Pi 2 pulsations and the eastward electrojet: A case study

We report the results of a case study of two Pi 2 pulsations observed near the eastward electrojet by the Scandinavian Magnetometer Array. The power of the two Pi 2 pulsations, calculated using a standard Fast Fourier Transform method, peaks near the centre of the eastward electrojet. For both events there is a strong latitudinal gradient in the power poleward of the equatorward border of the electrojet. The sense of polarisation is predominantly clockwise at the northern stations and anticlockwise at the southern stations although the reversal from clockwise to anticlockwise does not occur at a constant latitude. For the first event the polarisation reversal occurs at higher latitudes in the western half of the array; for the second the polarisation reversal occurs at higher latitudes at the edges of the array. The polarisation reversal does not appear to be related to the location of the eastward electrojet. Equivalent current vectors of the Pi 2 pulsations, obtained by rotating the band pass filtered data through 90°, exhibit clear vortex structures in both events. The vortices change sense of direction at half the period of the Pi 2 pulsation. A simple model for the ionospheric electric field in accord with the field line resonance theory reconstructs the basic features of the observed Pi 2 equivalent current system. We thus conclude that Pi 2 signatures in the region of the eastward electrojet and far away from the auroral break-up region are governed by the field line resonance mechanism.     

Die Bedeutung des elektromagnetischen Erdfeldes in der Bioklimatologie

Zusammenfassung Viele meteorobiologische Untersuchungen lassen vermuten, daß kolloidelektrische Vorgänge im Übertragungsmechanismus zwischen Umwelt und Organismen eine bedeutsame Rolle spielen. Diese Hinweise werden diskutiert und insbesondere die geoelektrischen Faktoren besprochen, die hierin von Einfluß sein können; als Indikatoren erscheinen Erdströme besonders geeignet. An speziellen Erdstromregistrierungen werden eine Anzahl atmosphärischer Einflüsse nachgewiesen. Registrierungen von elektromagnetischen Feldstörungen können aber darüber hinaus auch für die allgemeine Meteorologie und die Wettervorhersage bedeutungsvoll sein.

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Summary A great number of meteorobiological investigations induce to suppose that colloido-electric processes are of great importance for the mechanism of transmission between environment and organism. These aspects are discussed and especially the geo-electric factors which therein may have a considerable influence, whereof earth-currents are especially qualified as indicators. Different atmospheric influences are showed by special records of earth-currents; beyond it, the records of electromagnetic field perturbations seem to be important for general meteorology and for weather-forecasting.

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Résumé De nombreuses recherches météorobiologiques conduisent à l'hypothèse que des processus colloido-électriques jouent un rôle important dans le mécanisme de translation entre milieu et organisme. Ces aspects sont discutéet et surtout les facteurs géoélectriques qui peuvent y avoir une influence; comme indicateurs les courants telluriques paraissent être au premier plan. Certaines influences atmosphériques sont démontrées par des enregistrements spéciaux de courant tellurique. Par-dessus cela, des enregistrements des perturbations du champs électromagnétique peuvent être de grande importance pour la météorologie générale et pour les prévisions du temps.

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Mit 4 Textabbildungen.     

What makes a planet habitable?

This work reviews factors which are important for the evolution of habitable Earth-like planets such as the effects of the host star dependent radiation and particle fluxes on the evolution of atmospheres and initial water inventories. We discuss the geodynamical and geophysical environments which are necessary for planets where plate tectonics remain active over geological time scales and for planets which evolve to one-plate planets. The discoveries of methane–ethane surface lakes on Saturn’s large moon Titan, subsurface water oceans or reservoirs inside the moons of Solar System gas giants such as Europa, Ganymede, Titan and Enceladus and more than 335 exoplanets, indicate that the classical definition of the habitable zone concept neglects more exotic habitats and may fail to be adequate for stars which are different from our Sun. A classification of four habitat types is proposed. Class I habitats represent bodies on which stellar and geophysical conditions allow Earth-analog planets to evolve so that complex multi-cellular life forms may originate. Class II habitats includes bodies on which life may evolve but due to stellar and geophysical conditions that are different from the class I habitats, the planets rather evolve toward Venus- or Mars-type worlds where complex life-forms may not develop. Class III habitats are planetary bodies where subsurface water oceans exist which interact directly with a silicate-rich core, while class IV habitats have liquid water layers between two ice layers, or liquids above ice. Furthermore, we discuss from the present viewpoint how life may have originated on early Earth, the possibilities that life may evolve on such Earth-like bodies and how future space missions may discover manifestations of extraterrestrial life.     

