Spatial and temporal variation of drought index in a typical steep alpine terrain in Hengduan Mountains     

Gno-feng Zhu  Ling Yang  Da-he Qin  Hua-li Tong  Yuan-feng Liu  Jia-fang Li 《山地科学学报》2016,13(7):1186-1199

This study describes the spatial and temporal variation of a drought index and makes inferences regarding the environmental factors that influence this variability in the Hengduan Mountains. A drought index is typically used to determine the moisture conditions and the magnitude of water deficiency in a given area. Based on data from 26 meteorological stations over the period 1960-2012, the spatial and temporal variations of the drought index were analyzed using a thin plate smoothing splines method that considered elevation as a covariate. The drought index was estimated based on the potential evapotranspiration (E₀) as defined by the Penman Monteith model modified by FAO (1998). The results of the reported analysis showed that the drought index in the Hengduan Mountains has been decreasing since 1960 at a rate of -0.008/a. This represented a progressive shift from the "sub-humid" class, which typified the wider area in the Hengduan Mountains, toward the "humid" class, which appeared in the Hengduan Mountains areas. The drought index was relatively high in the north and low in the south and the variation of the drought index varied with seasons. The drought index showed increasing trends in summer and autumn and it is greater in autumn than in summer, while it showed a decreasing trend in spring and winter. Drought index is inversely proportional to the soil relative humidity and Normalized Difference Vegetation Index (NDVI).  相似文献   

Characterization of genome-wide microsatellites of <Emphasis Type="Italic">Saccharina japonica</Emphasis> based on a preliminary assembly of Illumina sequencing reads     

Linan Zhang  Jie Peng  Xiaojie Li  Cuiju Cui  Juan Sun  Guanpin Yang 《中国海洋大学学报(英文版)》2016,15(3):523-532

Microsatellites or simple sequence repeats (SSR) function widely and locate dependently in genome. However, their characteristics are often ignored due to the lack of genomic sequences of most species. Kelp (Saccharina japonica), a brown macroalga, is extensively cultured in China. In this study, the genome of S. japonica was surveyed using an Illumina sequencing platform, and its microsatellites were characterized. The preliminarily assembled genome was 469.4 Mb in size, with a scaffold N₅₀ of 20529 bp. Among the 128370 identified microsatellites, 90671, 25726 and 11973 were found in intergenic regions, introns and exons, averaging 339.3, 178.8 and 205.4 microsatellites per Mb, respectively. These microsatellites distributed unevenly in S. japonica genome. Mononucleotide motifs were the most abundant in the genome, while trinucleotide ones were the most prevalent in exons. The microsatellite abundance decreased significantly with the increase of motif repeat numbers, and the microsatellites with a small number of repeats accounted for a higher proportion of the exons than those of the intergenic regions and introns. C/G-rich motifs were more common in exons than in intergenic regions and introns. These characteristics of microsatellites in S. japonica genome may associate with their functions, and ultimately their adaptation and evolution. Among the 120140 pairs of designed microsatellite primers, approximately 75% were predicted to be able to amplify S. japonica DNA. These microsatellite markers will be extremely useful for the genetic breeding and population evolution studies of kelp.  相似文献   

Northern-Hemisphere snow cover patterns and formation conditions in winter 2007 and 2012     

Hongyan Cui  Qi Shu  Long Yu 《中国海洋大学学报(英文版)》2016,15(3):407-413

The Arctic sea ice minimum records appeared in the Septembers of 2007 and 2012, followed by high snow cover areas in the Northern Hemisphere winters. The snow cover distributions show different spatial patterns in these two years: increased snow cover in Central Asia and Central North America in 2007, while increased snow cover in East Asia and northwestern Europe in 2012. The high snow cover anomaly shifted to higher latitudes in winter of 2012 compared to 2007. It is noticed that the snow cover had positive anomaly in 2007 and 2012 with the following conditions: the negative geopotential height and the related cyclonic wind anomaly were favorable for upwelling, and, with the above conditions, the low troposphere and surface air temperature anomaly and water vapor anomaly were favorable for the formation and maintenance of snowfalls. The negative geopotential height, cyclonic wind and low air temperature conditions were satisfied in different locations in 2007 and 2012, resulting in different spatial snow cover patterns. The cross section of lower air temperature move to higher latitudes in winter of 2012 compared to 2007.  相似文献   

