气候变暖的适应行为与黑龙江省夏季低温冷害的变化   总被引：20，自引：3，他引：17  

方修琦  王媛  朱晓禧 《地理研究》2005,24(5):664-672

与气候变暖相联系的极端天气、气候事件及其影响的研究正日益受到重视,极端事件与气候变化直接相关,而极端事件的影响还与人类的适应行为密切相关。本文以农业对温度变化最敏感的黑龙江省为例,分析了变暖对夏季低温冷害事件的影响。结果显示,变暖后夏季出现低温冷害临界气温的概率减小;但由于人们追求更高经济效益的适应行为,在变暖的情况下种植更适应较暖气候条件的农作物,低温冷害的发生的频率和强度并不一定随变暖而减少,但作物单产期望值还是会增加。  相似文献   

1870-2011年全球海域SST变化趋势     

郑崇伟  周林  宋帅  潘静 《海洋与湖沼》2013,44(5):1123-1129

利用来自英国气象局哈德莱中心(Met Office Hadley Centre)的海表面温度(Sea Surface Temperature, SST)资料, 对全球海域近140余年来SST的长期变化进行分析。研究发现:(1)1870—2011年期间, 全球大部分海域的SST表现出显著的逐年线性递增趋势, 在两极大部分海域、格陵兰南部海域呈显著的递减趋势, 仅在部分小范围海域及一些零星海域的SST无显著变化。近海的递增趋势强于大洋, 大洋西岸的递增趋势强于大洋东岸。(2)近140余年来, 整体上全球的SST以0.0038℃/a的速度显著增加, 其中1870—1910年表现出较为显著的递减趋势, 1910年至今表现出较强的递增趋势。(3)1870—1910年期间, 全球大范围海域的SST无显著变化; 呈显著递减的海域主要分布于东海、阿拉斯加半岛南部海域、北大西洋30°N附近海域、冰岛南部海域、南印度洋西风带海域、新西兰附近海域; 呈显著递增的区域较为分散。1910—2011年期间, 全球大范围海域的SST逐年显著递增, 在两极大部分海域呈显著的递减趋势。(4)1870—1960年期间, 两极的SST走势较为平缓; 1960—2011年期间, 南极尤其是威德尔海的SST表现出显著的递减趋势, 其中逐8月的递减趋势尤为强劲; 北极逐2月、逐5月的SST呈显著性递减, 逐8月呈显著性递增且趋势较为强劲, 达到0.0402℃/a, 逐11月的SST无显著变化。  相似文献   

Reviewing evidence of marine ecosystem change off South Africa     

《African Journal of Marine Science》2013,35(3):427-448

Recent changes have been observed in South African marine ecosystems. The main pressures on these ecosystems are fishing, climate change, pollution, ocean acidification and mining. The best long-term datasets are for trends in fishing pressures but there are many gaps, especially for non-commercial species. Fishing pressures have varied over time, depending on the species being caught. Little information exists for trends in other anthropogenic pressures. Field observations of environmental variables are limited in time and space. Remotely sensed satellite data have improved spatial and temporal coverage but the time-series are still too short to distinguish long-term trends from interannual and decadal variability. There are indications of recent cooling on the West and South coasts and warming on the East Coast over a period of 20–30 years. Oxygen concentrations on the West Coast have decreased over this period. Observed changes in offshore marine communities include southward and eastward changes in species distributions, changes in abundance of species, and probable alterations in foodweb dynamics. Causes of observed changes are difficult to attribute. Full understanding of marine ecosystem change requires ongoing and effective data collection, management and archiving, and coordination in carrying out ecosystem research.  相似文献   

Fast and accurate earthquake location within complex medium using a hybrid globallocal inversion approach          下载免费PDF全文

