崩滑堰塞坝(湖)的地貌环境效应     

余国安  王兆印  黄河清  刘怀湘 《地球科学进展》2010,25(9):934-940

崩滑堰塞坝(湖)具有显著的地貌环境效应,这种效应在时间尺度上分为短期和长期2种,主要表现在河流水文过程、地貌演变、环境生态、景观等方面.堰塞坝形成初期河流原有生境受到干扰,河流生态和景观出现退化.堰塞体溃决强烈改变下游水文过程及河流地貌,严重冲击河流生境和生态,并可能对下游基础设施和群众生命财产造成灾难性破坏.长期稳定维持的堰塞坝深刻影响河流地貌过程,并显著改善河流生境、生态,提升景观水平.堰塞坝(湖)是河床持续下切、岸坡失稳而自然反馈形成的裂点,能增加河流阻力,控制河床下切,如能长期维持是河流健康稳定的促进因素.  相似文献   

旅游资源开发利用的外部性及其治理     

李霞 《广东海洋大学学报》2005,25(5):56-59

旅游资源具有公共属性,在旅游资源开发利用过程中相关契约的不完全性导致了产权界定不清,从而会导致负的外部性效果。在分析旅游资源开发利用的外部性问题的性质、特征及其治理难点基础上,进一步就如何治理此类外部性问题进行了探讨。  相似文献   

Autonomous video camera system for monitoring impacts to benthic habitats from demersal fishing gear, including longlines     

Robert Kilpatrick  Graeme EwingTim Lamb  Dirk WelsfordAndrew Constable 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(4):486-491

Studies of the interactions of demersal fishing gear with the benthic environment are needed in order to manage conservation of benthic habitats. There has been limited direct assessment of these interactions through deployment of cameras on commercial fishing gear especially on demersal longlines. A compact, autonomous deep-sea video system was designed and constructed by the Australian Antarctic Division (AAD) for deployment on commercial fishing gear to observe interactions with benthos in the Southern Ocean finfish fisheries (targeting toothfish, Dissostichus spp). The Benthic Impacts Camera System (BICS) is capable of withstanding depths to 2500 m, has been successfully fitted to both longline and demersal trawl fishing gear, and is suitable for routine deployment by non-experts such as fisheries observers or crew. The system is entirely autonomous, robust, compact, easy to operate, and has minimal effect on the performance of the fishing gear it is attached to. To date, the system has successfully captured footage that demonstrates the interactions between demersal fishing gear and the benthos during routine commercial operations. It provides the first footage demonstrating the nature of the interaction between demersal longlines and benthic habitats in the Southern Ocean, as well as showing potential as a tool for rapidly assessing habitat types and presence of mobile biota such as krill (Euphausia superba).  相似文献   

“核冬天”理论及气溶胶的短波吸收作用     

吴国雄 《成都信息工程学院学报》1987,(1)

本文扼要回顾了国外关于核爆炸对人类生命、自然环境及气候影响的研究;介绍了近几年关于“核冬天”研究的新成果。通过沙暴尘埃对短波辐射吸收强度的分析,讨论了浓密气溶胶的天气气候效应。  相似文献   

Bayesian Hierarchical ANOVA of Regional Climate-Change Projections from NARCCAP Phase II     

《International Journal of Applied Earth Observation and Geoinformation》2013

We consider current (1971–2000) and future (2041–2070) average seasonal surface temperature fields from two regional climate models (RCMs) driven by the same atmosphere–ocean general circulation model (GCM) in the North American Regional Climate Change Assessment Program (NARCCAP) Phase II experiment. We analyze the difference between future and current temperature fields for each RCM and include the factor of season, the factor of RCM, and their interaction in a two-way ANOVA model. Noticing that classical ANOVA approaches do not account for spatial dependence, we assume that the main effects and interactions are spatial processes that follow the Spatial Random Effects (SRE) model. This enables us to model the spatial variability through fixed spatial basis functions, and the computations associated with an ANOVA of high-resolution RCM outputs can be carried out without having to resort to approximations. We call the resulting model a spatial two-way ANOVA model. We implement it in a Bayesian framework, and we investigate the variability of climate-change projections over seasons, RCMs, and their interactions. We find that projected temperatures in North America are credibly higher, that the associated warming effects differ in spatial areas and in seasons, and that they are of much larger magnitude than the variability between RCMs.  相似文献   

相对论框架中的VLBI观测模型     

韩春好  黄天衣  许邦信 《测绘学院学报》1991,(2)

