Effects of precipitation and landuse on runoff during the past 50 years in a typical watershed in the Loess Plateau, China

In the past century, great progress has been made worldwide in our understanding of forest-water relationship. The successful forestation programs implemented in China-which have improved the ecological environmental conditions-have gained the attention of many researchers and highlighted the relationship between forestation and water yields. The arid and semi-arid Loess Plateau has received attention from water engineers and eco-hydrological researchers in China because of a shortage in water resources. We selected one of the oldest stations conducting soil and water conservation experiments, the Xifeng soil and water conservation station, and chose the Nanxiaohe catchment and its paired catchments （Yangjiagou catchment and Dongzhuanggou catchment） as our research areas. Trends in precipitation, air temperature, streamflow over the past 50 years, and the effect of changing land use on streamflow were analyzed. The Mann-Kendall test showed that precipitation had a negative trend （downward trend）, whereas air temperature showed a positive trend （upward trend） from the past to present in the Nanxiaohe catchment. However, the trends seen in precipitation, air temperature did not contain any ＂jumping points.＂ The paired catchment approach is used to detect the effects of land cover change on hydrology in the Yangjiagou and the contrast catchment, i.e., Dongzhuanggou catchment in our study. The results showed a large change in land use in the Yangjiagou catchment from 1954 to 2008. An increase in forested land （from 0% to 40.08% from 1954 to 2008） and a reduction of bare land （from 51.26% to 5.50% from 1954 to 2008） accounted for a large part of the change in land use. However, the land use changed little in the contrast catchment. The comparison of streamfiow in the paired catchments showed that forestation reduced streamflow by 49.63% （or 6.5 mm） each year.     

空洞性肺结核的CT诊断

目的：分析空洞性肺结核的ＣＴ表现和特征,探讨ＣＴ诊断该病的可靠性。材料与方法：２１例空洞性肺结构病人均做胸部ＣＴ和胸片检查,分析ＣＴ所见并与病理、胸片对照,１０例经组织病理学证实。１１例痰检和临床证实。结果：（１）肺上叶尖后段及下叶背段为空洞性肺结核的好发部位;（２）空洞呈圆形或椭圆形,空洞外壁较光整,空洞壁常有钙化;（３）空洞所属支气管壁不规则增厚;（４）临近空洞胸膜局限性增厚;（５）空洞以外肺     

Rare Earth Element Geochemistry of Late Palaeozoic Coals in North China

Instrumental Neutron Activation Analysis (INAA) was done to determine the abundances of rare earth elements (REE) of 58 samples of Late Palaeozoic Carboniferous-Permian coals and related rocks in North China. Detailed study of REE geochemistry shows that the ∑REE of most coals studied in this paper is in a normal range between 30×10-6 and 80×10-6 with a mean of 56×10-6. The REE in the Taiyuan Formation in the northern part of North China are much richer than those in the southern part. This is due to the shorter distance to the source area in the north. Moreover, the IREE is in positive correlation to coal ash, especially closely related to the content of clay minerals <2μm in size. This reveals that most REE were carried by terrigenous clastic materials, especially fine clay minerals. In the coals the light REE (LREE) are much richer than the heavy REE (HREE), and the LREE/HREE ratio in coals generally varies from 2 to 8. The LREE/HREE ratio of high-ash, low-sulphur coals is higher than that of lo     

Effect of altitude error on position precision of double-star position system

IntroductionDouble-Star is to use two stationary orbit satellitesto locate the target which is located in the overlayarea of the the satellites’wave-beam. The two sat-ellites can only supply two equations. In order toget the three-dimensional position of…     

Impact of in-consistency between the climate model and its initial conditions on climate prediction

