火箭观测到的中层垂直速度扰动细微结构          下载免费PDF全文

吴永富  H. -U. Widdel 《地球物理学报》1996,39(Z1):36-42

使用一枚携带ｃｈａｆｆ的火箭观测到的垂直速度数据，研究中层大气垂直速度扰动细微结构。结果表明，垂直速度扰动有明显的层状结构，各层厚度约１５０－５００ｍ，层间垂直分离距离在几百米到１－３ｋｍ间。在垂直速度方差和低Ｒｉ数峰值间以及动力不稳定和ＭＳＴ雷达回波区域间有好的对应关系。水平速度垂直波数谱与饱和谱在谱斜率和谱振幅上存在好的一致．这些观测结果表明，火箭测量到的细微结构可以用波场饱和解释。  相似文献   

Suspended sediment transport and deposition in a high arctic meromictic lake     

Michael J. Retelle  Jonathan K. Child 《Journal of Paleolimnology》1996,16(2):151-167

A study of sedimentary processes and sediment yields in a high arctic meromictic lake (Lake C2, Taconite Inlet, Northern Ellesemere Island, Canada) was undertaken from May 1990 through August 1992 to understand the links between climatic controls, hydrology, and the laminated sediment record preserved in the lake. Understanding the relationships between processes and the sediment record is critical for interpreting the climatic significance of the laminated sediments in a region where high resolution climate proxy records are quite limited.Sediment transport to Lake C2 is dominated by fluvial processes. During the early part of the melt season slushflows transport sediment to the lake surface. Subsequently, suspended sediment is delivered to the lake by the main inlet stream and distributed lakeward by a plume emanating the main inlet channel. Due to the strong density stratification of the water column the plume distributes sediment downlake by overflows and interflows in the epilimnion. In general, overflows are generated by lower discharge events whereas interflows penetrate to the halocline during high discharge with increased suspended sediment concentration.Sediment trap analysis demonstrates that suspended sediment transport and deposition responds to diurnal through annual changes in stream discharge. Seasonal and annual sediment trap yields agree with average accumulation rates determined from varve thickness measurements and cumulative suspended sediment discharge from the main inlet stream indicating a close link between climatological, hydrological, and sedimentological controls and varve deposition.This is the fourth in a series of papers published in this issue on the Taconite Inlet Lakes Project. These papers were collected by Dr R. S. Bradley.  相似文献   

分数布朗运动的小波分析     

王桥  胡毓钜 《武汉大学学报(信息科学版)》1995,(1)

给出了分数布朗运动的连续和离散小波分析，讨论了有关的性质，并将结果用于分维估值、分数布朗运动小波变换系数的相关性研究等方面．  相似文献   

A summary of sulfur dioxide emission rate measuremnts from Guatemalan volcanoes     

RJ Andres  WI Rose  RE Stoiber  SN Williams  O Matías  R Morales 《Bulletin of Volcanology》1993,55(5):379-388

Measurements of the sulfur dioxide (SO₂) emission rate from three Guatemalan volcanoes provide data which are consistent with theoretical and laboratory studies of eruptive and shallow magma chamber processes. In particular, unerupted magma makes a major contribution to the measured SO₂ emission rates at Santiaguito, a continuously erupting dacitic volcanic dome. Varying shallow magma convection rates can explain the variations in SO₂ emission rates at Santiaguito. At Fuego, a basaltic volcano currently in repose, SO₂ emission rate measurements are consistent with a high level magma body that is crystallizing and releasing volatiles. At Pacaya, a continuously erupting basaltic volcano, recent SO₂ emission rate measurements support laboratory simulation studies of strombolian eruptions; these studies indicate that the majority of gas escapes during eruptions and little gas escapes between eruptions.Average SO₂ emission rates over the last 20 years for Santiaguito, Fuego and Pacaya are 80, 160 and 260 Mg/d, respectively. On a global scale, these three volcanoes account for 1% of the annual global volcanic output of SO₂. Santiaguito and Pacaya, together, emit 6% of the total annual SO₂ emitted by continuously erupting volcanoes.Even though SO₂ measurements at these volcanoes have been made infrequently and by different investigators, the collective data help to establish a useful baseline by which to judge future changes. A more complete record of SO₂ emission rates from these volcanoes could lead to a better understanding of their eruption mechanisms and reduce the impact of their future eruptions on Guatemalan society.  相似文献   

Use of Factor Analysis to Study the Distribution of Metalliferous Bauxitic Tailings in the Seabed of the Gulf of Corinth,Greece     

Papatheodorou  G.  Lyberis  E.  Ferentinos  G. 《Natural Resources Research》1999,8(4):277-286

In 1994, a detailed marine environmental survey was carried out in surface sediments of the northern flank (Antikyra Bay) and the basin floor of the Gulf of Corinth. Metalliferous tailings (red-mud slurry) of a bauxite processing plant are discharged through a pipeline at a water depth of 100 m, in the Antikyra Bay, covering an area of 16 km². The bauxitic tailings are detached from the main deposit at the outfalls, flow as turbidity currents downslope, and are redeposited on the basin floor of the Gulf of Corinth, where they cover an area of about 277 km². One hundred sediment samples, that were collected from red-mud deposits and the surrounding natural sediments, were analyzed for Ag, Al, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Pb, Si, Ti, V, and Zn concentrations. Statistical analysis of the heavy metals concentrations using factor analysis allowed (i) an examination of the interrelations among metals and (ii) distinguishing possible sample groups on the basis of metal concentrations in order to study the mechanisms of transport of the red mud and the degree of mixing with natural sediments. Factor 1 (Al, Cr, Ti, Fe, Co, Ni, Pb, Ag, Hg, V, Cd, and Cu) and the positive pole of Factor 2 (Cu, Ag, Cd, and Hg) are red-mud factors, reflecting different metal behaviors, which are related to processes that take place during the transport and redeposition of the red mud. The negative poles of Factors 2 and 3 and the positive pole of Factor 4 are related to natural sediment supply processes. Q-mode factor analysis identifies three distinct sediment groups located in different areas, on the base of the degree of mixing of red mud with natural sediments.  相似文献   

