共查询到20条相似文献，搜索用时 281 毫秒
1.
根据史料和器测资料重建的气温和旱涝年代序列，对长江中游近５２０年的气候变率，变化趋势，准周期变动和突变特性进行了诊断研究，并对近百年气候变化的基本特征进行较细致的讨论，分析了旱涝变化与太阳活动的联系，得到了一些有意义的结果；在上述基础上对未来１５年气候的可以变化趋势进行了推测，在防灾减灾方面提出了看法和建议。 相似文献
2.
基于模式先验信息的贝叶斯集合降水概率预报试验 总被引：1，自引：0，他引：1
为了更好地利用降水预报历史先验概率分布函数信息修订集合概率预报效果,基于贝叶斯原理和贝叶斯降水概率预报模型,分别使用1952—2007年历史观测资料和2009—2011年6月24~120 h中国T213全球集合预报历史资料作为先验信息,对中国不同气候区代表站（广州、南京、武汉和成都）建立贝叶斯降水概率预报模型,对比不同先验信息下集合成员与集成贝叶斯降水概率预报拟合结果差异,分析先验信息对贝叶斯降水概率预报模型的影响,在此基础上,采用模式先验信息的贝叶斯降水概率预报模型,进行2008年6月降水概率预报试验。试验结果表明,由T213集合预报产生的先验信息较历史观测资料产生的先验信息更优,当先验信息的降水概率分布函数曲率最大处偏向降水大值区时,贝叶斯模型的降水预报结果也偏向降水大值区,反之亦然。结果还显示,先验信息对贝叶斯降水概率预报模型有重要影响,若先验信息偏向更多更大降水量时,贝叶斯降水概率预报对有降水的预报更优,若降水先验信息偏向更少更小降水量时,对无雨或微量降水预报效果越好。 相似文献
3.
随机天气模型参数化方案的研究及其模拟能力评估 总被引：8，自引：2，他引：6
文中介绍了随机天气模型 WGEN的基本结构及其模拟原理 ,并针对其中随机过程的统计结构特征和 GCMs输出要素的不同时空尺度特点 ,利用动态数据的参数化分析方法等统计学技术 ,确定了该模型参数的估计方法。同时基于蒙特卡罗数值计算原理 ,给出了 WGEN的随机试验方法 ,并通过模拟基准气候 ,从时间分布和空间场两方面对模型在中国东北地区的模拟效果及其能力进行了评估。结果表明 ,模型对于最高气温、最低气温、降水和辐射等要素均具有较好的模拟效果 ,模拟序列与观测序列的取值分布有较一致的概率特性。由此可以结合 GCMs大尺度网格上输出的月和年要素值 ,通过调控随机过程的参数 ,生成具有不同气候变率的 2× CO2 逐日气候变化情景 ,实现气候预测模式与气候影响模式的嵌套 ,进一步研究气候变率变化的可能影响。 相似文献
4.
