Global tidal parameters

Summary Global tidal parameters are shown to have recently increased in accuracy, after more than twenty years of LLR and a decade of superconducting gravimetry, whereas the numerical values for the Earth have not changed substantially. Numerical values of Love numbers for terrestrial planets and the moon are also given for degrees higher than four as load numbers are basically linear combinations of Love numbers, at least for spherical non-rotation approximations. Numerical values for planetary moons, as far as they are known, have also been included in the paper. The static and dynamic behaviour of long-period and pole tide is discussed. Inner solid and outer fluid core effects are critically reviewed, also in view of a century of terrestrial tide observations of the classical type. The separation of long-period tides from secular effects (on a rotating Earth) such as J_n (n<5), is considered.Dedicated to the Memory of M. S. Molodensky     

Magnesium in the marine sedimentary environment: Mg---NH4 ion exchange

The release of exchangeable Mg in marine sediments from displacement by ammonium ions was estimated by way of experimentally determining the parameters that govern this ion-exchange equilibrium on solid geochemical phases: smectite, humic acid, illite and opal.

We showed that: (a) both the conditional selectivity constant as well as the solid concentration are important parameters in determining the relative contribution of ammonium-exchangeable Mg from smectite, organic matter, illite and opal; and (b) that, except in the cases where opal or organic matter concentrations are very high, the clays are the dominant carrier phases for labile Mg which is exchangeable by ammonium.

A model, based on the sum of the contributions from the major geochemical phases present in the sediment reliably predicts the amount of Mg released by exchange with ammonium in marine sediments.     

Die Erhaltungstendenz meteorologischer Elemente und ihre rechnerische Erfassung

Zusammenfassung Für die gegenseitige Verknüpfung der aufeinander-folgenden Werte einer meteorologischen Zeitreihe — die in der Erhaltungstendenz aufscheint — wird der Autokorrelationskoeffizient als Maßzahl eingeführt. Seine Berechnung erfolgt nach Näherungsmethoden, die abgeleitet werden und die Rechenarbeit auf einen kleinen Bruchteil reduzieren.Im Anschluß daran wird der Begriff der autokorrelierten Zufallsreihe entwickelt. Diese ist durch die beiden Elemente Streuung und Autokorrelationskoeffizient definiert. Die Gesetzmäßigkeiten dieser Reihe werden untersucht und mit denen des tatsächlichen Temperaturablaufes verglichen. Es wird der Versuch gemacht, mit statistischen und wahrscheinlichkeits-theoretischen Methoden klimatologische Charakteristika zu errechnen. Es wird auch gezeigt, wie relativ gering periodische oder andere systematische Einflüsse gegenüber Vorgängen sich geltend machen, die man im statistischen Sinne als zufällige bezeichnet.Die Beispiele sind der Wiener Temperaturreihe und zwar den Jahren 1905–34 entnommen, die im Vergleich mit langjährigen Mittelwerten mancherlei Eigentümlichkeiten aufweisen. Doch wurden auch durch Einbeziehen der vorhergegangenen dreißig Jahre keine wesentlichen Abweichungen gefunden.Zweifellos eignen sich Luftdruckwerte zu ähnlichen Betrachtungen. Bewölkung und Niederschläge erfordern vielleicht andere Methoden. Hier dürfte der Begriff der Wahrscheinlichkeitsansteckung zum Ziele führen. Der Zusammenhang zwischen dem Korrelationskoeffizienten und der Dispersion von Häufigkeitsverteilungen bedarf noch einer Klärung.Die entwickelten Begriffe können aber vor allem auch in der Singularitätenforschung zur Anwendung kommen und hier mancherlei Mühe ersparen. Für innere Zusammenhänge und Gesetzmäßigkeiten einer Elementreihe wurde hier gleichsam eine Norm geschaffen. Echte Singularitäten müssen von ihr merklich abweichen.

