共查询到20条相似文献，搜索用时 31 毫秒
1.
Günther Böhnecke 《Ocean Dynamics》1957,10(2):33-38
Zusammenfassung Folgende fünf Hauptprogramme für weltweite ozeanographische Untersuchungen werden im Internationalen Geophysikalischen Jahr 1957/58 durchgeführt: Mittlerer Wasserstand, Lange Wellen, Tiefenzirkulation, Mehr-Schiffe-Beobachtungen und Polarfront-Aufnahmen. Auf ihre Planung und Zielsetzung wird eingegangen. AnnÄhernd vierzig Nationen setzen etwa sechzig Forschungsschiffe, vierhundert Küstenpegel und vierzig Wellenmesser ein. Die Bundesrepublik Deutschland ist mit den beiden Forschungsschiffen Anton Dohrn und Gauss am Programm Polarfront-Aufnahmen im Nordatlantischen Ozean beteiligt.
Oceanographic operations in the International Geophysical Year (IGY)An outline of their plannings and aims
Summary The following five main programs of worldwide oceanographic investigations will be carried out during the International Geophysical Year 1957/58: Mean Sea Level, Long Waves, Deep Sea Circulation, Multiple Ships Measurements, and Polar Front Survey. Their planning and aims are outlined. Some forty nations will be using sixty research ships, four hundred coastal tide gauges and forty wave recorders. The German Federal Republic participates in the operations of the Polar Front Survey in the North Atlantic with their two research ships Anton Dohrn and Gauss.
Travaux océanographiques pendant l'Année Géophysique Internationale de 1957/58Une vue d'ensemble sur leurs projets et leurs buts
Résumé Pour l'Année Géophysique Internationale de 1957/58 cinq programmes principaux furent établis pour l'exécution de recherches océanographiques dans le monde entier. Ces programmes comporteront les opérations suivantes: «Enregistrements du Niveau moyen de la mer», «Enregistrements des Ondes longues», «Circulation de l'eau. profonde», «Observations par navires multiples de recherche» et «Relèvements du Front Polaire». Leurs projets et leurs buts sont exposés. D'environ quarante nations emploieront soixante navires de recherche, quatre cents échelles de marée et quarante enregistreurs de vagues. La République Fédérale d'Allemagne participera avec ses navires de recherche «Anton Dohrn» et «Gauss» aux opérations du «Levé océanographique du Front Polaire» (Polar Front Survey) dans l'Atlantique nord.相似文献
2.
The response of the critical frequency of the ionosphere F2–layer, described by its main Fourier components (daily constant, diurnal and semidiurnal waves) and the lower thermosphere dynamics to the geomagnetic storms in July 1991 and February 1992 is studied. The daily constant displays a negative response, however, the magnitude of reaction depends on the season and latitude. The amplitudes of diurnal and semidiurnal waves increase during a geomagnetic storm, as this enhancement is very strong at high latitudes in winter. The prevailing neutral wind, especially the zonal wind, shows an inclination to decrease during the geomagnetic storm (the effect is more distinct in summer). The amplitudes of diurnal and semidiurnal tides also demonstrate a tendency toward reduction during high geomagnetic activity. 相似文献
3.
Analytical expressions for the exact 2 × 2 one-way propagator matrix of a plane S wave, propagating along the axis of spirality in the simple 1-D anisotropic simplified twisted crystal model, are presented. The analytical equations are useful in testing the applicability and accuracy of various approximate wavefield modelling methods, especially of the coupling ray theory and of its various quasi-isotropic approximations and various numerical implementations.In addition to the exact analytical solution of the elastodynamic equation in the simplified twisted crystal model, the analytical solutions of the equations of the four ray methods are given. The ray methods are (a) the coupling ray theory, (b) the coupling ray theory with the quasi-isotropic perturbation of travel times, (c) the anisotropic ray theory, (d) the isotropic ray theory. These four approximate solutions of the elastodynamic equation are roughly compared with the exact solution. Both the exact analytical solution and the analytical ray-theory solutions in the simplified twisted crystal model are also helpful in debugging computer codes for various approximate wavefield modelling methods, especially for the coupling ray theory. 相似文献
4.
