厄尼诺对人类社会的影响   总被引：3，自引：3，他引：0  

包澄澜  向元珍 《气象科学》2000,21(3):277-288

厄尼诺事件可引起全球气候异常及各种海洋－气象灾害。九十年代以来,前期连续发生三次厄尼诺事件,１９９７～１９９８年更发生了一百多年来最强的一次厄尼诺事件。这种异常的厄尼诺形势必将影响到九十年代更为频繁而严重的自然灾害。据１９４９－１９９１年历史资料统计,厄尼诺年的当年或次年夏季,西北太平洋的年台风发生总数为低值谷年,江淮流域则是洪涝年。九十年代前期,台风发生总数连续出现三个低值谷年,１９９８年只有极  相似文献   

ENSO事件对广西气候影响的统计分析     

李秀存  李耀先  张永强 《气象研究与应用》2000,21(2):21-25

根据1951-1998年广西8地市气象资料的统计分析,初步揭示了广西气候与厄尔尼诺、拉尼娜事件的相关关系,认为ENSO事件对广西气温影响比对降水的影响明显。在厄尔尼诺年,广西气象以正距平为主,尤其桂北偏暖明显,拉尼娜年广西气温以负距平为主,表现为明显的偏冷现象;厄尔尼诺年,桂北、桂东及沿海降水增多,桂西、桂南降水变化不大,拉尼娜年广西以降水偏少为特点。  相似文献   

广西严重冷冬前期强信号的探索   总被引：1，自引：0，他引：1  

陆丹 《气象研究与应用》2000,21(Z1):63-66

通过对广西严重冷冬年前期关键区500hPa环流和海温场分析,找出可用来综合判别和预报广西严重冷冬的强信号,同时这些强信号的提前性表明,大尺度环流的异常对未来广西严重冷冬产生的强迫作用可提前1年-2年半.  相似文献   

煤排烃史系统动力学模拟     

何光玉  徐顺利 《高校地质学报》2000,6(3):456-461

煤成烃研究的最新成果表明,反馈控制作用是影响煤排烃的一个重要因素。据此在常规排烃史模拟方法的基础上引入“系统论”和“系统动力学”的方法,建立了煤排烃史系统的系统动力学模型。模型包括古压力史、烃饱和度发育史和排烃量史等三个主要的子系统模型。该模型不仅较好地解决了煤排烃系统中存在的反馈控制作用问题, 而且较好地解决了系统中存在的参数的非线性特征问题。最后,将模型应用于辽河盆地东部坳陷荣兴屯地区煤排烃史研究,其结果表明,该区煤岩进入生、排烃高峰是在东营组三段沉积末以后,东营组一段沉积末以前,目前仍处于生、排烃高峰,且有近80%的油保留在深部地层中没有排出来。  相似文献   

Effect of γ-irradiation on clays and organoclays: a Mössbauer and XRD study     

D. Gournis  A. E. Mantaka-Marketou  M. A. Karakassides  D. Petridis 《Physics and Chemistry of Minerals》2000,27(7):514-521

The interaction of γ-rays with smectite clays induces noticeable changes in the structure and physicochemical properties of the minerals. For sodium-montmorillonite, Mössbauer spectra show that γ-irradiation causes a partial reduction of trivalent iron to the divalent state due to hydrogen radicals production from the radiolysis of interlayer water. The XRD results show no change in the interlayer space upon irradiation and therefore the radiolysis of interlayer water causes no measurable changes in the architectural organization of the interlayer environment. Intercalation of simple organic molecules (ethylene glycol, tert-butanol and tetraalkylammonium salts) causes partial oxidation of structural divalent iron and affects the Mössbauer parameters of the M₁ and M₂ ferric components. Irradiation of ethylene glycol- or tert-butanol-clay composites indicates reduction of trivalent iron to the divalent state. XRD data show that the irradiation of clay-ethylene glycol complex causes collapse of the initial double layer of glycol molecules to a single layer complex. Finally, XRD results show that the effects of γ-irradiation on clay-tetraalkylammonium complexes depend upon the chain length of the organic cations.  相似文献   

Structure and Mössbauer spectroscopy of barbosalite Fe2+Fe3+ 2 (PO4)2(OH)2 between 80 K and 300 K     

