五大连池地区矿泉水同位素研究

本文通过对五大连池地区矿泉水采样分析,进行同位素测年研究,提出该区矿泉水主要来于大气降水。原生冷矿水和次生冷矿水中的放射性碳都已经历了万年以上的蜕变,说明该区矿泉水地下迳流条件极差,其冷矿水形成时间长,资源有限,因此应有计划地合理开采利用,防止过量滥采而导致矿水资源枯竭。     

黔北镇远地区三丘田剖面寒武系明心寺组上段滨岸相沉积特征及其地质意义

沉积环境分析是古地理重建的核心内容,黔北地区寒武系明心寺组沉积环境研究存在较大争议,以致对中上扬子地区明心寺组沉积期古地理格局的认识不能统一。选取寒武系明心寺组发育齐全、出露良好的黔北镇远地区三丘田剖面为研究对象,通过野外剖面观察、室内薄片鉴定及碎屑岩粒度分析等方法对三丘田剖面明心寺组岩石学特征、沉积构造、沉积演化序列、沉积相类型进行了详细分析。结果表明:黔北镇远地区三丘田剖面寒武系明心寺组上段发育大套的石英粉-细砂岩,沉积构造以低角度冲洗交错层理为主,碎屑颗粒的成分和结构成熟度均较高;三丘田剖面明心寺组上段砂岩以双次跳跃组分为主,悬浮组分含量较少,纵向剖面自下而上显示为浅水陆棚→临滨→前滨→后滨演化序列,呈典型的陆棚相向滨岸相变化。综上所述,黔北镇远地区三丘田剖面寒武系明心寺组上段的沉积相为滨岸相。黔北镇远地区明心寺组滨岸相沉积的出现,指示了黔北地区区域上重新认识明心寺组沉积相的必要性,将直接影响对黔北地区乃至中上扬子地区寒武纪古地理格局及其大地构造背景的认识。     

达州市气候变化的特征分析

基于达县测站1961-2007年的地面常规观测资料,主要采用小波分析,结合趋势分析、功率谱分析等方法分析了达州市47年来近地表气温、降水随时间的变化特征.结果表明,达州市近50年来冬季(年平均)地表气温变暖幅度约为0.9℃(0.4℃),增温速率接近0.18℃/10a(0.08℃/10a),低于全球的升温幅度.利用小波分析方法研究冬季气温的周期性发现,达州市的冬季气温存在着明显的8年和50年以上的特征时间尺度和周期性振荡.通过对降水的趋势分析发现,夏季降水的增加幅度比年均显著.小波分析方法结果显示达州市的夏季降水同样存在50年以上的特征时间尺度,但在小尺度上20世纪70年代末前后存在不同的变化特征.     

Adding the missing third and fourth dimensions to trajectory analysis in carbonate systems

We developed a seismic geomorphology-based procedure to enhance traditional trajectory analysis with the ability to visualize and quantify lateral variability along carbonate prograding-margin types (ramps and rimmed shelves) in 3D and 4D. This quantitative approach analysed the shelf break geometric evolution of the Oligo-Miocene carbonate clinoform system in the Browse Basin and delineated the feedback between antecedent topography and carbonate system response as controlling factor on shelf break rugosity. Our geometrical analysis identified a systematic shift in the large-scale average shelf break strike direction over a transect of 10 km from 62° to 55° in the Oligo-Miocene interval of the Browse Basin, which is likely controlled by far-field allogenic forcing from the Timor Trough collision zone. Plotting of 3D shelf break trajectories represents a convenient way to visualize the lateral variability in shelf break evolution. Shelf break trajectories that indicate contemporaneous along-strike progradation and retrogradation correlate with phases of autogenic slope system re-organization and may be a proxy for morphological stability of the shelf break. Shelf break rugosity and shelf break trajectory rugosity are not inherited parameters and antecedent topography does not dictate long-term differential movement of the shelf margin through successive depositional sequences. The autogenic carbonate system response to antecedent topography smooths high-rugosity areas by filling accommodation and maintains a relatively constant shelf break rugosity of ~150 m. Color-coding of the vertical component in the shelf break trajectory captures the creation and filling of accommodation, and highlights areas of the transect that are likely to yield inconsistent 2D sequence stratigraphic interpretations.     