E. C. Butcher 《Pure and Applied Geophysics》1989,131(3):463-483
It is well-known that the amplitude and phase of theSq(H) variation show considerable variability from day to day. In this paper we consider one aspect of the phase variability—that associated with AQDs. AQDs (or abnormal quiet days) are defined as magnetically quiet days where the maximum excursion ofH at a mid-latitude station on the poleward side of the focus occurs outside the normal time range 0830–1330 LST. Such days exhibit properties, many of which appear quite distinct from the properties of the normalSq(H) variation. The properties of AQDs, and the proposals that have been made to explain them, are considered in detail. The consequences of these proposals and some problems which need to be addressed in order to obtain a fuller understanding of the dynamics of the ionosphere on AQDs are also discussed. 相似文献
5.
H. Walden 《Ocean Dynamics》1959,12(4):141-152
Zusammenfassung Visuelle Beobachtungen der Bordwetterwarten auf den Fischereischutzbooten Meerkatze und Poseidon sowie auf dem Fischereiforschungsschiff Anton Dohrn werden statistisch bearbeitet, um Feststellungen über die Art der Seegangsabnahme bei abflauendem Wind zu treffen. In ähnlicher Weise werden Beobachtungen des in der Deutschen Bucht stationierten Feuerschiffes P 8 untersucht. Trotz großer Streuung der Einzelwerte lassen sich vorläufige quantitative Zusammenhänge zwischen Seegangsabnahme und den die Seegangseigenschaften beeinflussenden Faktoren ermitteln.
Herrn Dr. Richard Becker bin ich für die Erstellung der statistischen Unterlagen zu Dank verpflichtet. Der Deutsche Wetterdienst hat die Untersuchung durch die Bereitstellung von Geldmitteln zur Durchführung der statistischen Arbeiten unterstützt. 相似文献
Essay at a statistical investigation of the properties of the wind generated sea at decreasing wind
Summary Visual observations of the meteorological stations on board the fishery protection vessels Meerkatze and Poseidon as well as on board the fishery research vessel Anton Dohrn are statistically elaborated with a view to determine the nature of decreasing sea at decreasing wind. In a similar way, observations from the light vessel P 8 in the German Bight are investigated. Though the variations of the individual values are quite appreciable it is possible to discern the existence of provisional quantitative correlations between the decrease of the sea and those factors influencing the properties of the sea.
Essai d'étudier d'une manière statistique les propriétés de la mer du vent en présence d'un vent affaiblissant
Résumé Des observations visuelles faites par les stations météorologiques à bord des navires garde-pêche «Meerkatze» et «Poseidon» ainsi qu'à bord du navire explorateur de pêche «Anton Dohrn» sont étudiées d'une manière statistique pour déterminer la nature de l'apaisement de la mer du vent en présence d'un vent affaiblissant. Les observations du bateau feu «P 8» dans la baie Allemande sont soumises à une étude analogue. Bien que les valeurs individuelles varient considérablement entre elles, on peut constater la présence des corrélations préliminaires quantitatives entre l'apaisement de la mer du vent et les facteurs influant sur les propriétés de la mer du vent.
Herrn Dr. Richard Becker bin ich für die Erstellung der statistischen Unterlagen zu Dank verpflichtet. Der Deutsche Wetterdienst hat die Untersuchung durch die Bereitstellung von Geldmitteln zur Durchführung der statistischen Arbeiten unterstützt. 相似文献
6.
N. D. Mtundu R. W. Koch 《Stochastic Environmental Research and Risk Assessment (SERRA)》1987,1(2):101-116
The dynamics of water within the unsaturated root zone of the soil are represented by a pair of stochastic differential equations (SDE's), one representing the so-called surplus state of the moisture and the other the deficit condition. The inputs to the model are the climatically controlled random infiltration events and evapotranspiration which are modeled as a compound Poisson process and a Wiener (Brownian motion) process, respectively.The solutions to these SDE's are not in close-form but sample functions are obtained by numerical integration. The moment properties of the soil moisture evolution process have also been derived analytically including the mean, variance, covariance and autocorrelation functions.To illustrate the model, climatic parameters representing the surplus and deficit cases and properties of clay loam soil have been used to numerically derived the corresponding sample functions. With proper selection of all the parameters, physically realistic sample trajectories can be obtained for the model. 相似文献
7.
