found that the simulations using different LBCs produce similar present-day summer rainfall patterns, but the predicted future changes differ significantly depending on how the LBC bias correction is treated. Specifically, both the bias correction applied at the synoptic scale and the bias correction applied to the monthly interpolated LBCs without diurnal cycle produce a spurious drying signal caused by physical inconsistency in the corrected future LBCs. Interpolated monthly LBCs with diurnal cycle alleviate the problem to a large extent. These results suggest that using bias-corrected LBCs to drive regional climate models may not guarantee reliable future projections although reasonable present climate can be simulated. Physical inconsistencies may be contained in the bias-corrected LBCs, increasing the uncertainties of RCM-produced future projections. 相似文献
9.
Violins and climate 总被引：4，自引：0，他引：4
Summary This paper explores the possibility of using ring-width measurements derived from string instruments as a potential source of palaeoclimate information. From a data-base of 1800 measured series, we have identified two sub-sets that compare well with living high elevation spruce (Picea abies (L.) Karst) chronologies from the Bavarian Forest and Austrian Alps. The problems of using historical tree-ring data for dendroclimatic purposes are addressed and by combining the living and historic ring-width data from these two regions, a preliminary proxy of past June/July mean temperatures is developed. This proxy summer temperature record shows striking similarities with a tree-ring based temperature reconstruction for the Central Eastern Alps, the CLIMHIST June/July temperature record from Switzerland and glacial records from the Austrian Alps. This explorative study demonstrates that ring-width series from string instruments may allow the identification of generalised source regions of wood used for instrument making and, most importantly, provide a new unique source for palaeoclimate information at a variety of both temporal and spatial scales for high elevations in central Europe. 相似文献
10.
大气环流的年代际变化 II.GCM数值模拟研究 总被引：17，自引：2，他引：15
类似大气环流模式比较计划（AMIP）的数值模拟,将实际观测的海表水温（SST）资料引入模式进行40多年的数值积分,得到长时间的大气环流模拟结果。分析数值模拟结果发现,无论是大气中的主要涛动和遥相关型,还是重要大气环流系统都极为清楚地存在着年代际变化特征,包括10～20年准周期振荡和可能的30年以上的准周期振荡;而且上述主要环流系统的形势及其年代际变化大都与实际观测资料所给出的结果相一致。顺便分析中国东部气候的模拟结果,年代际变化特征（包括60年代的气候突变）也很清楚,并同大气环流变化配合十分合理。结果也表明,同研究季节和年际变化一样,大气环流模式（AGCM）数值模拟也是研究大气环流和气候年代际变化的有效方法。 相似文献
11.
哈萨克斯坦是世界最大的内陆国家,拥有典型的大陆性气候和多样的地理环境及生态系统,同时哈萨克斯坦的自然环境和人类社会对于气候变化这一全球性问题是敏感的、脆弱的,需要运用科学的研究方法应对气候变化的挑战。通常,区域或局地尺度的气候变化影响研究需要对气候模式输出或再分析资料进行降尺度以获得更细分辨率的气候资料。近年来,大量验证统计降尺度方法在各个地区能力的研究见诸文献,然而在哈萨克斯坦地区验证统计降尺度方法的研究非常少见。本文使用了岭回归的方法对哈萨克斯坦地区11个气象站点1960~2009年的月平均气温进行了统计降尺度研究。结果显示,使用前30年数据和岭回归模型建立大尺度预报因子和观测资料的统计关系可以较好地预测后20年的月平均气温,预测能力在各站各月均有不同程度的差异,地形复杂的站点预测效果较差,夏季预测结果好于冬季;此外,将哈萨克斯坦地区平均来看则与观测数据相吻合。 相似文献
12.