Chaoying Bai  Rui Zhao  Stewart Greenhalgh 《地震科学（英文版）》2009,22(5):435-448

A novel hybrid approach for earthquake location is proposed which uses a combined coarse global search and fine local inversion with a minimum search routine, plus an examination of the root mean squares (RMS) error distribution. The method exploits the advantages of network ray tracing and robust formulation of the Fréchet derivatives to simultaneously update all possible initial source parameters around most local minima (including the global minimum) in the solution space, and finally to determine the likely global solution. Several synthetic examples involving a 3-D complex velocity model and a challenging source-receiver layout are used to demonstrate the capability of the newly-developed method. This new global-local hybrid solution technique not only incorporates the significant benefits of our recently published hypocenter determination procedure for multiple earthquake parameters, but also offers the attractive features of global optimal searching in the RMS travel time error distribution. Unlike the traditional global search method, for example, the Monte Carlo approach, where millions of tests have to be done to find the final global solution, the new method only conducts a matrix inversion type local search but does it multiple times simultaneously throughout the model volume to seek a global solution. The search is aided by inspection of the RMS error distribution. Benchmark tests against two popular approaches, the direct grid search method and the oct-tree important sampling method, indicate that the hybrid global-local inversion yields comparable location accuracy and is not sensitive to modest level of noise data, but more importantly it offers two-order of magnitude speed-up in computational effort. Such an improvement, combined with high accuracy, make it a promising hypocenter determination scheme in earthquake early warning, tsunami early warning, rapid hazard assessment and emergency response after strong earthquake occurrence.  相似文献   

Testing global geopotential models through comparison of a local quasi-geoid model with GPS/leveling data     

Pavel Novák  Jan Kostelecký  Jaroslav Klokočník 《Studia Geophysica et Geodaetica》2009,53(1):39-60

The satellite missions CHAllenging Minisatellite Payload (CHAMP) and Gravity Recovery And Climate Experiment (GRACE) provide accurate data that are routinely inverted into spherical harmonic coefficients of the geopotential forming a global geopotential model (GGM). Mean square errors of these coefficients, in some cases even entire covariance matrices, are included in the GGM. Due to estimation procedures with a large redundancy and insufficiently propagated observation errors, they often do not represent the actual accuracy of the harmonic coefficients, thus also gravity field parameters synthesized from the respective GGM. Since in most cases standard methods validating the GGMs reached their limits, new procedures and independent data are being currently sought. This article discusses an alternative validation procedure based on comparison of the GGMs with independent data represented by a set of GPS/leveling stations. Due to a different spectral content of the height anomalies synthesized from the GGMs and of those derived by combination of GPS-based ellipsoidal and leveled normal heights, the GGM-based low frequency height anomaly is enhanced for a high frequency component computed from local ground gravity and elevation data. The methodology is applied on a set of selected points of the European Vertical Reference Network and Czech trigonometric stations. In accordance with similar tests based on entirely independent data of cross-over altimetry, obtained results seem to indicate low-frequency deficiencies in the current GGMs, namely in those estimated from data of single-satellite missions.  相似文献   

Seismic reliability of V‐braced frames: Influence of design methodologies     

Alessandra Longo  Rosario Montuori  Vincenzo Piluso 《地震工程与结构动力学》2009,38(14):1587-1608

According to the most modern trend, performance‐based seismic design is aimed at the evaluation of the seismic structural reliability defined as the mean annual frequency (MAF) of exceeding a threshold level of damage, i.e. a limit state. The methodology for the evaluation of the MAF of exceeding a limit state is herein applied with reference to concentrically ‘V’‐braced steel frames designed according to different criteria. In particular, two design approaches are examined. The first approach corresponds to the provisions suggested by Eurocode 8 (prEN 1998—Eurocode 8: design of structures for earthquake resistance. Part 1: general rules, seismic actions and rules for buildings), while the second approach is based on a rigorous application of capacity design criteria aiming at the control of the failure mode (J. Earthquake Eng. 2008; 12 :1246–1266; J. Earthquake Eng. 2008; 12 :728–759). The aim of the presented work is to focus on the seismic reliability obtained through these design methodologies. The probabilistic performance evaluation is based on an appropriate combination of probabilistic seismic hazard analysis, probabilistic seismic demand analysis (PSDA) and probabilistic seismic capacity analysis. Regarding PSDA, nonlinear dynamic analyses have been carried out in order to obtain the parameters describing the probability distribution laws of demand, conditioned to given values of the earthquake intensity measure. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