Issues associated with the distinction between climatic and tectonic controls on Permian alluvial fan deposits from the Kotzen and Barnim Basins (North German Basin)

Facies analysis focussing on coarse-grained sediments has been carried out on more than 2500 m of drill cores from seven wells from southern margins of the North German Basin (NGB). The NGB forms a central element of the Southern Permian Basin (SPB). The wells exposed conglomerates and sandstones of the Rotliegend Grüneberg and Parchim Formations deposited in the Kotzen Basin and the Barnim Basin.17 lithofacies types have been grouped into six lithofacies associations. The studied successions are dominated by fluid gravity flow deposits (hyperconcentrated flows and stream flows) of alluvial fan and alluvial plain systems. Maximum particle size/bed thickness plots (MPS/BTh) support the interpretation as fluid gravity flow deposits. The MPS and BTh data have also been used to differentiate coarsening–thickening and fining–thinning trends of the fan systems.The dominance of water-rich mass flow processes together with sedimentary structures such as dewatering structures and outwashed tops suggests the presence of wet-type fans and plains under semi-humid to semi-arid seasonal climates in the central SPB. The investigated sediments show variation in clast composition subsequent to deep erosion processes on basin margins and changes of source areas. Synsedimentary normal faults and clastic dykes have been interpreted as indicators of tectonic activity of grabens itself and its frames. On a larger scale, then evolution from a half-graben to a graben is apparent for the Tuchen Sub-basin at least. The progradational/retrogradational cycles of the studied alluvial fan systems document combined local tectonic movements and influences of climatic changes. However, our data did not allow for a clear distinction between climatic and tectonic signals. Furthermore, a one-to-one correlation of fan cycles with depositional trends in the NGB basin centre would appear to be oversimplistic.     

Zur Deutung der Vertikalbewegungen der Festländer und Meere

Ohne Zusammenfassung     

Heat of formation of petalite, LiAlSi4O10

The enthalpy of formation of petalite, LiAlSi₄O₁₀, has been measured using high-temperature solution calorimetry. The measurements were carried out in a Calvet-type twin micro calorimeter at 728?°C. A 2PbO?·?B₂O₃ melt was used as a solvent. Tabulated heats of formation of the components and tabulated heat capacities of the reactants and the product (Robie and Hemingway 1995) were used to calculate the standard heat of formation of petalite from the measured heats of solution. The calculations yielded a mean value of Δ _f H ^pet _298.15=?4872±5.4 kJ mol^?1. This value may be compared to the heat of formation of Δ _f H ^pet _298.15= ?4886.5±6.3 kJ mol^?1 determined by the HF solution calorimetry by Bennington et?al. (1980). Faßhauer et?al. (1998) combined thermodynamic data with phase-equilibrium results to obtain best-fit thermodynamic results using the Bayes method, in order to derive an internally consistent dataset for phases in the NaAlSiO₄– LiAlSiO₄–Al₂O₃–SiO₂–H₂O system. They determined ?4865.6?±?0.8?kJ?mol^?1 as the enthalpy of formation of petalite, a value that is appreciably closer to the enthalpy found in this work.     

