三江平原土壤湿度记忆性及其与水热气候条件的关系     

王芳  梁静  孙洪伟  高永刚 《气象与环境学报》2022,38(4):102-109

利用1982—2020年三江平原19个国家气象观测站土壤湿度及同期降水、气温数据, 基于相关系数和自相关系数统计方法, 分析了黑龙江省三江平原土壤湿度记忆性及与降水、气温之间的关系。结果表明: 春、夏季三江平原土壤湿度记忆时间均在10—40 d, 各层土壤湿度记忆性的空间分布以中间层(10—20 cm)土壤湿度平均记忆时间最长, 呈上下层递减的趋势; 春季三江平原10—20 cm土层土壤湿度的记忆时长平均20 d, 夏季平均17 d; 夏季土壤湿度记忆性强度大于春季, 空间分布以三江平原西部的记忆性较强, 随着土层的增加土壤湿度记忆性有增大的趋势。降水是三江平原土壤湿度主要来源, 受降水和气温协同作用的影响, 夏、秋季土壤湿度与同期降水量、温湿指数均存在显著的正相关关系; 春季土壤湿度与前期秋冬季降水亦呈显著正相关, 与前期温湿指数呈负相关, 前期秋冬季气温的升高会促进土壤的融冻, 从而使当年春季土壤水分增加。  相似文献   

The Kinematics, Physical Condition and Magnetic Field of the W3 Irs5 Region     

Hiroshi Imai  Anuj P. Sarma 《Astrophysics and Space Science》2005,295(1-2):71-75

We have independently investigated water masers associated with the star-forming region W3 IRS5 with the VLBA. Imai et al., found that the maser 3-D motions exhibit outflows, which likely originate from two of the hyper-compact HII regions in this source. Sarma et al., have detected the Zeeman effect in water masers toward W3 IRS5 and measured line-of-sight magnetic field strengths of between 14 and 42 mG. The directions of maser linear polarization are well aligned in the whole maser region and perpendicular to the estimated magnetic field. These polarimetric results are consistent with an hourglass model of the magnetic field in W3 IRS5. Imai et al., also have analyzed the microstructures found in the individual maser features (1AU), which exhibit the fractal fashion and express turbulence on very small scales. Together, we have demonstrated that observations of water masers enable us to comprehensively enhance our understanding of the early stages of the formation of massive stars in clusters.  相似文献   

Petrogenesis of Songshugou dunite body in the Qinling orogenic belt,Central China: Constraints from geochemistry and melt inclusions   总被引：3，自引：0，他引：3  

SU Li    SONG Shuguang & ZHOU Dingwu . Key Laboratory of Continental Dynamics of the Ministry of Education  Department of Geology  Northwestern University  Xi’an  China  . The Geological Lab Center  China University of Geosciences 《中国科学D辑(英文版)》2005,48(8):1146-1157

The chemical variation of the Earth’s mantle rocks has been interpreted to reflect multiple episodes of partial melting. With the increasing of melt generation and extraction, the readily molten minerals and incompatible elements decrease in the residual mantle peridotite. The present-day gladiate of the Earth, however, cannot cause mantle batch melting[1], nor 40% partial melting that allows pyroxenes to be completely dissolved into melt and forms dunite[2,3]. Recent studies show that mantl…  相似文献   

Wavelet analysis of intermittent turbulence in a very stable nocturnal boundary layer: implications for the vertical mixing of ozone     

Jennifer?A.?SalmondEmail author 《Boundary-Layer Meteorology》2005,114(3):463-488

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Complex proximal deposition during the Plinian eruptions of 1912 at Novarupta,Alaska   总被引：2，自引：1，他引：1  

Bruce?F.?HoughtonEmail author  C.?J.?N.?Wilson  J.?Fierstein  W.?Hildreth 《Bulletin of Volcanology》2004,66(2):95-133

Proximal (<3 km) deposits from episodes II and III of the 60-h-long Novarupta 1912 eruption exhibit a very complex stratigraphy, the result of at least four transport regimes and diverse depositional mechanisms. They contrast with the relatively simple stratigraphy (and inferred emplacement mechanisms) for the previously documented, better known, medial–distal fall deposits and the Valley of Ten Thousand Smokes ignimbrite. The proximal products include alternations and mixtures of both locally and regionally dispersed fall ejecta, and numerous thin complex deposits of pyroclastic density currents (PDCs) with no regional analogs. The locally dispersed component of the fall deposits forms sector-confined wedges of material whose thicknesses halve radially from and concentrically about the vent over distances of 100–300 m (cf. several kilometers for the medial–distal fall deposits). This locally dispersed fall material (and many of the associated PDC deposits) is rich in andesitic and banded pumices and richer in shallow-derived wall-rock lithics in comparison with the coeval medial fall units of almost entirely dacitic composition. There are no marked contrasts in grain size in the near-vent deposits, however, between locally and widely dispersed beds, and all samples of the proximal fall deposits plot as a simple continuation of grain size trends for medial–distal samples. Associated PDC deposits form a spectrum of facies from fines-poor, avalanched beds through thin-bedded, landscape-mantling beds to channelized lobes of pumice-block-rich ignimbrite. The origins of the Novarupta near-vent deposits are considered within a spectrum of four transport regimes: (1) sustained buoyant plume, (2) fountaining with co-current flow, (3) fountaining with counter-current flow, and (4) direct lateral ejection. The Novarupta deposits suggest a model where buoyant, stable, regime-1 plumes characterized most of episodes II and III, but were accompanied by transient and variable partitioning of clasts into the other three regimes. Only one short period of vent blockage and cessation of the Plinian plume occurred, separating episodes II and III, which was followed by a single PDC interpreted as an overpressured "blast" involving direct lateral ejection. In contrast, regimes 2 and 3 were reflected by spasmodic sedimentation from the margins of the jet and perhaps lower plume, which were being strongly affected by short-lived instabilities. These instabilities in turn are inferred to be associated with heterogeneities in the mixture of gas and pyroclasts emerging from the vent. Of the parameters that control explosive eruptive behavior, only such sudden and asymmetrical changes in the particle concentration could operate on time scales sufficiently short to explain the rapid changes in the proximal 1912 products.Editorial responsibility: R. Cioni  相似文献   