200?years of European temperature variability: insights from and tests of the proxy surrogate reconstruction analog method 总被引：1，自引：0，他引：1
J?rg Franke J. Fidel Gonz��lez-Rouco David Frank Nicholas E. Graham 《Climate Dynamics》2011,37(1-2):133-150
Spatially resolved climate reconstructions are commonly derived from long instrumental series and proxy data via linear regression based approaches that use the main modes of the climate system. Such reconstructions have been shown to underestimate climate variability and are based upon the assumption that the main modes of climate variability are stationary back in time. Climate models simulate physically consistent climate fields but cannot be taken to represent the real past climate trajectory because of their necessarily simplified scope and chaotic internal variability. Here, we present sensitivity tests of, and a 200-year temperature reconstruction from, the PSR (Proxy Surrogate Reconstruction) method. This method simultaneously capitalizes on the individual strengths of instrumental/proxy data based reconstructions and model simulations by selecting the model states (analogs) that are most similar with proxy/instrumental data available at specific places and specific moments of time. Sensitivity experiments reveal an optimal PSR configuration and indicate that 6,500 simulation years of existing climate models provide a sufficient pool of possible analogs to skillfully reconstruct monthly European temperature fields during the past 200?years. Reconstruction verification based upon only seven instrumental stations indicates potential for extensions back in time using sparse proxy data. Additionally the PSR method allows evaluation of single time series, in this case the homogeneity of instrumental series, by identifying inconsistencies with the reconstructed climate field. We present an updated European temperature reconstruction including newly homogenized instrumental records performed with the computationally efficient PSR method that proves to capture the total variance of the target. 相似文献
13.
Marika Haupt Michael Friedrich Vladimir V. Shishov Tatjana Boettger 《Climatic change》2014,122(1-2):201-215
Tree-ring oxygen stable isotope data series from conifers growing on the Dachstein Plateau (Austrian Alps) were selected to demonstrate the applicability of the serial pooling method using shifted 5-year tree-ring blocks for summer temperature reconstruction. The addressed method allows the construction of long isotope chronologies with significant climate correlation and well preserved climate sensitivity applying the irreducible sample replication of five trees. The linear regression model for temperature reconstruction is verifiable and the predicted data are well correlated with instrumental data, especially reproducing the long-term temperature trend. However, the reduced mean variance leads to loss of extreme years, which can be regulated by the combination of one data series in annual resolution with five shifted 5-year block data series. This significantly improves the variance of the mean chronology, sufficiently to identify extremes. Therefore, we recommend the use of mixed data sets as a compromise between essential sample replication and economic considerations. 相似文献
14.
Downscaling GCM information to regional scales: a non-parametric multivariate regression approach 总被引：1，自引：0，他引：1
The multivariate adaptive regression splines (MARS) model was used to capture the observed relationships between sea level pressure (SLP) anomalies over the Euro-Atlantic sector and the winter time (December–February) monthly rainfall at eight sites in Portugal; possible anthropogenic changes of the rainfall in a perturbed future climate were then estimated by using both the observed SLP-rainfall relationships, described by MARS models, and the GCM simulated SLP, taken from the output of the Hadley Centre Transient Climate Change Experiment (UKTR). Also, principal component analysis was carried out to reduce the dimensionality of the SLP data, and to assess the ability of the GCM in simulating the large-scale circulation; the first six principal components were retained as predictors in the MARS model. The MARS model were built up by using the data for 1946–1991 as the training set and that for 1901–1943 as the testing set, showing satisfactory prediction skills. It is concluded that the UKTR control simulation successfully reproduced main features of the large-scale circulation, but the observed relationship between SLP and the regional rainfall was not well preserved. With respect to the 54-year experiment of perturbed run, the MARS estimation of rainfall and the relevant direct GCM rainfall output possess similar multi-annual variations; however, there are substantial differences regarding details; the change in the area mean of winter time mean monthly rainfall in Portugal estimated by MARS (indirect GCM output) is about –12.7 mm per 54-year, and the relevant direct GCM output is –16.9 mm/54-year. This reduction tendency is consistent with previously reported findings respecting rainfall in the Iberian Peninsula, which were based on the MPI (Max-Planck Institute for Meteorology) transient simulations. 相似文献
15.
BRIAN H. LUCKMAN 《Climatic change》1997,36(3-4):455-476
Available meteorological, dendrochronological and glacier area change data are reviewed for the central Canadian Rockies. Limited glacier inventory studies indicate a loss of ca 25% of glacier area (greater for smaller glaciers) since the Little Ice Age maximum 130–150 years ago. The few available long climacte records are from widely spaced, valley floor sites, well below treeline. Available gridded or regional climate data sets similarly contain no high elevation sites. The five long (75 yr) station records contain a strong common signal but show differences in the relative amplitude and timing of temperature variations indicating links to either prairie or pacific stations. However the station network is too sparse to define the spatial extent of these patterns. Tree-ring chronologies from a network of Picea engelmannii (21), Larix lyallii (17) and Pinus albicaulis (2) treeline sites are presented and reviewed. Residual chronologies show stronger intercorrelation than standard chronologies and the larix chronologies are more highly correlated than picea, probably because of the narrower range of sites sampled. Many standard chronologies show a strong common regional signal of above average growth in the late 17th, late 18th and mid-20th centuries and reduced growth in the early 17th, early 18th and for most of the 19th centuries. However, examination of individual chronologies shows strong local or sub-regional divergence from this pattern that reflects smaller scale climate or non-climatic influences. Differences in the density and location of sites between the climate and tree-ring networks will create problems in resolving climate variation at the sub-regional scale. 相似文献
16.
