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   

广西沿海地壳运动趋势及对环境的影响     

邓永光 《华东地质学院学报》2000,23(3):214-221

人类生存环境的变化是人类共同关心的环境问题之一,最直接影响环境变化的自然因素有气候变化、海平面和陆地的升降等,通过对有关广西沿海海平面和地壳运动资料的研究,初步分析了地壳运动对沿海地区产生的不良环境变化。  相似文献   

A two-dimensional analytical solution of groundwater responses to tidal loading in an estuary and ocean     

L. Li  D. A. Barry  C. Cunningham  F. Stagnitti  J. -Y. Parlange 《Advances in water resources》2000,23(8):176

Previous studies on tidal dynamics of coastal aquifers have focussed on the inland propagation of oceanic tides in the cross-shore direction, a configuration that is essentially one-dimensional. Aquifers at natural coasts can also be influenced by tidal waves in nearby estuaries, resulting in a more complex behaviour of head fluctuations in the aquifers. We present an analytical solution to the two-dimensional depth-averaged groundwater flow equation for a semi-infinite aquifer subject to oscillating head conditions at the boundaries. The solution describes the tidal dynamics of a coastal aquifer that is adjacent to a cross-shore estuary. Both the effects of oceanic and estuarine tides on the aquifer are included in the solution. The analytical prediction of the head fluctuations is verified by comparison with numerical solutions computed using a standard finite-difference method. An essential feature of the present analytical solution is the interaction between the cross- and along-shore tidal waves in the aquifer area near the estuary’s entry. As the distance from the estuary or coastline increases, the wave interaction is weakened and the aquifer response is reduced, respectively, to the one-dimensional solution for oceanic tides or the solution of Sun (Sun H. A two-dimensional analytical solution of groundwater response to tidal loading in an estuary, Water Resour Res 1997;33:1429–35) for two-dimensional non-interacting tidal waves.  相似文献   

云南程海现代沉积物环境记录研究   总被引：9，自引：0，他引：9  

陈敬安  万国江 《矿物学报》2000,20(2):112-116

本文通过对程海沉积物Ｃ、Ｈ、Ｎ等元素含量及其比值的综合分析,辨识了程海沉积物有机质Ｈ／Ｃ及Ｃ／Ｎ值的环境指示意义,发现它们增可作为程海水位波动及区域气候干湿变迁的替代性指标。研究结果表明：程海的水位和区域气候干湿主为化明显以历了两个不同的阶段,但整体上程海水位一直呈下降趋势,反映区域气候整体上向干旱化方向发展。  相似文献   

Spatial-temporal variability of the fluctuation of soil temperature in the Babao River Basin,Northwest China   总被引：2，自引：2，他引：0  

Ning  Lixin  Cheng  Changxiu  Shen  Shi 《地理学报(英文版)》2019,29(9):1475-1490

Journal of Geographical Sciences - The Babao River Basin is the “water tower” of the Heihe River Basin. The combination of vulnerable ecosystems and inhospitable natural environments...  相似文献   

Total solar eclipse effects on evapotranspiration captured by groundwater fluctuations in a Southern Appalachian fen     

Jeffrey D. Wilcox 《水文研究》2019,33(11):1538-1541

Solar eclipses provide opportunities to observe unusual natural phenomena. This paper presents data showing that diurnal groundwater fluctuations were briefly interrupted in a Southern Appalachian fen following a total solar eclipse on August 21, 2017. Groundwater levels, which were rapidly declining in the middle of a summer afternoon, nearly stabilized following totality. This anomaly in the water‐level record was caused by reduced evapotranspiration (ET). ET was significantly lower (36% ± 11%, p < 0.02) over a 45‐min time period following the eclipse when compared with other days within the study period, although the effects were short lived and did not have a significant impact on the daily total ET (p > 0.05). These findings may prompt evaluation of existing groundwater records along the path of totality from past eclipses or plan for studies ahead of future eclipses.  相似文献   

VARIABILITY IN THE WESTERN PACIFIC SUBTROPICAL HIGH AND ITS RELATIONSHIP WITH SEA TEMPERATURE VARIATION CONSIDERING THE BACKGROUND OF CLIMATE WARMING OVER THE PAST 60 YEARS     

