Variangular wind spirals     

Heinz H. Lettau  Walter F. Dabberdt 《Boundary-Layer Meteorology》1970,1(1):64-79

The term variangular is introduced to emphasize a significant difference between the present and certain earlier solutions to the problem of organized airmotion within the planetary boundary layer. The latter belong to the family of equiangular wind spirals and have the characteristic that the angle () formed by the vectors of shearing stress and geostrophic departure is invariant with height; it is shown that in this spiral-family, parabolic height-dependency of the effective (eddy) diffusivity (K) alone is permitted, including the asymptotic case of constant K; the famous Ekman spiral as well as the Rossby spiral are two prominent members of the family of equiangular wind spirals. The new variangular theory, as the name implies, permits variation of with height (z) and produces more versatile profiles of wind and stress due to less restraint in K (z). As an example of comparison with observed data, monthly mean wind profiles obtained at Plateau Station, Antarctica, are selected since they exhibit a noteworthy degree of variangularity, in relatively satisfactory agreement with properties of the new theoretical model for wind spirals.National Research Council Visiting Scientist Research Associate, Regional Environments Division, Earth Sciences Laboratory.  相似文献   

Anmerkungen zu „Geochemische Untersuchungen an Sedimenten des Persischen Golfs“     

Martin Hartmann  Heinz Lange  Eugen Seibold 《Contributions to Mineralogy and Petrology》1971,31(2):159-163

Ohne Zusammenfassung  相似文献   

Seismoglaziologische Untersuchungen nahe Byrd Station,Antarktis     

Dr. Heinz Kohnen  Prof. Dr. Charles R. Bentley 《Meteorology and Atmospheric Physics》1973,22(2-3):311-324

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Relations between metamorphism and orogeny in a typical section of the Indian Himalayas   总被引：3，自引：0，他引：3  

W. Frank  G. Hoinkes  Christine Miller  F. Purtscheller  W. Richter  M. Thöni 《Mineralogy and Petrology》1973,20(4):303-332

Summary A comprehensive geological and petrological investigation has been undertaken in an area of about 10 000 km² in the Indian Himalaya (S-Lahul, Himachal Pradesh). The development of mineral assemblages in metamorphic rocks of medium grade is considered to be a dominant Alpine event, although almost exclusively Paleozoic and Precambrian rocks have been involved. The Barrowian type of this metamorphism, ranging from the anchi- to the sillimanite zone, took place under the elavated T-gradient of about 4°C/100 m. It is suggested that normal geothermal conditions prevailed only in the outermost zone of this orogenic belt. In the Late Tertiary this metamorphic series has been moved as a huge nappe upon the Lower Himalaya. During this process a unique feature of reverse metamorphism has been formed. It can be shown that this feature was caused by a combination of metamorphism and very rapid tectonic movements.

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Beziehungen zwischen Metamorphose und Orogenese in einem typischen Querschnitt des Indischen Himalaya

Zusammenfassung Ein etwa 10 000 km² großes Gebiet des Indischen Himalaya (S-Lahul, Himachal Pradesh) wurde einer umfassenden geologischen und petrographischen Bearbeitung unterzogen. Die Ausbildung der in den mittelgradig metamorphen Gesteinen vorliegenden Mineralparagenesen wird als ein dominant alpines Ereignis betrachtet, obwohl fast nur paläozoische und präkambrische Gesteine einbezogen wurden. Die Metamorphose selbst ist von Barrow-Typus und reicht von der Anchi- bis zur Sillimanitzone. Sie fand unter einem erhöhten Temperaturgradienten von etwa 4°C/100 m statt. Nur in der äußersten Zone des Orogens entsprach der Gradient etwa normalen geothermischen Verhältnissen. Im Spättertiär wurde diese alpin-metamorphe Serie in Form einer mächtigen Kristallindecke dem Niedrigen Himalaya aufgeschoben. Dabei wurde eine einzigartige Zone inverser Metamorphose ausgebildet. Es konnte gezeigt werden, daß diese inverse Metamorphose durch das Zusammenwirken von Metamorphose und sehr rasch ablaufender Tektonik entstand.