英国CRU高分辨率格点资料揭示的20世纪中国气候变化 总被引：29，自引：1，他引：29
中国覆盖比较完整的台站观测始于1951年,1951年之前虽然有一些观测记录,但是残缺不全.所以要建立更长的气候序列就要吸收代用资料,但是代用资料可能与气候要素仅有一定程度的相关,不可能一一对应,因此应用代用资料重建的气候序列有一定的不确定性.英国East Anglia大学的Climatic Research Unit(简称CRU)通过整合已有的若干个知名数据库,重建了一套覆盖完整、高分辨率、且无缺测的月平均地表气候要素数据集,时间范围覆盖1901～2003年,空间为0.5°×0.5°经纬网格覆盖所有陆地.这套资料和中国已有的气候数据相比具有如下优点: 第一,中国西部20世纪前半期非常缺少观测,CRU资料尽管包含插值带来的误差,经比较仍可作为有一定信度的参考; 第二,中国现有的百年温度序列只是年或季分辨率,而CRU资料达到月分辨率; 第三,建立这个序列仅使用观测结果,做统计内插,不包括代用资料所带来的不确定性.因此,CRU的序列与用代用资料补充得到的序列在资料方面有较大不同,比较这两个序列,不仅可以进一步确认中国气候变化的特征,也可以彼此校正.结果表明:(1)CRU资料反映的全国年平均温度年际变化和考虑代用资料重建的序列吻合得很好,相关系数达到0.84;(2)区域尺度上,两者在10个典型分区的气温变率也相当一致,相关整体保持在0.8左右,仅新疆西南部和西藏西北部两者差异较大;(3)CRU资料揭示的中国年总降水量在1951～2000年的变化与160站观测吻合,相关系数达到0.93;(4)CRU资料的中国东部四季降水量和重建资料十分一致,秋季一致性最好,相关0.93;(5)CRU资料和重建的序列比较一致地表现出中国温度和降水年代际变化的主要特征,其给出的20世纪20年代中国大旱和20世纪40年代中国高温的空间分布与作者过去的结论相一致.这表明,作者过去重建的中国气候序列有比较大的可靠性,而CRU资料也提供了新的信息,特别是在20世纪前半期和中国西部. 相似文献
5.
对比国家气候中心耦合模式BCC_CSM1.1提交CMIP5的历史（Historical）试验和年代际（Decadal）回报试验对中国气候及其年代际变化的模拟。结果表明,Decadal试验回报的中国降水气候分布更接近观测,回报的中国东部气温和降水的年代际距平误差比Historical试验减小明显。对于发生在20世纪70年代末的中国东部降水年代际变化,Decadal试验能回报出长江中下游降水增多的特征,但Historical试验模拟的降水变化与观测相反。由于Decadal试验和Historical试验的区别之一是后者利用观测海温资料进行了初始化,为了探讨观测海温信息的重要性,进一步将Decadal试验与恢复（Nudging）试验（即模式积分过程中,模拟海温始终向观测海温恢复）的模拟结果进行对比。发现Nudging试验能够较好地模拟出“南涝北旱”型降水变化,也能够模拟出相应的东亚急流增强且偏南的特征。这表明气候模式对海温的回报能力是影响其对东亚气候年代际异常模拟的一个重要因素。 相似文献
6.
利用区域气候模式对我国南方百年气温和降水的动力降尺度模拟 总被引：1，自引：0，他引：1
本文采用NCAR的WRF3.5.1模式,以NOAA的20世纪再分析资料作为区域气候模式的初始场和侧边界场,对东亚地区进行了百年以上(1900~2010年)尺度、水平分辨率为50 km的动力降尺度数值模拟试验。通过与观测气候资料的对比,分析了驱动场(20世纪再分析资料)和区域气候模式对我国南方地区近50年(1961~2010年)气温和降水的气候平均态的模拟能力。结果表明:经过动力降尺度的区域气候模式试验结果能更好地模拟我国南方地区气温气候平均态和季节循环。WRF模式模拟的气温与观测的气温的空间相关系数均在0.97以上。年平均和夏季,WRF模式模拟的气温与观测的气温的偏差大多介于-1°C到+1°C之间。对于降水,WRF模式显著提高了我国南方降水的模拟能力。和驱动场相比,WRF模式模拟的降水与观测的偏差明显减小。夏季,WRF模式模拟的降水空间相关系数在0.5以上。由此延伸至对近百年我国南方地区三个子区域(华南地区、江淮地区和西南地区)四个时段(1914~1942年、1943~1971年、1972~2000年和2001~2010年)的分析,结果表明区域气候模式动力降尺度的结果在区域平均的气温和降水的模拟数值上与观测比较接近,夏季模拟能力有明显的提高,冬季存在气温模拟偏低的误差。对气温趋势分析表明,在20世纪40年代以后的两个时间段,区域气候模式明显提高了气温变化线性趋势的模拟性能。 相似文献
7.
8.
