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1.
Through the analysis of ensembles of coupled model simulations and projections collected from CMIP3 and CMIP5, we demonstrate that a fundamental spatial scale limit might exist below which useful additional refinement of climate model predictions and projections may not be possible. That limit varies among climate variables and from region to region. We show that the uncertainty (noise) in surface temperature predictions (represented by the spread among an ensemble of global climate model simulations) generally exceeds the ensemble mean (signal) at horizontal scales below 1000 km throughout North America, implying poor predictability at those scales. More limited skill is shown for the predictability of regional precipitation. The ensemble spread in this case tends to exceed or equal the ensemble mean for scales below 2000 km. These findings highlight the challenges in predicting regionally specific future climate anomalies, especially for hydroclimatic impacts such as drought and wetness. 相似文献
2.
There is unequivocal evidence of increased air temperatures in Spain as a result of climate change. Using organic matter, nitrate and soluble reactive phosphorus concentrations, we reconstructed changes in water quality in 15 montane, pristine streams between 1973 and 2005 in Spain. We also measured how loading rates of these variables change as a function of shifting temperatures. Almost half of tested variables were related with hypothesized trends of climatic change for air temperature. Concerning extreme events, the hypothesis of climatic change matched in 33% of all relationships, which mostly occurred in Northern Spain. Regional gradients of population change and soil degradation, however, did not explain the geographical distribution of climatic change effects. The main reason that effects on water quality are not ubiquitous and that constraining factors are hardly detected may be that long-term signals are the outcome of several interacting processes. These are still poorly known and may act at different spatial and temporal scales. Hence, a case-by-case approach might prove more fruitful than a regional one when studying water quality responses to climatic change. Consideration of the balance between extreme and normal events (storm- vs baseflow), catchment effects (land use and its effects on evapotranspiration and runoff) and in-stream processes (outgassing, mineralization, burial) could help increase our understanding of the responses of water quality to climatic change. 相似文献
3.
Simulations of long-term climatic variations require the use of coupled oceanic and atmospheric models. Given their different
scales in space and time and present computing limitations, asynchronous coupling schemes are often used. Comparing the evolutions of simple dynamic systems which we couple alternatively with synchronous
and asynchronous schemes, we show that the behaviour can be modified, not only in minute details, but drastically, if asynchronous
coupling is used with insufficient care. We study how it happens, then suggest methods to insure that the average behaviour
of more realistic models is not modified with asynchronous schemes. Other branches of physics with coupled non-linear systems
could make use of these remarks.
Received: 19 February 1997 / Accepted: 17 June 1998 相似文献
4.
由于分布广泛、分辨率高、定年准确和气候敏感性好等原因,树木年轮在重建过去区域、半球甚至全球气候环境变化中扮演着重要角色。天山地处中亚干旱区,气候变化波动大,对全球变化响应敏感,植物生长的干旱胁迫作用强烈,天山山区分布有大量雪岭云杉和西伯利亚落叶松等长龄且对气候敏感的针叶树种,因此天山山区是树轮气候研究的理想区域。天山山区树轮气候研究始于20世纪70年代,尤其是近10 a有了长足的进步,有关天山山区树轮气候研究已经在国际上有一定影响。本文通过综述国内外对天山山区树轮气候研究的现状和进展,总结了近200 a基于树轮资料的天山山区较为一致的气候变化规律,并为进一步开展天山山区树轮气候研究提出建议。天山山区未来树木年轮气候学研究应在开展大量不同区域树木年轮气候学重建基础上,尝试理解树木径向生长对气候的响应机理研究,同时选用不同数理方法和多树木年轮指标进行长时间尺度和大空间范围重建工作,并讨论中亚干旱区过去千年气候变化的影响机制。 相似文献
5.
Peruvian Pacific drainage catchments only benefit from 2% of the total national available freshwater while they concentrate almost 50% of the population of the country. This situation is likely to lead a severe water scarcity and also constitutes an obstacle to economic development. Catchment runoff fluctuations in response to climate variability and/or human activities can be reflected in extreme events, representing a serious concern (like floods, erosion, droughts) in the study area. To document this crucial issue for Peru, we present here an insightful analysis of the water quantity resource variability of this region, exploring the links between this variability and climate and/or anthropogenic pressure. We first present a detailed analysis of the hydroclimatologic variability at annual timescale and at basin scale over the 1970–2008 period. In addition to corroborating the influence of extreme El Niño events over precipitation and runoff in northern catchments, a mean warming of 0.2 °C per decade over all catchments was found. Also, higher values of temperature and potential and actual evapotranspiration were found over northern latitudes. We chose to apply the Budyko-Zhang framework that characterizes the water cycle as a function of climate only, allowing the identification of catchments with significant climatic and anthropogenic influence on water balance. The Budyko-Zhang methodology revealed that 11 out of 26 initial catchments are characterized by low water balance disparity related to minor climatic and anthropogenic influence. These 11 catchments were suitable for identifying catchments with contrasting change in their hydroclimatic behavior using the Budyko trajectories. Our analysis further reveals that six hydrological catchment responses can be characterized by high sensitivity to climate variability and land use changes. 相似文献
6.
