近30年京津冀地区冰雹的气候特征和突变分析   总被引：7，自引：0，他引：7  

闵晶晶  曹晓钟  段宇辉  刘还珠  王式功 《气象》2012,38(2):189-196

基于1979—2008年京津冀地区175个气象站的冰雹观测资料,应用气候趋势系数、倾向率、集中度和集中期,以及连续功率谱等方法,分析了京津冀地区及4个划分关键区冰雹发生的多时间尺度变化特征和变化趋势,并运用蒙特卡罗方法检验了气候趋势系数的显著性。结果表明：近30年该地区的冰雹有明显减少趋势,北部地区比南部地区减少幅度要大,山地区域比平原地区减少幅度大;基本上都存在2.0～2.5年的变化周期,该地区冰雹的发生具有准两年周期振荡的特征;南部平原冰雹发生的集中度最大,该区冰雹在年内发生时间最为集中;南部平原集中期较早,出现在6月初,其他几个关键区冰雹主要发生在6月底到7月初。应用气候要素累计距平曲线、Yamamoto方法进行了气候突变分析,结果表明京津冀地区冰雹在1993年发生了减少的突变,山地区域尤为显著。  相似文献   

1918—2010年天津降水指数变化特征   总被引：5，自引：0，他引：5       下载免费PDF全文

段丽瑶  刘爱霞  史珺 《气候变化研究进展》2012,8(3):171-177

利用天津1918—2010年逐日降水资料,分析了天津7个降水指数的长期变化趋势。结果发现:天津年降水量和降水日数年际差异较大,没有显著的趋势性变化。从1980年开始天津降水量和日数开始变小(少),方差也变小,四季中秋季降水量呈显著的增加趋势,夏季呈减少趋势,冬、春季变化较小。各极端降水指数中,均表现为线性趋势不明显,年际变化较大,20世纪90年代以来降水强度偏小,但呈缓慢的增加趋势,大雨日数也处于偏少阶段,大雨贡献率偏小,并呈减小趋势。四季中秋季连续5 d最大降水量呈显著的增加趋势,减少了秋季干旱的发生,最长连续无降水日数多发生在冬春季,近年来有增加的趋势。  相似文献   

旋回地层学研究现状和新进展   总被引：2，自引：2，他引：0  

陈留勤  段凯波  霍荣 《新疆地质》2009,27(3)

旋回地层学作为一门独立的地层分支学科诞生于20世纪80年代,它以米兰科维奇天文轨道旋回为理论基础,以露头剖面、岩心等为研究对象,应用地球化学、光谱分析和时间序列分析等方法,研究天文轨道参数周期性变化在地层记录中的沉积响应.旋回地层学的基本地层单位米级旋回,相当于层序地层概念体系中的准层序,二者相互联系又存在差异."天文地质年代表"的提出和"国际地质年表"把天文轨道因素作为确定地质年代的一种重要方法,突出显示旋回地层学在定量确定地质年代方面的优势.近年来在地层记录中识别出时间分辨率更高的亚米兰科维奇旋回信号不仅是该学科最新进展,也是沉积学和地层学新的生长点.  相似文献   

Geochemical constraints on mixed source and hydrocarbon filling process in the Yingjisu Sag,Tarim Basin,Xinjiang     

Lingyun Pang  Xiangchun Chang  Mingzhen Wang  Xinghe Yu  Lixin Ma  Yunge Duan 《中国地球化学学报》2009,28(3):308-313

The Yingjisu Sag was petroliferous for normal oil, condensate oil, reservoir bitumen and natural gases. Geochemical studies showed that natural gases in the Yingjisu Sag were a gas mixture consisting mainly of Cambrian pyrolysis gas, Jurassic condensate oil in well Yingnan 2 and normal oil in well Tadong 2, reflecting the characteristics of marine-phase gases and oils, while crude oils in well Longkou 1 demonstrated the characteristics of both marine and terrestrial oils, which were derived from lower algae and higher plants. Jurassic oils from wells Longkou 1 and Huayingcan 1 and Cambrian crude oils from well Tadong 2 were derived mainly from Cambrian-Lower Ordovician source rocks. Jurassic and Silurian reservoir bitumens from well Yingnan 2 were biodegradated, suggesting they are of marine and terrestrial origins. The bitumens have similar geochemical characteristics, which are correlated well with Ordovician crude oils from well Tadong 2 and Jurassic condensate oil from well Yingnan 2. Based on the characteristics of tectonic evolution in this area and the analysis of hydrocarbon accumulation, the constraints on the mixed source and hydrocarbon filling process in the Yingjisu Sag were brought forward.  相似文献   

Driving forces behind land use and cover change in the Qinghai-Tibetan Plateau: a case study of the source region of the Yellow River,Qinghai Province,China   总被引：3，自引：1，他引：2  

Xiang Song  Guoxian Yang  Changzhen Yan  Hanchen Duan  Guangyue Liu  Yanling Zhu 《Environmental Earth Sciences》2009,59(4):793-801

