Using geographic information system (GIS) techniques and the newest seasonal and annual average precipitation data of 679 meteorological stations from 1971 to 2000, the multiple regressions equations of the precipitat...Using geographic information system (GIS) techniques and the newest seasonal and annual average precipitation data of 679 meteorological stations from 1971 to 2000, the multiple regressions equations of the precipitation and topographical variables are established to extract the effect of topography on the annual and seasonal precipitation in the upper-middle reaches of the Yangtze River. Then, this paper uses a successive interpolation approach (SIA), which combines GIS techniques with the multiple regressions, to improve the accuracy of the spatial interpolation of annual and seasonal rainfall. The results are very satisfactory in the case of seasonal rainfall, with the relative error of 6.86%, the absolute error of 13.07 mm, the average coefficient of variation of 0.070, and the correlation coefficient of 0.9675; in the case of annual precipitation, with the relative error of 7.34%, the absolute error of 72.1 mm, the average coefficient of variation of 0.092, and the correlation coefficient of 0.9605. The analyses of annual mean precipitation show that the SIA calculation of 3-5 steps considerably improves the interpolation accuracy, decreasing the absolute error from 211.0 mm to 62.4 mm, the relative error from 20.74% to 5.97%, the coefficient of variation from 0.2312 to 0.0761, and increasing the correlation coefficient from 0.5467 to 0.9619. The SIA iterative results after 50 steps identically converge to the observed precipitation.展开更多
Based on data of radiation fog events in Xuanen, Hubei province, 2010, this paper analyzes the microphysical process and evolution characteristics of radiation fogs with complicated substrate in the upper and middle r...Based on data of radiation fog events in Xuanen, Hubei province, 2010, this paper analyzes the microphysical process and evolution characteristics of radiation fogs with complicated substrate in the upper and middle reaches of the Yangtze River, and compares them with findings in other areas. Results are as follows: radiation fog in Xuanen is evidently weaker in droplet number concentration and liquid water content than land fogs in other areas. Its liquid water content fluctuates obviously, 0.01g/m3 with visibility of 1,000 meters, which is quite different from that in urban areas, but similar to the Nanling Mountains. Bi-modal droplet distribution is likely to occur in Xuanen mountain radiation fog(MRF) events. Statistical analysis shows that the observed droplet size distribution can be piecewise described well by the Gamma distribution. There is a positive correlation between liquid water content, fog droplet concentration and mean radius, especially in the development and dissipation stage. Condensation growth and droplet evaporation are major processes of Xuanen MRF. The dissipation time coincided with the time when the grass temperature reached the peak value, which indicated that dew evaporation is a key role in maintaining Xuanen MRF. In the early stage of dense fog's growth, droplets with diameter of over 20 micrometers can be observed with visibility of800-1,000 m, which might be caused by the transportation of low cloud droplets to earth's surface by turbulence. Big droplets in the initial stage correspond to higher water content, leading to the higher observed value of water content of Xuanen MRF.展开更多
针对长江中上游鱼类资源领域研究,以主题“长江上游”“长江中游”“金沙江下游”“鱼类资源”“鱼类早期资源”为检索条件,筛选了2023年7月前中国知网及Web of Science核心合集数据库收录的503篇文献,利用CiteSpace进行文献计量分析并...针对长江中上游鱼类资源领域研究,以主题“长江上游”“长江中游”“金沙江下游”“鱼类资源”“鱼类早期资源”为检索条件,筛选了2023年7月前中国知网及Web of Science核心合集数据库收录的503篇文献,利用CiteSpace进行文献计量分析并绘制科学知识图谱,在此基础上从文献数量分布、研究机构及代表作者分布、研究主题内容、研究热点及演变趋势方面对长江中上游鱼类资源领域研究进行了综述。结果表明:中国科学院和中国水产科学研究院等是该领域的领军机构;从发展趋势上看,该领域已形成了鱼类资源现状及变化趋势、鱼类资源的影响机制以及鱼类资源的保护对策3个重要的研究热点和方向。后面需进一步完善江段鱼类资源的长期动态监测方法、梯级开发背景下鱼类资源的变动情况以及鱼类资源的协同保护方法等方面的研究。展开更多
