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41.
长期连续完整的历史气温资料是震前气温异常判别研究的重要数据基础。本文考虑了参考站与缺测站之间的距离,建立改进的线性回归模型。利用该模型插补缺测和错误的气温整点值数据,在一定程度上解决了长期连续观测数据缺测的情况。通过对收集的唐山观测站气温整点值数据进行插补,并应用插补完整的数据分析研究了2012年5月28日唐山4.8级地震前兆异常。结果表明:①插补值与其前后观测值衔接吻合,插补后完整连续数据符合夏高冬低的年变规律;②插补误差在±0.5℃范围内的比例为60.2%,在±0.8℃范围内的比例为80.3%,其误差绝对值大于1.0℃的比例为9.6%,平均绝对误差为0.84℃,插补值与观测值的相关系数大部分在0.9以上;③从3月27日起出现增温异常,特别是震前2天增温幅度约8℃。 相似文献
42.
43.
The Ecological-living-productive land(ELPL) classification system was proposed in an effort to steer China's land pattern to an ecological-centered path, with the development model shifting from a single function into more integrated multifunction land use. The focus is coordinating the man-land contradictions and developing an intensive, efficient and sustainable land use policy in an increasingly tense relationship between humans and nature. Driven by socioeconomic change and rapid population growth, many cities are undergoing urban sprawl, which involves the consumption of cropland and ecological land and threatens the ecological balance. This paper aims to quantitatively analyze the critical effects of ELPL changes on eco-environmental quality according to land use classification based on leading function of ecology, living and production from 1990 to 2015 with a case study of Xining City. Also, four future land use scenarios were simulated for2030 using the Future Land Use Simulation(FLUS) model that couples human and natural effects. Our results show a decrease in productive land(PL) and an increase in ecological land(EL) and living land(LL) in Xining City. Forestry ecological land(FEL) covered the top largest proportion; agriculture productive land(APL) showed the greatest reduction and urban and rural living land(U-RLL) presented a dramatic increase. The eco-environmental quality improved in 1990-2010, mainly affected by the conversion of APL to FEL and GEL. However, the encroachment of U-RLL into APL, other ecological land(OEL) and FEL was the main contributor to the decline in eco-environmental quality in 2010-2015 as well as the primary reason for the increase area of lower-quality. The Harmonious Development(HD)-Scenario, characterized by a rational allocation of LL and PL and a better eco-environment, would have implications for planning and monitoring future management of ELPL, and may represent a valuable reference for local policy-makers. 相似文献
44.
广州城市流浪乞讨者的空间管治与日常生活实践 总被引:2,自引:0,他引:2
以广州流浪乞讨者为研究对象,通过深度访谈等质性研究方法,解读针对流浪乞讨者的空间管治政策与手段,分析流浪乞讨者的日常生活实践与生境协商。研究发现:在地方城市政策对流动性与公共秩序限制的双重压力下,在流浪乞讨者的日常生活实践中,不仅有针对管治行动者而刻意为之的特殊营建,亦有基于程式化生活流程对自我身份认同的重塑与真情实感的展演。地方政府基于空间目标的救助与真实存在的日常生活实践存在着一种张力。研究关注了城市边缘群体日常生活对地理意义的主动塑造过程,对全面理解并规范管理中国城市流浪乞讨现象具有借鉴意义。 相似文献
45.
海洋盐业是中国海洋经济的重要部分,也是沿海传统产业之一,13世纪以来不断发展演变。将沿海分为北、东、南3个地带,搜集整理与海盐经济相关的多种历史文献及方志资料,运用地理学方法分析评估了海洋盐业百年尺度的动态演化过程,并比较了资源环境与管理政策的驱动作用及其差异。研究表明:① 沿海盐业表现为传统煎法长期主导、逐步废煎改晒的过程,不同盐区的演化进程存在显著差异,北部盐区最快,东部次之,南部整体发展缓慢;② 海盐生产重心长期位于东部的两淮盐区,19世纪后期向北部盐区快速迁移;③ 资源环境与生态差异促进了各岸段海盐生产演化分异,垄断性管理政策迟滞了海洋盐业的空间集聚进程,未来沿海开发与海洋盐业的可持续发展将主要依靠基于资源生态约束的管理政策与技术。 相似文献
46.
