地震地电阻率交流观测方法及观测实验

介绍地震地电阻率交流观测的原理及方法、观测系统的要求及主要技术指标,并在受地铁干扰严重的江宁台进行实验观测。初步观测结果表明,该系统观测结果与直流观测结果相当,能满足台站实际观测需求,同时达到抗干扰目的。证明采用交流供电方法进行地电阻率观测,能够在较强干扰背景下获取较高的信噪比,很好地抑制城市地铁、轻轨以及其他因素引起的电磁干扰。
     

Exploring spatiotemporal patterns and physical controls of soil moisture at various spatial scales

Soil moisture variability of various spatial scales is analyzed based on empirical orthogonal function (EOF) method using soil moisture datasets with various spatial resolutions: 1 km eco-hydrological model simulation, 0.25° passive microwave (Advanced Microwave Scanning Radiometer for the Earth Observing System, AMSR-E) dataset, and 0.5° land surface model simulation from Climate Predictor Center (CPC). All three datasets generate EOFs that explain similar variances with those generated from in situ observations from agro-meteorological network. Using AMSR-E product and eco-hydrological model simulation, it is found that the primary spatial pattern of soil moisture obtained from watershed scale has a strong connection to topographic attributes, followed by soil texture and rainfall variability, as suggested by the correlation between the primary EOF mode (EOF1) of soil moisture and landscape attributes. However, the EOF analysis of both AMSR-E and CPC datasets at regional scale reaches the conclusion that soil texture indices, such as sand and clay content, is of higher importance to soil moisture EOF1 spatial pattern (explaining 61 % variance) than topography is. Furthermore, correlation between soil moisture EOF1 and soil property is higher in spring than in autumn, which indicates that soil water-holding and drainage capabilities are more important under dry conditions. At national scale, the combined effects of topographic feature and soil property are clearly exhibited in EOF1. The study results reveal that different emphases should be placed on accurate acquisition of landscape attributes for soil moisture estimation according to various spatial scales.     

基于XML的网络专题地图集设计与实现

专题地图集是关于某一区域自然资源、社会经济、发展规划等方面的专题信息的地图图幅集合.将专题地图集在网络环境下进行发布,使专题地图信息服务于大众具有很强的现实意义.针对网络环境下的专题地图集存在结构组织不统一、地图表达不够美观、专题数据更新滞后等问题,引入网络动态专题地图集的概念,设计使用xml(Extended mar...     

地震前兆数据异常自动检测报警系统

通过对地震前兆数据的分析与研究,研制了一套地震前兆数据异常自动检测与报警系统.该系统可实现测项分量与检测方法的自由定制,通过利用相关分析、差分检测、固体潮相关检测、方差检测、台阶检测与金日光第四统计力学群子统计理论等多种检测方法,实现了对数据的自动异常检测与报警.试验证明,该系统有效可行,可为地震数据监测人员与地震预报...     

侧扫声呐系统在荣成海流能电站示范工程中的应用

介绍了侧扫声呐系统在荣成海流能电站示范工程中的应用,对侧扫声呐系统的工作原理、图谱的特点及影响图谱影像质量的因素进行了分析,基于海流能示范工程扫测图谱影像进行了数据处理与特征提取,并将地貌分类成果应用到设计施工中取得了较好的效果;对工程应用中遇到的问题进行了总结。     

Impacts of climate change on crop evapotranspiration with ensemble GCM projections in the North China Plain

