使用气象目标物验证珠海〖CDF*2〗澳门双偏振雷达的差分反射率标定

为了寻求适合珠海-澳门双偏振雷达的差分反射率标定方法,提升其探测的准确性和稳定性,对珠澳雷达的太阳法和垂直指向法的标定结果进行了分析对比。对比表明两个标定方法确定的系统偏差之间存在较大的差异。为了确定真实的系统偏差,基于业务运行的体积扫描数据,在初始差分相移订正的基础上,用差分相移、反射率、信噪比和相关系数作为筛选条件,筛选了适合作为标定参照物的小雨和干雪,对珠澳雷达的标定结果进行了验证并分析了标定误差的成因。结果表明以小雨和干雪作为目标物得到的差分反射率系统偏差和太阳扫描法得到的结果非常一致,且在超过两个月时间内表现较为稳定,可以用于对雷达系统的差分反射率偏差进行长期的在线监控。垂直指向法标定的结果存在明显偏差。与英国Thurnham C波段雷达以及南京大学C波段雷达的垂直入射标定数据的横向对比和分析表明,珠澳雷达的垂直指向法标定受到位于天线罩顶部的航空障碍灯和维护窗的影响,使得标定结果出现偏差。     

海河流域水汽输送及其变化特征分析

根据海河流域测站降水资料、NCEP/NCAR再分析资料和日本气象厅JRA-25资料,分析了1951—2008年夏季海河流域大气水汽含量的变化以及不同环流形势下的水汽输送特征,结果表明：海河流域大气水汽含量存在显著的年代际变化特征,与降水量存在显著统计相关;海河流域上空纬向水汽输送主要发生在850~700 hPa之间,经向水汽输送在850 hPa以下存在强的水汽输送带,它是海河流域水汽的主要贡献者,也是影响海河流域降水的最主要因素之一。气旋型环流和南风型环流对海河流域水汽输送有较大影响。     

钟祥市农村民居抗震性能调查

通过钟祥市农村民居抽样调查,对其民居建筑物质量现状进行评估和抗震性能评价,得出钟祥农居结构抗震设防存在如下问题:1)地基未做适当的处理;2)结构构造措施不到位;3)墙体强度低;4)建筑材料和施工质量差。     

Heterotrophic bacterial and <Emphasis Type="Italic">Synechococcus</Emphasis> spp. Growth and mortality along the inshore-offshore in the East China Sea in summer

This study used the dilution method to examine growth and grazing rates of heterotrophic bacteria and an autotrophic picoplankton, Synechococcus spp., from 1 to 11 July 2007 in the East China Sea. The main influence of oceanographic conditions in this aquatic system was the introduction of fresh, high-nutrient water from Changjiang River and the extremely nutrient-poor, high-salinity waters of Kuroshio Water. In these experiments, deviation from linearity in the relationship between dilution factor and net growth rate was significant in a large number of cases. Growth rates for heterotrophic bacteria ranged from 0.024 to 0.24, and for Synechococcus spp. from 0.03 to 0.21 h⁻¹. Grazing rates ranged from 0.02 to 0.19 and 0.01 to 0.13 h⁻¹, respectively. The spatial variations of Synechococcus spp. production to the primary production ratio (SP/PP) were low (<5%) in high Chl a environments and increased exponentially in low Chl a environments, indicating that Synechococcus spp. contributes to a large extent to the photosynthetic biomass in the open sea, especially in the more oligotrophic Kuroshio Water. Furthermore, the results of our dilution experiments suggest that nanoflagellates largely depend on heterotrophic bacteria as an important energy source. On average, heterotrophic bacteria contributes to 76 and 59% of carbon consumed by nanoflagellates within the plume (salinity <31) and outside of it (salinity >31).     

旅游目的地标志景区测度模型及广州实证解析

标志景区是旅游目的地的符号象征,成为人们感知和认识目的地的重点对象.通过对标志景区概念及其主要特征的认知与界定,选取市场影响度、价值贡献度、旅游吸引度和其他因素作为一级指标因子和12个测量指标建立标志景区测度逻辑模型,运用AHP方法确定模型中各因子权重,建立标志景区计量模型.以广州作为案例,对候选标志景区测度值进行解析,广州重要标志景区有越秀公园、广州塔、陈家祠、中山纪念堂、白云山风景区、北京路步行街、黄花岗七十二烈士陵园、南越王博物馆.     

