高分辨率遥感植被分类研究

以南京市区的植被覆盖为研究对象,基于IKONOS遥感影像,采用决策树分类算法,根据各种植被光谱特征建立知识库,提出基于光谱信息的植被分类方法,继而结合高分辨率影像特有的纹理特征引进局部一致性指数对该方法进行改进,提出结合纹理信息的高分辨率遥感植被分类方法,分类总体精度从仅利用光谱信息的83.16%显著提高到91.89%,Kappa系数达到0.8886。采用Quickbird遥感影像对该方法进行验证,分类总体精度为91.94%,Kappa系数为0.8783,表明该植被分类方法能有效地对植被进行分类与识别,精度较高,且对于不同数据源的植被分类具有一定的普适性,为实现植被的自动化提取提供了理论依据和有效的方法途径。     

杭州湾地区晚第四纪浅层生物气藏盖层物性封闭特征

杭州湾地区晚第四纪浅层生物气藏盖层存在孔隙水压力封闭和烃浓度封闭机理,但其是否存在物性封闭机理目前尚存在较大争议.研究区浅层生物气藏盖层埋藏浅、时代新、结构松散,对其物性封闭能力的评价不能直接套用深部成岩盖层的评价参数和方法.通过变水头渗透实验测定盖层和储层样品渗透率数值,以渗透率作为评价浅层生物气盖层物性封闭能力的参数,对研究区浅层生物气藏盖层的物性封闭特征及其影响因素进行了详细研究.结果表明盖层渗透率数值比储层小3个数量级,具有较强的物性封闭能力,有利于浅层生物气藏的保存.研究区浅层生物气盖层物性封闭能力的影响因素包括黏土含量及黏土矿物成分、含水饱和度和盖层厚度,黏土含量及黏土矿物成分对盖层物性封闭能力起决定性作用,较高的含水饱和度促进了盖层物性封闭能力的增强,盖层厚度对物性封闭能力起到了极为重要的补偿作用.     

西藏措勤盆地油气成藏条件分析

根据野外地质调查资料,对措勤盆地的油气生成、储集、运移、圈闭等条件进行了分析;认为盆地中发育的主要烃源岩有 7套,岩石类型主要为灰岩,储集层主要为各种灰岩和砂岩;有利的生储盖组合型式主要为自生自储自盖式及互层式生储盖组合;野外调查发现的油气苗及微观包裹体的研究均证实了盆地内油气运移过程的发生;推测盆地内主要的圈闭及油气藏类型为背斜及断层遮挡油气藏,K₂-R构造层主要发育完整的背斜油气藏,J-K ₁构造层主要发育被断层复杂化的背斜油气藏;建议将主要目的层放在较新的构造层中。     

一次副高影响下的局地强风暴触发及维持机制探析

利用自动站观测资料、FY-2G卫星资料和多普勒雷达等资料,对发生在副热带高压影响下的重庆局地强风暴过程进行了观测和数值模拟分析,探讨了其中尺度对流系统(MCS)演变,抬升触发和维持机制。结果表明:(1)在副热带高压影响下,重庆处于高温、高湿气团中,大气层结极不稳定;(2)此次局地风暴抬升触发的关键因子是地面附近浅薄边界层中尺度辐合线,辐合线由川渝盆地中西部MCS的雷暴高压与重庆地面热低压共同作用形成;(3)中尺度辐合线触发的对流风暴形成小范围冷池出流与环境风场形成新的辐合线,加强对流风暴发展,并再次触发新的对流单体。承载层平均风为偏南风,使得对流单体向北缓慢移动,冷池出流和边界层辐合线共同作用使得风暴单体向西向北传播和长时间维持。     

渤海西岸偏东风对天津局地大暴雨的影响分析

利用加密自动气象站、多普勒天气雷达和风廓线雷达等高时空分辨率资料,分析2017年7月6日天津一次局地大暴雨过程的中尺度对流系统发展演变特征,讨论渤海西岸边界层偏东风的垂直结构、温湿特性及其对局地大暴雨的作用。结果表明:局地大暴雨由两个暖区中尺度对流系统和一个低涡切变线系统造成,偏东风作用下的暖区第二个中尺度对流系统主导了局地大暴雨的形成。大暴雨中心两侧的温湿特征均呈“东高西低”分布,偏东气流具有暖湿特性,为暖区对流暴雨的发生发展提供了有利的环境条件。由于海陆地形差异,偏东气流自渤海向内陆推进过程中呈现明显的风速扰动特征,不仅导致水汽辐合,同时有利于上升运动发展。其中,0.6 km以下偏东风的中尺度扰动对局地大暴雨的触发和维持起重要作用,风速辐合强迫产生的上升气流是γ中尺度对流单体的重要触发机制,而强降水冷池出流与不断增强的暖湿偏东人流相互作用形成地面中尺度辐合线,使对流系统得以稳定维持,40 dBz以上强降水回波持续近3 h,平均6 min降水量达6.8 mm。此外,局地大暴雨的雨强变化与东风急流波动关系密切,急流的建立、发展、减弱和消失分别对应降水的陡增、峰值、减弱和陡降四个阶段。     