As one of the key grain-producing regions in China, the agricultural system in the North China Plain (NCP) is vulnerable to climate change due to its limited water resources and strong dependence on irrigation for crop production. Exploring the impacts of climate change on crop evapotranspiration (ET) is of importance for water management and agricultural sustainability. The VIP (Vegetation Interface Processes) process-based ecosystem model and WRF (Weather Research and Forecasting) modeling system are applied to quantify ET responses of a wheat-maize cropping system to climate change. The ensemble projections of six General Circulation Models (GCMs) under the B2 and A2 scenarios in the 2050s over the NCP are used to account for the uncertainty of the projections. The thermal time requirements (TTR) of crops are assumed to remain constant under air warming conditions. It is found that in this case the length of the crop growth period will be shortened, which will result in the reduction of crop water consumption and possible crop productivity loss. Spatially, the changes of ET during the growth periods (ET_g) for wheat range from ?7 to 0 % with the average being ?1.5?±?1.2 % under the B2 scenario, and from ?8 to 2 % with the average being ?2.7?±?1.3 % under the A2 scenario/consistently, changes of ET_g for maize are from ?10 to 8 %, with the average being ?0.4?±?4.9 %, under the B2 scenario and from ?8 to 8 %, with the average being ?1.2?±?4.1 %, under the A2 scenario. Numerical analysis is also done on the condition that the length of the crop growth periods remains stable under the warming condition via breeding new crop varieties. In this case, TTR will be higher and the crop water requirements will increase, with the enhancement of the productivity. It is suggested that the options for adaptation to climate change include no action and accepting crop loss associated with the reduction in ET_g, or breeding new cultivars that would maintain or increase crop productivity and result in an increase in ET_g. In the latter case, attention should be paid to developing improved water conservation techniques to help compensate for the increased ET_g.     

区域资源环境与经济发展关系的时空分析

为揭示中国资源环境与经济发展相互关系的时空演变特征或规律,借助"驱动力-状态-响应"(DSR)概念模型,构建区域资源环境负荷指数,应用脱钩理论及基于弹性分析法改进的脱钩程度判定标准,以1998-2008年为时间界限,以T1、T2、T3、T4和T5个时期为时间尺度,以全国及31个省、直辖市、自治区为空间尺度,试图对中国及...     

Relationship between polar motion and key hydrological elements at multiple scales

Science China Earth Sciences - Changes in the elements of the Earth system are closely related. Finding the key factors linked with hydrological changes is significant for in-depth analysis of...     

地理空间数据访问控制威胁模型及应对策略

针对由于缺少对地理空间数据访问控制安全威胁因素的详细分析使得现有的地理空间访问控制模型不够完善的问题,该文提出了地理空间数据访问控制安全威胁模型——STALE模型。该模型结合空间关系、多尺度、属性等地理空间数据特征,详细描述了地理空间数据文件与数据库在访问控制中存在的安全威胁。在此基础上,针对模型中各类威胁因素,提出了应对策略,并进行了实验验证,证明了STALE模型的实用性。     

Assessment of pollution status of Dalianhu water sources in Shanghai,China and its pollution biological characteristics

The present study was undertaken aiming to assess the water quality state of different parts (i.e. external river, aquaculture ponds, lake area, water forests, internal river and swampland) of Dalianhu water sources in Shanghai (China), by investigating the community structure characteristics of zooplankton and benthos along with some water quality parameters (TN, TP, COD, etc.). Some diversity indices were calculated, including Shannon–Wiener index (H) for both zooplankton and benthos, Margalef’s diversity index (D) for zooplankton and Goodnight modified index (G) and Biological pollution index (BPI) for benthos. The obtained results shows that in Dalianhu water sources, the Shannon–Wiener index of zooplankton (H _z) is 0.3–1.83, the Margalef’s diversity index of zooplankton (D) is 1.0–10.4. The Shannon–Wiener index of benthos (H _b) is 0.81–1.26, the Goodnight modified index of benthos (G) is 0.30–0.88, the Biological pollution index (BPI) is 1.1. These findings determine the water quality in Dalianhu water sources which belong to the moderate pollution. By comprehensive analysis together with zooplankton, benthos indices and water physicochemical parameters, the pollution level of Dalianhu water sources is in turn water forest, inner river, aquaculture ponds, external river and lake area, showing that the pollution of the Dalianhu water sources is mainly internal. It was suggested that the further work departments should be carried out to strengthen the necessary consolidate management and ecological repair.