本文以太阳系质心参考系为基础推导了VLBI时延和引力延迟的后牛顿表达式;讨论了各天体对VLBI时延的影响量级及其作用范围;并根据地心参考系与太阳系质心参考系的坐标转换关系,给出了地心参考系中的VLBI观测模型。建议采用(25)式和(16)式作为VLBI时延和引力延迟改正的计算公式。  相似文献   

Some Effects of Rotation Rate on Planetary-Scale Wave Flows     

Li Guoqing  Robin Kung  Richard L. Pfeffer 《大气科学进展》1993,10(3):296-306

A series of experiments were performed in a rotating annulus of fluid to study effects of rotation rate on planeta-ry-scale baroclinic wave flows. The experiments reveal that change in rotation rate of fluid container causes variation in Rossby number and Taylor number in flows and leads to change in flow patterns and in phase and amplitude of quasi-stationary waves. For instance, with increasing rotation rate, amplitude of quasi-stationary waves increases and phase shifts upstream. On the contrary, with decreasing rotation rate, amplitude of quasi-stationary waves decreases and phase shifts downstream. In the case of the earth’s atmosphere, although magnitude of variation in earth’s rotation rate is very small, yet it causes a very big change in zonal velocity component of wind in the atmosphere and of currents in the ocean, and therefore causes a remarkable change in Rossby number and Taylor number deter-mining regimes in planetary-scale geophysical flows. The observation reveals that intensity and geographic location of subtropic anticyclones in both of the Northern and Southern Hemispheres change consistently with the variation in earth’s rotation rale. The results of fluid experiments are consistent, qualitatively, with observed phenomena in the atmospheric circulation.  相似文献   

香港地区海陆风的显式模拟研究   总被引：2，自引：2，他引：2  

陈训来  王安宇  李江南  刘吉  林文实  冯瑞权 《气象科学》2007,27(5):473-480

利用MM5模式对香港地区的海陆风进行了显式数值研究,模拟的风向、风速和温度与站点的观测值比较一致,较详细地分析了海陆风的日变化规律和三维结构特征,结果显示香港地区海风分布复杂,主要受偏西、偏南和偏东海风气流的影响,形成多个辐合带,海风锋最远可以深入内陆约90 km;陆风较简单,主要是偏北气流,陆风的风速和强度都比海风要弱,与山谷风、城市热岛环流等形成弱的辐合。香港是一个海岸曲折、多丘陵的地区,其中75%的面积是山区,为了研究这些丘陵地形对香港地区海陆风的影响,设计了保留海陆分布,去掉丘陵地形的敏感性试验,结果表明,由于丘陵地形的存在,在白天地形的热力作用是主要的,增强了海风的强度;而晚上动力阻挡作用比较明显,减弱了陆风的强度。  相似文献   

SiO2地温计沸腾校正方法在高原地区的适用性分析     

李义曼  庞忠和  罗霁  陈凯 《地质论评》2021,67(2):67030018-67030018

热储温度是开展地热资源研究的关键参数之一。地热勘查中常用基于地热流体化学和同位素数据的经验公式来评价没有钻孔或者钻孔未达到实际热储层情况下深部热储的温度。SiO2地温计应用最为广泛,对于发生了绝热沸腾的地热流体,通常采用Fournier等提出的100℃沸腾条件下的校正公式。考虑到海拔会影响沸点,本文从SiO2溶解度方程和温度相关性着手,评价了SiO2地温计沸腾校正方法在高原地区的适用性。结果表明Fournier（1977）及Fournier 和 Potter（1982）提出的100℃条件下SiO2绝热沸腾校正方法得到的误差分别为2.4%和1.1%,可以代表深部热储温度,即SiO2地温计沸腾校正方法在高原地区也是适用的。  相似文献   

热红外发射率对热红外成像及其图像判读的影响     

王品清 《遥感学报》1988,(3)

在热红外扫描图像的判读工作中,热红外发射率是一个极为重要的影响因素。在某些特定条件下,这一因素的影响是十分显著的。然而,迄今为止,这一因素在热红外图像的判读工作中还没有引起人们的足够重视。本文试图从热红外辐射定律出发,结合白天和夜间的热红外遥感图像资料,以及地面温度测量数据来说明这一因素的影响,并较详细地讨论了一些与热红外发射率有关的影响因素。但是,如何在成像或者在图像判读过程中消除这一影响因素,还有待于进一步的研究。  相似文献