基于Argo浮标和EOF建立区域海水三维声速场的方法

本文提出了一种利用Argo浮标数据和经验正交函数(EOF)建立区域海水三维声速场的方法。利用局部区域内的Argo观测数据对该方法进行了验证,利用少量Argo浮标数据即可建立精度较高的三维海水声速场模型,预测区域内任意剖面的中误差在1 m/s左右。     

城市轨道交通的隧道结构断面测量方法研究

本文就城市轨道交通的隧道结构断面的测量方法进行了研究,提出了一种采用地面激光扫描仪技术的测量方法,研究了此方法的主要工作流程、基本原理和方法。把此方法用到天津城市轨道交通二号线工程,使用地面激光扫描仪测量隧道的结构断面,其精度和效率较常规仪器和方法都有显著提高。     

Medium time-scale behaviour of adjacent embayed beaches: Influence of low energy external forcing

Medium term (decadal) beach profile response to external forcing was assessed on two adjacent embayed beaches (North and South Sands) in Pembrokeshire, West Wales. Both have contrasting physical and geological characteristics: a headland bay backed by dunes and a constrained embayment backed by geological promontories, promenades, walls and rock revetments. Paired t-tests showed significant changes at all cross-shore profile locations (95% confidence), with south and north shores respectively exhibiting falling and rising beach levels. South to north sediment transport was revealed by volumetric variation (r = 0.83), and longshore sediment distribution (r = 0.91). North Beach level variations lagged behind South Beach by one-year (r = 0.85). A reduction in high wind speed frequency, coincidental to spring tides, was correlated with falling South Beach levels (r = 0.87) and rising North Beach levels (r = −0.92). Heavily refracted Atlantic swells also have contrasting effects on these systems. Multiple regression models applied to beach level change for both systems showed high correlation (R² = 0.93 and 0.85 respectively), suggesting that swell wave period and strong north-westerly winds that occur during high spring tides had cumulative effects. Furthermore, variations in the North Atlantic Oscillation (NAO) index were correlated to cumulative changes in mean sea level, wind wave height and south-westerly winds (R² = 0.75). While NAO variations were linked to variations in South Beach morphology, it was insignificant on North Beach (r = −0.72 and −0.14 respectively). Cross-correlation analyses showed that North Beach morphological changes lagged behind NAO Index variation by one-year with much improved correlation (r = 0.77). A similar scenario existed when comparing Mean Sea level and beach level differences (r = −0.54 and −0.32 respectively). Similar behaviour should be exhibited at other worldwide embayments, and it is suggested that this work is repeated to establish specific responses, to will underpin intervention or no active intervention strategies.     

应用多种探测资料对比分析两次突发性局地强降水

为了做好突发性局地暴雨的临近预报和预警,利用常规天气图、BJ-ANC系统的北京区域雷达拼图和VDRAS风场、地面自动站、风廓线雷达的水平风垂直廓线、卫星云图等多种探测资料,对2009年7月13日和2008年8月14日北京城区的两次突发性强对流局地暴雨天气的影响系统和中尺度系统进行了对比分析,提炼了城区突发对流性暴雨预报预警的预报着眼点。分析表明：两个个例在水汽输送条件、中低层的动力条件、冷空气侵入等方面有有利的天气尺度条件;暴雨之前卫星云图上介于南北两个系统之间的晴空区、对流系统的发生发展与1 km以下的中尺度辐合中心的联系等方面有相似之处;而在雷达回波的移向移速、各层VDRAS风场配置及风廓线雷达资料中水平风垂直廓线结构等方面有差异。通过分析研究,进一步提高了运用高时空分辨率资料作短时突发性对流性暴雨的预报能力,这对于主汛期的预报和服务工作有十分重要的作用。     

声速误差对圆走航水下控制点定位影响分析

针对圆走航定位声速剖面测量不准确引起水下控制点坐标解算存在偏差的问题,首先介绍了声速不确定性对测距误差的影响,并将声速测距误差分成背景声速剖面误差、随机误差、测距误差长周期项和测距误差短周期项,再通过分析坐标改正数方程得到不同声速测距误差项对控制点坐标定位的影响。最后,设计2组仿真实验对该理论进行验证,实验结果与理论推导的结论一致。     

An experimental study of the water transfer through confined compacted GMZ bentonite

GMZ bentonite has been considered as a possible material for engineered barrier in the Chinese program of nuclear waste disposal at great depth. In the present work, the hydraulic conductivity of this bentonite was determined by simultaneous profile method. A specific infiltration cell equipped with five resistive relative humidity probes was designed for this purpose. The water retention properties were studied under both confined and unconfined conditions; the results show that at high suctions (> 4 MPa) the water retention capacity is independent of the confining condition, and by contrast, at low suctions (< 4 MPa) the confined condition resulted in significant low water retention. Furthermore, the microstructure was investigated at mercury intrusion porosimetry (MIP) and Environmental Scanning Electron Microscope (ESEM) in different states: on oven-dried powder, bentonite slurry, as-compacted and wetted samples. It has been observed that the soil powder is constituted of aggregates of various sizes; these aggregates are destroyed by full saturation at a water content equal to the liquid limit; compaction at the initial water content of 11–12% and a dry density of 1.7–1.75 Mg/m³ led to a microstructure characterized by a dense assembly of relatively well preserved aggregates; saturation of the compacted sample under constant volume condition defined a non-homogeneous microstructure with the presence of well preserved aggregates. This non-homogeneous microstructure would be due to the non uniform distribution of the generated swelling pressure within the soil sample upon wetting. The hydraulic conductivity determined has been found decreasing first and then increasing with suction decrease from the initial value of about 80 MPa to zero; the decrease can be attributed to the large pore clogging due to soft gel creation by exfoliation process, as observed at ESEM.     

