山西近50a初霜冻的气候变化特征及其周期分析   总被引：1，自引：0，他引：1  

李芬  于文金  张建新  李娜  闫永刚 《南京气象学院学报》2012,(6):754-761

初霜冻13的变化对农业生产的布局和耕作模式具有一定的影响。利用山西62个气象观测站点1961－2010年的逐年初霜冻日及逐日最低地温资料,应用统计学方法分析了山西初霜冻日的变化特征,结果表明：1）山西近50a平均初霜冻日的时间分布总体为推后趋势,且具有明显的年代际特征,20世纪70年代、90年代初霜冻日提早显著,20世纪60年代、80年代和21世纪初霜冻日明显推后。2）山西近50a平均初霜冻日的空间分布为“5级阶梯”型分布,从9月中旬到11月上旬,自北向南相继出现初霜冻。3）M—K突变检验表明,山西近50a平均初霜冻日在1989年发生了一次显著的气候突变。4）山西近50a初霜冻日变化趋势的分布具有明显的区域特征,大部分地区初霜冻日有推后的趋势,但南部和中南部的部分地区初霜冻日有提前的趋势。5）Morlet小波分析结果表明,山西的初霜冻、轻微初霜冻、中度初霜冻和重度初霜冻发生的主周期分别为5a、2a、5a、6a;目前山西正处在初霜冻和轻微初霜冻的推后期、中度初霜冻和重度初霜冻的提前期。  相似文献   

独立周跳和非独立周跳在高次差法中的分析     

姚全德 《地理空间信息》2012,(3):88-90

GPS信号在传送过程中,载波相位由于受到信号的遮挡、干扰、接收机故障等原因的影响,引起整周计数部分突变,从而产生周跳。周跳会造成观测数据不准确,直接影响到GPS测量的精度。针对GPS周跳中存在独立周跳和非独立周跳的问题,依据高次差法的特征子序列对非差载波相位进行模拟分析,通过实验研究结果表明:高次差法能有效地探测出间隔2个历元的非独立周跳,但对于间隔3个以上的历元无能为力;连续周跳的情况对高次差法探测周跳的能力没有影响。  相似文献   

岩溶关键带水循环过程研究进展   总被引：1，自引：0，他引：1       下载免费PDF全文

吕玉香  胡伟  杨琰 《水科学进展》2019,30(1):123-138

岩溶关键带处于岩石、水、土壤、大气、生物五圈交汇地带。正确认识岩溶关键带的结构、功能及其水文循环过程是当前地球关键带与岩溶水科学研究的关键问题。剖析了岩溶关键带水循环过程与演变规律、水循环过程在岩溶关键带中的作用,探寻变化环境下岩溶关键带水循环过程演变的规律与驱动机制,总结不足与问题,提出未来研究的总体趋势和方向:岩溶关键带形成与演化和水循环过程相互作用机制;岩溶关键带水循环驱动的物质转化与能量迁移过程及其耦合;水循环过程在不同时空尺度上对全球变化与人类活动干扰的响应;多种观测与模拟手段的综合应用。  相似文献   

岩溶关键带及其碳循环研究进展   总被引：1，自引：0，他引：1  

吴泽燕  章程  蒋忠诚  罗为群  曾发明 《地球科学进展》2019,(5):488-498

岩溶关键带的范畴包含了大气-(降水)-植被-土壤-裂隙-基岩-水组成的“碳-水-钙”循环强烈的表层岩溶带以及岩溶管道-洞穴-地下河-隔水层组成的巨大岩溶地下空间,岩溶关键带碳循环是岩溶地球系统科学研究的前沿方向。总结概括了岩溶地球系统科学发展至今的岩溶关键带范畴内碳循环及其对大气CO2源汇效应的研究成果,包括早期碳运移模型、当前主流的区域岩溶碳汇量的计算方法和结果以及“生物碳泵”的新发现等,讨论了当前岩溶碳循环研究框架过于单一或不一致以及碳周转时间尺度等问题,提出应对岩溶关键带碳输入、赋存以及碳输出的各个环节做出系统化监测,通过联网在线高分辨率监测站点的建设以及“3S”技术实现点位到区域的研究,使岩溶碳汇在全球碳循环模型中的重要性更具说服力。  相似文献   