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Summary The autocorrelation coefficient is introduced as a measure for the mutual correlation of successive values of a series of meteorological observations, involving the tendency of weather persistence. Its calculation by approximation methods is derived and numerical calculating considerably reduced. Thereupon the concept of the autocorrelated fortuity-series is developed which is defined by the two elements: standard deviation and autocorrelation coefficient. The characteristics of this series are examined and confronted with the actual distribution of temperature. An attempt has been made to calculate climatological characteristics by the methods of statistics and probability theory. The influence of periodic or other systematic phenomena is shown to be relatively small when compared with those denoted as fortuitous in the sense of statistics. Examples are given from the Vienna temperature series of the years 1905–1934 showing various peculiarities in comparison with the mean values of a longer period. However, no essential differences have been found by including the precedent 30 years. There is no doubt that observations of atmospheric pressure offer themselves to similar considerations, while cloudiness and precipitation call perhaps for other methods, such as connected with the concept of probability infection. The connection between the correlation coefficient and the dispersion of frequency distributions must still be cleared. The concepts developed in this paper may also be applied to investigations on singularities and facilitate the research work on this field. The internal connections and regularities of a series are so to say standardized whereby genuine singularities can easily be recognized.

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Résumé Dans le but de faire apparaître une corrélation entre les termes successifs d'une série d'observations météorologiques, l'auteur introduit un coefficient d'autocorrélation dont le calcul se fait par des méthodes d'approximation réduisant considérablement le calcul numérique. On applique le procédé à une série caractérisée par la dispersion et le coefficient d'autocorrélation. On étudie les lois de formation de cette série et on la compare à la distribution réelle de la température. On tente de calculer les caractéristiques climatologiques par des méthodes statistiques et probabilistes. On montre aussi combien des facteurs périodiques ou systématiques ont peu d'effet sur des grandeurs purement aléatoires. A titre d'exemple figure la série viennoise de température des années 1905/1934 qui présente plusieurs singularités qui toutefois ne disparaissent pas lorsqu'on ajoute à la série celle des trente années précédentes.Les observations de la pression se prêtent à des considérations analogues. La nébulosité et les précipitations exigent peut-être d'autres méthodes, comme celle de la contagion aléatoire. La relation entre le coefficient de corrélation et la dispersion des distributions de fréquences devrait être encore étudiée. Les notions développées ici trouvent surtout leur application dans l'étude des singularités qu'elles simplifient; elles conduisent à une mesure de l'homogénéité statistique d'une série tandis que les vraies singularités s'en ecartent.

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Mit 7 Textabbildungen.     

Vertical Land Motion in the Mediterranean Sea from Altimetry and Tide Gauge Stations

We have computed estimates of the rate of vertical land motion in the Mediterranean Sea from differences of sea level heights measured by the TOPEX/Poseidon radar altimeter and by a set of tide gauge stations. The comparison of data at 16 tide gauges, using both hourly data from local datasets and monthly data from the PSMSL dataset, shows a general agreement, significant differences are found at only one location. Differences of near-simultaneous, monthly and deseasoned monthly sea level height time-series have been considered in order to reduce the error in the estimated linear-term. In a subset of 23 tide gauge stations the mean accuracy of the estimated vertical rates is 2.3 ± 0.8 mm/yr. Results for various stations are in agreement with estimates of vertical land motion from geodetic methods. A comparison with vertical motion estimated by GPS at four locations shows a mean difference of -0.04 ± 1.8 mm/yr, however the length of the GPS time-series and the number of locations are too small to draw general conclusions.     

Comparison of Earth’s magnetospheric magnetic field models in the context of cosmic ray physics

Over the last two decades, models of the Earth’s magnetospheric magnetic field have been continuously improved to describe more precisely the different magnetospheric current systems (magnetopause current, symmetric and partial ring currents, tail currents and field aligned currents). In this paper we compare the different Tsyganenko models and the Alexeev and Feldstein model in the context of cosmic ray physics. We compare the vertical cutoff rigidity and asymptotic direction of vertical incidence obtained with these models for the January 20, 2005, ground level enhancement and for the big magnetic storm of April 6, 2000. For the event of January 20, 2005, we study the impact of the differences in asymptotic direction obtained with the models on the radiation dose computation at aircraft altitude. For the magnetic storm of April 6, 2000, we discuss the importance of the different magnetospheric current systems in causing cutoff rigidity variations. Finally we summarise the advantages and drawbacks of the different models in the context of space weather.