利用ERA-Interim再分析资料作为边界条件,基于耦合陆面模式Noah-MP的区域气候模式WRF在东亚区域进行了动力降尺度模拟(简称WRF2),对比格点观测资料,评估了动力降尺度对青藏高原极端气温指数的模拟能力,在此控制试验基础上,分别将WRF的陆面模式替换为Noah LSM,边界条件替换为CCSM4,进行了两组敏感性试验(分别是WRF1和WRF3),通过与控制试验的比较,分析了边界条件和陆面模式对极端气温指数模拟的影响。结果表明,WRF2能较好地模拟青藏高原极端气温指数气候态的空间分布,但存在一定的冷偏差;受边界条件影响WRF3模拟的极端气温指数的气候倾向率存在负偏差。同时,尽管采用不同的边界条件,耦合相同陆面过程的两次数值试验对极端气温空间分布的模拟能力相似,相比WRF2,WRF1表现出更强的冷偏差;但边界条件对极端气温指数气候倾向率的影响大于陆面模式,WRF3模拟的极端气温指数气候倾向率与观测结果更为接近。 相似文献
9.
利用我国541个测站1960—2010年气温资料以及国家气候中心参加第5次耦合模式比较计划 (CMIP5) 的气候系统模式BCC_CSM1.1的历史试验和年代际试验结果,评估了该模式对我国近50年气温变化特征的模拟能力, 对模式的年代际试验结果进行了误差订正,并给出未来10~20年我国气温变化的预估。结果表明:历史试验和年代际试验均模拟出了与观测较为一致的增暖趋势,但均没有观测资料的增暖幅度大。其中,历史试验比年代际试验更接近于观测。年代际尺度上,模式对我国东部的模拟要好于西部;年际尺度上,模式的高预报技巧区在我国西北地区西南部和东部、西南地区北部。历史试验和年代际试验对我国气温空间场整体分布模拟较好,误差订正后的年代际试验结果对空间气温场的模拟有更好把握。相对于观测资料得到的1960—2010年0.27℃/10 a的增温速率,模式预估我国2011—2030年平均气温变化速率达到0.48℃/10 a, 上升趋势更加明显。 相似文献
10.
CMIP5模式对中国年平均气温模拟及其与CMIP3模式的比较 总被引：5，自引：0，他引：5
利用CRUT3v和CN05两套观测资料,评估25个CMIP5模式对1906-2005年中国年平均气温变化的模拟能力,并与CMIP3模式对比。结果表明：1906-2005年中国平均温升速率为0.84℃/100a,CMIP5多模式集合平均模拟的增温率为0.77℃/100a。模式对20世纪后期温升模拟好于前期,仅有两个模式能模拟中国20世纪40年代异常增暖。模式对气温气候态空间分布模拟较好,但在中国西部地区存在最大模拟冷偏差和不确定性。1961-1999年,中国北方增暖大于南方。多模式集合平均可以较好地模拟气温变化线性趋势的空间分布,但对南北气温变化趋势的差异模拟过小。总体说来,在中国平均气温变化趋势、气温气候态空间分布和气温变化趋势空间分布三方面,CMIP5模式都较CMIP3模式有所提高。 相似文献
11.
基于贝叶斯融合方法的高分辨率地面-卫星-雷达三源降水融合试验 总被引：15，自引：1，他引：14
为了探讨一种适用于区域性的地面、雷达、卫星等多源降水资料融合的方法,一种曾用于高分辨雷达、卫星土壤湿度产品反演的贝叶斯融合(Bayesian Merging)方法被尝试应用于江淮地区1 h-0.05°×0.05°经纬度高分辨率的雷达估测降水、卫星反演降水与地面站点观测降水3种资料的融合。在应用该方法时,通过2009年8月样本统计分别估计卫星和雷达反演降水的误差关系,通过曲线拟合建立误差方程,并以卫星资料作为背景场,但在融合时将雷达估测降水作为新的观测信息与地面观测降水同时引入。融合试验检验结果表明:贝叶斯融合方法能够有效实现雷达、地面、卫星3种不同来源资料的融合,该方法生成的多源融合产品的精度均优于任何单一来源的降水产品。 相似文献
12.
