共查询到20条相似文献，搜索用时 468 毫秒
1.
Kristina Blennow Mikael Andersson Johan Bergh Ola Sallnäs Erika Olofsson 《Climatic change》2010,99(1-2):261-278
We estimated how the possible changes in wind climate and state of the forest due to climate change may affect the probability of exceeding critical wind speeds expected to cause wind damage within a forest management unit located in Southern Sweden. The topography of the management unit was relatively gentle and the forests were dominated by Norway spruce (Picea abies (L.) Karst.). We incorporated a model relating the site index (SI) to the site productivity into the forest projection model FTM. Using estimated changes in the net primary production (NPP) due to climate change and assuming a relative change in NPP equal to a relative change in the site productivity, we simulated possible future states of the forest under gradual adjustment of SI in response to climate change. We estimated changes in NPP by combining the boreal-adapted BIOMASS model with four regional climate change scenarios calculated using the RCAO model for the period 2071–2100 and two control period scenarios for the period 1961–1990. The modified WINDA model was used to calculate the probability of wind damage for individual forest stands in simulated future states of the forest. The climate change scenarios used represent non-extreme projections on a 100-year time scale in terms of global mean warming. A 15–40% increase in NPP was estimated to result from climate change until the period 2071–2100. Increasing sensitivity of the forest to wind was indicated when the management rules of today were applied. A greater proportion of the calculated change in probability of wind damage was due to changes in wind climate than to changes in the sensitivity of the forest to wind. While regional climate scenarios based on the HadAM3H general circulation model (GCM) indicated no change (SRES A2 emission scenario) or a slightly reduced (SRES B2 emission scenario) probability of wind damage, scenarios based on the ECHAM4/OPYC3 GCM indicated increased probability of wind damage. The assessment should, however, be reviewed as the simulation of forest growth under climate change as well as climate change scenarios are refined. 相似文献
2.
There are a number of sources of uncertainty in regional climate change scenarios. When statistical downscaling is used to obtain regional climate change scenarios, the uncertainty may originate from the uncertainties in the global climate models used, the skill of the statistical model, and the forcing scenarios applied to the global climate model. The uncertainty associated with global climate models can be evaluated by examining the differences in the predictors and in the downscaled climate change scenarios based on a set of different global climate models. When standardized global climate model simulations such as the second phase of the Coupled Model Intercomparison Project （CMIP2） are used, the difference in the downscaled variables mainly reflects differences in the climate models and the natural variability in the simulated climates. It is proposed that the spread of the estimates can be taken as a measure of the uncertainty associated with global climate models. The proposed method is applied to the estimation of global-climate-model-related uncertainty in regional precipitation change scenarios in Sweden. Results from statistical downscaling based on 17 global climate models show that there is an overall increase in annual precipitation all over Sweden although a considerable spread of the changes in the precipitation exists. The general increase can be attributed to the increased large-scale precipitation and the enhanced westerly wind. The estimated uncertainty is nearly independent of region. However, there is a seasonal dependence. The estimates for winter show the highest level of confidence, while the estimates for summer show the least. 相似文献
3.
Potential climate change impact on wind energy resources in northern Europe: analyses using a regional climate model 总被引：7，自引：0，他引：7
There is considerable interest in the potential impact of climate change on the feasibility and predictability of renewable
energy sources including wind energy. This paper presents dynamically downscaled near-surface wind fields and examines the
impact of climate change on near-surface flow and hence wind energy density across northern Europe. It is shown that: Simulated
wind fields from the Rossby Centre coupled Regional Climate Model (RCM) (RCAO) with boundary conditions derived from ECHAM4/OPYC3
AOGCM and the HadAM3H atmosphere-only GCM exhibit reasonable and realistic features as documented in reanalysis data products
during the control period (1961–1990). The near-surface wind speeds calculated for a climate change projection period of 2071–2100
are higher than during the control run for two IPCC emission scenarios (A2, B2) for simulations conducted using boundary conditions
from ECHAM4/OPYC3. The RCAO simulations conducted using boundary conditions from ECHAM4/OPYC3 indicate evidence for a small
increase in the annual wind energy resource over northern Europe between the control run and climate change projection period
and for more substantial increases in energy density during the winter season. However, the differences between the RCAO simulations
for the climate projection period and the control run are of similar magnitude to differences between the RCAO fields in the
control period and the NCEP/NCAR reanalysis data. Additionally, the simulations show a high degree of sensitivity to the boundary
conditions, and simulations conducted using boundary conditions from HadAM3H exhibit evidence of slight declines or no change
in wind speed and energy density between 1961–1990 and 2071–2100. Hence, the uncertainty of the projected wind changes is
relatively high. 相似文献
4.