F. Errulat 《Ocean Dynamics》1951,4(4-6):185-185
Summary With a view to avoiding the well-known discrepancy in the physical and earth magnetical denomination of the earth's magnetic poles it is suggested to call them henceforth arctic magnetic pole and antarctic magnetic pole.
Propos relatif à la dénomination des pôles géomagnétiques
Résumé Tenant compte de la discordance entre la dénomination scientifique des pôles magnétiques de la terre et celle qui est habituelle l'auteur propose de les nommer pôle magnétique arctique et pôle magnétique antarctique.相似文献
8.
Prof. Dr. Manfredo Vanni 《Pure and Applied Geophysics》1950,17(3-4):234-237
Summary The writer wants to emphasize the necessity of reorganizing rationally the system of the meteorologic observatories in the Western Alps, especially of the ones on the highest mountains which are the most important for the study of the variations of glaciers. For that reorganization it is necessary to remember the variety of the climatic regions into which the Western Alps may be divided. The writer proposes the institution of other observatories employing the new important aerial-ropeways of Breauil and of Mount Blanc, and the new big and high-situated hotels and shelters which are opened all year round. The author insists particularly, on the necessity of doing up the observatories of Col d'Olen and Margherita on Mount Rosa which have not worked any more since ten years. 相似文献
9.
This paper gives a short overview of the observational results on galactic magnetic fields. Interstellar magnetic fields, as deduced from multi-frequency polarization observations, show a well-ordered structure largely following the spiral arms. In some galaxies an axisymmetric spiral pattern dominates (the field being directed inwards), while others exhibit a dominant bisymmetric spiral field or mixed modes, as predicted from non-linear dynamo theory.
As long as star formation activity is low, the magnetic fields are rather regular. Strong star formation leads to turbulent cloud motions and supernova explosions, which tangle the field, so that the radio emission is only weakly polarized. As a consequence the highest fractional polarizations and polarized intensities at centimeter wavelengths are found in interarm regions. At decimeter wavelengths, galactic disks become optically thick for polarized emission.
In NGC 6946 the regular field is concentrated in narrow magnetic arms located in between the optical spiral arms. The field cannot simply be frozen into the gas and oriented by a density-wave flow. A galactic dynamo may provide a stable spiral pattern of the field, but non-axisymmetric models are still being developed. 相似文献
10.
Dr. James R. Wait 《Pure and Applied Geophysics》1954,28(1):47-56
Summary The radiation fields of a vertical electric antenna situated on a horizontally stratified ground are discussed. The attenuation and wave-tilt of the surface wave and the height-gain factor are shown to be a function of the horizontal stratification in the ground. It is possible that the results have application to an airborne geophysical exploration scheme. 相似文献
11.
Sid P. Halsor 《Bulletin of Volcanology》1989,51(4):271-280
Irregularly shaped, large and clear (LAC) glass inclusions are present in plagioclase phenocrysts in several andesitic lavas erupted from Tolimán volcano, Guatemala. Their morphology is different from densely spaced, fine-grained glass inclusions that form concentric zones in dusty or cellular textured plagioclase phenocrysts. The large size of LAC inclusions make them suitable for microprobe analysis and average bulk compositions are presented for glasses in 30 phenocrysts from eight lava samples. Their compositions are rhyolitic and in disequilibrium, or out-range (Anderson 1976) with respect to whole-rock and groundmass glass compositions. LAC inclusions typically occur in large, tabular plagioclase phenocrysts with relatively uniform, sodic compositions (An 40–54). Compositions of feldspar phenocrysts not containing LAC inclusions range from An 41 to An 81. Petrographic and chemical data support a primary origin for LAC glasses, suggest mixing of mafic and silicic magmas, and also constrain a mechanism for magma mixing. Rapid growth of plagioclase and entrapment of LAC glass occurs during mixing in a vapor-rich silicic liquid under low degrees of undercooling. These conditions are possibly produced in a high-level magma body such as that envisioned by Huppert et al. (1982), where replenishment and subsequent crystallization of a hydrous magma induces density instability and mixing with the resident magma. 相似文献
12.