Analysis of the distribution of inorganic constituents in a landfill leachate-contaminated aquifer: Astrolabe Park,Sydney, Australia     

L.?B.?JorstadEmail author  J.?Jankowski  R.?I.?Acworth 《Environmental Geology》2004,46(2):263-272

An investigation was conducted at Astrolabe Park landfill, a decommissioned municipal landfill in Sydney, Australia, to assess the physical and chemical processes affecting the distribution of inorganic constituents in the leachate plume. The plume is migrating from the landfill towards a groundwater-fed pond into which leachate-impacted groundwater discharges. Borehole geophysical logging and depth-discrete groundwater sampling were used to delineate the distribution of the leachate plume along two groundwater flow paths between the landfill and the shore of the pond. Borehole geophysical logs indicate a strong correlation between bulk and fluid electrical conductivity (EC) values, and help to identify small-scale heterogeneities that comprise a major constraint on contaminant transport within the aquifer. Variations in the distribution of several indicator parameters (EC, HCO₃^–, pH, Eh, NH₄⁺/NO₃^–, S^2–/SO₄^2–) are used to assess the dominant processes affecting contaminant distribution along the flow path, including mixing of fresh and contaminated groundwater, oxidation/reduction reactions and ion exchange.  相似文献   

现代海底热液活动区的分布与构造环境分析   总被引：8，自引：2，他引：6  

栾锡武 《地球科学进展》2004,19(6):931-938

对全球490多个热液活动区的三维空间分布和构造背景进行了研究,对发育热液活动的构造环境进行了分类,并对各种构造环境发育热液活动的频度进行了统计分析。根据已有的统计数据指出了现代海底热液活动的三维空间分布规律,并对此进行了理论分析。指出现代海底热液活动区主要沿大洋中脊、弧后盆地和板内火山分布,并主要限于40°N和40°S中、低纬度带之间,水深集中在 1300～3700 m之间。出现热液活动概率最高的水深为 2600 m,其次为 1700 m、1900 m、 2200 m、3000 m和 3700 m,平均水深为 2532 m。扩张轴的中轴谷、海底火山口及不发 育中轴谷的扩张脊是发育热液活动的主要构造背景。并提出,现代海底热液活动总是出现在构造活动的部位,但并不是构造活跃的部位就发育热液活动。热液活动的发育和构造并不直接相关但却和岩浆发育密切相关。热液活动的发育在位置上受控于岩浆活动,在时间上,它发生在岩浆活动结束后,是强烈的热膨胀、热冷缩后的释热形式。  相似文献   

Alkaline intrusion in a granulite ensemble in the eastern ghats belt,India: Shear zone pathway and a pull-apart structure     

S.?BhattacharyaEmail author  Rajib?Kar 《Journal of Earth System Science》2004,113(1):37-48

The alkaline complex of Koraput, Orissa, India, is one of several bodies in the high-grade Eastern Ghats belt, but this one is an integral part of the high-grade belt and remote from the western boundary against the Bastar craton. The Koraput complex forms a lozenge-shaped intrusion into the metapelitic granulites and is bounded by shear zones. The combined effect of movement along these shear zones, is a northeasterly elongated sygmoidal cavity with maximum width along the northwesterly trending Reidel shear. Thus the Koraput alkaline complex can be considered to have been emplaced in a pull-apart structure, developed in the granulitic country rocks. Moreover, in view of the fact that the western margin of the high-grade Eastern Ghats belt bears clear evidence of collisional features, rather than that of rifting or break-up, the rift-valley model for the alkaline magmatism in this high-grade belt appears untenable.  相似文献   

Simulation of Gravity Currents Using VOF Model     

ZOU  Jian-feng 《中国海洋工程》2002,16(4):525-536

By the Volume of Fluid (VOF) rnultiphase flow model two-dimensional gravity currents with three phases including air are numerically simulated in this article. The necessity of consideration of turbulence effect for high Reynolds numbers is demonstrated quantitatively by LES (the Large Eddy Simulation) turbulence model. The gravity currents are simulated for h ≠ H as well as h= H, where h is the depth of the gravity current before the release and H is the depth of the in-truded fluid. Uprising of swell occurs when a current flows horizontally into another lighter one for h ≠ H. The problems under what condition the uprising of swell occurs and how long it takes are considered in this article. All the simulated results are in reasonable agreement with the experimental results available.  相似文献   

Three-Dimensional Computations of Multiple Tandem Jets in Crossflow     

肖洋李行伟  唐洪武YU Dae-Young 《中国海洋工程》2006,20(1):99-112

1 .IntroductionAn effective method of wastewater disposal in estuarine and coastal watersisto discharge partiallytreated effluentthrougha submerged multiport diffuserlocated atthe end of a sea outfall .Atypical dif-fuser designinvolves multiple jets all discharginginthe same direction awayfromthe shoreline ,per-pendicular to an alongshore ambient current to minimize the environmental impact .This is one type ofa multiple jet groupin crossflow(MJGC) . Whenthe jets are arrangedintandem,withthe…  相似文献