Effects of changes in vegetation on precipitation in the northern Tianshan Mountains evaluated using multiple time scales     

Qinming Sun  Tong Liu  Zhiquan Han  Yongping Wu  Bai-Lian Li 《Journal of Earth System Science》2016,125(3):507-519

This study used a combination of the wavelet cross-correlation technique and numerical analysis of vegetative feedback to study the role of climate–vegetation feedback from 1981 to 2009 in the northern Tianshan Mountains, Xinjiang Province, China. The study area included the Irtysh River, the Bortala and Ili River valleys, the northern slopes of the Tianshan Mountains, and the western Junggar Basin. The feedback effects of changes in vegetation on precipitation appeared to vary in these five regions when different time scales are used to examine them. The most useful time scale was generally found to be 4–6 months. Time lag was another characteristic of this process, and the optimal time lag was 3–4 months. Nevertheless, optimal time scale and time lag did not differ significantly in these five regions. In this way, the correct time scale of the effects of variations in vegetation on precipitation in this cold, arid area was found. This time scale and time lag can be assessed through wavelet cross-correlation analysis. Then numerical analysis can be used to improve the accuracy of the analysis.  相似文献   

北京昌平高崖口-南口隐伏岩溶水系统地质构造新认识   总被引：2，自引：0，他引：2       下载免费PDF全文

雷晓东  关伟  郭彤  杨全合  胡圣标  郭高轩 《地质科学》2016,(1):116-127

高崖口-南口岩溶水系统是北京七大岩溶水系统之一,其东北部位于昌平南口,是隐伏岩溶地下水排泄区。查明该区地质构造发育情况,可以为评价岩溶水资源及北京优选战略后备水源地提供依据。本文在分析前人区域性重磁资料基础上,完成了5条总长30 km、总测点数626个的可控源音频大地电磁测深(CSAMT)剖面,采用SCS2D程序对CSAMT数据进行了二维反演解释,并实施了4眼勘探孔。物探和钻探研究结果表明:南口-孙河断裂是该系统的北东边界,走向北西,倾向南西,在雪山村附近断层落差达1017.5 m,是目前发现的断距最大的地区;断裂上盘蓟县系碳酸盐岩与侏罗系火山岩的地层界线,向西移动了2.4 km;南口山前断裂是山区裸露岩溶与平原隐伏岩溶的分界断裂,断裂走向北东,倾向南东,断距大于700 m,断裂上盘曹庄至南口一带有燕山期二长岩侵入,流村-葛村一带有燕山期闪长岩侵入。广泛发育的断层、岩体和火山岩,使这一区域岩溶含水层空间受到较大制约。  相似文献   

吉木萨尔凹陷芦草沟组烃源岩评价及页岩油富集条件探讨          下载免费PDF全文

邱振  陶辉飞  卢斌  吴晓智  杨智  唐勇  崔景伟  周杰 《地质科学》2016,(2):533-546

准噶尔盆地吉木萨尔凹陷芦草沟组为一套优质陆相烃源岩, 是我国当前页岩油气研究的热点地区之一.基于吉木萨尔凹陷18口井芦草沟组约为580 m岩心观察、薄片观察、地球化学测试等数据, 对芦草沟组烃源岩岩石类型、地球化学特征等方面开展了研究与评价, 结果表明: 1)芦草沟组烃源岩整体上为优质烃源岩, 且以Ⅰ-Ⅱ型有机质类型为主, 处于低熟至成熟阶段; 2)烃源岩主要划分为5种类型, 包括纯页岩、白云质页岩、纯泥岩, 白云质泥岩和粉砂质泥岩, 其有机质类型和丰度存在一定差异.综合研究得出, 吉木萨尔凹陷芦草沟组优质有效烃源岩的有机质丰度下限值为2.0%, 并认为TOC≥2.0%的烃源岩段也是该区页岩油发育的有利层段.  相似文献   