Theodor Stocks 《Ocean Dynamics》1949,2(6):295-298
Summary Echo soundings of the U.S. Cruiser Milwaukee in the Puerto Rico Trough in 1939 are briefly discussed, and two depths of 30246 feet or 9219 m, found at 19° 36 N, 68° 20.5 W and at 19° 35N, 68° 8.75W, are stated to be the greatest depths which are known so far in the Atlantic Ocean. 相似文献
13.
MAGSAT data and Curie-depth below Deccan flood basalts (India) 总被引：3，自引：0，他引：3
Ground and airborne magnetic data are severely disturbed due to random susceptibility variations in Deccan flood basalts. However, Magnetic Satellite (MAGSAT) data over the Deccan flood basaltic region of the Indian subcontinent exhibit filtering of surficial noise. Three passes over Deccan traps show a low at about 20°N latitude and a high at about 23°N latitude. Spectral analysis of these passes and an available 2-D MAGSAT vertical intensity map indicate a deep (40±4 km) magnetic interface. It is interesting to note that the determination of Curie-depth from MAGSAT matches and confirms the geothermal data model. The estimates correspond to the Moho depth derived from gravity and deep seismic sounding studies. The study suggests a continental shield-like geothermal gradient of about 14°C/km below the area. 相似文献
14.
Walter Hansen 《Ocean Dynamics》1954,7(1-2):55-58
Summary The main subject of Ekman's most careful and detailed analysis of the current measurements of Armauer Hansen is to elucidate the periodical character of ocean currents. A survey of his results is given in table 2 and by means of an outline chartlet a comparison is made between the values which are derived from the observations on board Armauer Hansen and those attained by the reviewer by numerical calculation.
V. W. Ekmann, Studies on Ocean Currents. Geofysiske Publikasjoner Vol. XIX, No. 1, Bergen 1953. 相似文献
Les observations faites à bord du navire Armauer Hansen en 1930 à ses mouillages dans l'Atlantique et leur exploitation par V. W. Ekman
Résumé Le but principal de V. W. Ekman dans son analyse scrupuleuse et détaillée des mesures de courant est d'élucider le caractère periodique des courants océaniques. Les résultats les plus importants en sont donnés dans la table 2; en outre le rapporteur compare ces résultats empiriques d'Ekman avec ses propres calculs numériques en les confrontant dans une petite carte.
V. W. Ekmann, Studies on Ocean Currents. Geofysiske Publikasjoner Vol. XIX, No. 1, Bergen 1953. 相似文献
15.
Theodor Stocks 《Ocean Dynamics》1952,5(2-3):149-153
Summary Comparisons between three series of echo soundings taken by the survey- and research ships Meteor and Gauss across the shoals of the Stoller Grund and the Gabels Flach in 1934 and 1951 confirm that from the nature of the recorded echo qualitative conclusions in respect to the thickness of soft sedimentary layers can be drawn.
Fonds amortissant et non-amortissant le son aux alentours du Stoller Grand et du Gabeis Flach (Kieler Bucht) — discutés par rapport à la géologie
Résumé Trois séries de sondages par écho qui furent effectués par dessus les bancs de sables du Stoller Grund et du Gabels Flach (Kieler Bucht) en 1934 et 1951 au bord du Meteor et du Gauss, navires hydrographiques et explorateurs, sont comparées entre elles. Ces comparaisons confirment qu'il est possible de déduire qualitativement de la nature des enregistrements l'épaisseur des couches de sédiments moux.相似文献
16.
