Decoupling of stalagmite-derived Asian summer monsoon records from North Atlantic temperature change during marine oxygen isotope stage 5d

The Asian monsoon is an important component of the global climate system. Seasonal variations in wind, rainfall, and temperature associated with the Asian monsoon systems affect a vast expanse of tropical and subtropical Asia. Speleothem-derived summer monsoon variation in East Asia was previously found to be closely associated with millennial-scale change in temperature in the North Atlantic region between 75 and 10 ka. New evidence recovered from East Asia, however, suggests that the teleconnection between summer monsoon in East Asia and temperature change in the North Atlantic region may have significantly reduced during 120 to ~ 110 ka, a period directly after the full last interglaciation and corresponding roughly to marine oxygen isotope stage 5d. This reduction may be due to the low ice volume in the North Hemisphere at that time, which makes the millennial-scale change in temperature in the North Atlantic region less effective in influencing the Asian summer monsoon. This is important for investigating the mechanisms controlling the Asian summer monsoon and the paleoclimatic teleconnection between East Asia and the North Atlantic region, and for predicting monsoon-associated precipitation in East Asia under a global-warming trend.     

北京西山南部构造序列初探

笔者利用解析构造学方法,初步确定了本区的构造序列。它反映了从下部构造层次到上部构造层次的系统变化,从早期的层内固态流变经压扁作用和弯曲作用到后期的剪切破裂变形过程中岩石韧性递减的系统演变。由于岩浆侵入而使其间增加了一个韧性再增强的变形期。     

Some Investigations on Early Organization of Karst System

Karstsystemsaredynamicsystemsinspontaneoussuc-cessiveevolutionarisenfromtheinteractionbetweenwaterflowandsolub1emedium-Thecircu1ationofwaterprogres-sivelyandcontinuouslymodifiesthestructureofmediumfield,consequentlymodifyingthehydraulicbehaviorofthesystemitself'Someauthors(e.g.,FordandWilliams,l989)believedthatmostcarbonaterockswillbecomeconduitaquifersifsurficialerosionisnegligibleorsufficienttimeisgiven.Karstsystemsfailtodevelopconnectedconduiteitherduetoincompleteextension(becauseinsuffici…     

A new theoretical solution of the effect of atmospheric pressure on water level

Based on the partial differential equation governing the effect of atmospheric pressure on water level of confined well, deriving the boundary condition and considering the seepage water between well and aquifer, the author obtained the analytical solution of water level change in time domain under the action of an atmospheric pressure history with the Laplace transform method. This solution is composed of two terms:stable and retarded terms. The stable term is the multiplication of barometric efficiency and simultaneous atmospheric pressure, and it implies the value of water level after infinite time when the atmospheric pressure is a constant from the time in question. The retarded term is the transient process due to the time lag of water exchange between well and aquifer. From the solution, it is obtained that the interference of atmospheric pressure on water level is the integral superimposition of the contribution of all atmospheric pressure changes before the time in question. So that, we further found out the response function of pulsive atmospheric pressure history. Calculation shows: (1) The pulsive response function starts from zero and tends to a steady value, which is proportional to the barometric efficiency, when the time tends to infinity; (2) The retarded time depends on the mechanical property of aquifer and the radius of well. The larger the seepage coefficient, the smaller the radius of well and the thicker the aquifer, then the shorter the retarded time gets. This solution can be used as the theoretical basis for further analysis of the atmospheric effect and practical correcting method in the future.     

潟湖潮汐通道水力特性与治理

综合论述了潟湖潮汐通道口门之流速、断面面积、通道长度、延时角和饱满系数之间的关系,以及沿岸漂沙对口门的影响。对不同类型的潟湖潮汐通道,提出了中潮位射流导流堤、口门复式断面和通道分汊等治理方法及其通道口门相关尺度的具体计算。     

Measurement of six degree-of-freedom ground motion by using eight accelerometers

A new integrated measuring system with eight force-balance accelerometers is proposed to obtain a direct measurement of six degree-of freedom （DOF） ground motions, including three rotational and three actual translational acceleration components without gyroscopes. In the proposed measuring system, the relationship between the output from eight force-balance accelerometer and the six DOF motion of the measuring system under an earthquake are described by differential equations. These equations are derived from the positions and directions of the eight force-balance accelerometers in the measuring system. The third-order Runge-Kutta algorithm is used to guarantee the accuracy of the numerical calculation. All the algorithms used to compute the six DOF components of the ground motion are implemented in a real-time in Digital Signal Processor （DSP）. The distortion of the measured results caused by position and direction errors of the accelerometers in the measuring system are reduced by multiplying a compensation coefficient C to the output and subtracting static zero drift from the measured results, respectively.     