Ari Venäläinen Heikki Tuomenvirta Riikka Lahtinen Martti Heikinheimo 《Climatic change》2001,50(1-2):111-128
The influence of the predicted climate warming on soil frost conditions in Finland was studied using a climate scenario based on a Hadley Centre (U.K.) global ocean-atmosphere general circulation model (HadCM2) run. HadCM2 results were dynamically downscaled to the regional level using the regional climate model at the Rossby Centre (Sweden). The future period this study focuses on is the end of the 21st century. The study was limited to ground surface conditions in which snow has been removed. The predicted air temperature rise was interpreted in terms of changes in soil frost conditions using an empirical dependence that was found between measured soil frost depths and the sum of daily mean air temperatures calculated from the beginning of the freezing period. On average the annual maximum soil frost depth will decrease in southern and central Finland from the present approx. 100–150 cm by about 50 cm. In northern Finland the change will be from depths of about 200–300 cm to about 100–200 cm depending on station. The annual maximum soil frost depth in the future would thus be about the same in northern Finland as it is in the current climate in southern Finland. In southern Finland after about 100 years the ground will seldom be frozen in December and even in January there will be no soil frost in about half of the years. In Central and northern Finland the probability of completely unfrozen ground in December–March is very small, even in the future. 相似文献
5.
Empirical-statistical downscaling and error correction of regional climate models and its impact on the climate change signal 总被引：7，自引：3，他引：4
Realizing the error characteristics of regional climate models (RCMs) and the consequent limitations in their direct utilization
in climate change impact research, this study analyzes a quantile-based empirical-statistical error correction method (quantile
mapping, QM) for RCMs in the context of climate change. In particular the success of QM in mitigating systematic RCM errors,
its ability to generate “new extremes” (values outside the calibration range), and its impact on the climate change signal
(CCS) are investigated. In a cross-validation framework based on a RCM control simulation over Europe, QM reduces the bias
of daily mean, minimum, and maximum temperature, precipitation amount, and derived indices of extremes by about one order
of magnitude and strongly improves the shapes of the related frequency distributions. In addition, a simple extrapolation
of the error correction function enables QM to reproduce “new extremes” without deterioration and mostly with improvement
of the original RCM quality. QM only moderately modifies the CCS of the corrected parameters. The changes are related to trends
in the scenarios and magnitude-dependent error characteristics. Additionally, QM has a large impact on CCSs of non-linearly
derived indices of extremes, such as threshold indices. 相似文献
6.
城市化发展显著改变城市下垫面几何形态,导致局地风环境品质恶化,产生城市风环境问题。本文基于超越概率阈值法,结合计算流体力学数值模拟,建立适用于住宅区风环境品质定量评估的一般方法和流程。并以重庆市龙湖社区为例,从大概率和偶发事件的角度对住宅区精细化风环境品质进行评估。结果表明：受复杂下垫面影响,住宅区风环境品质存在明显的区域差异。在开阔空间、与盛行风向一致的街道以及高层建筑周围,风速整体偏大,风环境品质较差,等级为1级乙;在建筑物密集区和封闭的小区内部,风速整体偏小,风环境品质较好,等级为1级甲。城市下垫面的摩擦阻力作用,使住宅区平均风速降低,小区整体风环境品质等级趋于良好。风环境品质评估对促进精细化气象服务水平的提升和城市防灾减灾能力的提高有一定的积极作用。 相似文献
7.