Understanding the Biogeochemical Process and Mechanism of Ecosystem Carbon Cycle from the Perspective of the Earth's Critical Zone     

Xuefa Wen  Xinyu Zhang  Jie Wei  Sidan Lü  Jing Wang  Changhua Chen  Xianwei Song  Jingyuan Wang  Xiaoqin Dai 《地球科学进展》2019,34(5):471-479

Previous research rarely considers the biogeochemistry process of the whole rock weathering layer-soil profile. The aim of Critical Zone science is re-understanding the structure and function of ecosystems from the canopy to bedrock, which emphasizes the relationship of material and energy between atmosphere and plant, between plant and soil, between soil and river in small watershed on the watershed scale. Carbon fixation and allocation are the key starting processes. Decomposition and transformation of soil carbon are the key turnover processes. Carbon migration and balance in small watershed are the key transfer processes. Further research is needed in the process, mechanism and ecology function of ecosystem carbon cycle from the canopy to bedrock based on the watershed scale. Carbon isotope technology has the function of indication, tracing and integration. Based on the ¹³C natural tracing and artificial labelling methods, we can further understand the process and mechnism of carbon biogeochemistry.  相似文献   

The State of Arts: Sources,Microbial Processes and Ecological Effects of Iron in the Marine Environment     

Shibo Feng  Yuelu Jiang  Zhonghua Cai  Yanhua Zeng  Jin Zhou 《地球科学进展》2019,34(5):513-522

Iron is the fourth most abundant element in the earth's crust, and it often appears as a trace element in the ocean. Iron has a variable valence and diverse functions, and is an important force to regulate marine primary productivity and drive the geochemical cycle in the ocean. Previous studies have shown that iron plays an important role in maintaining primary productivity, coupling matter cycles, and regulating the transformation of biogenic factors. In recent years, with the development of microbial ecology, iron research has enter more in-depth levels, including microbial-driven iron oxidation-reduction behavior, metabolic processes, and interactions with other major elements(C/N/P). This paper attempts to review the latest progress of iron, focusing on the published literatures of the past fifteen years. Firstly, we explained the sources and occurrence states of iron in the ocean (such as dissolved, colloidal, granular and organic state); Secondly, we reviewed the types and process mechanisms of microbial-mediated iron redoxbehavior (for example nitrate oxidation, and biological reduction, etc.); Finally, we summarized the coupling relationship between iron and C/N/P cycle. Additionally, the ecological roles of iron in specific ecological event (for instance algal bloom) has also been described. Furthermore, the "chemical-biological-physical" theoretical framework for marine iron research is also discussed. The purpose of this paper is to provide more information for marine microecological research and their effects on iron cycle under changing environment, such as global change.  相似文献   

Research on Climate Feedback of Human Water Use and Its Impact on Terrestrial Water Cycles —Advances and Challenges     

Zhenghui Xie  Si Chen  Peihua Qin  Binghao Jia  Jinbo Xie 《地球科学进展》2019,34(8):801-813