孙圣杰  李栋梁 《热带气象学报(英文版)》2018,24(4):468-480

By adopting characteristic index data for the Western Pacific Subtropical High (WPSH) from the National Climate Center of China, U.S. National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP/NCAR) reanalysis data, and the National Oceanic and Atmospheric Administration (NOAA) sea surface temperature (SST) data, we studied the WPSH variability considering the background of climate warming by using a Gaussian filter, moving averages, correlation analysis, and synthetic analysis. Our results show that with climate warming over the past 60 years, significant changes in the WPSH include its enlarged area, strengthened intensity, westward extended ridge point and southward expanded southern boundary, as well as enhanced interannual fluctuations in all these indices. The western ridge point of the WPSH consistently varies with temperature changes in the Northern Hemisphere, but the location of the ridgeline varies independently. The intensity and area of the WPSH were both significantly increased in the late 1980s. Specifically, the western ridge point started to significantly extend westward in the early 1990s, and the associated interannual variability had a significant increase in the late 1990s; in addition, the ridgeline was swaying along the north-south-north direction, and the corresponding variability was also greatly enhanced in the late 1990s. With climate warming, the SST increase becomes more weakly correlated with the WPSH intensity enhancement but more strongly correlated with the westward extension of the ridge point in the equatorial central and eastern Pacific Ocean in winter, corresponding to an expanding WPSH in space. In the northern Pacific in winter, the SST decrease has a weaker correlation with the southerly location of the ridgeline but also a stronger correlation with the westward extension of the ridge point. In the tropical western Pacific in winter, the correlations of the SST decrease with the WPSH intensity enhancement, and the westward extension of the ridge point is strengthened. These observations can be explained by strengthened Hadley circulations, the dominant effects of the southward shift, and additional effects of the weakened ascending branch of the Walker circulation during warm climatological periods, which consequently lead to strengthened intensities, increased areas, and southward expansions of the WPSH in summer.  相似文献   

灰色自记忆模型的高层建筑物沉降分析     

杨帆  田振凯 《测绘科学》2017,42(11)

针对GM(1,1)模型对非线性数据的沉降趋势及其波动特征无法进行准确地预测,而灰色残差模型和灰色马尔科夫模型又无法解决这个问题,提出了灰色自记忆预测模型。该模型利用了自记忆原理考虑过去和现在对未来的影响的记忆性特点,克服了GM(1,1)模型对初值比较敏感、预测精度低等局限性,提高了对波动性数据的预测能力。通过实例验证表明了灰色自记忆模型的可靠性和可行性。  相似文献   

东北地区资源型城市经济转型发展波动特征与影响因素——基于面板数据模型的分析   总被引：3，自引：2，他引：1  

陈妍  梅林 《地理科学》2017,37(7):1080-1086

借助H-P滤波和面板数据回归模型分析2000~2014年东北资源型城市转型以来经济发展的趋势特征和影响因素。结果表明：① 东北资源型城市经济总量保持上升趋势,但存在明显的周期性波动,与国家振兴老工业基地政策和城市产业结构调整历程相吻合;② 第三产业发展和市场化进程对经济增长的促进作用逐渐增强,而技术进步、对外开放程度等因素作用强度仍然较弱;③ 东北资源型城市转型发展可划分为试验阶段、全面启动阶段和深化阶段,经济转型深化过程中应加强实践探索,激励体制机制创新,构建有利于衡量测度的指标体系。  相似文献   

海温热力强迫-涛动和低频振荡机理的动力学研究     

张韧  余志豪  蒋全荣 《热带气象学报》2001,17(2):135-143

用动力分析和数值计算的方法讨论了对海温热力强迫的响应，结果表明，对于行星尺度系数，海温热力场的持续强迫作用可以很快激发出稳定的大气平衡态响应，该响应表现出明显的大尺度东－西及南－北向涛动特征，对于天气尺度系统，海温热力场则主要激发出大气低频振荡，研究结果揭示了海温势力构型与大气响应形式的基本对应关系和动力过程，提出了一些新观点。  相似文献