2001年华西秋雨时空分布特点及其成因分析

分析了2001年华西秋雨的时空分布特点和大尺度环流背景及天气系统的主要特征, 并对秋雨形成的主要物理机制进行了诊断和分析。结果显示, 2001年秋季, 华西地区阴雨日数多, 雨区集中, 强降水时段集中在9月份。该月, 巴尔喀什湖地区500 hPa呈准稳定的低压槽, 其上不断有短波分裂东移, 携带冷空气经高原东移, 与强大的副热带高压西南侧的东南暖湿气流和来自孟加拉湾的西南暖湿气流交汇于四川盆地、陇南、陕南一带, 致使该地区持续阴雨天气。诊断分析表明, 9月, 青藏高原地区对流旺盛, 水汽凝结释放潜热, 使其成为一个强大的热源中心; 而江淮、江南一带多受西北太平洋副热带高压控制, 盛行下沉气流, 为热源低值区; 四川盆地处于高原高能量带与盆地以东低能量带之间的能量锋区。此能量锋区的存在促使从巴尔喀什湖低压槽分裂东移的短波槽在该地区发展。同时, 东路冷空气的渗入进一步加大了能量锋区的强度, 激发不稳定能量释放, 造成了四川盆地部分地区出现大暴雨甚至特大暴雨。     

Multifractal features of the particle-size distribution of suspended sediment in the Three Gorges Reservoir,China

The Three Gorges Reservoir(TGR)in China is the largest hydroelectric project in the world,but the threat of sediment affecting ecological sustainability of the reservoir is a topic of concern.Sediment particlesize distribution(PSD)is informative in understanding sediment transport dynamics and biochemical functions.It is,therefore,important to quantitatively characterize the distribution of sediment particles.In the current study,fractal theory is applied to determine the PSD of suspended sediment in the TGR.The results show that the volumetric fractal dimension(D_v)exhibits a significant seasonal difference(p<0.05),reflecting sediment source and hydrodynamic sorting control the granularity of suspended sediment in the TGR.More specifically,suspended sediment particles are coarser in the wet season than in the dry season for the Yangtze River,and the opposite is true for the Ruxi River,an important tributary.The generalized dimension spectrum,D(q)-q,and multifractal singularity spectrum,f[α(q)]-α(q),were calculated for each suspended sediment sample.Thereafter,the parameters,D(0),D(1),D(2),α(0),Δα(q),andΔf[α(q)],were determined to characterize the PSD.As a result,the coarser suspended sediment during the wet season is characterised by a more complex PSD pattern,with a wider range of particle sizes,greater heterogeneity,and greater homogeneity of distribution over the measurement interval.However,the multifractal structure of the PSD of suspended sediment is more complex during the dry season than during the wet season,with higher local dispersion and variability.The findings of the current study highlight that multifractal analysis provides important insight for understanding the PSD of suspended sediment in the TGR.     

基于WebGIS的区域自动气象站数据综合处理系统的研发

通过研究各厂家自动气象站的数据采样方式、存储方式,运用WebGIS和数据库技术,采用asp．net开发平台,设计开发了一套基于WebGIS的自动气象站数据查询系统,使多厂家气象自动站数据在同一界面显示,提供多种形式的统计查询,方便用户分析和应用。成果可为相似系统的开发提供关键技术和方法方面的借鉴。     

Delayed impacts of the El Niño episodes in the central Pacific on the summertime climate anomalies of eastern China in 2003 and 2007

In the summers of 2003 and 2007, eastern China suffered similar climate disasters with severe flooding in the Huaihe River valley and heat waves in the southern Yangtze River delta and South China. Using SST data and outgoing longwave radiation (OLR) data from NOAA along with reanalysis data from NCEP/NCAR, the 2002/03 and 2006/07 El Nino episodes in the central Pacific and their delayed impacts on the following early summertime climate anomalies of eastern China were analyzed. The possible physical progresses behaved as follows: Both of the moderate El Nino episodes matured in the central equatorial Pacific during the early winter. The zonal wind anomalies near the sea surface of the west-central equatorial Pacific excited equatorial Kelvin waves propagating eastward and affected the evolution of the El Ni\~no episodes. From spring to early summer, the concurring anomalous easterly winds in the central equatorial Pacific and the end of upwelling Kelvin waves propagating eastward in the western equatorial Pacific, favored the equatorial warm water both of the SST and the subsurface temperature in the western Pacific. These conditions favored the warm state of the western equatorial Pacific in the early summer for both cases of 2003 and 2007. Due to the active convection in the western equatorial Pacific in the early summer and the weak warm SST anomalies in the tropical western Pacific from spring to early summer, the convective activities in the western Pacific warm pool showed the pattern in which the anomalous strong convection only appeared over the southern regions of the tropical western Pacific warm pool, which effects the meridional shift of the western Pacific subtropical high in the summer. The physical progress of the delayed impacts of the El Ni\~no episodes in the central equatorial Pacific and their decaying evolution on the climate anomalies in eastern China were interpreted through the key role of special pattern for the heat convection in the tropical western Pacific warm pool and the response of the western North Pacific anomalous anticyclone.     