Sensitivity of southern African maize yields to the definition of sowing dekad in a changing climate
Most African countries struggle with food production and food security. These issues are expected to be even more severe in
the face of climate change. Our study examines the likely impacts of climate change on agriculture with a view to propose
adaptation options, especially in hard hit regions. We use a crop model to evaluate the impact of various sowing decisions
on the water satisfaction index (WSI) and thus the yield of maize crop. The crop model is run for 176 stations over southern
Africa, subject to climate scenarios downscaled from 6 GCMs. The sensitivity of these simulations is analysed so as to distinguish
the contributions of sowing decisions to yield variation. We compare the WSI change between a 20 year control period (1979–1999)
and a 20 year future period (2046–2065) over southern Africa. These results highlight areas that will likely be negatively
affected by climate change over the study region. We then calculate the contribution of sowing decisions to yield variation,
first for the control period, then for the future period. This contribution (sensitivity) allows us to distinguish the efficiency
of adaptation decisions under both present and future climate. In most countries rainfall in the sowing dekad is shown to
contribute more significantly to the yield variation and appears as a long term efficient decision to adapt. We discuss these
results and additional perspectives in order to propose local adaptation directions. 相似文献
8.
Evaluation of different downscaling techniques for hydrological climate-change impact studies at the catchment scale 总被引：4，自引：0，他引：4
Hydrological modeling for climate-change impact assessment implies using meteorological variables simulated by global climate models (GCMs). Due to mismatching scales, coarse-resolution GCM output cannot be used directly for hydrological impact studies but rather needs to be downscaled. In this study, we investigated the variability of seasonal streamflow and flood-peak projections caused by the use of three statistical approaches to downscale precipitation from two GCMs for a meso-scale catchment in southeastern Sweden: (1) an analog method (AM), (2) a multi-objective fuzzy-rule-based classification (MOFRBC) and (3) the Statistical DownScaling Model (SDSM). The obtained higher-resolution precipitation values were then used to simulate daily streamflow for a control period (1961–1990) and for two future emission scenarios (2071–2100) with the precipitation-streamflow model HBV. The choice of downscaled precipitation time series had a major impact on the streamflow simulations, which was directly related to the ability of the downscaling approaches to reproduce observed precipitation. Although SDSM was considered to be most suitable for downscaling precipitation in the studied river basin, we highlighted the importance of an ensemble approach. The climate and streamflow change signals indicated that the current flow regime with a snowmelt-driven spring flood in April will likely change to a flow regime that is rather dominated by large winter streamflows. Spring flood events are expected to decrease considerably and occur earlier, whereas autumn flood peaks are projected to increase slightly. The simulations demonstrated that projections of future streamflow regimes are highly variable and can even partly point towards different directions. 相似文献
9.
《大气与海洋》2013,51(1):63-78
Abstract Although the Mesoscale Community Compressible (MC2) model successfully reproduces the wind climate (for wind energy development purposes) of the Gaspé region, equivalent simulations for the steep mountainous southern Yukon have been unsatisfactory. An important part of the problem lies in the provision of suitable boundary conditions in the lower troposphere. This paper will describe an alternative provision of boundary conditions to the MC2 model based partly on standard National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) Reanalysis statistics, however, with modified lower tropospheric conditions based on local radiosonde measurements. The MC2 model is part of the AnemoScope wind energy simulation toolkit which applies statistical‐dynamical downscaling of basic large‐scale weather situations (i.e., the NCEP/NCAR Reanalysis) to simulate the steadystate wind climate of a complex region. A case study summarized here imposes a typical mean winter temperature inversion on the boundary conditions to reduce downward momentum transfer in the MC2 model over the Whitehorse region. In conjunction with this step, the geostrophic wind at the boundaries is held constant (with height) in speed and direction, based on the (observed) dominant southwesterly winds above the mountaintops. The resulting simulation produces wind directions within the modelled domain that are in much better agreement with the available measurements. However, despite the imposed atmospheric stability, downward transfer of horizontal momentum from aloft still appears to exceed that occurring in nature. It is recommended that (in future studies of this type regarding mountain wind climate) the input statistics processed from the NCEP/NCAR Reanalysis be modified by referencing the geostrophic winds to a level above the mountaintops. It is also suggested that converting to a height (z) coordinate system may reduce the erroneous downward momentum transfer found in the present terrain‐following grid. 相似文献
10.
