基于SVD和修正Z指数的汛期旱涝预测及其应用   总被引：2，自引：0，他引：2  

周后福  方茸  张建军  钱玉萍 《气候与环境研究》2010,15(1):64-72

利用奇异值分解(SVD)方法、500hPa高度场、太平洋海温场和降水资料,建立起汛期降水的预测方程;经过适应本地化的Z指数修正,将预测结果转化为旱涝等级;将SVD技术与修正的Z指数结合起来,实现旱涝的气候预测;将研究成果推广应用到气象、防汛抗旱部门。结果表明:1)影响江淮分水岭地区汛期降水的因子有5个,分别是太平洋地区2个,印度半岛附近2个,欧洲地区1个;2)理论上的Z指数等级不符合江淮分水岭地区的实际状况,因而必须对Z指数进行修正。经过修正后的各个旱涝等级的划分概率较为合理,说明Z指数的5级指标是可靠的;3)利用5个影响因子可以建立汛期降水量与影响因子之间的预报方程,在共计8年的旱涝滚动预测和实况检验中,等级相符的有7年,只有2003年的预测试验相差一个等级,5级的预测准确率达到87.5%;4)经过气象、防汛抗旱部门2008年的应用,旱涝等级的预测意见和实际基本吻合,说明预测技术的应用情况良好。  相似文献   

Temporal Characteristics of Pacific Decadal Oscillation (PDO) and ENSO and Their Relationship Analyzed with Method of Empirical Mode Decomposition (EMD)   总被引：3，自引：1，他引：3  

HE Juanxiong  YU Zhihao  YANG Xiuqun 《Acta Meteorologica Sinica》2005,19(1):83-92

1. IntroductionPacific Decadal Oscillation (PDO) is a long-termENSO-like variability of the North Pacific. It can becharacterized by the first principal component of EOFof the North Pacific SST (Zhu and Yang, 2003; Tren-berth, 1990; Yang and Zhang, 2003). ENSO is thestrongest signal of annular change of global climatesystem (Trenberth, 1997). The spatial pattern of PDOis a wedge similar to El Nino. In the cool (warm)phases of PDO, the central and northwest Pacific is ofwarm (co…  相似文献   

中国重力异常的小波变换与多尺度分析   总被引：111，自引：19，他引：111       下载免费PDF全文

侯遵泽  杨文采 《地球物理学报》1997,40(1):85-95

阐述了小波变换及多尺度分析方法的原理，利用二维小波多尺度分析方法对中国布格重力异常进行了分解，并从其中划分出有意义的剩余异常．模型结果证明方法有效．由于本文方法可以将重力异常分解成各种几何尺度意义下的不同成分，这为重力解释和研究地壳的结构提供更多更新的依据．  相似文献   

Flood pattern and weather determine Populus leaf litter breakdown and nitrogen dynamics on a cold desert floodplain     

D.C. Andersen  S.M. Nelson 《Journal of Arid Environments》2006,64(4):626-650

Patterns and processes involved in litter breakdown on desert river floodplains are not well understood. We used leafpacks containing Fremont cottonwood (Populus deltoides subsp. wislizenii) leaf litter to investigate the roles of weather and microclimate, flooding (immersion), and macroinvertebrates on litter organic matter (OM) and nitrogen (N) loss on a floodplain in a cool-temperate semi-arid environment (Yampa River, northwestern Colorado, USA). Total mass of N in fresh autumn litter fell by 20% over winter and spring, but in most cases there was no further N loss prior to termination of the study after 653 days exposure, including up to 20 days immersion during the spring flood pulse. Final OM mass was 10–40% of initial values. The pattern of OM and N losses suggested most N would be released outside the flood season, when retention within the floodplain would be likely. The exclusion of macroinvertebrates modestly reduced the rate of OM loss (by about 10%) but had no effect on N dynamics over nine months. Immersion in floodwater accelerated OM loss, but modest variation in litter quality did not affect the breakdown rate. These results are consistent with the concept that decomposition on desert floodplains progresses much as does litter processing in desert uplands, but with periodic bouts of processing typical of aquatic environments when litter is inundated by floodwaters. The strong dependence of litter breakdown rate on weather and floods means that climate change or river flow management can easily disrupt floodplain nutrient dynamics.  相似文献   

Effect of hematite on thiosulphate leaching of gold     

D. Feng  J.S.J. van Deventer 《International Journal of Mineral Processing》2007

Hematite, as a typical iron oxide slime in sulphide ore slurries, was artificially added into the leaching systems of pure gold and a sulphide ore respectively, in an attempt to investigate the effect of iron oxide slimes on the ammoniacal thiosulphate leaching of gold. The presence of hematite significantly reduced the dissolution of gold and this detrimental effect became more pronounced with increasing hematite concentration. Hematite formed coatings on gold surfaces, which could prevent leach solution from diffusing to the gold surfaces and hence, inhibit gold dissolution. Hematite catalysed the oxidative decomposition of thiosulphate to polythionates with oxygen present. XPS studies indicated a thin layer of iron oxide coating as well as the deposition of some copper and sulphur species on gold surfaces. SEM images revealed a lesser extent of corrosion for gold after leaching in the presence of hematite. The gold extraction from the sulphide ore was reduced with the addition of hematite and this effect became more noticeable with an addition of hematite at a higher concentration. A natural guar type surfactant (Gempolym M47) reduced the detrimental effect of hematite on gold extraction likely due to the prevention of hematite coating on gold and mineral particles and the dispersion of the mineral slurry. Gempolym M47 stabilised thiosulphate by weakening the interaction between cupric ions and thiosulphate and by minimising the catalytic effect of hematite on thiosulphate decomposition.  相似文献   

