地块波浪运动及意义     

李侠  何安明 《地球科学与环境学报》1998,20(3)

论述了地块波浪运动的概念、形成机制及其传播和效应,并给出了简单的数学模型,最后指出了地块波浪的两个极重要的特性（周期性和翘倾性）及实践意义。  相似文献   

鄂尔多斯地区南缘奥陶纪层序地层及海平面变化   总被引：10，自引：0，他引：10  

贾振远  蔡华  蔡忠贤  秦玉娟 《地球科学》1997,6(5)

鄂尔多斯地区南缘奥陶纪可划分为１２个层序（ｓｅｑｕｅｎｃｅｓ）．本区奥陶纪地壳演化正处于重要关键时期，早奥陶世（冶里－亮甲山期、马家沟期、峰峰期）为被动大陆边缘，划分为７个层序．海平面突然上升，尔后逐渐下降．中、晚奥陶世（赵老峪期、上店期）演化为主动大陆边缘，可划分为５个层序．海平面就鄂尔多斯地区整体而言发生大规模海退，露出海面．但就鄂尔多斯地区南缘则海水突然加深，随后海平面渐渐下降．晚奥陶世卡拉道克世末鄂尔多斯地区海水全部退出．  相似文献   

Faure序列的周期性及快速构造     

林鹭 《华东地质学院学报》2003,26(2):113-114

通过分析Faure序列的结构，得到Faure序列的周期性以及模2下Faure序列的快速算法。该算法无需直接写出相关矩阵，仅包含矩阵及向量的逻辑运算和加法运算，不包含乘法运算。  相似文献   

气候演变中的冰和碳   总被引：18，自引：0，他引：18  

汪品先 《地学前缘》2002,9(1):85-93

地质历史上充满着冰盖消长 (“暖室期”和“冰室期” ,“冰期”和“间冰期”)与大气CO2 增减的周期性变化 ,而两者之间的关系并不清楚。由于冰盖变化的地质标志比大气CO2 变化的标志容易认识 ,长期以来古气候研究侧重“冰” ,而对“碳”即碳循环的研究不足 ,通常将碳循环的变化解释为冰盖变化的结果。近年来越来越多的发现表明 ,单纯用水循环的物理过程不能解释冰盖演变的许多现象 ,而且大气CO2 变化往往领先于冰盖。揭示碳循环变化对冰盖演变的影响 ,认识生物地球化学过程在冰期旋回中的作用 ,将不同纬区对地球轨道驱动全球气候的影响区分开来 ,才有可能正确预测未来气候的演变方向。  相似文献   

Mid‐ and late‐Holocene climatic changes: a test of periodicity and solar forcing in proxy‐climate data from blanket peat bogs     

Frank M. Chambers  Jeffrey J. Blackford 《第四纪科学杂志》2001,16(4):329-338

A wide range of palaeoenvironmental evidence from the Holocene has suggested periodicities in the Earth's climate of 10s to 1000s of years. Identifying these millennial‐, century‐ and decadal periodicities, and their impacts, is critical in developing a fuller understanding of natural climate variability. Any solar‐induced climatic change needs to be distinguished from other causes of natural climate variability and from short‐term catastrophic events induced either by external or internal processes. Such events might themselves generate a periodicity, or in combination with other forcing factors they may contribute towards a periodicity (and so spuriously imply a universal and continuing periodicity in the climate record), or they may resonate with a solar‐induced periodicity. Here, evidence from peat records for periodicity in climate change over the mid to late Holocene is reviewed and this is followed by a test of the replicability of claimed periodicities using blanket peat data covering the past 2000 yr from four sites in the British Isles. Results suggest that the mires studied do go through phases of being responsive to periodic forcing factors, with ca. 200, ca. 80 and 60–50 yr wavelengths reflected in some data sets. However, the patterns shown are not consistent. This could be the result of local conditions at individual mires (human impact, sensitivity and vegetation succession) or of changes in the strength or nature of global forcing factors. Assessing a solar–mire link remains difficult because the century‐scale variations of the Sun show different intervals between solar minima, the durations of which are themselves unequal, and because the proxy‐climate data‐sets from peat profiles may themselves not be dated with sufficient precision and/or accuracy. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

