青藏高原1985年冬季异常少雪和1986年异常多雪的环流及气候特征对比研究   总被引：13，自引：2，他引：11  

陈乾金  王丽华  高波  张家诚 《气象学报》2000,58(2):202-213

利用青藏高原冬季异常积雪资料对比分析了 1 985年冬季异常少雪和 1 986年冬季异常多雪时期大气环流及热带海洋特征。分析结果表明 ,高原冬季多雪与少雪时中高纬度大气环流显著不同。与此同时 ,低纬热带环流及海洋特征也有明显的差异。探讨了造成这种差异的可能原因。  相似文献   

A PRELIMINARY VALIDATION STUDY OF THE SEASONAL FORECAST OF CCCMA MODEL OVER CHINA          下载免费PDF全文

DONG Min  Francis ZWIERS  YE Zhengqing 《Acta Meteorologica Sinica》2000,14(3):268-279

In this study we validate the raw ensemble mean forecasts of the CCCma's GCM2 modelagainst surface temperature and precipitation data obtained from 160 Chinese stations.It is foundthat despite the lagre biases,the model was able to produce seasonal anomalies that haveproperties that are reasonably close to those that are observed.This anomaly is the quantity ofinterest when forecasting seasonal climatic conditions.The root mean squared difference(RMSD)between the forecast and observed anomaly leads us to be modestly optimistic about the prospectsfor using dynamical models to forecast the interannual variability of some meteorological elements.The correlation analysis of the forecast and observation also supports the result given by theRMSD analysis and provides a tool for identify the forecast confidence level in various regions,  相似文献   

洱海沉积物粒度记录与气候干湿变迁   总被引：21，自引：2，他引：19  

陈敬安  万国江 《沉积学报》2000,18(3):341-345

通过对洱海现代沉积物的精细采样,将放射性核素精确计年与沉积物粒度研究相结合,重建了 6 0 0多年来洱海区域气候的干湿变迁,为恢复百年尺度的气候干湿变化提供了一条新途径。研究结果表明,15世纪是洱海地区最为湿润的一个世纪;洱海区域存在 10 0a、2 0 0a两种时间尺度的气候干湿准周期波动;自 19世纪末以来洱海区域气候整体上向干旱化方向发展,目前正处于干旱期末期,预计气候将由干旱转向湿润。  相似文献   

空间数据库引擎(SDE)在地图资源数据库管理中的应用   总被引：1，自引：0，他引：1  

胡卫民  徐雪仁  郭建恩  黄翰榕 《国土资源遥感》2000,11(4):67-70

随着地图资源数据在各个领域深入广泛的应用,作为应用基础和前提的地图资源数据的管理显得尤其重要。本文介绍了利用ESRI公司的空间数据库引擎(SDE),实现地图资源数据库管理的方法。该方法改变了传统的文件管理方式,不仅提高了地图数据资源的安全性,而且能使地图数据便于管理和使用,同时实现了局域网内地图资源的共享。  相似文献   

我国月降水量气候噪声的估计   总被引：10，自引：1，他引：9       下载免费PDF全文

柳艳菊马开玉  林振山 《应用气象学报》2000,11(2):165-172

利用我国大陆均匀分布的70个测站1961~1991年逐日降水量资料, 讨论了月降水量的气候噪声的3种估计方法, 并分别用改进后的方法估计了1、4、7、10月四个有代表性月份降水量的气候噪声.结果表明:我国月降水量的气候噪声随着降水量增加, 具有明显的季节变化, 一般夏季月份的噪声显著大于冬季月份, 秋季月份稍高于春季月份.从空间分布看, 春、夏、秋、冬全国绝大部分地区的气候噪声由南向北、由沿海向内陆明显减小.  相似文献   