Georg Ribi 《Aquatic Sciences - Research Across Boundaries》1992,54(1):85-90
Larvae of perch (Perca fluviatilis L.) reared in tanks for 27 days survived better in lake water to which 2% of artificial sea water had been added (46.6% average survival rate) than in lake water only (13.5% survival). One week after hatching, over 90% of the larvae had their guts filled in all tanks. During the following week the populations divided into floaters (fish with an inflated swimbladder) and sinkers (fish apparently lacking a functional swim-bladder). Although they continued feeding, sinkers remained smaller than floaters and most of them died. 相似文献
17.
Justus Rosenhagen 《Ocean Dynamics》1949,2(1-3):102-107
Summary It is suggested to identify civil twilight only with a distinct range of the intensity of global illumination according to practical needs (i. e., in case of cloudiness, independent of astronomical data), whereas astronomical twilight means the whole interval between the sun's altitudes of 0° and –17°. 相似文献
18.
Greg Holloway 《Surveys in Geophysics》2004,25(3-4):203-219
Traditional ocean modeling treats fields resolved on the model grid according to the classical dynamics of continua. Variability on smaller scales is included through sundry eddy viscosities, mixing coefficients and other schemes. In this paper we develop an alternative approach based on statistical dynamics. First, we recognize that we treat probabilities of flows, not the flows themselves. Modeled dependent variables are the moments (expectations) of the probabilities of possible flows. Second, we address the challenge to obtain the equations of motion for the moments of probable flows rather than the (traditional) equations for explicit flows. For linear terms and on larger resolved scales, the statistical equations agree with classical dynamics where those of traditional modeling works well. Differences arise where traditional modeling would relegate unresolved motion to eddy viscosity, etc.. Instead, changes of entropy (<-log P> over the probability distribution of possible flows) with respect to the modeled moments act as forcings upon those moments. In this way we obtain a consistent framework for specifying the terms which, traditionally, represent subgridscale effects. Although these statistical equations are close to the classical equations in many ways, important differences are also evident; here, two phenomena are described where the results differ. We consider eddies interacting with bottom topography. It is seen that traditional eddy viscosity and/or topographic drag, which would reduce large scale flows toward rest, are wrong. The second law of thermodynamics is violated; the arrow of time is running backwards! From statistical dynamics, approximate corrections are obtained, yielding a practical improvement to the fidelity of ocean models. Another phenomenon occurs at much smaller scales in the turbulent mixing of heat and salt. Even when both heat and salt are stably stratifying, their rates of turbulent transfer should differ. This suggests a further model improvement. 相似文献
19.
We consider an inverse problem of determination of short-period (high-frequency) radiator in an extended earthquake source. This radiator is assumed to be noncoherent (i.e., random), it can be described by its power flux or brightness (which depends on time and location over the extended source). To decide about this radiator we try to use temporal intensity function (TIF) of a seismic waveform at a given receiver point. It is defined as (time-varying) mean elastic wave energy flux through unit area. We suggest estimating it empirically from the velocity seismogram by its squaring and smoothing. We refer to this function as observed TIF. We believe that one can represent TIF produced by an extended radiator and recorded at some receiver point in the earth as convolution of the two components: (1) ideal intensity function (ITIF) which would be recorded in the ideal nonscattering earth from the same radiator; and (2) intensity function which would be recorded in the real earth from unit point instant radiator (intensity Green's function, IGF). This representation enables us to attempt to estimate an ITIF of a large earthquake by inverse filtering or deconvolution of the observed TIF of this event, using the observed TIF of a small event (actually, fore-or aftershock) as the empirical IGF. Therefore, the effect of scattering is stripped off. Examples of the application of this procedure to real data are given. We also show that if one can determine far-field ITIF for enough rays, one can extract from them the information on space-time structure of the radiator (that is, of brightness function). We apply this theoretical approach to short-periodP-wave records of the 1978 Miyagi-oki earthquake (M=7.6). Spatial and temporal centroids of a short-period radiator are estimated. 相似文献
20.
In this paper we have tried to present, coherently, a review of the observations of natural VLF radio emissions, termed chorus, that have been made on the ground and aboard satellites, and also their dependence on various geomagnetic phenomena. We have highlighted current theoretical interpretations of the generation and propagation of chorus signals. 相似文献