新探测仪器资料在短时强降水过程中的应用   总被引：1，自引：0，他引：1  

崔雅琴  张佃国  龚佃利  王洪  张骞  刘泉  张秋晨 《气象科技》2016,44(6):875-881

结合新一代多普勒天气雷达观测,利用德国RPG-HATPRO-G3型14通道并行地基微波辐射计观测的温度和液态水路径数据、THIES公司THIES CLIMA LNM型地面激光雨滴谱仪获取的地面雨强资料,综合分析了2015年8月3日济南短时强降水天气过程逆温层分布特征、液态水路径变化、雨滴谱特征分布及拟合分析。结果表明,由于受强对流降水过程中的潜热增温作用,大气中存在逆温层,且较强;液态水含量存在较强的短时积聚现象,降水前液态水含量路径起伏较大,跃增非常明显,伴随降水强度的减弱,液态水路径起伏减小;整个降水过程中,前期雨滴谱呈现双峰分布,强降水和后期降水为单峰谱,雨滴谱特征符合Gamma分布。  相似文献   

新疆准噶尔含煤盆地基本构造格架与认识   总被引：1，自引：0，他引：1  

王佟  冯帆  江涛  王庆伟  夏玉成  韦波  杨曙光 《地质学报》2016,90(4):628-638

基于盆地煤田构造与赋煤特征的综合分析,辅以准噶尔盆地西北、东北、东部和南部典型构造剖面的解析分析,厘清了准噶尔盆地的基本构造形态,呈现出如下规律:一是准噶尔现今构造格局于喜山运动中晚期定格,长期处于近南北向构造挤压应力场环境,总体具隆坳相间、南北分带、东西分块的构造格局;二是盆缘四周构造变形强烈,向盆内逐渐减弱且层次变浅,整体呈"环带"构造,反映出准噶尔盆地主体受控于周缘造山带和自盆缘向盆内挤压应力场的动力学、运动学和几何学特征;三是准噶尔盆地大规模聚煤作用是在早中侏罗世短暂的引张或弱挤压的区域构造应力场背景下完成的;四是准噶尔盆地周缘推覆带为可能的煤炭资源勘查开发远景区。  相似文献   

Efficiency and kinetics in treatment of wastewater from garages and residential oil spills using membrane bioreactor technology     

M. C. Sichinga  J. Frazee  A. Z. Tong 《International Journal of Environmental Science and Technology》2016,13(1):135-146

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A two-surface plasticity model for stiff clay   总被引：1，自引：1，他引：0  

P. Y. Hong  J. M. Pereira  A. M. Tang  Y. J. Cui 《Acta Geotechnica》2016,11(4):871-885

This paper presents a constitutive model for describing some important features of the behavior of natural stiff clay evidenced experimentally such as the limited elastic zone, the presence of strain hardening and softening, and the smooth transition from elastic behavior to a plastic one. The model, namely ACC-2, is an adapted Modified Cam Clay model with two yield surfaces: similarly to bounding surface plasticity theory, an additional yield surface—namely Inner yield surface—was adopted to account for the plastic behavior inside the conventional yield surface. A progressive plastic hardening mechanism was introduced with a combined volumetric-deviatoric hardening law associated with the Inner yield surface, enabling the plastic modulus to vary smoothly during loading paths. The main feature of the proposed model is that its constitutive equations can be simply formulated based on the consistency condition for the Inner yield surface, so that it can be efficiently implemented in a finite element code using a stress integration scheme similar to that of the Modified Cam Clay model. Furthermore, it is proved to be an appropriate model for natural stiff clay: the simulations of a set of tests along different mechanical loading paths on natural Boom Clay show good agreement with the experimental results.  相似文献