近千年青藏高原的温度变化

Temperature variations on the Tibetan Plateau during the last millennium are revealed by comparing a Qamdo tree-ring δ13C, the Dasuopu ice-core δ18O series, and a previous composite temperature reconstruction. Results show that an obvious warm period during 1200-1400 AD corresponds to the Medieval Warm Period (MWP) when summer temperature was 1.2℃ higher than the recent 1000 years average, and a cool phase from 1400 to 1700 AD, with summer temperature being 0.5℃lower than long-term average, can be correlated to the Little Ice Age (LIA). The 13th century was the warmest phase during the past 1000 years, while the coldest period occurred during 1000-1200 AD. The 20th century warming was characterized by rapid winter temperature rise while summer temperature at that time displayed a slight downward trend.     

Influences of environmental changes on water storage variations in Central Asia

The spatio-temporal pattern of the global water resource has significantly changed with climate change and intensified human activities. The regional economy and ecological environment are highly affected by terrestrial water storage (TWS), especially in arid areas. To investigate the variation of TWS and its influencing factors under changing environments, the response relationships between TWS and changing environments (climate change and human activities) in Central Asia have been analyzed based on the Gravity Recovery and Climate Experiment (GRACE) data, Climatic Research Unit (CRU) climate data and Moderate Resolution Imaging Spectroradiometer (MODIS) remote sensing data products (MOD16A2, MOD13A3 and MCD12Q1) from 2003 to 2013. The slope and Pearson correlation analysis methods were used. Results indicate that: (1) TWS in about 77 % of the study area has decreased from 2003 to 2013. The total change volume of TWS is about 2915.6 × 10⁸ m³. The areas of decreased TWS are mainly distributed in the middle of Central Asia, while the areas of increased TWS are concentrated in the middle-altitude regions of the Kazakhstan hills and Tarim Basin. (2) TWS in about 5.91% of areas, mainly distributed in the mountain and piedmont zones, is significantly positively correlated with precipitation, while only 3.78% of areas show significant correlation between TWS and temperature. If the response time was delayed by three months, there would be a very good correlation between temperature and TWS. (3) There is a significantly positive relationship between TWS and Normalized Difference Vegetation Index (NDVI) in 13.35% of the study area. (4) The area of significantly positive correlation between TWS and evapotranspiration is about 31.87%, mainly situated in mountainous areas and northwestern Kazakhstan. The reduction of regional TWS is related to precipitation more than evaporation. Increasing farmland area may explain why some areas show increasing precipitation and decreasing evapotranspiration. (5) The influences of land use on TWS are still not very clear. This study could provide scientific data useful for the estimation of changes in TWS with climate change and human activities.     

中国西北干旱区小冰期的湿度变化特征

选取中国西北干旱区11 条具有明确古湿度指示意义的气候记录, 结合冰芯、地层沉积、 湖泊沉积、树木年轮、河流阶地等各种研究资料和历史记载, 研究中国西北干旱区小冰期的湿 度变化。结果表明研究区小冰期(1400-1920 AD) 从整体而言处于相对湿润的阶段: 区内高大 山系降水处于较高时段- -西昆仑山古里雅冰芯积累量增大, 天山山间湖泊水位回升, 祁连山 敦德冰芯孢粉总浓度增加; 而盆地内流系统水量也出现了相应的变化- -塔里木盆地克里雅 河和塔里木河流量增大, 准噶尔盆地艾比湖水位上升, 巴丹吉林沙漠地下水补给量上升, 居延 海入湖水量增大, 湖面扩展, 青海湖盆地降水增加, 有效湿度增大, 苏干湖水体盐度降低, 入湖 水量/ 蒸发量之比升高。同时, 较高分辨率的湿度资料显示, 研究区东-南边缘地带在小冰期 内部存在次一级的干湿波动, 两个湿度较高的时期出现在16 世纪和18 世纪, 分别与小冰期内 部的两个相对温暖时期有很好的对应。中国西北相对湿润的小冰期主要是西风带强度增加和 位置南移造成该区域降水增多和全球性普遍降温导致有效湿度增大两个因素共同作用的结果, 研究区边缘地带小冰期内部冷干暖湿的配置则主要体现了夏季风的影响。     

郴县铜金岭含锡石铁帽研究

含锡石铁帽系铜金岭原生含锡多金属矿床经次生氧化、分解作用后,机械地堆积于表生带和其附近洼地的微喀斯特化灰岩的次生氧化富集带的产物。锡石主要来源于云母-萤石交代岩脉带的锡矿体(化)。是湘南寻找和预测高-中温岩浆热液型锡多金属矿床的重要地质标志     

微波在高纯石英提纯实验中的应用

随着水晶资源的日益枯竭,利用脉石英制备高纯石英以代替水晶已经成为一项需要迫切解决的技术问题。高纯石英中,铁杂质是最主要同时也是对产品质量影响最大的有害杂质之一,如何有效地除去脉石英中的铁杂质一直就是高纯石英生产中的难点和重点。当前主要是用酸浸的方法降低铁杂质的含量,主要存在的问题是处理时间较长,同时铁杂质含量也不容易降得更低。通过对微波在高纯石英提纯实验中应用的研究,表明微波可以有效地“打开”石英矿物中含铁的包裹体,不仅能促进含铁杂质矿物的酸浸去除,还可以极大地加快酸浸的速度,促进高纯石英的生产,同时为微波技术在高纯石英生产中的应用奠定了坚实的基础。