Base cation concentrations in forest litter and topsoil have different responses to climate and tree species along elevational gradients 总被引:1,自引:0,他引:1
XUE Feng ZHAO Ming-fei WANG Yu-hang KANG Mu-yi XING Kai-xiong WANG Guo-yi SHI Jing-jing CHEN Chen JIANG Yuan 《山地科学学报》2019,(1)
The forest litter is an essential reservoir of nutrients in forests, supplying a large part of absorbable base cations(BC) to topsoil, and facilitating plant growth within litter-soil system. To characterize elevational patterns of base cation concentrations in the forest litter and topsoil, and explore the effects of climate and tree species, we measured microclimate and collected the forest litter and topsoil(0-10 cm) samples across an elevational range of more than 2000 m(1243 ~ 3316 m a.s.l.),and analyzed the concentrations of BC in laboratory. Results showed that: 1) litter Ca concentration displayed a hump-shaped pattern along the elevational gradients, but litter K and Mg showed saddle-shaped patterns. Soil Ca concentration increased with elevation, while soil K and Mg had no significant changes. 2) Ca concentration in the forest litter under aspen(Populus davidiana) was significantly higher than that in all other species, but in topsoil, Ca concentration was higher under coniferous larch and fir(Larix chinensis and Abies fargesii). Litter K and Mg concentrations was higher under coniferous larch and fir, whereas there were nosignificant differences among tree species in the concentrations of K and Mg in topsoil. 3) Climatic factors including mean annual temperature(MAT), growing season precipitation(GSP) and non-growing season precipitation(NGSP) determined BC concentrations in the forest litter and topsoil. Soil C/N and C/P also influenced BC cycling between litter and soil. Observation along elevations within different tree species implies that above-ground tree species can redistribute below-ground cations, and this process is profoundly impacted by climate. Litter and soil Ca, K and Mg with different responses to environmental variables depend on their soluble capacity and mobile ability. 相似文献
47.
基于内蒙古磴口荒漠生态系统国家定位观测研究站监测数据,分析2014年1—12月不同土层的地温数据及同期气象数据,进而阐明乌兰布和沙漠东北缘地温变化特征。结果表明:(1)乌兰布和沙漠地温及气温具有显著的日变化特征,气温最高值与最低值出现时刻相对巴丹吉林沙漠提前2 h,相对东部地区滞后1 h;地温与气温季节变化特征一致,各季节地温最值出现时刻相对气温滞后1 h;(2)地温变化速率随着土壤深度的增加而减小,在土壤深度达到70 cm以后,地温全年在0℃以上;低于0℃的5 cm地温持续时间约为4个月;(3)地温与空气温度、太阳辐射变化趋势一致,地温相对太阳辐射及气温明显滞后。相关分析与逐步回归表明,对地温变化起决定作用的环境因子为空气温度、蒸发量、太阳总辐射、风速、空气相对湿度、降水。 相似文献
48.
Journal of Geographical Sciences - Runoff generation is an important part of water retention service, and also plays an important role on soil and water retention. Under the background of the... 相似文献
49.
Application of the standard Eulerian model to simulations of sand scour results in unrealistic phenomena. Therefore, the present work develops a modified Eulerian model based on sand incipient motion theory. The modified model is applied for simulating a two-dimensional single vertical jet and a moving planar jet. The simulation results generally demonstrate fairly good agreement with published results of scour profiles and the velocity contours of the water and sand phases. In addition, equations to describe self-similar scour profiles for the moving planar jet cases are given. The results demonstrate that the modified model efficiently and accurately simulates the two-dimensional sand scour produced by jets, particularly for the moving jet cases. 相似文献
50.
风和径流量对长江口缺氧影响的数值模拟 总被引:1,自引:1,他引:0
受自然和人类活动的影响,海洋缺氧现象日益严重,威胁着海洋生态环境,海洋缺氧问题已经引起了人们的广泛关注。本文应用区域海洋模式并耦合生态模式,对东海的生态系统进行了数值模拟和分析研究。与观测数据比较显示,该模型能较好地模拟长江口外生态变量的分布趋势。另外本文通过设置不同敏感性实验,探讨风和径流量对长江口底层缺氧现象的影响,结果分析表明,风和径流量对长江口外缺氧区的形成有显著的影响。径流量变化虽然对长江口外缺氧区的季节变化影响并不显著,但是对缺氧区域面积却存在显著的影响。径流量增加,水体层化增强,表层叶绿素浓度增加,最终导致缺氧区域范围扩展;径流量减小,水体层化减弱,表层叶绿素浓度减小,缺氧区域范围缩小。风向和风速的改变不仅影响长江口外缺氧区的季节变化,还影响缺氧区域面积。 相似文献