Long-term and short-term vertical velocity profiles across the forearc in the NE Japan subduction zone

We estimated the long-term vertical velocity profile across the northeastern Japan forearc by using the height distribution of late Quaternary marine and fluvial terraces, and we correlated the ages of the two marine terraces with marine isotope stages (MIS) 5.5 and 5.3 or 5.1 by cryptotephra stratigraphy. The uplift rate, estimated as 0.11-0.19 m ka^− 1 from the relative heights between the terrace surfaces and eustatic sea levels, was nearly equal to, or slightly slower than, the uplift rate farther inland (0.15-0.19 m ka^− 1), as determined from the relative heights of fill terrace surfaces. In contrast, the short-term vertical velocity profile, obtained from GPS observations, showed that the forearc is currently subsiding at a maximum rate of 5.4 ± 0.4 mm yr^− 1. Thus, the current short-term (geodetic) subsidence does not reflect long-term (geological) tectonic movement. Short-term vertical deformation is probably driven by subduction erosion or elastic deformation caused by interplate coupling, or both. However, long-term uplift is probably due not to moment release on the mega-thrust but to crustal thickening.     

从地震看重力侧向滑动构造与油气——兼论马西逆同生断层不是反转构造

重力构造作用分为侧向运动和垂向运动两大类。以渤海湾盆地及准噶尔盆地中的构造为实例,介绍了重力侧向滑动的六种构造样式,包括滑动断阶、逆牵引背斜、地层补偿堑背斜、滑落背斜、滑覆构造(逆同生断层)、推滑覆构造等。对其形成背景和形成机制逐一进行了分析,指明了这些构造的含油气潜力。这六种构造样式均可形成有利的油气圈闭,在勘探中应予以足够的重视。特别指出冀中坳陷马西逆同生断层不属于反转构造,而是由重力作用所产生的滑动推挤所致,为一典型的滑覆构造。     

乌鲁木齐河源1号冰川冰芯剖面物理特征及其形成机理研究

冰芯中的化学成分,记录了古环境和古气候的诸多信息,已有广泛研究.而冰芯剖面的物理特征,由冰芯形成时的水热条件和冰川运动变质作用所决定,同样记录了气候、环境和冰川运动的诸多信息.根据在乌鲁木齐河源1号冰川钻取的6根冰芯的详尽资料,结合冰流模式对冰芯冰龄的估算,分析研究了不同冰川带冰芯剖面的物理特征、形成机理和相应的水热条件.结果表明:积累区冰芯以粒雪一冰交替的原生沉积层为主,受冰川流动引起的动力变质作用影响较小,与该区成冰环境和冰川温度密切相关;平衡线附近的冰芯4.3 m以上主要是由渗浸冻结冰组成的原生沉积层,与附近的成冰环境相吻合,以下部分主要是经过动力变质作用的冰体,源于冰川上部的积累物;消融区冰芯主要由冰川上部下流的冰川冰组成,模拟显示该区冰芯冰龄较长,受局部成冰环境的影响很小.通过对不同区域冰芯特征比较,发现各成冰带的冰芯组成及污化层差别较大;在东、西支冰川同时期冰芯剖面的对比中,发现海拔相近点冰芯剖面组构相近,说明通过冰芯资料来探讨冰川内部特征以及该区域气候环境演变历史等较具代表性.     

乌鲁木齐市城区和郊区近地层风速廓线

利用乌鲁木齐市5座100 m气象塔10层风速观测资料,分析了乌鲁木齐市城区和郊区近地层风速季节变化和日变化特征。结果表明：（1）乌鲁木齐市风速最大值出现在14：00-16：00,最小值多在夜间或上午。冬季风速最小、夏季最大;冬季风速始终处于较为稳定、有微小波动的低值区;夏季风速表现出一定的变化趋势。（2）夏季风速在一年里波动最大,随地势降低波动减小,南郊最大（1.5~6.4 m·s^-1）,北郊最小（1.3~4.6 m·s^-1）;秋季和春季风速波动次之;冬季风速波动最小,南郊最大（1.3~4.6 m·s^-1）,北郊最小（0.7~2 m·s^-1）。（3）近地层100 m内城区和北郊风速随高度变化较小,冬季基本为1~2 m·s^-1,而南郊风速随高度增加变化幅度最大,从1 m·s^-1增加到4 m·s^-1以上;愈近地面,城区与郊区风速相差愈大,近地面城区平均风速明显低于郊区,春季、夏季、秋季和冬季分别低5%~32%、8%~30%、15%~37%、14%~48%。（4）近地层风速廓线在近中性层结时一般符合对数风速廓线模式,对数律显著性不强的时段主要在正午前后。