Improving the forecast precision of river stage spatial and temporal distribution using drain pipeline knowledge coupled with BP artificial neural networks: a case study of Panlong River,Kunming, China     

Zhiqiang Xie  Qingyun Du  Fu Ren  Xiaowei Zhang  Sam Jamiesone 《Natural Hazards》2015,77(2):1081-1102

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Late Holocene (~ 2 ka) East Asian Monsoon variations inferred from river discharge and climate interrelationships in the Pearl River Estuary   总被引：1，自引：0，他引：1  

Qingyun Nan  Tiegang Li  Jinxia Chen  Rajiv Nigma  Xinke Yu  Zhaokai Xu  Zaibao Yang 《Quaternary Research》2014

A sediment core from the Pearl River Estuary (PRE) was analyzed for grain size and organic geochemistry parameters (TOC and δ¹³C_org). The results showed that high mean grain-size value and increased sand content were correlated with the high TOC and negative δ¹³C_org. These results indicated high river runoff in the PRE area. Peak river discharge occurred during the periods 1900–1750, 1500–1600, 1400–1200, 1000–900 and 750–600 cal yr BP. The main changes recorded in grain-size distributions, TOC contents, and δ¹³C_org variations appear to be directly related to monsoon precipitation in the sediment source area. An increased East Asian summer monsoon rainfall (EASM) and/or an enhanced East Asian winter monsoon rainfall could result in the increasing of monsoon rainfall. Typhoon related rainfalls could act as positive influence on precipitation levels. The study of the correlations between the rainfall records and ENSO activities revealed a close relationship between the monsoon rainfall in the PRE and the tropical Pacific variations. The frequent occurrence of ENSO might result in the southern migration of the EASM rain belt and lead to more typhoon-derived rainfall in the PRD during the late Holocene.  相似文献   

月球形状及其重力场EI北大核心CSCD     

李斐  郑翀  叶茂  郝卫峰  邓青云  张文松  郑英君  鄢建国  Jean-Pierre Barriot 《测绘学报》2022,51(6):897-908

本文首先从测绘科学与技术在月球探测中的应用角度,对月球形状及重力场的研究进展、获取方法及代表性成果进行了综述;进而针对现有的月球DEM及重力场模型中存在的主要问题进行分析,并提出了解决方案;最后结合各国的探月计划和我国正在实施的“嫦娥”四期工程,对月球形状和重力场研究面临的机遇和挑战进行了展望。  相似文献   

综合性大学一流GIS专业建设的探索与实践     

杜清运  任福  沈焕锋  张琛 《地理信息世界》2021,28(1):1-6

综合性大学一流本科专业建设是全面振兴本科教育、提高高校人才培养能力、实现高等教育内涵式发展的重要途径.从地理信息科学(GIS)专业学科依托切入,归纳了测绘地理信息行业特征,剖析了智能时代发展对GIS专业带来的新要求.并结合武汉大学GIS专业建设实践,探索专业建设思路和创新举措,从培养目标、师资建设、课程体系、教学模式、国际交流、质量保障等方面展开讨论,为推进国家一流专业建设提供参考.  相似文献   

Evaluation of phosphorus bioavailability in sediments of the shallow lakes in the middle and lower reaches of the Yangtze River region,China   总被引：3，自引：0，他引：3  

Shengrui Wang  Xiangcan Jin  Qingyun Bu  Haiqing Liao  Fengchang Wu 《Environmental Earth Sciences》2010,60(7):1491-1498

Phosphorus (P) fractions and their bioavailability in the sediments from the middle and lower reaches of the Yangtze River region were investigated using different chemical extraction methods. The results show that the contents of bioavailable P in the sediments extracted by different extraction procedures varied greatly. But their rank order was similar. Potentially releasable P (PRP) was the largest, followed by algal available P (AAP), NaHCO₃ extractable P (Olsen-P), water soluble P (WSP), and readily desorbable P. PRP contributed approximately 60% to total P (TP) in most sediments, AAP 20%, Olsen-P 15%, WSP 2%, and readily desorbable P (RDP) 0.5%. For the heavily polluted sediments, their bioavailable P extracted from TP mainly originated from inorganic P (IP), IP mainly originated from NaOH–P, the bioavailable P concentrations can be evaluated by measuring the concentrations of TP, NaOH–P, and IP. For the slightly polluted sediments, the bioavailable P can only be evaluated by different chemical extractable methods.  相似文献   

南充暴雨的季节内振荡特征     

高青云 《四川气象》1999,9(3):25-26

利用波谱对南充暴雨的季节内振荡进行了分析。结果表明：该地暴雨存在显著的周期倍和分叉特征，与夏季风季节内振荡十分一致。在长中短期暴雨中具有重要的可操作意义。  相似文献   