山东半岛北岸跨锋面物质输运对辽东半岛东岸沉积有机质含量及来源的影响

深入理解气候变化影响下海洋动力过程变化及其多重环境效应,是了解海岸海洋系统未来演化趋势的重要途径。因此,本文在辽东半岛东岸泥质区取柱状样一根,通过沉积物粒度、TOC/TN含量、δ13C以及δ15N等指标,分析气候变化下山东半岛北岸跨锋面物质输运强度变化,及其对辽东半岛东岸泥质区沉积有机质含量和来源的影响。结果表明,高海面时期以来,山东半岛北岸跨锋面物质输运可分为两个变化阶段：6.5～2.9 cal ka BP,其强度随冬季风和黄海暖流的不断减弱而减弱;2.9 cal ka BP至今,由于冬季风较弱而黄海暖流总体强盛,其强度随黄海暖流的波动而呈现4段式的复杂变化。此外,辽东半岛东岸泥质区陆源和海源有机质含量与其强度呈正相关,相应于跨锋面物质输运强度的变化,6.5～2.9 cal ka BP期间,陆源和海源有机质含量持续减少,而2.9 cal ka BP至今则呈现复杂的4段式变化。总体上看,自6.5 cal ka BP以来,陆源有机质贡献率不断下降而海源有机质贡献率逐渐上升。     

Fair and equitable sharing of benefits from the utilization of marine genetic resources in areas beyond national jurisdiction: Bridging the gaps between science and policy

Marine genetic resources are a subject of a growing body of research and development activities, as demonstrated by the abundance of marine patented genes reported in GenBank. Given the lack of a comprehensive legal regime for the management of marine genetic resources in areas beyond national jurisdiction, the General Assembly of the United Nations met in 2006 to discuss whether there are regulatory or governance gaps and how to address them. Besides the crystallization of the different political positions, the process is now advancing towards making a decision about whether to develop an international instrument under the United Nations Convention on the Law of the Sea (UNCLOS) for the conservation and sustainable use of marine biological diversity, within which the regulation of access to genetic resources and the sharing of benefits from their utilization has emerged as an in-dissociable issue. In order to propose concrete options to be considered for the establishment of a legal framework addressing these issues, policy-makers need to better understand the feasibility, the costs and the modalities of scientific activities undertaken, together with the actual level of commercialization of new products. They also need to be aware of the already advanced practices in place within the scientific community, especially regarding sharing of non-monetary benefits. This paper particularly highlights and discusses practical scenarios to advance in the international process, based on the approaches adopted in other regional and international regimes for the management of genetic resources and on the best practices developed within the scientific community.     

云GIS应用于数字城市设计与实现

针对数字城市地理空间框架建设中存在的问题,本文研究和设计实现云环境下GIS应用,构建云GIS实验环境,和传统GIS环境实验结果对比,得出结论:云GIS在基础设施框架、提高硬件资源利用率以及提供高性能的服务方面具有诸多优势,能解决现在数字城市项目建设中存在的问题,值得研究和应用推广。     

Evaluating channel response to an extreme sedimentation event in the context of historical range of variability: Upper Colorado River,USA

In May 2003, a breach in a large irrigation ditch within Rocky Mountain National Park (RMNP) initiated a debris flow that entered Lulu Creek and the Colorado River, where 36 000 m³ of sediment substantially altered channel forms and processes. We present a proof of concept to understand whether the 2003 disturbance is within the historical range of variability (HRV), and whether the recovery potential of the system is sufficient to adapt to the disturbance. Flow and sediment regimes, and channel morphology and stability were monitored on Lulu Creek and the Colorado River from 2004 to 2011. Dominant channel response following the debris flow within Lulu Creek included step development, bed armoring, and channel widening. Step height‐to‐length ratios (H/L) for three reaches on Lulu Creek are outside the HRV of reference channels, with one reach approaching reference conditions. Erosion of approximately 23% of the debris fan volume occurred as a result of the long duration 2011 peak flow. Sediment within the Lulu Creek fan will persist for ~30–190 years, assuming current maximum and mean removal rates. Planform changes on the Colorado River since the debris flow include an increase in single‐thread geometries, with braided reaches where bar deposition occurred. Bedload transport and grain‐size analysis of bedload indicate translational spreading of a sand wave front with a dispersive component in steeper reaches. Lulu Creek is returning to a condition of natural variability, but the Colorado River is outside the HRV expected for steep‐gradient, pool‐riffle channels. Applying HRV to a situation where management questions require a longer term perspective, and pre‐disturbance baseline data are limited, is a useful approach. The HRV analysis facilitates a better understanding of site variability and delineates the range of possibilities of channel form and process to achieve management goals. Copyright © 2012 John Wiley & Sons, Ltd.