Climate impacts of environmental degradation in Sudan   总被引：1，自引：0，他引：1  

Nadir Ahmed Elagib  Martin G. Mansell 《GeoJournal》2000,50(4):311-327

There exists an impressive amount of work for Sudan showing the anthropogenic degradation of natural vegetation cover. However, there are few examples of consequent climatic changes in literature. This work, thus, seeks to assess such effects of environmental forcing on various climatic patterns over the past few decades. Within the frame of the present analysis, the results are quite striking and are in concordance with scientific contentions that such land degradation could result in climatic modification. Higher temperature and less rainfall, sunshine duration and global radiation have been noticed. Evapotranspiration has responded more to the warming and drying conditions, thus showed signs of increasing rates, especially during the wet season. However, the extent of increase seems to have been suppressed by the decrease in sunshine duration and solar radiation as well as the inconsistent behaviour of wind speed. Changes in the variability of the within-year monthly observations have also occurred, thus suggesting an increase in the occurrence of extremes. The observed climatic modification in the country has exaggerated the insidious drought conditions. The present findings are hoped to contribute to our understanding of the effects of environmental problem and assist in considering policy responses. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Community forest management in Mexico: carbon mitigation and biodiversity conservation through rural development   总被引：1，自引：0，他引：1  

Daniel Klooster  Omar Masera   《Global Environmental Change》2000,10(4):2184

Forest management is an important carbon mitigation strategy for developing countries. As demonstrated by the case of Mexico, community forest management is especially effective because it offers tangible local benefits while conserving forests and sequestering carbon. Community forestry receives minimal government support now, but the clean development mechanism (CDM) of the Kyoto Protocol could leverage additional resources to promote the approach in Mexico and elsewhere. We argue that adequately designed and implemented, community forestry management projects can avoid deforestation and restore forest cover and forest density. They comprise promising options for providing both carbon mitigation and sustainable rural development. These kinds of projects should be included in the CDM.  相似文献   

Climate change in Lake Baikal: diatom evidence in an area of continuous sedimentation     

M. Bangs  R. W. Battarbee  R. J. Flower  D. Jewson  J. A. Lees  M. Sturm  E. G. Vologina  A. W. Mackay 《International Journal of Earth Sciences》2000,89(2):251-259

The presence of inhomogeneous sedimentation is acknowledged as being an important problem in palaeolimnological studies. Sediment records can be disturbed by erosional and redepositional events, which redeposit microfossils within a basin and may then lead to misinterpretations of fossil diatom assemblages. This study uses a combination of sedimentological tools, magnetic susceptibility measurements and high-resolution diatom analysis to show that a sediment core, BAIK80, taken in 345 m water depth from a shoulder region in the North Basin of Lake Baikal, is free of disturbances. Our results confirm that the sediment record is consistent and continuous for the uppermost sediment. Consequently, the fossil diatom data can be used to establish a continuous record of past climate variability over approximately the past 1300 years. Distinct changes occur in downcore abundances of endemic taxa Aulacoseira baicalensis and Cyclotella minuta, and principal components analysis (PCA) indicates a gradual transformation of taxa over the past 1300 years. These changes are likely to be related to climate, although definite links still have to be established. Received: 15 December 1998 / Accepted: 13 September 1999  相似文献   

全球小冰期的气候变化   总被引：1，自引：0，他引：1  

王立国  钟巍  李偲 《冰川冻土》2002,24(6):750-758

根据全球小冰期气候信息的不同代用指标的结果分析,全球小冰期冷、暖气候变化趋势具有一致性.其中,太阳活动是影响全球小冰期气候变化的主要因素,强火山爆发及厄尔尼诺事件则是其强化因素,这些因素通过海-气作用这一复杂机制对全球气候产生深远影响.  相似文献   

应用线性光谱分离技术研究喀斯特地区土地覆被变化——以贵州省关岭县为例   总被引：24，自引：3，他引：21  

万军  蔡运龙 《地理研究》2003,22(4):439-446

喀斯特地区土地覆被主要类型除了和非喀斯特地区一样的植被和裸露土壤外,还存在一个广泛分布的裸露基岩,一般遥感处理方法不具备直接定量提取这三类土地覆被参数的能力。基于地物光谱线性混合模型的线性光谱分离技术,可以在亚象元的尺度上直接获取植被覆盖、裸露土壤和裸露基岩等在各象元区域内的比例,非常适合用于喀斯特地区的土地覆被变化的研究。本文利用1987年2月17日和1999年12月27日LandsatTM各6波段遥感影像,使用ENVI软件,分离出植被、裸露土壤、裸露岩石和阴影等土地覆被丰度和RMS的空间分布。对比结果表明,研究区1987～1999年,植被覆盖率上升593%,裸露土壤面积下降1215%,裸露基岩面积上升408%。表明研究区尽管植被在恢复、水土流失总量在减少,但石漠化面积在明显上升,生态形势依旧严峻。  相似文献