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With 13 Figures

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Dedicated to Prof. Dr. Dr. h. c.B. Sander on the occasion of his 90th birthday.  相似文献   

Late Quaternary glacial and climatic history of northern Cumberland Peninsula,Baffin Island,N.W.T., Canada     

Gifford H. Miller 《Quaternary Research》1973,3(4):561-583

Radiocarbon dates on molluses in marine facies associated with glacial deposits in northern Cumberland Peninsula indicate both main fiord (Laurentide) ice and local glaciers remained at their late Wisconsin maxima until ca. 8000 BP. Essentially continuous deglaciation followed; local corrie glaciers melted out by 7100 BP and by 5500 BP fiord glaciers had receded behind the present margin of the Penny Ice Cap. The Hypsithermal warm interval probably lasted from ca. 8000 to 5000 BP. Lichenometry and radiocarbon dates on peat and buried organic horizons delimit a detailed Neoglacial chronology. Of 46 outlet and corrie glaciers investigated, the oldest Neoglacial moraines are dated lichenometrically at 3200 ± 600 BP. Subsequent advances terminated immediately prior to ca. 1650, 780, 350, and 65 yr BP, the most recent of which marked the most extensive ice coverage during the Neoglacial. The highest occurrence of lateral moraines from late Wisconsin advances of local and Laurentide ice suggest that at the late Wisconsin glacial maximum, depression of snowline varied from 450 m below present at the coast to 350 m below present level in the vicinity of the Penny Ice Cap. Moraines, surrounded by glacial ice and lying above the present steady-state ELA, suggest that during the Hypsithermal snowline was up to ca. 200 m above its present elevation. A radiometrically controlled reconstruction of relative summer paleotemperatures for the postglacial derived independently of lichenometry agrees well with the lichenometric age dating of moraines. The data suggest that between ca. 1650 and 900 BP climatic conditions were unfavorable for glacier growth, whereas the period ca. 800-65 yr BP was one of general glacial activity. During the last decade permanent snow cover has been increasing in the area. Previously reported data on climatic trends in the Canadian Arctic based on palynological analyses are similar to the chronology reported here.  相似文献   

Carbon monoxide on the primitive earth     

James E. Van Trump  Stanley L. Miller 《Earth and Planetary Science Letters》1973,20(1):145-150

The reaction of CO + OH^? in aqueous solution to give formate was studied as a carbon monoxide sink on the primitive earth and in the present ocean. The reaction is first order in OH^? and first order in the molar CO concentration. The second order rate constant is given by log k(M^?1hr^?1) = 15.83?4886/T between 25°C and 60°C. Using the solubility of CO in sea water, and assuming a pH of 8 for a primitive ocean of the present size, the halflife of CO in the atmosphere is calculated to be 12 × 10⁶ yr at 0°C and 5.5 × 10⁴ yr at 25°C.Three other CO sinks would have been important in the primitive atmosphere: CO + H₂ → H₂CO driven by various energy sources, CO + OH → CO₂ + H, and the Fischer-Tropsch reaction of CO + H₂ → hydrocarbons, etc. It is concluded that the lifetime of a CO atmosphere would have been very short on the geological time scale although the relative importance of these four CO sinks is difficult to estimate.The CO + OH^? reaction to give formate is a very minor CO sink on the earth at the present time.  相似文献   

Numerical experiments on the stability of preplanetary disks     

P.M. Cassen  B.F. Smith  R.H. Miller  R.T. Reynolds 《Icarus》1981,48(3):377-392

Gravitational stability of gaseous protostellar disks is relevant to theories of planetary formation. Stable gas disks favor formation of planetesimals by the accumulation of solid material; unstable disks allow the possibility of direct condensation of gaseous protoplanets. We present the results of numerical experiments designed to test the stability of thin disks against large-scale, self-gravitational disruption. The disks are represented by a distribution of about 6 × 10⁴ point masses on a two-dimensional (r, φ) grid. The motions of the particles in the self-consistent gravity field are calculated, and the evolving density distributions are examined for instabilities. Two parameters that have major influences on stability are varied: the initial temperature of the disk (represented by an imposed velocity dispersion), and the mass of the protostar relative to that of the disk. It is found that a disk as massive as 1M_⊙, surrounding a 1M_⊙ protostar, can be stable against long-wavelength gravitational disruption if its temperature is about 300°K or greater. Stability of a cooler disk requires that it be less massive, but even at 100°K a stable disk can have an appreciable fraction ($\text{～}\text{1}\text{3}$) of a solar mass.  相似文献   