11.
E. García-Bustamante J. F. González-Rouco J. Navarro E. Xoplaki J. Luterbacher P. A. Jiménez J. P. Montávez A. Hidalgo E. E. Lucio-Eceiza 《Climate Dynamics》2013,40(3-4):935-949
The wind power generated during winter months 1999–2003 at several wind farms in the northeastern Iberian Peninsula is investigated through the application of a statistical downscaling. This allows for an improved understanding of the wind power variability and its relationship to the large scale atmospheric circulation. It is found that 97 % of the variability of this non-climatic variable is connected to changes in the atmospheric circulation. The methodological uncertainty associated with multiple configurations of the statistical downscaling method replicates well the observed variability of the wind power, an indication of the robustness of the methodology to changes in the model set up. In addition, the use of the statistical model is extended out of the observational period providing an estimation of the long-term variability of wind power throughout the twentieth century. The extended wind power reconstruction shows large inter-annual and multidecadal variability. Alternative approaches to calibrate the empirical downscaling model using actual wind power observations have also been investigated. They involve the estimation of wind power changes from downscaled wind values and make use of several transfer functions based on the linearity between wind and wind energy. The performance of the latter approaches is similar to the direct downscaling of wind power and may allow wind power production estimations even in the absence of historical wind turbine records. These results can be of great interest for deriving medium/long term impact-oriented energy assessments, especially when wind power observations are missing as well as in the context of climate change scenarios. 相似文献
12.
Summary “Koshava” is a gusty wind of changeable intensity, blowing from a south-easterly direction, over Serbia, Romania and Bulgaria.
It is caused by the interaction between the synoptic circulation and the orography of the Carpathian and the Balkan mountains.
This paper analyzes wind data measured at the Belgrade-Observatory during the longest period of consecutive days of “Koshava”
which occurred from 14 January to 13 February 1972. Mean hourly wind speed data has been examined using spectral analysis.
The power spectra are calculated using autocorrelation spectral analysis, the multi-taper method and wavelet transform. The
maximum of which is about 122 h (5 days) corresponds to the time span of synoptic processes. 相似文献
13.
M. Burlando 《Theoretical and Applied Climatology》2009,96(1-2):69-83
In 2008, Burlando et al. proposed a two-stage clustering technique for the classification of mesoscale wind regimes. The first stage of this classification scheme is based on a hierarchical cluster analysis, according to Ward’s minimum variance technique applied to an Euclidean distance, for a first-guess subdivision of the events into groups. In the second stage, a partitional k-means clustering for the optimal reassignment of the events among clusters is performed. Following this methodology, in the present paper, the synoptic-scale wind fields over the Mediterranean Sea have been analysed in order to check the suitability of this technique to a higher-dimensional phase space. The study is based on a 30-year-long data set of wind speed and direction at 10 m above sea level obtained from the reanalysis of the European Centre for Medium-range Weather Forecasts. The cluster analysis has been performed on wind speeds only, while wind directions have been used to show the existence, in the spatial structure of the wind climate regimes, of particular regions which correspond to the main topographic and/or thermal forcing of the Mediterranean. These regions are the peaks of the probability density function in the climatological phase space of wind speed patterns recognised by the clustering algorithm. The final classification has been able to identify, for instance, the surface circulation patterns corresponding to Mistral events in the western Mediterranean sub-basin and Etesian winds in the eastern sub-basin. 相似文献
14.