[Scholar＇＇s Introducation]——Prof. ＆ Ph. D DU Qingyun     

Du Qingyun 《地球空间信息科学学报》2003,6(3):75-76

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春季长江中下游旱涝的环流特征及对前期海温异常的响应   总被引：1，自引：0，他引：1  

李超  张庆云 《气象学报》2013,71(3):452-461

春季长江中下游降水有显着的年际、年代际变化特征,进入21世纪以来长江中下游春季降水偏少现象频繁发生.根据中国国家气候中心160站月平均降水资料和美国国家环境预报中心/国家大气研究中心(NCEP/NCAR)月平均再分析资料,重点探讨春季(3-5月)长江中下游地区降水异常的环流特征、可能成因、机理以及对外强迫的响应.春季长江中下游降水异常偏多(少)的环流主要特征是:高层200hPa风场上东亚副热带西风急流中心位置比气候态偏北(南);中层500hPa亚洲地区的阻塞高压主要发生在乌拉尔山(鄂霍次克海)附近、西太平洋副热带高压位置偏北(南);低层850hPa风场的东亚沿海地区为偏南(北)风距平,有利于(不利于)水汽向长江中下游地区输送.大气环流内部动力过程的分析指出:东亚地区上空Eliassen-Palm(EP)通量散度在40°N为正(负)异常、30°N为负(正)异常,有利于东亚高空西风急流中心位置偏北(南),从而导致春季长江中下游降水偏多(偏少).春季长江中下游降水异常偏多(少)年最显着的前期外强迫信号表现为赤道太平洋海温呈现厄尔尼诺(拉尼娜)型.  相似文献   

高有机质输入对底栖有孔虫的抑制作用——以西北太平洋菲律宾海MD06-3054孔为例   总被引：1，自引：1，他引：0  

陈双喜  南青云  李铁刚  唐正  仇晓华 《第四纪研究》2011,31(2)

底栖有孔虫古生产力指标-底栖有孔虫堆积速率(Benthic Foraminifera Accumulation Rate,简称BFAR)和小泡虫超科的Uvigerina与Bulimina两属在种群中的百分含量(简称"U+B含量")是目前古海洋学研究的常用方法.然而,从MD06-3054孔的记录中发现,两指标与有机质输入之间不仅不存在很好的线性关系.而且当有机质输入大于阀值时,两指标均随沉积物中总有机碳(Total Organic Carbon,简称TOC)含量的增加而明显地降低,说明过高有机质的输入还会抑制底栖有孔虫的生长和繁盛.另外,还发现当TOC含量较高时,U+B含量指标较BFAR指标相对更适用.  相似文献   

Redox conditions in sediments and during sedimentation in the Ontong Java Plateau, west equatorial Pacific     

路波  李铁刚  于心科  常凤鸣  南青云 《中国海洋湖沼学报》2011,29(6):1309-1324

Redox-sensitive elements in sediments, such as manganese (Mn), vanadium (V), molybdenum (Mo), and uranium (U), are promising indicators of past redox conditions during sedimentation and early diagenesis. However, in the Ontong Java Plateau, west equatorial Pacific, there are sparse datasets of redox-sensitive elements in sediment cores. Here, we present a 250 ka record of redox sensitive elements from a 460 cm gravity core at site WP7 (3°56′S, 156°E, water depth 1 800 m), which was recovered from the southwest Ontong Java Plateau during the 1993 cruise of R/V Science I of the Institute of Oceanology, Chinese Academy of Sciences (IOCAS). Relative to the Post-Archean Australian Shale (PAAS), authigenic Mn, cobalt (Co), nickel (Ni), Mo, V, U, and cadmium (Cd) were found at constantly low levels except when peaks occurred at several depth intervals. Manganese, Co, Ni, and Mo concentrations were elevated at 25-35 cm due to Mn redox cycling. The core was divided into three distinct sections, the top 0-25 cm being oxic, a suboxic section at 25-35 cm and from 35-460 cm which was anoxic. Differential authigenic enrichments of Co, Ni, Mo, V, U, and Cd at the same depth intervals were observed indicating that the enrichments happened during sedimentation or diagenesis and suffered no post settlement redox changes. Therefore, no significant changes in redox conditions during sedimentation must have happened. The water at depth on the Ontong Java Plateau during past 250 ka must have been well oxygenated, possibly resulted from the more or less continuous presence of oxygen-rich deep water like the modern Antarctic Intermediate Water (AAIW) and Antarctic Circumpolar Water (ACW); while it’s slightly less oxygenated in glacial intervals, possibly due to ventilation weakening and/or the surface productivity increase.  相似文献