Measuring place-based accessibility under travel time uncertainty

Travel time uncertainty has significant impacts on individual activity-travel scheduling, but at present these impacts have not been considered in most accessibility studies. In this paper, an accessibility evaluation framework is proposed for urban areas with uncertain travel times. A reliable space-time service region (RSTR) model is introduced to represent the space-time service region of a facility under travel time uncertainty. Based on the RSTR model, four reliable place-based accessibility measures are proposed to evaluate accessibility to urban services by incorporating the effects of travel time reliability. To demonstrate the applicability of the proposed framework, a case study using large-scale taxi tracking data is carried out. The results of the case study indicate that the proposed accessibility measures can evaluate large-scale place-based accessibility well in urban areas with uncertain travel times. Conventional place-based accessibility indicators ignoring travel time reliability can significantly overestimate the accessibility to urban services.     

泥河水库春季水-气界面二氧化碳通量与其影响因子的相关性分析

利用静态箱-气相色谱法对泥河水库春季水-气界面二氧化碳通量值进行连续24h观测,对其变化趋势及影响因素加以分析。结果表明:泥河水库24h均为大气CO2的源,其碳通量均值为26.50mg/(m2·h),全天源的极大值出现在1∶00为32.38mg/(m2·h),源的极小值出现在13∶00为20.15mg/(m2·h)。在春季影响泥河水库水-气界面CO2通量变化的主要因素是气温、叶绿素和风速,相关系数分别为0.671、0.625、0.253。结论:水库水-气界面CO2通量的变化是多种因素共同作用的结果,春季水库是大气CO2主要碳源之一。     

高空基本天气系统类别自动识别与沙尘暴系统识别试验

针对大气环流形势,从天气系统的定义出发,面向气象业务MICAPS格点文件数据格式,在矢量旋转追踪法等值线分析的基础上,有序提取等值线的控制点。经过滤波、查找各等值线特性点、剔除异常点等处理,获取沙尘暴高空影响天气系统的基本节点。利用多种特征参量设计了方便可行的算法,完成了槽脊系统的数据构建、分析并确定其地理位置。通过对数据场数值结构分析,建立了确定闭合天气系统位置及其高、低性质的算法。使用Visual Basic语言,开发了相应的沙尘暴高空基本影响天气系统类别自动分析软件,为实现概念模型自动预报系统、提高沙尘暴业务预报现代化水平打下了基础。     

喜马拉雅山北坡卡鲁雄曲径流与气候变化

以冰川融水补给为主的喜马拉雅山北坡的卡鲁雄曲流域,近20年平均气温以0.34 ^oC/10a的趋势上升,高于西藏年均温0.26 ^oC/10a的增长率,更是明显高于全国和全球气温的增长率,且极端最高温都出现在20世纪90年代。后10年气温 (1994~2003年) 比前十年 (1983~1993年) 升高0.5 ^oC,径流量增加了26%;不同月份径流增加强度不同,10~2月增加了44%,7~9月增加了27%,3~6月增加了24%。径流对气候变化的响应最灵敏 (一年中有8个月的增加趋势通过了α = 0.05的显著性检验),尤其是秋冬季的径流 (增加趋势超过α = 0.01的显著性检验)。受冰川消融和季风影响,不同时期的径流有不同的影响因素,但存在共性,即气温对径流起着积极主导作用,而降水对径流的影响具有不确定性,即正负双面效应。     

Assessment on variability of extreme climate events for the Upper Thames River basin in Canada

Climate change may affect magnitude and frequency of regional extreme events with possibility of serious impacts on the existing infrastructure systems. This study investigates how the current spatial and temporal variations of extreme events are affected by climate change in the Upper Thames River basin, Ontario, Canada. A weather generator model is implemented to obtain daily time series of three climate variables for two future climate scenarios. The daily time series are disaggregated into hourly to capture characteristics of intense and rapidly changing storms. The maximum annual precipitation events for five short durations, 6‐, 12‐, 24‐, 48‐, and 72‐h durations, at each station are extracted from the generated hourly data. The frequency and seasonality analyses are conducted to investigate the temporal and spatial variability of extreme precipitation events corresponding to each duration. In addition, this study investigates the impacts of increase in temperature using reliability, resilience, and vulnerability. The results indicate that the extreme precipitation events under climate change will occur earlier than in the past. In addition, episodes of extremely high temperature may last longer up to 19·7% than under the no‐change climate scenario. This study points out that the revision of the design storms (e.g. 100‐ or 250‐year return period) is warranted for the west and the south east region of the basin. Copyright © 2011 John Wiley & Sons, Ltd.