Boundary conditions in the hydromagnetic dynamo problem

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Retention of riverine iron in estuaries

Retention of Fe flocs, resulting from the mixing of river water and seawater, was examined in three Maine estuaries. Riverine Fe was found to remain fairly conservative with salinity, implying that the process of floccufation does not necessarily remove Fe from water parcels. Laboratory experiments corroborated the field data by demonstrating that neither gravity nor suspended sediment were very effective in removing flocculated Fe from suspension. However, input of a tannery effluent did appear to result in scavenging of Fe from estuarine waters. Flocculated riverine Fe was found to increase considerably the Fe concentrations of estuarine bottom sediments, with the amount of iron per sediment specific surface area dependent on mean river flow entering an estuary. While no long term retention efficiencies could be calculated for these estuaries, it seems likely that a significant portion of flocculated riverine Fe escapes to shelf waters.     

Chemical composition and physical properties of lithium-iron micas from the Krušné hory Mts. (Erzgebirge)

Compositions of natural lithium-iron micas are approximated best by the sidero-phyllite-polylithionite join. These micas contain little or no magnesium and manganese. Their octahedral sheets contain close to two trivalent cations (mainly aluminum) in small crystallographic sites and a variable quantity of lithium and R⁺² (mainly iron) in large sites. Octahedral vacancies are situated mostly in large sites. Lithium and R⁺² approach a 44 replacement relationship in micas with octahedral occupancy close to six. Lithium and fluorine show a good positive correlation (small excess of fluorine over lithium), which indicates a crystallochemical association between them. There is a less distinct positive correlation between lithium and R⁺⁴.Based on simplifications, a calculation shows that about two-thirds of octahedral vacancies are caused by substitutions within the octahedral sheet, one-third, by tetrahedral substitutions. Different methods of calculating the crystallochemical formula yield slightly different numbers of octahedral vacancies, but do not affect the mica's position in plots of physical parameters against composition. If a crystallochemical formula is calculated from analysis of a mica contaminated with quartz, topaz, or feldspar, the apparent number of octahedral vacancies increases; such a formula exhibits unusual behavior in composition plots.     

Vlf experiment with the interkosmos-5 satellite

Summary The Interkosmos5 VLF experiment consisted of a spectrum analyser with twelve narrow-band channels and broadband measurements between0.07 and20 kHz using an analogue telemetry with a tape recorder on board. The apparatus used in the experiment is shortly described, some examples ofVLF phenomena observed are given and a review of all analogue data recorded is shown in a graphical calendar.     

Zur statistischen Mechanik der Lufthülle der Erde

Zusammenfassung Es wird versucht, die Methoden der statistischen Mechanik auf die statistische Behandlung der kontinuierlichen Mannigfaltigkeit der Erdatmosphäre zu übertragen. Dazu ist es notwendig, daß die hydrodynamischen Bewegungsgleichungen auf eine Hamiltonsche Form gebracht werden. In Analogie zur statistischen Mechanik wird ein Gibbsscher Ansatz einer kanonischen Gesamtheit gemacht, in den die Energiefunktion, die die Atmosphäre als Ganzes beschreibt, eingeht. Mit diesem Ansatz wird die Wahrscheinlichkeit angegeben, daß ein bestimmter Zustand der Atmosphäre, der als Phasenpunkt in einem Phasenraum aufgefaßt wird, in einem Volumelement dieses Phasenraumes anzutreffen ist. Diese Ausgangswahrscheinlichkeit gestattet es, in einem Anwendungsbeispiel eine Verbindung zwischen der mittleren geometrischen Temperaturzustandskurve und der Verteilung der Gesamtmasse der Atmosphäre auf die verschiedenen Dichtewerte herzustellen.

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Summary An attempt is made to apply methods of statistical mechanics to the continuous diversity of the terrestrial atmosphere. To this purpose the hydrodynamic equations of motion must be expressed in Hamiltonian form. In analogy to statistical mechanics a Gibbs arrangement of a canonical totality is set up involving the energy-function by which the atmosphere is described as a whole. By this arrangement the probability is given that a certain state of the atmosphere considered as phase point in a phase space exists in a volume-element of this phase space. This initial probability makes it possible to establish, in a practical example, a relation between the average geometrical curve of temperature state and the distribution of the whole mass of the atmosphere over the different density values.

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Résumé On tente d'appliquer les méthodes de la mécanique statistique au traitement statistique de la diversité continue de l'atmosphère terrestre. Il est nécessaire pour cela de ramener les équations hydrodynamiques du mouvement aux formes de Hamilton. Par analogie à la mécanique statistique on établit un théorème de Gibbs concernant un ensemble canonique et dans lequel s'insère la fonction d'énergie décrivant l'atmosphère dans son ensemble. Ce théorème fournit la probabilité qu'un état détermié de l'amtosphère considéré comme point de phase dans un espace de phase est rencontré dans un élément de volume de cet espace. Cette probabilité initiale permet, dans un exemple concret, d'établir une relation entre la courbe géométrique moyenne d'état de température et la distribution de la masse totale de l'atmosphère selon les différentes valeurs de la densité.

     

The Effect of Geomagnetic and Solar Activity on the Distribution of Controlling Pressure Formations in the Northern Hemisphere in Winter

The distribution of controlling pressure formations, occurring in the Northern Hemisphere during the winters (January and February) of the years 1952 – 1996, has been analysed. It was found that the deepening of the Icelandic and Aleutian pressure lows is connected not only with a particular QBO phase and level of geomagnetic activity (Bochníek et al., 1999) but also with a particular level of solar activity.     

On the Integrability of Limited-Area Numerical Weather Prediction Model ALADIN over Extended Time Periods

This note summarizes results of the first integration of regional numerical weather prediction model ALADIN in a climate mode. The ALADIN model, developed in an international cooperation led by Météo France, is operationally used for weather prediction. The grid step of the model is 12 km; the integration domain covers a major part of Europe. A one-month-long run has been performed with this model on observed boundary conditions (represented by assimilations by the global model ARPEGE). It is demonstrated that no excessive error is generated and accumulated in the model during the integration; hence the model is integrable for extended time periods and may serve a basis for a development towards a regional climate model.     

Prolonged Dry Episodes over North America: New Tendencies Emerging During the Last 40 Years

A disproportionate increase in precipitation coming from intense rain events, in the situation of general warming (thus, an extension of the vegetation period with intensive transpiration) and an insignificant change in total precipitation could lead to an increase in the frequency of potentially serious type of extreme events: prolonged periods without precipitation (even when the mean seasonal rainfall totals increase). This paper investigates whether this development is already occurring during the past several decades over North America south of 55°N, for the same period when changes in frequency of intense precipitation events are being observed. Lengthy strings of “dry” days without sizeable (>1.0 mm) precipitation were assessed only during the warm season (defined as a period when mean daily temperature is above the 5℃ threshold) when water is intensively used for transpiration and prolonged periods without sizable rainfall represent a hazard for terrestrial ecosystem's health and agriculture. During the past four decades, the mean duration of prolonged dry episodes (20 days or longer in southeastern Canada, 1 month or longer in the Eastern United States and along the Gulf Coast of Mexico and 2 months or longer in the Southwestern United States and Northern Mexico) has significantly increased. As a consequence, the return period of 1 month long dry episodes over the Eastern U.S. has been reduced more than twofold from 15 to 6~7 years. The longer average duration of dry episodes has occurred during a relatively wet period around most of the continent south of 55°N but is not observed over the Northwestern U.S. and adjacent regions of Southern Canada. 