基金The National 973 Project of China, No.2001CB309404 O versea O utstanding Youth Cooperation Project, N o. 40128001/D 05N ationalN aturalScience Foundation ofChina,N o.49375248 Zhejiang Province Science Research (C33)Project,N o.2004C33082
文摘Using geographic information system (GIS) techniques and the newest seasonal and annual average precipitation data of 679 meteorological stations from 1971 to 2000, the multiple regressions equations of the precipitation and topographical variables are established to extract the effect of topography on the annual and seasonal precipitation in the upper-middle reaches of the Yangtze River. Then, this paper uses a successive interpolation approach (SIA), which combines GIS techniques with the multiple regressions, to improve the accuracy of the spatial interpolation of annual and seasonal rainfall. The results are very satisfactory in the case of seasonal rainfall, with the relative error of 6.86%, the absolute error of 13.07 mm, the average coefficient of variation of 0.070, and the correlation coefficient of 0.9675; in the case of annual precipitation, with the relative error of 7.34%, the absolute error of 72.1 mm, the average coefficient of variation of 0.092, and the correlation coefficient of 0.9605. The analyses of annual mean precipitation show that the SIA calculation of 3-5 steps considerably improves the interpolation accuracy, decreasing the absolute error from 211.0 mm to 62.4 mm, the relative error from 20.74% to 5.97%, the coefficient of variation from 0.2312 to 0.0761, and increasing the correlation coefficient from 0.5467 to 0.9619. The SIA iterative results after 50 steps identically converge to the observed precipitation.
基金National Natural Science Foundation of China(41375138,41305120,41275151)Natural Science Foundation of Jiangsu Province,China(BK20130988)+1 种基金Specialized Research Fund for the Doctoral Program of Higher Education(20133228120002)Graduate Student Innovation Plan at the Universities of Jiangsu province(N0782002211)
文摘Based on data of radiation fog events in Xuanen, Hubei province, 2010, this paper analyzes the microphysical process and evolution characteristics of radiation fogs with complicated substrate in the upper and middle reaches of the Yangtze River, and compares them with findings in other areas. Results are as follows: radiation fog in Xuanen is evidently weaker in droplet number concentration and liquid water content than land fogs in other areas. Its liquid water content fluctuates obviously, 0.01g/m3 with visibility of 1,000 meters, which is quite different from that in urban areas, but similar to the Nanling Mountains. Bi-modal droplet distribution is likely to occur in Xuanen mountain radiation fog(MRF) events. Statistical analysis shows that the observed droplet size distribution can be piecewise described well by the Gamma distribution. There is a positive correlation between liquid water content, fog droplet concentration and mean radius, especially in the development and dissipation stage. Condensation growth and droplet evaporation are major processes of Xuanen MRF. The dissipation time coincided with the time when the grass temperature reached the peak value, which indicated that dew evaporation is a key role in maintaining Xuanen MRF. In the early stage of dense fog's growth, droplets with diameter of over 20 micrometers can be observed with visibility of800-1,000 m, which might be caused by the transportation of low cloud droplets to earth's surface by turbulence. Big droplets in the initial stage correspond to higher water content, leading to the higher observed value of water content of Xuanen MRF.
文摘针对长江中上游鱼类资源领域研究,以主题“长江上游”“长江中游”“金沙江下游”“鱼类资源”“鱼类早期资源”为检索条件,筛选了2023年7月前中国知网及Web of Science核心合集数据库收录的503篇文献,利用CiteSpace进行文献计量分析并绘制科学知识图谱,在此基础上从文献数量分布、研究机构及代表作者分布、研究主题内容、研究热点及演变趋势方面对长江中上游鱼类资源领域研究进行了综述。结果表明:中国科学院和中国水产科学研究院等是该领域的领军机构;从发展趋势上看,该领域已形成了鱼类资源现状及变化趋势、鱼类资源的影响机制以及鱼类资源的保护对策3个重要的研究热点和方向。后面需进一步完善江段鱼类资源的长期动态监测方法、梯级开发背景下鱼类资源的变动情况以及鱼类资源的协同保护方法等方面的研究。