Research on land use and cover change (LUCC) is an important aspect of the study of global change or global warming. The Qinghai-Tibetan Plateau is a good place to study global change because of its unique natural conditions, so we chose the source region of China’s Yellow River for a case study of the driving forces behind LUCC. We used Landsat images obtained in 1989, 2000, and 2005 to establish databases of land use and cover at these times. We then derived LUCC information by overlaying these layers using GIS software. By studying the processes responsible for LUCC, we analyzed the driving forces, which included climatic change, human activities, animal and insect damage, and the influences of government policies. During the 16-year study period, LUCC occurred slowly in response to two groups of processes: natural and anthropogenic. The main driving forces included climate change (the region is becoming drier and warmer), human activities (especially overgrazing), and animal and insect damage. Although political measures such as key national projects to improve the ecological environment could help to restore the region’s vegetation and slow desertification, the region’s fragile ecosystems and harsh natural conditions will make it extremely difficult to rehabilitate the eco-environment.  相似文献   

农业气象类科技成果推广应用经济效益分析方法探讨   总被引：2，自引：0，他引：2  

徐凤梅  王红红  段越林  祝永锋  王伟  冉献忠 《气象与环境科学》2008,31(1):45-47

以科技部农业科技成果转化项目"黄淮平原农业干旱监测预警及综合防御技术推广应用"为例,对科学技术进步奖经济效益分析项目逐项解析后得出:该项目推广应用经济效益显著,对农业经济的贡献主要是节约开支、减少水资源和作物秸秆的无效浪费,对于培肥地力、改善作物的土壤生态环境以及对当季和下茬作物高产具有十分重要的意义.但对于改善生态环境而获得的生态效益分析方法,需利用其他指标进一步探讨.  相似文献   

辽西建昌盆地九佛堂组珍稀化石层的划分与对比   总被引：1，自引：0，他引：1  

段冶  张立君  张立军  胡东宇 《地质科学》2010,45(2):606-613

为研究热河生物群的鸟类、爬行类和被子植物的早期演化、辐射迁移、生物多样性及其协同进化,笔者在建昌盆地测制了九佛堂组剖面,并系统采集了以珍稀化石为重点的生物化石。结合前人研究成果,将九佛堂组自下而上分为第一段至第三段,其中九佛堂组第一段西店层含鸟类、爬行类和龟类等珍稀化石,尚见介形类化石Cypridea decorosa,C.jianchanensis,Yumenia jianchanensis,Limnocypridea slundensis,L.levigata,L.rara等,表明该层的介形类化石与喀左九佛堂小孤山—烧锅地剖面及朝阳县波罗赤小北山—黄道营子剖面的九佛堂组第一段下部介形类化石组合面貌基本一致,其所在层位亦应相当。  相似文献   

三峡库区优质柑橘产业带建设土地整理模式     

张仕超  尚慧  余端  魏朝富 《地理研究》2011,30(11):2099-2108

以三峡库区优质柑橘产业带建设土地整理模式研究为目标,以重庆市万州区甘宁镇永胜等两个村土地整理项目（标准化柑橘园）为例,从工程、生物技术方面探讨了改土和配套农业产业化基础设施建设。研究表明：以三峡库区优质柑橘产业带建设目标的土地整理模式必须立足库区复杂多样的立地条件和生态一经济功能差异,配套服务早、中、晚熟不同柑橘品种产...  相似文献   

The luminescence dating chronology of a deep core from Bosten Lake (NW China) in arid central Asia reveals lake evolution over the last 220 ka     

Guoqiang Li  Yanwu Duan  Xiaozhong Huang  Jan‐Pieter Buylaert  Wei Peng  David B. Madsen  Zhiguo Rao  Linlin She  Haichao Xie  Jianhui Chen  Fahu Chen 《Boreas: An International Journal of Quaternary Research》2017,46(2):264-281

The lacustrine deposits of lakes in arid central Asia (ACA) potentially record palaeoclimatic changes on orbital and suborbital time scales, but such changes are still poorly understood due to the lack of reliable chronologies. Bosten Lake, the largest freshwater inland lake in China, is located in the southern Tianshan Mountains in central ACA. A 51.6‐m‐deep lacustrine succession was retrieved from the lake and 30 samples from the succession were used for luminescence dating to establish a chronology based on multi‐grain quartz OSL and K‐feldspar post‐IR IRSL (pIRIR₂₉₀) dating. Quartz OSL ages were only used for samples from the upper part of the core. The K‐feldspar luminescence characteristics (dose recovery test, anomalous fading test, first IR stimulation temperature plateau test) are satisfactory and from the relationship amongst the quartz OSL, IR₅₀ and pIRIR₂₉₀ doses we infer that the feldspar signals are likely to be well bleached at deposition. Bacon age‐depth modelling was used to derive a chronology spanning the last c. 220 ka. The chronology, lithology and grain‐size proxy record indicate that Bosten Lake formed at least c. 220 ka ago and that lake levels fluctuated frequently thereafter. A stable deep lake occurred at c. 220, 210–180, c. 165, 70–60, 40–30 and 20–5 ka, while shallow levels occurred at c. 215, 180–165, 100–70, 60–40 and 30–20 ka. Bosten Lake levels decreased by at least ~29 m and possibly the lake even dried up between c. 160 and c. 100 ka. We suggest that the water‐level fluctuations in the lakes of ACA may not respond directly to climatic changes and may be affected by a number of complex factors.  相似文献   

Monitoring and Analysis of Land Subsidence Along Beijing-Tianjin Inter-City Railway     

Duan GuangYao  Gong HuiLi  Liu Huanhuan  Zhang Youquan  Chen BeiBei  Lei KunChao 《Journal of the Indian Society of Remote Sensing》2016,44(6):915-931

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