Climate and land use patterns are expected to change dramatically in the coming century, raising concern about their effects on wildfire patterns and subsequent impacts to human communities. The relative influence of climate versus land use on fires and their impacts, however, remains unclear, particularly given the substantial geographical variability in fire-prone places like California. We developed a modeling framework to compare the importance of climatic and human variables for explaining fire patterns and structure loss for three diverse California landscapes, then projected future large fire and structure loss probability under two different climate (hot-dry or warm-wet) and two different land use (rural or urban residential growth) scenarios. The relative importance of climate and housing pattern varied across regions and according to fire size or whether the model was for large fires or structure loss. The differing strengths of these relationships, in addition to differences in the nature and magnitude of projected climate or land use change, dictated the extent to which large fires or structure loss were projected to change in the future. Despite this variability, housing and human infrastructure were consistently more responsible for explaining fire ignitions and structure loss probability, whereas climate, topography, and fuel variables were more important for explaining large fire patterns. For all study areas, most structure loss occurred in areas with low housing density (from 0.08 to 2.01 units/ha), and expansion of rural residential land use increased structure loss probability in the future. Regardless of future climate scenario, large fire probability was only projected to increase in the northern and interior parts of the state, whereas climate change had no projected impact on fire probability in southern California. Given the variation in fire-climate relationships and land use effects, policy and management decision-making should be customized for specific geographical regions. 相似文献
15.
Regression-based statistical downscaling model (SDSM) is an appropriate method which broadly uses to resolve the coarse spatial resolution of general circulation models (GCMs). Nevertheless, the assessment of uncertainty propagation linked with climatic variables is essential to any climate change impact study. This study presents a procedure to characterize uncertainty analysis of two GCM models link with Long Ashton Research Station Weather Generator (LARS-WG) and SDSM in one of the most vulnerable international wetland, namely “Shadegan” in an arid region of Southwest Iran. In the case of daily temperature, uncertainty is estimated by comparing monthly mean and variance of downscaled and observed daily data at a 95 % confidence level. Uncertainties were then evaluated from comparing monthly mean dry and wet spell lengths and their 95 % CI in daily precipitation downscaling using 1987–2005 interval. The uncertainty results indicated that the LARS-WG is the most proficient model at reproducing various statistical characteristics of observed data at a 95 % uncertainty bounds while the SDSM model is the least capable in this respect. The results indicated a sequences uncertainty analysis at three different climate stations and produce significantly different climate change responses at 95 % CI. Finally the range of plausible climate change projections suggested a need for the decision makers to augment their long-term wetland management plans to reduce its vulnerability to climate change impacts. 相似文献
16.
M. A. Novitskii L. K. Kulizhnikova O. Yu. Kalinicheva D. Gaitandzhiev D. Barantiev E. Bachvarova K. Krysteva 《Russian Meteorology and Hydrology》2012,37(3):159-164
The characteristics of wind speed and wind direction in the boundary atmospheric layer measured at the meteorological station
in Akhtopol (Bulgaria) are presented. The measurements were carried out with the Scintec sodar and MK-15 automatic meteorological
station. The sodar measurement data on wind parameters at different heights in different months are presented as well as the
frequency of inshore and offshore wind directions, that enables to trace the intensity of the breeze circulation. The frequency
of calms and wind speeds at the heights of 50, 100, and 200 m according to gradations for different months and the probability
of wind of various speeds depending on the direction are also given. The breeze front characteristics in June–September of
2009 are computed from the speed and direction of surface wind measured with the acoustic anemometer of MK-15 complex. 相似文献
17.
W. Gorter J. H. van Angelen J. T. M. Lenaerts M. R. van den Broeke 《Climate Dynamics》2014,42(5-6):1595-1611
The present and twenty-first century near-surface wind climate of Greenland is presented using output from the regional atmospheric climate model RACMO2. The modelled wind variability and wind distribution compare favourably to observations from three automatic weather stations in the ablation zone of southwest Greenland. The Weibull shape parameter is used to classify the wind climate. High values (κ > 4) are found in northern Greenland, indicative of uniform winds and a dominant katabatic forcing, while lower values (κ < 3) are found over the ocean and southern Greenland, where the synoptic forcing dominates. Very high values of the shape parameter are found over concave topography where confluence strengthens the katabatic circulation, while very low values are found in a narrow band along the coast due to barrier winds. To simulate the future (2081–2098) wind climate RACMO2 was forced with the HadGEM2-ES general circulation model using a scenario of mid-range radiative forcing of +4.5 W m?2 by 2100. For the future simulated climate, the near-surface potential temperature deficit reduces in all seasons in regions where the surface temperature is below the freezing point, indicating a reduction in strength of the near-surface temperature inversion layer. This leads to a wind speed reduction over the central ice sheet where katabatic forcing dominates, and a wind speed increase over steep coastal topography due to counteracting effects of thermal and katabatic forcing. Thermally forced winds over the seasonally sea ice covered region of the Greenland Sea are reduced by up to 2.5 m s?1. 相似文献
18.