成都茶馆空间随机聚集分形特征研究

以成都市茶馆游憩场点系统为研究对象,在全市尺度和著名旅游地标、著名茶馆为中心的0.5 km、1.0 km等多级尺度下,对各茶馆子系统随机聚集维数进行测算。研究发现成都市茶馆系统具有空间随机聚集分形结构特征,而且存在明显的尺度效应。全市尺度下,以天府广场(城市空间分布中心和市行政中心)为中心,成都茶馆呈离心状态分布,空间结构随机聚集性较弱。在0.5 km尺度下,以杜甫草堂等5 个著名旅游地标为系统中心,茶馆子系统未能表现出明显的分形结构特征;以10 个著名茶馆为系统中心,茶馆子系统空间分布呈向心状态分布,空间结构随机聚集性较强。在1.0 km尺度下,以著名旅游地标为系统中心,茶馆子系统多呈现双分形结构,随着尺度范围增大茶馆子系统分形结构特征发育趋于明显;以著名茶馆为系统中心的茶馆子系统,空间结构随机聚集性很强,因此著名茶馆是1.0 km尺度下的茶馆系统自我演化的聚集中心。案例证明分形理论可以在多种空间尺度下指示城市游憩场点系统的微观结构。     

智能电源管理系统在北京市测震台网的应用

北京市测震台网的智能电源管理系统安装运行改善了测震台站的电源管理现状,变被动管理为主动管理,有效提高台站运行率,并在一定程度上节约运行经费。     

Comprehensive analysis and artificial intelligent simulation of land subsidence of Beijing, China

Mechanism and modeling of the land subsidence are complex because of the complicate geological background in Beijing, China. This paper analyzed the spatial relationship between land subsidence and three factors, including the change of groundwater level, the thickness of compressible sediments and the building area by using remote sensing and GIS tools in the upper-middle part of alluvial-proluvial plain fan of the Chaobai River in Beijing. Based on the spatial analysis of the land subsidence and three factors, there exist significant non-linear relationship between the vertical displacement and three factors. The Back Propagation Neural Network (BPN) model combined with Genetic Algorithm (GA) was used to simulate regional distribution of the land subsidence. Results showed that at field scale, the groundwater level and land subsidence showed a significant linear relationship. However, at regional scale, the spatial distribution of groundwater depletion funnel did not overlap with the land subsidence funnel. As to the factor of compressible strata, the places with the biggest compressible strata thickness did not have the largest vertical displacement. The distributions of building area and land subsidence have no obvious spatial relationships. The BPN-GA model simulation results illustrated that the accuracy of the trained model during fifty years is acceptable with an error of 51% of verification data less than 20 mm and the average of the absolute error about 32 mm. The BPN model could be utilized to simulate the general distribution of land subsidence in the study area. Overall, this work contributes to better understand the complex relationship between the land subsidence and three influencing factors. And the distribution of the land subsidence can be simulated by the trained BPN-GA model with the limited available dada and acceptable accuracy.     

Carbon dynamics in woody biomass of forest ecosystem in China with forest management practices under future climate change and rising CO2 concentration

It is critical to study how different forest management practices affect forest carbon sequestration under global climate change regime. Previous researches focused on the stand-level forest carbon sequestration with rare investigation of forest carbon stocks influ- enced by forest management practices and climate change at regional scale. In this study, a general integrative approach was used to simulate spatial and temporal variations of woody biomass and harvested biomass of forest in China during the 21st century under dif- ferent scenarios of climate and CO2 concentration changes and management tasks by coupling Integrated Terrestrial Ecosystem Carbon budget （InTEC） model with Global Forest Model （G4M）. The results showed that forest management practices have more predominant effects on forest stem stocking biomass than climate and CO2 concentration change. Meanwhile, the concurrent future changes in cli- mate and CO2 concentration will enhance the amounts of stem stocking biomass in forests of China by 12%-23% during 2001-2100 relative to that with climate change only. The task for maximizing stem stocking biomass will dramatically enhance the stem stocking biomass from 2001~100, while the task for maximum average increment will result in an increment of stem stocking biomass before 2050 then decline. The difference of woody biomass responding to forest management tasks was owing to the current age structure of forests in China. Meanwhile, the sensitivity of long-term woody biomass to management practices for different forest types （coniferous forest, mixed forest and deciduous forest） under changing climate and CO2 concentration was also analyzed. In addition, longer rotation length under future climate change and rising CO2 concentration scenario will dramatically increase the woody biomass of China during 2001~100. Therefore, our estimation indicated that taking the role of forest management in the carbon cycle into the consideration at regional or national level is very important to project the forest carbon sequestration under future climate change and rising atmospheric CO2 concentration.     

1956-2003年拉萨河流域径流变化趋势

Taking the Lhasa River Basin above Lhasa hydrological station in Tibetan Plateau as a study area, the characteristics of the annual and monthly mean runoff during 1956-2003 were analyzed, based on the hydro-data of the two hydrological stations （Lhasa and Tanggya） and the meteorological data of the three meteorological stations （Damxung, Lhasa and Tanggya）. The trends and the change points of runoff and climate from 1956 to 2003 were detected using the nonparametric Mann-Kendall test and Pettitt-Mann-Whitney change-point statistics. The correlations between runoff and climate change were analyzed using multiple linear regression. The major results could be summarized as follows： （1） The annual mean runoff during the last 50 years is characterized by a great fluctuation and a positive trend with two change points （around 1970 and the early 1980s）, after which the runoff tended to increase and was increasing intensively in the last 20 years. Besides, the monthly mean runoff with a positive trend is centralized in winter half-year （November to April） and some other months （May, July and September）. （2） The trends of the climate change in the study area are generally consistent with the trend of the runoff, but the leading climate factors which aroused the runoff variation are distinct. Precipitation is the dominant factor influencing the annual and monthly mean runoff in summer half year, while temperature is the primary factor in winter season.