北京地区气候变量的多分形特征研究

在气候系统的变量时间序列中往往存在着不同尺度间的自相似结构,这种自相似结构,又称为分形的特征.本文运用多分形去趋势波动分析方法(MF-DFA),分析北京市近50年来不同气象变量的逐日序列,并用一个扩展的二项式串级模式来分别估计其多分形谱.结果表明,平均气温等变量表现出多重分形的特征,并且多分形谱宽一致.而气温日较差和日照时数则表现出单分形的特征.且这种分形特征与长程记忆性相关,为中长期气候预测提供了理论基础.     

长江流域降水变化及其趋势演变

本文对中国长江流域降水趋势进行了分析.指出对月降水量而言,20世纪后50年不同区域出现1不胃的降水趋势变化特征.趋势插补法研究表明中国降水时空分布趋势十分明显.对长江流域长期降水资料分析研究指出夏季月份降水时间更集中,而对年降水而言在一些站则表现出明显的周期变化.     

新04井(泉)流体测项长程趋势变化分析

在深入剖析新疆新04井(泉)水文地质构造背景的基础上,探讨了新04井(泉)流体测项长程趋势变化与区域地震活动性、气温等物理场的相关性。新04井(泉)流体测项长程趋势变化是由于区域应力场增强与浅层水渗入量增加共同作用的结果。     

2011年日本东北大地震特低频地磁信号的分形标度特征研究

本文选择2011年3月11日M9.0日本东北大地震震中附近三个地磁台站16个月(2010/01/01—2011/04/30)的特低频地磁观测资料,采用去倾扰动分析方法,得到了这三个台站地磁记录的非均匀标度特征随时间的变化,提出了一种能反映地磁三分量非均匀标度特征同步变化的指标,并据此探讨了特低频地磁信号分形标度特征变化与日本东北大地震之间的可能关联性,初步结果表明,这三个台站的特低频地磁信号分形标度特征指标在日本东北大地震前25~50天左右呈现出同步的异常增加,基于磁静日观测资料的随机合成地磁数据的统计检验结果可知前述异常并非随机异常,而是一种具有统计显著性的异常,可能反映了日本东北大地震对周边地磁信号内在的非线性系统特征产生了有统计意义的影响.     

地电阻率趋势变化的形态特征与地震

总结26年来全国近百个台站的地电阻率观测资料, 发现可将以月均值为基本数据的地电阻率趋势变化形态分为5种类型, 其中的3种类型属异常变化, 它们有互不相同的定性、定量特征, 并且与地震的关系也不相同：漏斗型地电阻率趋势变化与强震相对应, 勺型变化则与中强震活动有较好的对应关系, 而斜型趋势变化一般不对应地震。本文由受压岩石的实验结果对不同类型的形态特征以及与地震的关系进行了初步的讨论, 认为不同地电阻率趋势变化形态实际上反映了地下岩土层所处的应力状态不同：漏斗型反映了地下岩土层处于高应力状态: 勺型反映地下介质处于中高应力状态: 而斜型则反映地下介质的应力在松弛。所有这些认识对于中期地震预报是有用的。     

累计去趋势法在分析降水与形变关系中的应用

论述累计去趋势法的原理,举例说明在降水与形变分析中的应用效果。对流动水准、台站水准及流动重力单测站的同场地的降水量进行累计去趋势计算,然后分别与观测数据进行对比。通过分析发现,经过处理后的降水量变化曲线除去原来的突跳变化,增大了降水量在后续时间中的影响力,而且降水量与形变的正常变化趋势更加一致。根据处理后的降水量变化与形变变化趋势的对应关系,也更容易判断形变是否出现异常变化。     

气候序列的均一化——定量评估气候变化的基础

长期气象观测序列是反映气候变化的最基本依据.然而,几乎所有气象站都要经历迁址或观测仪器、规则和方法等方面的变更,导致观测序列相应时段的系统性偏差.均一化就是要校订这类系统性偏差,以确切评估时间序列中的变化趋势.近年来随着气候变化研究的深入,均一化也从早期主要着眼于平均态校订发展到更注重极端天气气候信息的校订.本文结合理想的和实际的气候序列分析,演示均一化的基本思路;简介近年来就中国区域气候序列的均一化研究取得的一些新认识,并就该领域存在的（特别是涉及气候极值或极端天气以及多要素物理联系等方面）问题,展望进一步研究.     