腐解9个月后杉木枯枝落叶化感物质对杉木的化感作用   总被引：5，自引：0，他引：5  

曹光球  刘学芝  林思祖  胡宗庆  王凌霄 《亚热带资源与环境学报》2007,2(2):15-20

采用有机溶剂与蒸馏水混和浸提杉木枯枝落叶腐解9个月后化感物质,应用杉木种子发芽试验进行生物检测.结果表明:杉木枯枝落叶腐解9个月后,杉木枯枝落叶中的弱极性化感物质对绝对发芽率、绝对发芽势、胚根长、胚轴长及干物质量等指标表现为抑制作用,对鲜物质量则表现为轻微的促进作用;极性化感物质对杉木种子发芽各指标均等表现为抑制作用.腐解土中的弱极性化感物质对杉木种子发芽各指标均表现为抑制作用,极性化感物质对绝对发芽率、绝对发芽势、胚轴长及干物质量等表现为抑制作用,但对胚根长、鲜物质量表现为促进作用.  相似文献   

腐解9个月后杉木枯枝落叶化感物质对杉木的化感作用     

曹光球  刘学芝  林思祖  胡宗庆  王凌霄 《福建地理》2007,(2)

采用有机溶剂与蒸馏水混和浸提杉木枯枝落叶腐解9个月后化感物质,应用杉木种子发芽试验进行生物检测.结果表明:杉木枯枝落叶腐解9个月后,杉木枯枝落叶中的弱极性化感物质对绝对发芽率、绝对发芽势、胚根长、胚轴长及干物质量等指标表现为抑制作用,对鲜物质量则表现为轻微的促进作用;极性化感物质对杉木种子发芽各指标均等表现为抑制作用.腐解土中的弱极性化感物质对杉木种子发芽各指标均表现为抑制作用,极性化感物质对绝对发芽率、绝对发芽势、胚轴长及干物质量等表现为抑制作用,但对胚根长、鲜物质量表现为促进作用.  相似文献   

InSAR相位分解及其在生成DEM和研究地震形变场中的应用   总被引：1，自引：1，他引：1       下载免费PDF全文

罗小军  黄丁发  刘国祥 《地震工程学报》2006,28(3):204-209,190

InSAR是极具发展潜力的微波遥感新技术,可应用于数字高程模型的产生、制图和大范围微小地表形变的测量。考虑参考面、地形和地表形变等因素,本文从几何角度分析和讨论了In-SAR的相位分解,并给出了各相位分量的函数表达式,阐述了地表高程和形变信息提取的基本原理。最后以JERS和ENVISAT卫星数据为例,展示了合成孔径雷达干涉测量在生成数字高程模型和提取地震形变场中的应用及其数据处理过程。  相似文献   

500hPa环流变化与山东春季降水异常   总被引：2，自引：1，他引：1  

高留喜  安兴琴  刘秦玉  黎清才  高慧君 《气象科学》2004,24(4):440-447

应用SVD技术,诊断分析了北半球500hPa高度场与山东春季降水的关系。结果表明：山东春季降水与北半球500hPa高度场关系密切,山东春季降水与东亚上空500hPa高度场具有很好的同步联系。前期(冬季)日本东北部500hPa高度场是影响山东南部春季降水的关键区,具有预测意义。500hPa高度距平场东高西低型是造成山东春季降水的主要大气环流形势,西高东低型是造成山东少雨的主要大气环流形势。  相似文献   

Ab initio study of the high-pressure behavior of CaSiO3 perovskite     

Daniel Y. Jung  Artem R. Oganov 《Physics and Chemistry of Minerals》2005,32(2):146-153

Using density functional simulations, within the generalized gradient approximation and projector-augmented wave method, we study structures and energetics of CaSiO₃ perovskite in the pressure range of the Earths lower mantle (0–150 GPa). At zero Kelvin temperature the cubic CaSiO₃ perovskite structure is unstable in the whole pressure range, at low pressures the orthorhombic (Pnam) structure is preferred. At 14.2 GPa there is a phase transition to the tetragonal (I4/mcm) phase. The CaIrO₃-type structure is not stable for CaSiO₃. Our results also rule out the possibility of decomposition into oxides.

Daniel Y. JungEmail: Phone: +41-44-6323744Fax: +41-44-6321133

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