This paper evaluated the impacts of climate change mitigation technology options on CO2 emission reductions and the effects of model representations regarding renewable intermittency on the assessment of reduction by using a world energy systems model. First, different diffusion scenarios for carbon dioxide capture and storage (CCS), nuclear power, and wind power and solar PV are selected from EMF27 scenarios to analyze their impacts on CO2 emission reductions. These technologies are important for reducing CO2 intensity of electricity, and the impacts of their diffusion levels on mitigation costs are significant, according to the analyses. Availability of CCS in particular, among the three kinds of technologies, has a large impact on the marginal CO2 abatement cost. In order to analyze effects of model representations regarding renewables intermittency, four different representations are assumed within the model. A simplistic model representation that does not take into consideration the intermittency of wind power and solar PV evaluates larger contributions of the energy sources than those evaluated by a model representation that takes intermittency into consideration. Appropriate consideration of renewables intermittency within global energy systems models will be important for realistic evaluations of climate change mitigation scenarios. 相似文献
19.
利用全球大气环流模式BCC_AGCM2.0,通过青藏高原不同区域不同粗糙度的改变,模拟了青藏高原风电场开发造成的动力和热力强迫扰动对我国气候变化的影响。模拟结果表明,青藏高原热力场和动力场扰动对我国不同区域气候变化有着显著的影响,热力场的扰动会使华北地区的夏季降水明显减少,长江以南地区冬季气温降低,而动力场的扰动则会引起南方地区夏季降水增加,冬季气温明显上升。而且随着粗糙度的增大,长江以南地区冬季850 hPa水汽输送明显减小,而华北地区夏季的水汽输送也呈现出显著减少趋势。 相似文献
20.
Robust projections of Fire Weather Index in the Mediterranean using statistical downscaling 总被引：2，自引：2，他引：0
J. Bedia S. Herrera D. San Martín N. Koutsias J. M. Gutiérrez 《Climatic change》2013,120(1-2):229-247
The effect of climate change on wildfires constitutes a serious concern in fire-prone regions with complex fire behavior such as the Mediterranean. The coarse resolution of future climate projections produced by General Circulation Models (GCMs) prevents their direct use in local climate change studies. Statistical downscaling techniques bridge this gap using empirical models that link the synoptic-scale variables from GCMs to the local variables of interest (using e.g. data from meteorological stations). In this paper, we investigate the application of statistical downscaling methods in the context of wildfire research, focusing in the Canadian Fire Weather Index (FWI), one of the most popular fire danger indices. We target on the Iberian Peninsula and Greece and use historical observations of the FWI meteorological drivers (temperature, humidity, wind and precipitation) in several local stations. In particular, we analyze the performance of the analog method, which is a convenient first choice for this problem since it guarantees physical and spatial consistency of the downscaled variables, regardless of their different statistical properties. First we validate the method in perfect model conditions using ERA-Interim reanalysis data. Overall, not all variables are downscaled with the same accuracy, with the poorest results (with spatially averaged daily correlations below 0.5) obtained for wind, followed by precipitation. Consequently, those FWI components mostly relying on those parameters exhibit the poorest results. However, those deficiencies are compensated in the resulting FWI values due to the overall high performance of temperature and relative humidity. Then, we check the suitability of the method to downscale control projections (20C3M scenario) from a single GCM (the ECHAM5 model) and compute the downscaled future fire danger projections for the transient A1B scenario. In order to detect problems due to non-stationarities related to climate change, we compare the results with those obtained with a Regional Climate Model (RCM) driven by the same GCM. Although both statistical and dynamical projections exhibit a similar pattern of risk increment in the first half of the 21st century, they diverge during the second half of the century. As a conclusion, we advocate caution in the use of projections for this last period, regardless of the regionalization technique applied. 相似文献