对1952—1980年我国连续的月地面气温用时间序列ARMA（p、q）模型进行随机建模。月温度由60个站组成，用经验正交函数加以展开，取不同的样本长度即348,336和300月，以便考察经验正交展开的稳定性。前四个主成分，即z1,z2,z3,z4取为多维时间序列的变数，因为它们的总方差贡献达99.26%。在这四个主成分序列中的决定性周期用周期图和最大熵方法加以揭露。对一维变量zi,(i=1,2,3,4)的ARMA（p,q）的模型识别用Pandit-Wu方法进行，这样就可求得实验模型。用zi模型的外推值来预报月温度场。距平预报的命中率评分为78.3%，高于目前的业务长期天气预报。 相似文献
17.
An improvement of analog model strategy for more reliable local climate change scenarios 总被引：2，自引：0，他引：2
Summary Downscaled results derived using a linear regression model are compared with corresponding analysis based on an analog model, and the effect of systematic biases in climate models is examined. Here, a correction of the biases in the climate model is achieved using a common principal component analysis basis and by adjusting the part of the principal components corresponding to the control period. The results suggests that the downscaled results have a distribution more similar to the observations if the systematic biases are corrected for. The analog model can utilise weighted as well as unweighted principal components as input, and the effect of this choice was ex-amined. The results suggest that the weighted principal components yield more realistic results than the unweighted ones.Analog models are by definition incapable of making extrapolations outside the range of observed values whereas a linear model is well-suited for extrapolation. A combined approach involves superimposing a linear trend from the regression-based model onto the results of the analog model. It is theoretically possible for the combined method to make projections with a realistic level of variance as well as higher values than in the calibration data sample. A comparison between the linear, analog, and the combined strategies suggest that the linear model not always give the strongest trend, but also that the combined method may shift the analog-derived distribution towards higher values. 相似文献
18.
To highlight the compatibility of climate model simulation and proxy reconstruction at different timescales, a timescale separation merging method combining proxy records and climate model simulations is presented. Annual mean surface temperature anomalies for the last millennium (851–2005 AD) at various scales over the land of the Northern Hemisphere were reconstructed with 2° × 2° spatial resolution, using an optimal interpolation (OI) algorithm. All target series were decomposed using an ensemble empirical mode decomposition method followed by power spectral analysis. Four typical components were obtained at inter-annual, decadal, multidecadal, and centennial timescales. A total of 323 temperature-sensitive proxy chronologies were incorporated after screening for each component. By scaling the proxy components using variance matching and applying a localized OI algorithm to all four components point by point, we obtained merged surface temperatures. Independent validation indicates that the most significant improvement was for components at the inter-annual scale, but this became less evident with increasing timescales. In mid-latitude land areas, 10–30% of grids were significantly corrected at the inter-annual scale. By assimilating the proxy records, the merged results reduced the gap in response to volcanic forcing between a pure reconstruction and simulation. Difficulty remained in verifying the centennial information and quantifying corresponding uncertainties, so additional effort should be devoted to this aspect in future research. 相似文献
19.
20.
Frequency-Dependent Climate Signal in Upper and Lower Forest Border Tree Rings in the Mountains of the Great Basin 总被引：3，自引：0，他引：3
We examine the relationships, over the past millennium, between tree-ring chronologies from long-lived pines at their upper and lower limits in four mountain ranges in and near to the semi-arid Great Basin. We confirm LaMarche's (1974a) finding, based on a single mountain range in this same region, and a much shorter period of comparison, that climate responses are frequency dependent. In particular, upper and lower forest border chronologies in each mountain range are strongly coherent at decadal periods and less, with particular strength in the 3–7 year band. Thisvariability is significantly correlated with precipitation. Conversely, we find no significant correlation between the low frequency fluctuations (60 years and longer) of upper and lower forest border chronologies. There are, however, significant correlations between the low-frequency components of the upper forest border chronologies in the different ranges, consistent with their containing a growing season temperature signal on decadal time scales. The four upper forest border chronologies all show an anomalous increase in growth since the late 19th century, and an apparent change in climate control of ring growth. 相似文献