景洪5.1,5.5级地震地下水动态预报启示

本动态追踪了１９９７年景兴５．１、５．５级中强震的孕震－发震的整个过程,异常阶段属性清楚,异常发展层次分明,有动态感,过程清晰完整,表明中强地震亦有孕震过程。震前异常阶段的属性和异常的准同步是地震预测的主要依据。跟踪各类异常,掌握地震孕育发展的进程,把握时机有可能预报一些地震。本是“八五”、“九五”攻关成果运用的结果之一。     

新疆河流年径流量对夏季0C层高度变化的响应

According to climate features and river runoff conditions, Xinjiang could be divided into three research areas: The Altay-Tacheng region, the Tianshan Mountain region and the northern slope of the Kunlun Mountains. Utilizing daily observations from 12 sounding stations and the annual runoff dataset from 34 hydrographical stations in Xinjiang for the period 1960-2002, the variance of the summertime 0℃ level height and the changing trends of river runoff are analyzed both qualitatively and quantitatively, through trend contrast of curves processed by a 5-point smoothing procedure and linear correlation. The variance of the summertime 0℃ level height in Xinjiang correlates well with that of the annual river runoff,especially since the early 1990s, but it differs from region to region, with both the average height of the 0℃ level and runoff quantity significantly increasing over time in the Altay-Tacheng and Tianshan Mountain regions but decreasing on the northern slope of the Kunlun Mountains. The correlation holds for the whole of Xinjiang as well as the three individual regions, with a 0.01 significance level. This indicates that in recent years, climate change in Xinjiang has affected not only the surface layer but also the upper levels of the atmosphere, and this raising and lowering of the summertime 0℃ level has a direct impact on the warming and wetting process in Xinjiang and the amount of river runoff. Warming due to climate change increases the height of the 0℃ level, but also speeds up, ice-snow melting in mountain regions, which in turn increases river runoff, leading to a season of plentiful water instead of the more normal low flow period.     

变暖背景下陕西极端气候事件变化分析

利用1961-2010年陕西省78个气象观测站的逐日最高温度、最低温度、平均温度以及日降水量资料,采用趋势分析方法对该地区极端气候事件的变化进行了分析。结果表明:①近50 a来陕西降水极端事件没有显著的增减变化趋势,但存在明显的阶段性。②近50 a来区域严重干燥事件在显著增加而严重湿润事件趋于减少,2000年以后严重干湿事件均偏多,区域降水有向不均衡、极端化发展的趋势。③区域年极端高（低）温事件在近50 a来呈现显著的增加（减少）趋势,其空间分布具有较好的一致性。极端温度事件的变化在各季节存在差异,冬、春季变暖的趋势比较显著。在显著变暖的20世纪90年代以后,相对于降水极端事件,温度极端事件显现地更为突出。     

基于探地雷达的土体构型无损探测方法研究

土体构型对土壤水分、溶质运移过程和作物成长等有显著影响,常规测量采用人工挖土壤剖面取样、实验室化验分析等方法,其周期长效率低。针对以上问题,以探地雷达波形及其图像为研究对象,从检测土体构型的属性(层次、层厚、土质)入手,提出了一种使用探地雷达快速测量土壤土体构型的无损探测方法。基于探地雷达波形图像的纵向梯度信息能够反应土壤分层,采用包络检波法从探地雷达回波中提取包络信号,利用Hilbert分析其瞬时相位来确定分层位置;鉴于土壤介电常数与雷达回波振幅的关系,采用探地雷达回波振幅反演各层介电常数,由介电常数推算雷达波在土壤中的传播速度,以此得到土壤剖面各层厚度;根据探地雷达波形图的图像噪声与土壤砂壤比之间存在定量关系,提出采用主成分分析方法对每一层土质的图像进行噪声估计求得各层土壤的含砂量,结合支持向量机进而辨识各层土壤土质。建立涵盖地域信息、土壤指标、探测信息、图像多特征融合信息的土体构型知识库,并编制快速识别土壤土体构型的信息系统,在内蒙古自治区呼和浩特市周边2个试验基地、6个采样点、4类土壤土体构型使用该方法进行野外探测验证。研究表明:在上述地区地表以下1 m范围内的土体构型识别正确...