Observations of high co rotational lines in post-AGBs and PN     

K. Justtanont  A. G. G. M. Tielens  C. J. Skinner  M. R. Haas 《Astrophysics and Space Science》1995,224(1-2):305-308

We present a preliminary interpretation of high CO rotational line data obtained from KAO. The possibility of either a PDR or a shock model is considered in order to explain the observations.  相似文献   

Englacial and proglacial glaciotectonic processes at the snout of a thermally complex glacier in Svalbard     

Michael J. Hambrey  David Huddart 《第四纪科学杂志》1995,10(4):313-326

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Conditioning mean steady state flow on hydraulic head and conductivity through geostatistical inversion   总被引：5，自引：2，他引：3  

A. F.?Hernandez  S. P.?NeumanEmail author  A.?Guadagnini  J.?Carrera 《Stochastic Environmental Research and Risk Assessment (SERRA)》2003,17(5):329-338

Nonlocal moment equations allow one to render deterministically optimum predictions of flow in randomly heterogeneous media and to assess predictive uncertainty conditional on measured values of medium properties. We present a geostatistical inverse algorithm for steady-state flow that makes it possible to further condition such predictions and assessments on measured values of hydraulic head (and/or flux). Our algorithm is based on recursive finite-element approximations of exact first and second conditional moment equations. Hydraulic conductivity is parameterized via universal kriging based on unknown values at pilot points and (optionally) measured values at other discrete locations. Optimum unbiased inverse estimates of natural log hydraulic conductivity, head and flux are obtained by minimizing a residual criterion using the Levenberg-Marquardt algorithm. We illustrate the method for superimposed mean uniform and convergent flows in a bounded two-dimensional domain. Our examples illustrate how conductivity and head data act separately or jointly to reduce parameter estimation errors and model predictive uncertainty.This work is supported in part by NSF/ITR Grant EAR-0110289. The first author was additionally supported by scholarships from CONACYT and Instituto de Investigaciones Electricas of Mexico. Additional support was provided by the European Commission under Contract EVK1-CT-1999-00041 (W-SAHaRA-Stochastic Analysis of Well Head Protection and Risk Assessment).  相似文献   

Measurement of Impact Ejecta from Regolith Targets in Oblique Impacts     

S. Yamamoto 《Icarus》2002,158(1):87-97

This paper reports the results of experiments on projectile impact into regolith targets at various impact angles. Copper projectiles of 240 mg are accelerated to 197 to 272 m s⁻¹ using an electromagnetic gun. The ejecta are detected by thin Al foil targets as secondary targets, and the resulting holes on the foil are measured to derive the spatial distribution of the ejecta. The ejecta that penetrated the foil are concentrated toward the downrange azimuths of impacting projectiles in oblique impacts. In order to investigate the ejecta velocity distribution, the nondimensional volume of ejecta with velocities higher than a given value is calculated from the spatial distribution. In the case of the vertical impact of the projectile, most ejecta have velocities lower than 24% of the projectile speed (∼50 m s⁻¹), and there are only several ejecta with velocities higher than 72 m s⁻¹. This result confirms the existence of an upper limit to the ejection velocity in the ejecta velocity distribution (Hartmann cutoff velocity) (W. K. Hartmann, 1985, Icarus63, 69-98). On the other hand, it is found that, in the oblique impacts, there are a large number of ejecta with velocities higher than the Hartmann cutoff velocity. The relative quantity of ejecta above the Hartmann cutoff velocity increases as the projectile impact angle decreases. Taking these results with the results of S. Yamamoto and A. M. Nakamura (1997, Icarus128, 160-170) from impact experiments using an impact angle of 30°, it can be concluded that the ejecta from these regolith targets exhibit a bimodal velocity distribution. Below a few tens of m s⁻¹, we see the expected velocity distribution of ejecta, but above this velocity we see a separate group of high-velocity ejecta.  相似文献   

21世纪矿业应向后工业发展势态倾斜--适者生存和可持续发展   总被引：5，自引：0，他引：5  

裴荣富 《地球科学》2002,27(1):72-80

“后工业”（post-industry)是知识经济或曰“新经济”的发展时代。这个时代的自然资源和一般劳动力资源,包括矿产资源在国民经济和社会发展中的基础地位逐渐为知识产权、市场网络、信息、创新环境等后天获得性资源,以及为创新人才的新“认知”（recognized intellect,RI)所代替。然而,据矿产资源分布及其成矿既具有一定的全球统一性又有区域的特殊性,以及不同国家（地区）对矿产资源勘查程度的不均衡性,特别是矿业活动与其他产业性质的不同,如何能按不同国家（地区）的具体发展状况,做好21世纪矿业向“后工业”发展势态的倾斜,达到适者生存和矿业可持续发展的目标是当代探讨的重大问题。在概括阐述了21世纪矿业发展势态、矿业活动特点及其自然属性的基础上,提出了矿业可持续发展的地质勘查和矿业活动决策支持系统的模拟,以及对当前紧缺铜矿资源可持续发展的新“认知”。  相似文献