Impact of climate change on ecohydrologic processes of Mediterranean watersheds are significant and require quick action toward improving adaptation and management of fragile system. Increase in water shortages and land use can alter the water balance and ecological health of the watershed systems. Intensification of land use, increase in water abstraction, and decline in water quality can be enhanced by changes in temperature and precipitation regimes. Ecohydrologic changes from climatic impacts alter runoff, evapotranspiration, surface storage, and soil moisture that directly affect biota and habitat of the region. This paper reviews expected impacts of climatic change on the ecohydrology of watershed systems of the Mediterranean and identifies adaptation strategies to increase the resilience of the systems. A spatial assessment of changes in temperature and precipitation estimates from a multimodel ensemble is used to identify potential climatic impacts on watershed systems. This is augmented with literature on ecohydrologic impacts in watershed systems of the region. Hydrologic implications are discussed through the lens of geographic distribution and upstream-downstream dynamics in watershed systems. Specific implications of climatic change studied are on runoff, evapotranspiration, soil moisture, lake levels, water quality, habitat, species distribution, biodiversity, and economic status of countries. It is observed that climatic change can have significant impacts on the ecohydrologic processes in the Mediterranean watersheds. Vulnerability varied depending on the geography, landscape characteristics, and human activities in a watershed. Increasing the resilience of watershed systems can be an effective strategy to adapt to climatic impacts. Several strategies are identified that can increase the resilience of the watersheds to climatic and land use change stress. Understanding the ecohydrologic processes is vital to development of effective long-term strategies to improve the resilience of watersheds. There is need for further research into ecohydrologic dynamics at multiple scales, improved resolution of climatic predictions to local scales, and implications of disruptions on regional economies. 相似文献
7.
F. S. Rodrigo 《Climatic change》2008,87(3-4):471-487
In this work a simple approach to reconstruct climatic variables from documentary data is proposed. This approach may be especially
useful when an overlapping period between documentary and instrumental data is not available. On the other hand, the method
avoids use artificial statistical procedures to rescale the reconstructed series and overcome the problem of the loss of variance.
The methodology allows reconstruct changes in the mean value and standard deviation of the climate variables. It is based
on accounting the number of extreme events in past, and inferring mean value and standard deviation using the assumption of
normal distribution for the climatic variables. The application of the method is only possible if a sufficient number of events
is recorded in the data base. It is useful to reconstruct changes in the long-time scale, using at least decadal periods as
time units. The method is applied to winter rainfall series corresponding to 30-year periods in Andalusia (southern Spain),
obtaining results comparable with those of previous analysis. 相似文献
8.
Rex J Fleming 《Climate Dynamics》1993,8(3):135-150
Climate models, ranging from statistical-dynamical to the explicit-dynamical, contain a range of uncertainties related to the parameterization constants associated with the various forcing terms used therein. Quantifying the impacts of such uncertainties has heretofore received little attention. The impact of this aspect of the dynamics of uncertainty was revealed in a series of dynamical systems of increasing complexity. The inevitability of climate drift was discussed, with one aspect being revealed as the non-Gaussian nature of most forcing terms. For those dynamical systems which are chaotic in nature, it was shown how stochastic dynamic equations can be used to describe the uncertainty, even with uncertainty in the critical forcing terms. The possibility of climate transitions driven by stochastic forcing occurring on much faster time scales (i.e., weather disturbances) has been shown by numerous authors. The caution shown here is that even very small uncertainty in a forcing term occurring on the slow climate time scales can lead to such transitions more easily. Conversely, a deterministic parameterization on the slowly varying time scale may be just slightly incorrect in a particular model formulation and lead to the wrong climatic state. In view of such concerns, the framework for attacking the difficult nonlinear problem of uncertain parameterization constants in complex GCMs is outlined.The National Center for Atmospheric Research is sponsored by the National Science Foundation 相似文献
9.