CLIMATE CHANGE: LONG-TERM TRENDS AND SHORT-TERM
OSCILLATIONS 总被引：2，自引：0，他引：2
Identifying the Northern Hemisphere (NH) temperature reconstruction and instrumental data for
the past 1000 years shows that climate change in the last millennium includes long-term trends and various
oscillations. Two long-term trends and the quasi-70-year oscillation were detected in the global temperature
series for the last 140 years and the NH millennium series. One important feature was emphasized that
temperature decreases slowly but it increases rapidly based on the analysis of different series. Benefits can be
obtained of climate change from understanding various long-term trends and oscillations. Millennial temperature
proxies from the natural climate system and time series of nonlinear model system are used in understanding the
natural climate change and recognizing potential benefits by using the method of wavelet transform analysis. The
results from numerical modeling show that major oscillations contained in numerical solutions on the
interdecadal timescale are consistent with that of natural proxies. It seems that these oscillations in the climate
change are not directly linked with the solar radiation as an external forcing. This investigation may conclude
that the climate variability at the interdecadal timescale strongly depends on the internal nonlinear effects in the climate system. 相似文献
13.
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
14.
L. C. Sloan 《Theoretical and Applied Climatology》2006,86(1-4):271-279
Summary The methods of reconstructing ancient climate information from the rock record are summarized, and the climate forcing factors
that have been active at global and regional scales through Earth history are reviewed. In this context, the challenges and
approaches to modeling past climates by using a regional climate model are discussed. A significant challenge to such modeling
efforts arises if the time period of interest occurred prior to the past ∼3–5 million years, at which point land–sea distributions
and topography markedly different from present must be specified at the spatial resolution required by regional climate models.
Creating these boundary conditions requires a high degree of geologic knowledge, and also depends greatly upon the global
climate model driving conditions. Despite this and other challenges, regional climate models represent an important and unique
tool for paleoclimate investigations. Application of regional climate models to paleoclimate studies may provide another way
to assess the overall performance of regional climate models. 相似文献
15.
Reliable paleoclimate reconstructions are needed to assess if the recent climatic changes are unusual compared to pre-industrial climate variability. Here, we focus on one important problem in climate reconstructions: Transfer functions relating proxies (predictors) and target climatic quantities (predictands) can be seriously biased when predictand and predictor noise is not adequately accounted for, resulting in biased amplitudes of reconstructed climatic time series. We argue for errors-in-variables models (EVM) for unbiased identification of linear structural relationships between noisy proxies and target climatic quantities by (1) introducing underlying statistical concepts and (2) demonstrating the potential biases of using the EVM approach, the most commonly used direct ordinary least squares (OLS) regression, inverse OLS regression, or the reduced major axis method (??variance matching??) with a simulation example of artificial noise-disturbed sinusoidal time series. We then develop an alternative strategy for paleoclimate reconstruction from tree-ring and other proxy data, explicitly accounting for the identified problem. 相似文献
16.
Evaluation of proxy-based millennial reconstruction methods 总被引：2，自引：1，他引：1
A range of existing statistical approaches for reconstructing historical temperature variations from proxy data are compared using both climate model data and real-world paleoclimate proxy data. We also propose a new method for reconstruction that is based on a state-space time series model and Kalman filter algorithm. The state-space modelling approach and the recently developed RegEM method generally perform better than their competitors when reconstructing interannual variations in Northern Hemispheric mean surface air temperature. On the other hand, a variety of methods are seen to perform well when reconstructing surface air temperature variability on decadal time scales. An advantage of the new method is that it can incorporate additional, non-temperature, information into the reconstruction, such as the estimated response to external forcing, thereby permitting a simultaneous reconstruction and detection analysis as well as future projection. An application of these extensions is also demonstrated in the paper. 相似文献
17.