G. J. Redhammer  G. Tippelt  G. Roth  W. Lottermoser  G. Amthauer 《Physics and Chemistry of Minerals》2000,27(6):419-429

Natural barbosalite Fe²⁺Fe³⁺ ₂ (PO₄)₂(OH)₂ from Bull Moose Mine, South Dakota, U.S.A., having ideal composition, was investigated with single crystal X-ray diffraction techniques, Mössbauer spectroscopy and SQUID magnetometry to redetermine crystal structure, valence state of iron and evolution of ⁵⁷Fe Mössbauer parameter and to propose the magnetic structure at low temperatures. At 298?K the title compound is monoclinic, space group P2₁/n, a _o ?= 7.3294(16)?Å, b _o ?=?7.4921(17)?Å, c _o ?=?7.4148 (18)?Å, β?=?118.43(3)°, Z?=?2. No crystallographic phase transition was observed between 298?K and 110?K. Slight discontinuities in the temperature dependence of lattice parameters and bond angles in the range between 150?K and 180?K are ascribed to the magnetic phase transition of the title compound. At 298?K the Mössbauer spectrum of the barbosalite shows two paramagnetic components, typical for Fe²⁺ and Fe³⁺ in octahedral coordination; the area ratio Fe³⁺/Fe²⁺ is exactly two, corresponding to the ideal value. Both the Fe²⁺ and the Fe³⁺ sublattice order magnetically below 173?K and exhibit a fully developed magnetic pattern at 160?K. The electric field gradient at the Fe²⁺ site is distorted from axial symmetry with the direction of the magnetic field nearly perpendicular to V_zz, the main component of the electric field gradient. The temperature dependent magnetic susceptibility exhibits strong antiferromagnetic ordering within the corner-sharing Fe³⁺-chains parallel to [101], whereas ferromagnetic coupling is assumed within the face-sharing [1?1?0] and [?1?1?0] Fe³⁺-Fe²⁺-Fe³⁺ trimer, connecting the Fe³⁺-chains to each other.  相似文献   

Mössbauer and molecular orbital study of chlorites     

A. Lougear  M. Grodzicki  C. Bertoldi  A. X. Trautwein  K. Steiner  G. Amthauer 《Physics and Chemistry of Minerals》2000,27(4):258-269

The different Fe²⁺ lattice sites in iron-rich chlorites have been characterized by Mössbauer spectroscopy and molecular orbital calculations in local density approximation. The Mössbauer measurements were recorded at 77?K within a small velocity range (±3.5?mm?s^?1) to provide high energy resolution. Additionally, measurements were recorded in a wider velocity range (±10.5?mm?s^?1) at temperatures of 140, 200, and 250?K in an applied field (7?T) parallel to the γ-beam. The zero-field spectra were analyzed with discrete Lorentzian-shaped quadrupole doublets to account for the Fe²⁺ sites M1, M2, and M3 and with a quadrupole distribution for Fe³⁺ sites. Such a procedure is justified by the results obtained from MO calculations, which reveal that different anion (OH^?) distributions in the first coordination sphere of M1, M2, and M3 positions have more influence on the Fe²⁺ quadrupole splitting than cationic disorder. The spectra recorded in applied field were analyzed in the spin-Hamiltonian approximation, yielding a negative sign for the electric field gradient (efg) of Fe²⁺ in the M1, M2, and M3 positions. The results of the MO calculations are in quantitative agreement with experiment and reveal that differences in the quadrupole splittings (ΔE _Q ), their temperature dependence and in the isomer shifts (δ) of Fe²⁺ in M1, M2, and M3 positions can theoretically by justified. Therefore, the combined Mössbauer and MO investigation shows that the three Fe²⁺ lattice sites in the chlorites investigated here can be discriminated according to their ΔE _Q -δ parameter pairs. With the calculated average iron-oxygen bond strength, the MO study provides an explanation for the observed trend that the population of the three lattice sites by Fe²⁺ increases according to the relation M1?相似文献   

非晶态Ni-S合金的晶化行为     

杜敏  高荣杰  魏绪钧 《中国海洋大学学报(自然科学版)》2000,30(1):127-130

以电沉积方法制备了非晶态Ni-S合金,用差示扫描量热(DSC)和X-射线衍射(XRD)方法对非晶态Ni-S合金的晶化温度、晶化过程和晶体结构的转化等行为进行了研究。结果表明镀层在380K有少量Ni发生晶化,在440K发生3Ni+2S生成Ni  相似文献   

The role of non-prevailing wind direction on resuspension and redistribution of sediments in a shallow lake     

Charlotta Borell Lövstedt  Lars Bengtsson 《Aquatic Sciences - Research Across Boundaries》2008,70(3):304-313

  相似文献   

古里雅冰芯气候记录对ENSO事件的响应   总被引：10，自引：4，他引：6  

杨梅学  姚檀栋 《冰川冻土》2003,25(1):27-33

ENSO现象是一个产生于大尺度海-气相互作用的全球事件, 它是影响全球中低纬度大部分地区气候年际变化的一个重要的因子. 通过高通滤波法、累积异常法以及非参数检验等方法, 对古里雅冰芯中所记录的气候信息与ENSO事件进行相关分析表明, 在厄尔尼诺年, 古里雅冰芯中记录的降水量显著减少, 但对于δ¹⁸O而言, 虽然也在厄尔尼诺年偏低, 但未达到显著性水平.  相似文献