Suzette G. A. Flantua John H. van Boxel Henry Hooghiemstra John van Smaalen 《Climate Dynamics》2007,29(7-8):697-712
Climate changes affect the abundance, geographic extent, and floral composition of vegetation, which are reflected in the
pollen rain. Sediment cores taken from lakes and peat bogs can be analysed for their pollen content. The fossil pollen records
provide information on the temporal changes in climate and palaeo-environments. Although the complexity of the variables influencing
vegetation distribution requires a multi-dimensional approach, only a few research projects have used GIS to analyse pollen
data. This paper presents a new approach to palynological data analysis by combining GIS and spatial modelling. Eastern Colombia
was chosen as a study area owing to the migration of the forest–savanna boundary since the last glacial maximum, and the availability
of pollen records. Logistic regression has been used to identify the climatic variables that determine the distribution of
savanna and forest in eastern Colombia. These variables were used to create a predictive land-cover model, which was subsequently
implemented into a GIS to perform spatial analysis on the results. The palynological data from the study area were incorporated
into the GIS. Reconstructed maps of past vegetation distribution by interpolation showed a new approach of regional multi-site
data synthesis related to climatic parameters. The logistic regression model resulted in a map with 85.7% predictive accuracy,
which is considered useful for the reconstruction of future and past land-cover distributions. The suitability of palynological
GIS application depends on the number of pollen sites, the distribution of the pollen sites over the area of interest, and
the degree of overlap of the age ranges of the pollen records. 相似文献
10.
11.
基于1983—2012年国家气候中心第2代月动力延伸模式 (DERF2.0) 回报资料和春播历史资料,结合NCEP/NCAR再分析资料,选取影响长江中下游地区春播期气候条件的关键环流因子。利用最优子集回归方法建立针对长江中下游地区春播期气候条件的动力模式解释应用预测模型,并对不同起报时次的模式解释应用预测结果进行检验评估。检验结果表明:该解释应用方案对于长江中下游春播期气候条件有较好的预测能力,且随着起报时间的临近,预测技巧整体呈上升趋势。1983—2012年的回报检验还显示,解释应用方案能够较好地模拟出连续不利日数和不利日数的年际变率,同时对年代际变率也有所体现。 相似文献
12.
《Global Environmental Change》2005,15(1):9-21
The significance of multiple scales within processes of global environmental change has attracted increasing attention. Yet the fundamental tasks of linking multiple levels at which regulatory decisions are required to multiple scales of impacts have only recently been identified. This paper addresses the importance of attention to multiple scales in regulatory decisions, how those decisions should link together across scales of governance or decision-making, and how mismatches among scales of impact and scales of regulation can lead to regulatory gaps and breakdowns. This paper begins by presenting a definition of a cross-scale regulatory problem, building on the concept of an externality. It argues that virtually all-significant environmental regulatory problems involve multiple scales at which decisions are required, and that coordination of these decisions is one of the major issues in regulatory design. The paper provides a generalization of what is needed for effective cross-scale regulation, and then discusses the example of salmon aquaculture in British Columbia to illustrate these points. In our view, gaps and mismatches in the regulatory framework across institutional scales appear to contribute to social controversy over salmon aquaculture. These gaps include (i) the site-by-site orientation of the current regulatory process, even though the major impacts are cumulative, and regional in significance, and (ii) the degree to which limitations on the extent of salmon aquaculture are implemented by local governments, even though provincial and federal governments have the mandate and expertise to address these questions. 相似文献
13.
Agriculture in India is highly sensitive to climatic variations particularly to rainfall and temperature; therefore, any change in rainfall and temperature will influence crop yields. An understanding of the spatial and temporal distribution and changing patterns in climatic variables is important for planning and management of natural resources. Time series analysis of climate data can be a very valuable tool to investigate its variability pattern and, maybe, even to predict short- and long-term changes in the series. In this study, the sub-divisional rainfall data of India during the period 1871 to 2016 has been investigated. One of the widely used powerful nonparametric techniques namely wavelet analysis was used to decompose and de-noise the series into time–frequency component in order to study the local as well as global variation over different scales and time epochs. On the decomposed series, autoregressive integrated moving average (ARIMA) and artificial neural network (ANN) models were applied and by means of inverse wavelet transform, the prediction of rainfall for different sub-divisions was obtained. To this end, empirical comparison was carried out toward forecast performance of the approaches namely Wavelet-ANN, Wavelet-ARIMA, and ARIMA. It is reported that Wavelet-ANN and Wavelet-ARIMA approach outperforms the usual ARIMA model for forecasting of rainfall for the data under consideration. 相似文献
14.