中国北方地区旱涝的年代际预测分析研究 总被引：7，自引：8，他引：7
基于状态空间重构理论和嵌入定理,给出场时间序列预测模型的建立思路。与单点时间序列预测分析方法相比,场时间序列预测分析方法的优点在于,在寻找吸引子上某个相点的最邻近点及其映象以建立预测模型时,不局限于它自身的时间序列,而是在区域内所有相点的时间序列所构成的整个吸引子上寻找。这样,在一定程度上改进单点时间序列的“遍历性”,以提高预测精度。在此基础上,利用中国北方地区534年旱涝等级资料,对中国北方几个区域年代际尺度的旱涝变化及其极端旱(涝)出现频率进行预测试验分析。 相似文献
18.
This paper overviews observations and examines modeling issues associated with the mean state, climate variability and climate change in West Africa. The Tropical Rain Measuring Mission (TRMM) satellite allows for the first time estimates of Unconditional, Convective and Stratiform rain rates in West Africa. The 1998 estimated TRMM rates are compared to long-term observed rain rates and a merged rain data set (CMAP) during 1998. Further, the TRMM estimates are compared to the simulated rain rates from the Community Climate Model Version 3.6. The TRMM Precipitation Radar rain estimates are generally lower than either the long-term observations or the CMAP rates during 1998. Moreover, the TRMM rain estimates show a significant fraction of the total rain (convective + stratiform) is characterized as stratiform rain (30–40%). The CCM3 simulates primarily convective rain and negligible amounts of non-convective rain for West Africa. Furthermore, the TRMM high-resolution rain patterns strongly imply that rain in West Africa occurs on mesoscales in association with mesoscale convective systems (squall lines, mesoscale convective complexes and non-squall tropical clusters). We demonstrate this by briefly examining two mesoscale convective systems during May 1998 with METEOSAT data. Regional climate models may offer the best solution to understanding climate change in West Africa because of their ability to capture mesoscale systems and better their representation of orographic features. Adequate boundary conditions from Global Climate Models are still necessary for regional climate model simulations to successfully reproduce mean climate conditions and provide understanding with respect to future climate change. Observations in West Africa should be maintained or increased for monitoring climate variability and possibility of climate change in West Africa, proper initialization of numerical weather prediction models and the validation of climate models. 相似文献
19.
Probabilistic projections of change in regional temperature and precipitation previously derived allow for the range of sensitivities to global warming simulated by CMIP3 models. However, the changes were relative to an idealized base climate for 1980–1999, disregarding observed trends, such as those in rainfall in some Australian regions. Here we propose a method that represents projections for both forced change and decadal means as time series that extend from the observed series, illustrated using data for central Victoria. The main idea is to estimate the time-evolving underlying (or forced) past climate then convert this to a series of absolute values, by using the mean of the full observational record. We again use the pattern scaling assumption, and combine the CMIP3 sensitivities used for future change with a global warming series beginning at 1900. Like the confidence interval of regression theory, the analysis gives an estimate of the range of the underlying climate at each decade. This range can be augmented to allow for natural variability. A Bayesian theory can be applied to combine the model-based sensitivity with that estimated from observations. The time series are modified and the persistence of current observed anomalies considered, ultimately merging the probabilistic projections with the observed record. For some other cases, such as rainfall in southwest and north Australia and temperature in the state of Iowa, the two sensitivity estimates appear less compatible, and possible additional forcings are considered. Examples of the potential use of such time series are presented. 相似文献
20.
Credible climate predictions require a rational quantification of uncertainty, but full Bayesian calibration requires detailed estimates of prior probability distributions and covariances, which are difficult to obtain in practice. We describe a simplified procedure, termed precalibration, which provides an approximate quantification of uncertainty in climate prediction, and requires only that uncontroversially implausible values of certain inputs and outputs are identified. The method is applied to intermediate-complexity model simulations of the Atlantic meridional overturning circulation (AMOC) and confirms the existence of a cliff-edge catastrophe in freshwater-forcing input space. When uncertainty in 14 further parameters is taken into account, an implausible, AMOC-off, region remains as a robust feature of the model dynamics, but its location is found to depend strongly on values of the other parameters. 相似文献