Geodynamics and state of the earth's interior     

Heinz Stiller  Siegfried Franck  Diedrich Möhlmann 《Journal of Geodynamics》1984,1(1):79-100

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A BME solution of the inverse problem for saturated groundwater flow   总被引：3，自引：3，他引：0  

M. L.?SerreEmail author  G.?Christakos  H.?Li  C. T.?Miller 《Stochastic Environmental Research and Risk Assessment (SERRA)》2003,17(6):354-369

In most real-world hydrogeologic situations, natural heterogeneity and measurement errors introduce major sources of uncertainty in the solution of the inverse problem. The Bayesian Maximum Entropy (BME) method of modern geostatistics offers an efficient solution to the inverse problem by first assimilating various physical knowledge bases (hydrologic laws, water table elevation data, uncertain hydraulic resistivity measurements, etc.) and then producing robust estimates of the subsurface variables across space. We present specific methods for implementing the BME conceptual framework to solve an inverse problem involving Darcys law for subsurface flow. We illustrate one of these methods in the case of a synthetic one-dimensional case study concerned with the estimation of hydraulic resistivity conditioned on soft data and hydraulic head measurements. The BME framework processes the physical knowledge contained in Darcys law and generates accurate estimates of hydraulic resistivity across space. The optimal distribution of hard and soft data needed to minimize the associated estimation error at a specified sampling cost is determined. This work was supported by grants from the National Institute of Environmental Health Sciences (Grant no. 5 P42 ES05948 and P30ES10126), the National Aeronautics and Space Administration (Grant no. 60-00RFQ041), the Army Research Office (Grant no. DAAG55-98-1-0289), and the National Science Foundation under Agreement No. DMS-0112069.  相似文献   

Chemical Mechanism Development: Laboratory Studies and Model Applications     

Harald Geiger  Ian Barnes  Karl H. Becker  Birger Bohn  Theo Brauers  Birgit Donner  Hans-Peter Dorn  Manfred Elend  Carlos M. Freitas Dinis  Dirk Grossmann  Heinz Hass  Holger Hein  Axel Hoffmann  Lars Hoppe  Frank Hülsemann  Dieter Kley  Björn Klotz  Hans G. Libuda  Tobias Maurer  Djuro Mihelcic  Geert K. Moortgat  Romeo Olariu  Peter Neeb  Dirk Poppe  Lars Ruppert  Claudia G. Sauer  Oleg Shestakov  Holger Somnitz  William R. Stockwell  Lars P. Thüner  Andreas Wahner  Peter Wiesen  Friedhelm Zabel  Reinhard Zellner  Cornelius Zetzsch 《Journal of Atmospheric Chemistry》2002,42(1):323-357

Within the German Tropospheric Research Programme (TFS) numerous kinetic and mechanistic studies on the tropospheric reaction/degradation of the following reactants were carried out: oxygenated VOC, aromatic VOC, biogenic VOC, short-lived intermediates, such as alkoxy and alkylperoxy radicals.At the conception of the projects these selected groups were classes of VOC or intermediates for which the atmospheric oxidation mechanisms were either poorly characterised or totally unknown. The motivation for these studies was the attainment of significant improvements in our understanding of the atmospheric chemical oxidation processes of these compounds, particularly with respect to their involvement in photooxidant formation in the troposphere. In the present paper the types of experimental investigations performed and the results obtained within the various projects are briefly summarised. The major achievements are highlighted and discussed in terms of their contribution to improving our understanding of the chemical processes controlling photosmog formation in the troposphere.  相似文献