Simulations of the effects of soil temperature and humidity disturbances on regional climate of China 总被引：1，自引：0，他引：1
Zheng Yiqun Qian Yongfu Yu Ge Gui Qijun Zeng Xinmin Liu Huaqiang 《Meteorology and Atmospheric Physics》2002,81(1-2):85-102
Summary ?This simulation study was applied by a regional climate model (RegCM2) and forced by reasonable soil temperature and humidity
disturbances, in order to examine the disastrous weather and climate-produced such disturbances that were performed in a series
of experiments of different climatic zones, seasons and space/time scales, to recognize the persistence and to understand
the mechanisms of their respective climatic responses under the current climatic background of China.
The simulation results showed that, in regions of East Asian monsoon climate, the soil humidity disturbance (SHD) has greater
impact on posterior climate responses than the temperature disturbance has. The SHD forcing exerts noticeable influence on
rainfall generally. Although the centers of changed precipitation generally do not coincide with those of the disturbances,
the centers are located mostly in downwind areas of the SHD core and in areas of prevailing updraft, even some places far
away; with neighboring dry/moist SHD zones, a bigger rainfall increase tends to show up in the dry region instead of in the
wet one.
The simulation suggested that the SHD lasts for a rather long time, whose length is controlled by the presence of a positive
feedback between the precipitation, the synchronous circulation patterns, the latitude and season, and the intensity of the
SHD forcing.
This study has found that the humidity disturbance (especially from rainfall) is in good correspondence to posterior temperature
that the previous SHD enhancement leads to the subsequent temperature drop in the surface and near-surface layer, while the
centers of lowered temperature can remain more than three months.
Received April 3, 2001; Revised December 19, 2001 相似文献
15.
Detlef P. van Vuuren Jae Edmonds Steven J. Smith Kate V. Calvin Joseph Karas Mikiko Kainuma Nebojsa Nakicenovic Keywan Riahi Bas J. van Ruijven Rob Swart Allison Thomson 《Climatic change》2010,103(3-4):635-642
Long-term scenarios developed by integrated assessment models are used in climate research to provide an indication of plausible long-term emissions of greenhouse gases and other radiatively active substances based on developments in the global energy system, land-use and the emissions associated with these systems. The phenomena that determine these long-term developments (several decades or even centuries) are very different than those that operate on a shorter time-scales (a few years). Nevertheless, in the literature, we still often find direct comparisons between short-term observations and long-term developments that do not take into account the differing dynamics over these time scales. In this letter, we discuss some of the differences between the factors that operate in the short term and those that operate in the long term. We use long-term historical emissions trends to show that short-term observations are very poor indicators of long-term future emissions developments. Based on this, we conclude that the performance of long-term scenarios should be evaluated against the appropriate, corresponding long-term variables and trends. The research community may facilitate this by developing appropriate data sets and protocols that can be used to test the performance of long-term scenarios and the models that produce them. 相似文献
16.
Theory for Reconstruction of an Unknown Number of Contaminant Sources using Probabilistic Inference 总被引：1，自引：0，他引：1
Eugene Yee 《Boundary-Layer Meteorology》2008,127(3):359-394
We address the inverse problem of source reconstruction for the difficult case of multiple sources when the number of sources
is unknown a priori. The problem is solved using a Bayesian probabilistic inferential framework in which Bayesian probability
theory is used to derive the posterior probability density function for the number of sources and for the parameters (e.g.,
location, emission rate, release time and duration) that characterize each source. A mapping (source–receptor relationship)
that relates a multiple source distribution to the concentration measurements made by an array of detectors is formulated
based on a forward-time Lagrangian stochastic model. A computationally efficient methodology for determination of the likelihood
function for the problem, based on an adjoint representation of the source–receptor relationship and realized in terms of
a backward-time Lagrangian stochastic model, is described. An efficient computational algorithm based on a parallel tempered
Metropolis-coupled reversible-jump Markov chain Monte Carlo (MCMC) method is formulated and implemented to draw samples from
the posterior probability density function of the source parameters. This methodology allows the MCMC method to initiate jumps
between the hypothesis spaces corresponding to different numbers of sources in the source distribution and, thereby, allows
a sample from the full joint posterior distribution of the number of sources and the parameters for each source to be obtained.