全球地震、火山分布及其变化特征   总被引：2，自引：0，他引：2       下载免费PDF全文

洪汉净  陈会仙  赵谊  胡久常 《地震地质》2009,31(4):573

地震和火山都反映了地球表层的构造活动,因而地震活动区往往也是火山活动区。根据全球大震、火山活动目录,分析研究了全球地震、火山分布的特征。描述了各区的地震、火山活动分布,总结了地震、火山活动强度的时、空分布特征。全球地震、火山活动可以分为碰撞带、大陆区和大洋区。大陆地震以其片状的分散分布而不同于板块边缘的带状分布,大陆火山活动比大洋火山更受应力场的影响。大洋区地震活动相对较弱,岩浆活动主要是平静的岩浆溢出与洋中脊的扩张,往往没有形成火山喷发。有记录的火山喷发主要来自深部地幔的热柱。俯冲-碰撞活动区地震活动与火山喷发最强烈,大角度俯冲的弧后火山活动最强,当板块运动方向与板块边缘走向成小角度相交时,缺少正面俯冲的动力,火山活动相对平静。>500km深震的地段,火山活动较弱。火山与地震强烈活动的大多在大地水准面(Geoid)异常高的区域。地震与火山平均纬度随时间表现出同步的变化外,火山和大震活动也显示了大致同步的变化  相似文献   

全球化与全球变化关系研究     

田光进 《热带地理》2009,29(2)

全球化是本世纪人类社会发展的最重要特征之一,它不仅促进了产品和服务的流动,而且促进了劳动力、金融、资源及环境生产要素等的流动,技术的发展提高了生产效率和物质要素的可利用性.全球化扩大了人类活动的范围和影响程度,对人类社会、政治、文化、经济等各个方面都产生了影响,从而加深了全球环境变化.全球环境变化已经成为伞球化进程的重要方面,人类对全球环境变化的应对方式直接关系到人类的生存及可持续发展.全球化深化了国际分工,发达国家制造业大量向发展中国家转移,从而导致发展中国家承担了更多的环境污染,造成发展中国家碳排放增长较快.在全球化进程中,中国在享受初级产品大量出口并产生顺差的同时,也把环境污染输入进来,并把大量资源输出去,从而造成中国资源紧张和环境污染.随着中国经济实力的增强,中国的政治、文化等都会在全球产生更大影响,研究全球化进程对中国现代化进程的影响及中国现代化进程对全球化的影响、全球化进程与全球环境变化的关系具有重要的理论和实践意义.  相似文献   

全球变化对宁夏近40 a极端气温变化的影响   总被引：4，自引：1，他引：3  

赵光平  杨淑萍  穆建华  马力文  陈晓娟  周虎 《中国沙漠》2009,29(6):1207-1211

 对全球气候变暖背景下宁夏气候变化基本事实,利用近40多年来宁夏基本气象资料,对年平均气温、极端气温的变化进行了研究。结果表明,近40多年宁夏年平均气温呈连续上升趋势,1986年之后增温速率加快,增温幅度高于全国平均值;年极端最高气温、极端最低气温均在波动中持续上升,年极端最低气温上升幅度明显超过年极端最高气温;各季极端最高、极端最低气温呈非对称性变化,秋季各地极端最高气温增温幅度超过极端最低气温,但春夏冬三季极端最低气温增温远比极端最高气温明显,该特点在夏季表现得更突出;各月极端最高气温、极端最低气温均呈升温趋势。  相似文献   

Modelling for prediction of global deforestation based on the growth of human population   总被引：1，自引：0，他引：1  

Krishna Pahari  Shunji Murai 《ISPRS Journal of Photogrammetry and Remote Sensing》1999,54(5-6)

Deforestation due to ever-increasing activities of the growing human population has been an issue of major concern for the global environment. It has been especially serious in the last several decades in the developing countries. A population-deforestation model has been developed by the authors to relate the population density with the cumulative forest loss, which is defined and computed as the total forest loss until 1990 since prior to human civilisation. NOAA-AVHRR-based land cover map and the FAO forest statistics have been used for 1990 land cover. A simulated land cover map, based on climatic data, is used for computing the natural land cover before the human impacts. With the 1990 land cover map as base and using the projected population growth, predictions are then made for deforestation until 2025 and 2050 in both spatial and statistical forms.  相似文献