城市化对北京气象站极端气温指数趋势变化的影响

利用5个乡村气象站和北京气象站(简称北京站)1960~2008年日最高、最低气温资料,比较分析了北京地区城市和乡村极端气温指数年、季节的时间变化以及城市化对北京站各极端气温指数趋势变化的影响.结果表明:1960~2008年北京站霜冻日数、冷夜日数、冷昼日数和平均日较差均显著减少,暖夜日数、暖昼日数、平均最高气温和平均最低气温均显著上升,这些指数的趋势变化全部通过了0.01显著性水平检验,其中霜冻日数、冷夜日数、暖夜日数、平均最低气温、平均气温日较差等与最低气温有关的极端气温指数比冷昼日数、暖昼日数、平均最高气温等基于最高气温记录的极端气温指数变化趋势更明显;城市化因素已致使北京站1960~2008年期间霜冻日数、冷夜日数和平均气温日较差显著减少,暖夜日数和平均最低气温显著增加,这些与最低气温有关的极端气温指数序列,其城市化影响都通过了0.01显著性水平检验.在北京站的霜冻日数、冷夜日数和平均气温日较差长期减少趋势中,城市化影响分别达到-5.78 d/10a、-17.83 d/10a和-0.73 ℃/10a,而在北京站暖夜日数和平均最低气温增加趋势中,城市化影响分别为14.76 d/10a和0.70 ℃/10a.在所有与最低气温有关的年平均极端气温指数的趋势变化中,城市化影响贡献率均达到100%,即观测到的趋势变化完全是由城市化因素造成的.城市化致使四季北京站冷夜日数、平均气温日较差均显著减少,暖夜日数、平均最低气温均显著增加,其中平均最低气温和平均气温日较差序列中的城市化影响在冬季最大,暖夜日数序列中的城市化影响在夏季最显著.     

北京城市热岛的时空变化分析

利用1987、1999、2000、2001、2002和2005年六幅陆地卫星影像研究北京市规划区地表城市热岛（SUHI）．首先用决策树分类法进行分类,得到六幅不同时相的土地利用／覆盖分类图像．根据Artis＆Carnahan算法利用热红外通道的灰度值计算地表辐射亮温,基于分类结果进行比辐射率纠正,计算地表温度．通过分析北京市规划区1987～2005年间地表城市热岛的特征,发现不同土地利用／土地覆盖类型与地表城市热岛有密切关系;2001年、2002年和2005年影像中市区的热岛分布的破碎度增加,由原来的集中分布慢慢向周围扩散,并在市区中心植被覆盖高的区域出现蓝色“凉爽”区;地表城市热岛增加的区域与城市扩展区域一致,城市化过程是城市热岛面积不断增加的主要的原因．     

植被电磁散射的半空间模型研究

本文给出了地面植被电磁散射的半空间模型研究方法.在以往的相关文献中,均采用自由空间格林函数求解单个叶片散射体的散射场,本文利用半空间并矢格林函数求出了单个散射体的散射场,然后运用Monte Carlo方法模拟生成地面植被层,得到了在半空间下植被层的电磁散射特性,计算出了单、双站雷达散射截面,并与自由空间下的散射场做了相互对比.结果表明,在半空间格林函数下得到的散射场更为适用于描述地面植被的电磁散射特性.     