We investigated the influence of dynamical in-consistency of initial conditions on the predictive skill of decadal climate predictions. The investigation builds on the fully coupled global model “Coupled GCM for Earth Simulator” (CFES). In two separate experiments, the ocean component of the coupled model is full-field initialized with two different initial fields from either the same coupled model CFES or the GECCO2 Ocean Synthesis while the atmosphere is initialized from CFES in both cases. Differences between both experiments show that higher SST forecast skill is obtained when initializing with coupled data assimilation initial conditions (CIH) instead of those from GECCO2 (GIH), with the most significant difference in skill obtained over the tropical Pacific at lead year one. High predictive skill of SST over the tropical Pacific seen in CIH reflects the good reproduction of El Niño events at lead year one. In contrast, GIH produces additional erroneous El Niño events. The tropical Pacific skill differences between both runs can be rationalized in terms of the zonal momentum balance between the wind stress and pressure gradient force, which characterizes the upper equatorial Pacific. In GIH, the differences between the oceanic and atmospheric state at initial time leads to imbalance between the zonal wind stress and pressure gradient force over the equatorial Pacific, which leads to the additional pseudo El Niño events and explains reduced predictive skill. The balance can be reestablished if anomaly initialization strategy is applied with GECCO2 initial conditions and improved predictive skill in the tropical Pacific is observed at lead year one. However, initializing the coupled model with self-consistent initial conditions leads to the highest skill of climate prediction in the tropical Pacific by preserving the momentum balance between zonal wind stress and pressure gradient force along the equatorial Pacific.

     

基于高分辨率数值模拟的杭州市通风廊道气象效应研究

城市通风廊道能增加城市空气流通能力,缓解城市热岛,为了定量评估城市通风廊道的气象效应,本文采用区域边界层化学模式(RBLM-Chem),利用杭州市高分辨率地表类型、城市建筑等资料,开展了杭州市通风廊道影响的模拟研究,模式水平分辨率为250 m。本文针对冬季和夏季两个典型个例进行数值模拟和敏感性试验,夏季个例时间为2013年8月12日,盛行南风,风向顺着通风廊道;冬季个例时间为2014年1月28日,盛行东风,风向垂直于通风廊道。主要结论如下:城市绿色通风廊道有增加风速、降低气温、提高湿度的作用,与没有通风廊道的情况相比,夏季风顺着廊道方向时,廊道区域风速平均增加可达1.4 m/s,廊道区域内60 m高度风速平均增加可达1 m/s。而冬季风垂直于廊道时,廊道区域风速增加较小,仅有0.5 m/s左右。通风廊道夏季降温幅度平均可达2.7°C,冬季降温幅度较小,仅有0.6°C左右。通风廊道对气象场的影响随风向向下游延伸,夏季在通风廊道下游250 m处,风速增加、气温下降、相对湿度增加最大值分别为1.5 m/s、2.9°C、3.1%,即使在通风廊道下游1500 m处,最大降温仍有1.2°C。     

Dome A冰川学研究进展及深冰芯计划展望

目前,位于东南极冰盖分冰岭中心的冰穹-Dome A已成为深入理解南极冰盖演化、稳定性和找寻地球气候久远记录的研究热点。通过整理总结在Dome A获得的冰川学研究进展,结合国际冰芯科学研究计划(International Partnerships in Ice Core Sciences,简称IPICS)有关寻找最古老冰芯的相关资料,对Dome A的气象要素、地貌、冰厚、冰下地形、冰体流速、冰盖内部结构等环境特征进行归纳分析,讨论Dome A冰川学的最新发展及其对深冰芯钻探计划的影响,并分析概述Dome A深冰芯钻探需考虑的问题和未来发展动向。     

Modeling the adsorption of Cd (II), Cu (II), Ni (II), Pb (II) and Zn (II) onto montmorillonite

The adsorption of five toxic metallic cations, Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II), onto montmorillonite was investigated as a function of pH and ionic strength and a two-site surface complexation model was used to predict the adsorption data. The results showed that in the lower pH range, 3∼6 for Cd, Cu, Ni and Zn, and 3∼4.5 for Pb, the adsorption was greatly affected by ionic strength, while in the higher pH range, the adsorption was not. In the lower pH range, the metallic cations were mainly bound through the formation of outer-sphere surface on the permanently charged basal surface sites (≡X⁻), while in the higher pH range the adsorption occurred mainly on the variably charged edge sites (≡SOH) through the formation of inner-sphere surface complexes. Acid-base surface constants and metal binding constants for the two sites were optimized using FITEQL. The adsorption affinity of the five metallic cations to the permanently charged sites of montmorillonite was Pb > Cu > Ni ≈ Zn ≈ Cd, while that to the variable charged sites was Pb ? Cu > Zn > Cd > Ni.