Die ozeanographischen Arbeiten im Internationalen Geophysikalischen Jahr (IGJ)

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.

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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.

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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.

     

Theory of electromagnetic surface waves over geological conductors

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.     

Analytical One-Way Plane-Wave Solution in the 1-D Anisotropic “Simplified Twisted Crystal” Model

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.     

Vorschlag betreffend die Bezeichnung der erdmagnetischen Pole

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.

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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.

     

The role of sediments in the phosphorus cycle in Lake Lugano. I. Geochemical approach

The bottom sediment from three coring stations in Lake Lugano (Lago di Lugano) show major differences in their role in the P-cycles related to their geochemistry and characteristics of sedimentation. In the northern basin, the deepest sediment may be considered practically inactive, due to a permanently reduced condition at the sediment-water interface. In the southern basin, the sediments are active with respect to P-recycling with strong seasonal variations. One of the sites (Figino) behaves as a sink for P due to a high iron content and an important rate of detrital sedimentation.     

Observed Response of the Ionospheric F2–Layer and Lower Thermosphere to Geomagnetic Storms during High Solar Activity

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.     

AbnormalSq behaviour

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.     

Versuch einer statistischen Untersuchung über die Eigenschaften der Windsee bei abnehmendem Wind

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.

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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.

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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.

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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.     

Étude statistique des crochets magnétiques à Tamanrasset

Résumé On compare, en premier lieu, les crochets magnétiques donnés par le Bulletin de l'I.A.G.A. avec les crochets visibler sur les enregistrements de Tamanrasset entre 1949 et 1957. 33% des crochets sont retrouvés, et on étudie leur fréquence. Celle-ci suit le cycle solaire, esdt minimum l'hiver et plus élevéc l'après-midi que le matin. L'obíssance à la loi deMcNish ne semble pas prouvéc. L'amplitude la plus probable est de 7 . — On étudie ensuite des phénomènes ressemblant aux crochets (faux crochets) et caractérisés par une allure bien définie des dérivéesdH/dt etdD/dt. Leur fréquence ne suit pas le cycle solaire, est minimum à l'équinoxe et uniforme dans le cours de la journée. L'amplitude la plus probable est de 7 à 10 , et la durée de développement de l'ordre de 5 minutes. La direction du vecteur perturbation est NNW ou SSE, avec prédominance du SSE, ce qui correspond dans l'ionosphère à un courant WSW-ENE. L'existence des faux crochets peut expliquer certaines confusions dans l'identification des crochets.

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Summary First of all, we compare the magnetic crochets given by the I.A.G.A.-Bulletin with the crochets we can see on Tamanrasset records between 1949 and 1957. We find out 33% of these crochets and we study their frequency. It follows the solar cycle, it is minimum during winter and greater in the afternoon than in the morning. Obedience toMcNish law does not seem to be proved. The more probable amplitude is 7 . — Then we study phenomena looking like crochets (false crochets) which are caracterised by a well definite feature ofdH/dt anddD/dt. Their frequency does not follow solar cycle, it is minimum et equinox and level during the course of the day. The more probable amplitude is from 7 to 10 , and the development plasts about 5 minutes. The direction of disturbance vector is NNW or SSE, with predominance of SSE, which sould correspond to a WSW-ENE stream in the inosophere. The existence of false crochets may explain some confusions when we identify crochets.

     

Großkreisdifferenzgleichen

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.     

Investigation of the instability of graveyard orbits due to the earth's gravitational perturbations

Summary The Banach theorem is applied to the Lagrange planetary equation for the semimajor axis of a geostationary satellite orbit to estimate the stability of near-geostationary satellite orbits. To achieve a graveyard (disposal) orbit, which will not interfere (=cross) the initial geostationary orbit, the geostationary semi-major axis a_g have to be increased at least by 50 km. Numerical results for a variety of graveyard orbits show that the increase of a_g by about 100 km will yield sufficiently stable orbits (accounting for the Earth's gravitational perturbations only) during the next 150 years.Dedicated to the 75th Birthday of Professor Academician Tibor Kolbenheyer     

Divergent distributions of prey and predator,a fishing effect?

To compare the vertical distributions of benthos and fish species of Upper Lake Constance (Bodensee), 552 benthos samples were taken with an Auerbach grab at four transects (10–250 m). An additional 54 samples (1–10 m) were collected elsewhere. Complementary data was taken from the literature. In winter, most fish feed on benthos, mainly chironomids, but in summer less than 5% do so. Formerly the bottom gill-netting aimed mainly at catchingCoregonus pidschian, but it now aims atPerca fluviatilis. Contrary to expectation, in winter the greatest abundance ofP. fluviatilis is much deeper (55 m) than that of its preferred food, i.e. chironomids (<20 m). Comparably,C. pidschian also stayed deeper than its main food source (chironomids and mollusks).Lota lota, Salvelinus profundus andS. alpinus — unlike the unwanted cyprinids — also stay or stayed deeper than the attractive chironomids. It is argued that the fish reduce their predation risk, i.e. the risk of being gillnetted in the upper 50 m, by selecting the deeper less dangerous, but also less food-abundant habitat. Balancing predation risk against food abundance may have led to survival of the deepest.     

Radio Emission from Galactic Disks

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.     

Two 1993 Kamchatka earthquakes

Two earthquakes occurred in 1993 off southern Kamchatka. They have similar surface wave magnitudes, focal mechanisms, and depths, but have distinctly different characteristics. The November earthquake is a standard or impulsiveM7 underthrusting event. The June earthquake is a tsunamigenic or low-stress-drop event with several unusual characteristics, including a large, diffuse aftershock zone, directivity, and a long source time function. The 1993 earthquakes ruptured a segment of the Kamchatka Arc which has not ruptured since 1904. The 1993 earthquakes seem to signal the midpoint in the southern Kamchatka seismic cycle.     

On vortex flow structures in the outer heliosphere

Summary The vortex flow pattern in the outer heliosphere is calculated on the basis of hydrodynamical equations. Quantitative solution in cylindrical coordinates is used. Moving vortices may be formed due to the heliolatitudinal solar wind velocity dependence and nonstationary boundary conditions near the Sun. The flow pattern consists of a system of cyclones and anticyclones.     

On some effects connected with electromagnetic induction in a rotating earth

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The vibration magnetometer and the processing of its output signal strongly affected by noise

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The periodicity of aurorae in the years 1001–1900

Summary The sequence of aurorae, observed at latitudes up to 55° between the years 1001 and 1900 was processed by methods of spectral analysis. The same methods were applied to parts of various duration of this interval. The periods predominant in the time series under investigation were determined. In all the selected parts of the interval, these periods are always located within the same frequency band. Their position is related to the periods corresponding to mutual conjunctions of the large planets.

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Asymmetry in a nearly symmetric dynamo

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Method for numerical computing of wave fields of sources in nonuniform media

Summary An effective method of computing wave fields is proposed. It is applicable in regions intermediate to a slowly varying (geometrical optics) and strongly nonuniform medium (full-wave solution).

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