The terrestrial water cycle is the mutual transformation of surface and near-surface water, which controls the supply of fresh water resources. It is affected by human activities, solar radiation and gravity, as well as climate and environmental conditions. Inter-basin water transfer, irrigation, crop cultivation and harvesting, exploitation of groundwater water and other human activities lead to the change of spatial and temporal distribution of soil moisture, the underground water level, surface albedo, surface evaporation, as well as water and energy exchange between land surface and atmosphere. Human water use generates important feedback on the climate and changes the processes of the terrestrial water cycle significantly. The spatial and temporal distribution of precipitation in China is uneven. In addition, human activities further exacerbate the fragility of water resources and the contradiction between supply and demand, posing a serious challenge to the sustainable development of social economy. Therefore, understanding the laws and mechanisms of terrestrial water cycle change is very important for water resources utilization and human sustainable development. From the perspective of climate change and human activities, this paper summarized the impact of human activities on terrestrial water cycle and the progress of climate feedback research. It is urgent to consider the evolution of terrestrial water cycle and its climate under the dual impact of natural and human activities, and develop the large-scale land surface hydrological models and climate models with human water use, crop planting and irrigation, lateral groundwater flow. From the perspective of a fully coupled system, we need quantitatively to assess the climate feedback of human water use and its impact on the terrestrial water cycle process, and to explore its mechanism. We need to distinguish the contribution of human water activities and global climate change to the evolution of terrestrial water cycle in the context of climate change, and to propose water resources management strategies to address climate change.  相似文献   

山东城顶山地区牛山旋回火山岩地球化学特征及幔源分析     

殷天涛  李守军  司双印 《江苏地质》2019,43(4):553-559

通过探讨山东城顶山地区牛山旋回火山岩地球化学特征,对其幔源特征进行分析。地球化学特征分析结果表明城顶山地区的岩石为高钾岩石,具有贫硅铝、富镁钙的特征及明显的富钛特征;微量元素分析结果显示,大离子亲石元素Sr含量较高,牛山旋回火山岩的稀土元素总量∑REE在140～177μg/g之间,LREE/HREE在3.58～4.90之间,显示出岩浆分异程度低、分馏不明显的特点,分配型式为轻稀土弱富集型平缓的右倾曲线,与裂谷玄武岩相似,指示了其源区的特点,推测其来源为地幔物质熔融形成的原生岩浆。分析结果可作为进一步研究山东大陆碱性玄武岩的参考。  相似文献   

青海德令哈地区近400年来的降水量变化与太阳活动   总被引：19，自引：11，他引：8       下载免费PDF全文

黄磊  邵雪梅 《第四纪研究》2005,25(2):184-192

使用多种数学统计方法分析了德令哈地区降水量变化与太阳活动之间的关系,发现近400年来降水量的长期变化与太阳黑子周期长度(SCL)和太阳黑子周期上升支长度之间存在着较好的反相关关系,当SCL偏短、太阳黑子周期上升支长度偏短时,太阳活动偏强,德令哈地区降水量偏多,反之偏少。功率谱和小波分析发现降水量序列中存在着与太阳活动的多种周期相一致的周期,对降水量与太阳活动在不同时间尺度上周期变化之间的关系进行了详细分析。交叉小波分析发现太阳活动主要在百年左右尺度的周期变化上影响德令哈地区降水量的长期变化,太阳活动周期变化的信号越强,对降水量变化的影响越大。文章最后对太阳活动影响德令哈地区降水量变化的可能机制进行了探讨。  相似文献   

河流碳循环对全球变化的响应与反馈   总被引：10，自引：0，他引：10  

姚冠荣  高全洲 《地理科学进展》2005,24(5):50-60

河流连接陆地生态系统和海洋两大活动碳库,构成全球碳循环的一个关键环节。河流碳的输出及循环过程与近岸水域环境、海洋碳库变动及全球气候系统紧密相关。有机碳在全球碳循环系统中处于核心地位,了解河流有机碳通量及性质变化是目前河流碳循环研究的重要内容之一。流域面积的大小及气候和环境性质的差异对河流碳的输移及循环过程影响显著。目前,亚洲季风流域尤其是众多的小流域缺乏系统的有关悬移质生源要素的信息。陆地侵蚀-沉积过程控制着河流碳的主要来源和归宿。当前,人类活动主宰着陆地的侵蚀-沉积状况,这在很大程度上表现为加速了陆地生态系统碳库的扰动与再沉积,并加强了河流向海洋的碳输送。  相似文献