Multifractal detrended fluctuation analysis of streamflow series of the Yangtze River basin,China

Scaling and multifractal properties of the hydrological processes of the Yangtze River basin were explored by using a multifractal detrended fluctuation analysis (MF‐DFA) technique. Long daily mean streamflow series from Cuntan, Yichang, Hankou and Datong stations were analyzed. Using shuffled streamflow series, the types of multifractality of streamflow series was also studied. The results indicate that the discharge series of the Yangtze River basin are non‐stationary. Different correlation properties were identified within streamflow series of the upper, the middle and the lower Yangtze River basin. The discharge series of the upper Yangtze River basin are characterized by short memory or anti‐persistence; while the streamflow series of the lower Yangtze River basin is characterized by long memory or persistence. h(q) vs q curves indicate multifractality of the hydrological processes of the Yangtze River basin. h(q) curves of shuffled streamflow series suggest that the multifractality of the streamflow series is mainly due to the correlation properties within the hydrological series. This study may be of practical and scientific importance in regional flood frequency analysis and water resource management in different parts of the Yangtze River basin. Copyright © 2008 John Wiley & Sons, Ltd.     

洞庭湖流域气候变化特征(1961-2003年)

以22个气象站1961-2003年的气象观测数据为基础,对洞庭湖流域的气温、降水和参照蒸散量进行趋势与突变分析．从1970年开始,洞庭湖流域经历了一个缓慢而稳定的增温过程,1990s发生突变进入快速增温时期;尤其是是在春、冬季节,这种突变式的增温特征非常显著;秋季持续而稳定增温,而夏季气温并无明显变化．进入1990s,洞庭湖流域降水有明显增多,尤其是夏季降水突变式增加;与此同时,夏季暴雨频率也突变式增大,但是暴雨强度并无明显变化．1900s迄今,参照蒸散量持续而稳定的减少,夏季减少量尤为显著．全球变暖的区域响应,驱动洞庭湖流域水循环速度加快,夏季降水增多,而蒸发能力减弱,这是1990s洞庭湖流域洪水频发的主要气候因子．     

Possible climate change evidence in ten Mexican watersheds

This paper suggests possible evidence of climate change in Mexico at the watershed level, based solely on historical data. The official Mexican climate dataset was used to find the best set of stations for each watershed. Maximum and minimum temperatures and rainfall in ten watersheds are analyzed from 1970 to 2009. Maximum temperature trends show a significant increment in most of these watersheds. Furthermore, Daily Temperature Range (DTR) exhibits a positive trend (increments), thus implying an increase in temperature extremes. This study also shows that the difference between maximum and minimum monthly temperature trends is negatively correlated with monthly precipitation trends. As a result, land-use and land-cover changes could be the main drivers of climate change in the region.     

Multivariate analysis of flood characteristics in a climate change context of the watershed of the Baskatong reservoir,Province of Québec,Canada

The analysis of the impact of climate change (CC) on flood peaks has been the subject of several studies. However, a flood is characterized not only by its peak, but also by other characteristics such as its volume and duration. Little effort has been directed towards the study of the impact of CC on these characteristics. The aim of the present study is to evaluate and compare flood characteristics in a CC context, in the watershed of the Baskatong reservoir (Province of Québec, Canada). Comparisons are based on observed flow data and simulated flow series obtained from hydrological models using meteorological data from a regional climate model for a reference period (1971–2000) and a future period (2041–2070). To this end, two hydrological models HSAMI and HYDROTEL are considered. Correlations, stationarity, change‐points, and the multivariate behaviour of flood series were studied. The results show that, at various levels, all flood characteristics could be affected by CC. Copyright © 2011 John Wiley & Sons, Ltd.     

A low-order model for the response of the Atlantic thermohaline circulation to climate change