The proposed methodology for source reconstruction is tested using synthetic concentration data generated for cases involving
two and three unknown sources. 相似文献
17.
J. J. Oñate Rubalcaba 《Theoretical and Applied Climatology》1997,56(1-2):83-87
Summary The rescaled range analysis was applied to the annual precipitation series from 10 weather stations in Spain for the period 1901–1989. The analysis reveals that the series of precipitations fits a fractal distribution, with a mean fractal dimension of 1.32 ± 0.01. This lies in the same order of magnitude as the fractal dimensions obtained from other macrometeorological and paleoclimatic registers. The favourable comparison between fractal dimensions of the variables on both small time scales and long-term time spans suggests that such values are characteristic of climatic change over the spectral range of 10 to 106 years. The results contribute to the establishment of this assumption as a valid hypothesis for the interpolation of climatic change from one scale to the next, and also in applications such as hydrological design.With 2 Figures 相似文献
18.
Tiganadaba Lodoun Moussa Sanon Alessandra Giannini Pierre Sibiry Traoré Léopold Somé Jeanne Millogo Rasolodimby 《Theoretical and Applied Climatology》2014,117(3-4):485-494
In the Sahel region, seasonal predictions are crucial to alleviate the impacts of climate variability on populations' livelihoods. Agricultural planning (e.g., decisions about sowing date, fertilizer application date, and choice of crop or cultivar) is based on empirical predictive indices whose accuracy to date has not been scientifically proven. This paper attempts to statistically test whether the pattern of rainfall distribution over the May–July period contributes to predicting the real onset date and the nature (wet or dry) of the rainy season, as farmers believe. To that end, we considered historical records of daily rainfall from 51 stations spanning the period 1920–2008 and the different agro-climatic zones in Burkina Faso. We performed (1) principal component analysis to identify climatic zones, based on the patterns of intra-seasonal rainfall, (2) and linear discriminant analysis to find the best rainfall-based variables to distinguish between real and false onset dates of the rainy season, and between wet and dry seasons in each climatic zone. A total of nine climatic zones were identified in each of which, based on rainfall records from May to July, we derived linear discriminant functions to correctly predict the nature of a potential onset date of the rainy season (real or false) and that of the rainy season (dry or wet) in at least three cases out of five. These functions should contribute to alleviating the negative impacts of climate variability in the different climatic zones of Burkina Faso. 相似文献
19.
气候平均状况的变化对气候极值出现概率的影响 总被引：6，自引：1，他引：6
在概率统计理论的基础上，建立符合正态分布和г分布的气候要素分布模型来讨论极值事件对各个参数的敏感性，得出尺度参数对极端事件概率的影响力最大，进而研究了平均值或标准差的变化对极端事件的影响，为气候极值预测和气候模式设计提供了借鉴。 相似文献
20.
B. G. Hunt 《Climate Dynamics》2008,30(5):467-483
Outputs from a 10,000-year simulation with a coupled global climatic model for present climatic conditions have been used
to investigate the behaviour of the Pacific Decadal Oscillation (PDO), the North Pacific Oscillation (NPO) and related phenomena.
The analysis reveals a wide range of temporal variability for these Oscillations, suggesting that observations to date provide
only a limited sample of possible outcomes. In addition, the simulation suggests that the current observed phase relation
between the PDO and NPO may not be typical of longer-term variability. Climatic jumps appear to be a ubiquitous feature of
climatic variability, and while, as observed, the most common interval between such jumps is about 20 years, intervals of
up to 100 years occur in the simulation. The probability density functions of the PDO and NPO are very close to Gaussian,
with the PDO being represented by an auto-regressive function of order one, while the NPO consisted of white noise. An FFT
analysis of PC1 of the PDO revealed periodicities concentrated near 10 years, while for the NPO the principal periodicities
were decadal to bidecadal. Global distributions of the distributions of the correlations between PC1 or the NPO and selected
climatic variables were similar, and in agreement with observations. These correlations highlight the inter-relationships
between these two Oscillations. The above correlations were not necessarily stable in time for a given geographical point,
with transitions occurring between positive and negative extremes. Climatic jumps were identified with transitions of both
the PDO and NPO, with magnitudes of importance as regards climatic perturbations. Spatial patterns of the changes associated
with such jumps have global scales, and the need to consider the implications of these jumps in regard to greenhouse induced
climatic change is noted. 相似文献