陕西及我国东部区域气候变化研究   总被引：4，自引：2，他引：4  

王川  杜继稳  杜川利  袁君健 《气象》2005,31(4):22-26

利用我国500多年旱涝资料，分析陕西及其东部区域历史上发生的旱涝周期及气候突变，发现陕西旱涝存在22年、169年左右的变化周期，陕西1645年左右发生过气候突变，分别比华北地区早6～7年，比华东地区早40～50年。同时分析近50年气候资料发现，陕西及东部地区降水均存在着一定的周期变化，且变化有所差异。定义了陕北区域旱涝指数，在未来十年，陕北地区旱涝变化趋势是正常偏旱。  相似文献   

新沂地电场日变化特征及频谱分析   总被引：1，自引：1，他引：0  

张彩艳  李飞  张秀霞  杨冯威  纪加迎 《地震地磁观测与研究》2011,32(5):72-77

通过对新沂地电场平静时段资料与地磁场资料对比分析,结果显示:新沂地震台地电场变化和变化磁场密切相关,其中NS向的主体变化和地磁场H分量的变化准同步;EW向主体变化虽与地磁场H分量变化有相同之处,但其变化形态与其反向,且不尽相同.运用快速傅里叶变换进行频谱分析,发现:新沂地电场NS向和EW向与地磁场H分量的优势周期存在不...  相似文献   

基于小波分析的长江和黄河源区汛期、枯水期径流特征   总被引：9，自引：2，他引：7  

邴龙飞  邵全琴  刘纪远  赵志平 《地理科学》2011,31(2):232-238

利用db3小波分解和重构1965~2007年长江源沱沱河站、直门达站和黄河源吉迈站、唐乃亥站春汛期、夏汛期和枯水期流量数据,除沱沱河外,各站春汛期、夏汛期和枯水期流量皆呈下降趋势,各站流量下降速率依次为夏汛期>春汛期>枯水期。沱沱河站多年流量呈增加趋势,夏汛期变化速率依然高于春汛期。应用复Morlet小波分别分析上述4个水文站实测流量的周期特征。黄河源总体存在11~12a波动周期;长江源春汛期有4~6a波动周期,夏汛期有13~14a波动周期。不同流域春汛期、夏汛期和枯水期主周期分布规律不同。  相似文献   

基于小波理论的沉降监测数据序列分析   总被引：4，自引：0，他引：4  

王坚  高井祥  郑南山 《大地测量与地球动力学》2005,25(4):91-95

介绍了基于小波理论的沉降数据分析的理论背景、内容及实现方法。结合兖州地区某矿的沉降实测资料,研究了沉降数据降噪、沉降剧烈程度探测以及沉降数据中周期性识别3个方面的内容。  相似文献   

Timing and prediction of climate change and hydrological impacts: periodicity in natural variations     

Y. Jeffrey Yang  James A. Goodrich 《Environmental Geology》2009,57(5):1065-1078

Hydrological impacts from climate change are of principal interest to water resource policy-makers and practicing engineers. Predictive climatic models have been extensively investigated to quantify the impacts. Palaeoclmatic investigations, on the other hand, show unequivocal and strong periodicity of climate variations in proxy evidence. Yet how to use the periodicity in future hydroclimatic timing and forecasting has received less attention. This paper examines the periodicity in Pleistocene–Holocene glacial–interglacial events and in modern precipitation records, and discusses a way in which the periodicity is used for hydroclimatic predictions. The analysis, based on published CO₂, ΔT (δ²H) and δ¹⁸O proxy data of polar ice cores and deep oceanic benthic fossils, shows a periodicity in a ~100, ~40 or 25 kyear duration consistent with Milankovitch orbital regulations during the glacial–interglacial periods. On a fine time scale, millennium and multi-decadal periodicity is observed in high-resolution proxy variations of Greenland ice cores and in instrumental precipitation records of the contiguous USA. A basic periodicity of decadal and multi-decadal changes in ~20 and ~10–15 year duration is apparent in wavelet frequency analysis of both ice core proxy and precipitation data. While the kyear-scale periodicity is found of global prevalence, the millennium and decadal variations vary in space and are region-specific. Based on these findings, a generalized time-downscaling hierarchy of periodicity is proposed as a potential approach for timing and forecasting future hydroclimatic conditions at a resolution relevant to the water resources engineering and management.  相似文献