Concern has been expressed that anthropogenic climate change may lead to a slowdown or even collapse of the Atlantic thermohaline circulation (THC). Because of the possibly severe consequences that such an event could have on the northern North Atlantic and northwestern Europe, integrated assessment models (IAMs) are needed to explore the associated political and socioeconomic implications. State-of-the-art climate models representing the THC are, however, often too complex to be incorporated into an integrated assessment framework. In this paper we present a low-order model of the Atlantic THC which meets the main requirements of IAMs: it (1) is physically based, (2) is computationally highly efficient, (3) allows for comprehensive uncertainty analysis and (4) can be linked to globally aggregated climate models that are mostly used in IAMs. The model is an interhemispheric extension of the seminal Stommel model. Its parameters are determined by a least-squares fit to the output of a coupled climate model of intermediate complexity. Results of a number of transient global warming simulations indicate that the model is able to reproduce many features of the behaviour of coupled ocean–atmosphere circulation models such as the sensitivity of the THC to the amount, regional distribution and rate of climate change.Responsible Editor: Richard Greatbatch     

Reservoir performance under uncertainty in hydrologic impacts of climate change

Relatively few studies have addressed water management and adaptation measures in the face of changing water balances due to climate change. The current work studies climate change impact on a multipurpose reservoir performance and derives adaptive policies for possible future scenarios. The method developed in this work is illustrated with a case study of Hirakud reservoir on the Mahanadi river in Orissa, India, which is a multipurpose reservoir serving flood control, irrigation and power generation. Climate change effects on annual hydropower generation and four performance indices (reliability with respect to three reservoir functions, viz. hydropower, irrigation and flood control, resiliency, vulnerability and deficit ratio with respect to hydropower) are studied. Outputs from three general circulation models (GCMs) for three scenarios each are downscaled to monsoon streamflow in the Mahanadi river for two future time slices, 2045–65 and 2075–95. Increased irrigation demands, rule curves dictated by increased need for flood storage and downscaled projections of streamflow from the ensemble of GCMs and scenarios are used for projecting future hydrologic scenarios. It is seen that hydropower generation and reliability with respect to hydropower and irrigation are likely to show a decrease in future in most scenarios, whereas the deficit ratio and vulnerability are likely to increase as a result of climate change if the standard operating policy (SOP) using current rule curves for flood protection is employed. An optimal monthly operating policy is then derived using stochastic dynamic programming (SDP) as an adaptive policy for mitigating impacts of climate change on reservoir operation. The objective of this policy is to maximize reliabilities with respect to multiple reservoir functions of hydropower, irrigation and flood control. In variations to this adaptive policy, increasingly more weightage is given to the purpose of maximizing reliability with respect to hydropower for two extreme scenarios. It is seen that by marginally sacrificing reliability with respect to irrigation and flood control, hydropower reliability and generation can be increased for future scenarios. This suggests that reservoir rules for flood control may have to be revised in basins where climate change projects an increasing probability of droughts. However, it is also seen that power generation is unable to be restored to current levels, due in part to the large projected increases in irrigation demand. This suggests that future water balance deficits may limit the success of adaptive policy options.     

Implications of climate change for sustainable water resources management in India

This paper presents an overview of the current water resources scenario in India, and recent work carried out in India to assess the climate change impact on hydrology and water resources. Issues that need to be addressed with respect to climate change/variability in sustainable water resources planning and management are discussed.     

Mapping of climatic parameters under climate change impacts in Iran

ABSTRACT

This research aims to provide a comprehensive evaluation of climate change effects on temperature, precipitation and potential evapotranspiration over the country of Iran for the time periods 2010–2039, 2040–2069 and 2070–2099, and under scenarios A2 and B2. After preparation of measured temperature and precipitation data and calculation of potential evapotranspiration for the base time period of 1960–1990 for 46 meteorological stations (with a nationwide distribution), initial zoning of these three parameters over the country was attempted. Maximum and minimum temperatures and values of precipitation were obtained from the HadCM3 model under scenarios A2 and B2 for the three time periods, and these data were downscaled. Corresponding maps were prepared for the three parameters in the three time periods, and spatial and temporal variations of these climatic parameters under scenarios A2 and B2 were extracted and interpreted. Results showed that the highest increase in temperature would occur in western parts of the country, but the highest increase of potential evapotranspiration would occur in the central region of Iran. However, precipitation would vary temporally and spatially in different parts of the country depending on the scenario used and the time period selected.

Editor Z. W. Kundzewicz; Associate editor not assigned