Strahlungsmessungen als Hilfsmittel zur Diagnose atmosphärischer Zustände und Vorgänge

Zusammenfassung An einem umfangreichen Beobachtungsmaterial besonders der zenitalen Himmelsstrahlung wird die Brauchbarkeit von Strahlungsmessungen mit verschiedenen Empfängern für die Überwachung atmosphärischer Trübungsverhältnisse und der Struktur der Trübung erprobt. Der Einfluß der selektiven Eigenschaften der einzelnen Empfängertypen auf die Meßvorgänge wird eingehend erörtert. Es wird gezeigt, daß Polarisations-und Farbwerte der zenitalen Himmelsstrahlung, die mit verhältnismäßig einfachen Mitteln (Selen-Photoelementen) gewonnen werden können, schon wesentliche Einblicke in den Trübungscharakter der Atmosphäre ermöglichen. Eine Verfeinerung der Analyse ist durch Intensitäts- und Polarisationsmessungen in engen Spektralbereichen, wie sie durch Verwendung von Interferenzfiltern in Verbindung mit Photomultipliern möglich sind, zu erreichen. Im Hinblick auf die noch unbefriedigende Bestimmung des Gesamtwasserdampfgehalts aus den atmosphärischen Absorptionsbanden bei durchgehender Strahlung wird auf die Möglichkeit, sie durch Messung der langwelligen Ausstrahlung zu kontrollieren und zu verbessern, hingewiesen.

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Summary On the basis of an extensive material of observations, in particular of zentithal sky radiation, the applicability of radiation measurements with different receivers for the control of atmospheric turbidity conditions and the structure of turbidity is investigated. The influence of the selective prpperties of the different receiver types on the measuring processes is discussed in detail. It is shown that polarisation and colour values of zenithal sky radiation obtainable by relatively simple means (selenium rectifier cells) give considerable insight into the character of atmospheric turbidity. An improvement of the analysis can be reached by measurements of intensity and polarisation within small spectral ranges such as are possible by applygin interference filters in combination with photomultipliers. With regard to the yet unsatisfactory determination of total water vapour contents from the atmospheric absorption bands of transmitted radiation the possibility is emphasized to control and improve it by measuring the outgoing long-wave radiation.

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Résumé Au moyen d'un riche matériel d'observations concernant surtout le rayonnement du ciel zénital on étudie la valeur de différents récepteurs en vue du contrôle du trouble atmosphérique et notamment de sa structure. On discute l'effet des propriétés sélectives des récepteurs sur lesprocédés des mesures. On montre que la polarisation et la couleur du rayonnement du ciel zénital mesurées par des moyens relativement simples (cellules au sélénium) fournissent déjà d'utiles renseignements sur le caractère du trouble atmosphérique. On arrive à améliorer les résultats par des mesures d'intensité et de polarisation à l'intérieur de régions spectrales étroites, ainsi que par l'emploi de filtres à interférences combinés avec des photomultiplicateurs. Considérant que la teneur totale en vapeur d'eau de l'atmosphère ne se détermine qu'imparfaitement par la transmission dans les bandes d'absorption, l'auteur évoque la possibilité de la déterminer par la mesure du rayonnement effectif à grande longueur d'onde.

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Mit 12 Textabbildungen.     

A New Method for the Determination of Area-Averaged Turbulent Surface Fluxes from Low-Level Flights Using Inverse Models

The low-level flight method (LLF) has been combined with linear inverse models (IM) resulting in an LLF+IM method for the determination of area-averaged turbulent surface fluxes. With this combination, the vertical divergences of the turbulent latent and sensible heat fluxes were calculated from horizontal flights. The statistical errors of the derived turbulent surface fluxes were significantly reduced. The LLF+IM method was tested both in numerical and field experiments. Large-eddy simulations (LES) were performed to compare ‘true’ flux profiles with ‘measurements’ of simulated flights in an idealised convective boundary layer. Small differences between the ‘true’ and the ‘measured’ fluxes were found, but the vertical flux divergences were correctly calculated by the LLF+IM method. The LLF+IM method was then applied to data collected during two flights with the Helipod, a turbulence probe carried by a helicopter, and with the research aircraft Do 128 in the LITFASS-98 field campaign. The derived surface fluxes were compared with results from eddy-covariance surface stations and with large-aperture scintillometer data. The comparison showed that the LLF+IM method worked well for the sensible heat flux at 77 and 200 m flight levels, and also for the latent heat flux at the lowest level. The model quality control indicated failures for the latent heat flux at the 200 m level (and higher), which were probably due to large moisture fluctuations that could not be modelled using linear assumptions. Finally the LLF+IM method was applied to more than twenty low-level flights from the LITFASS-2003 experiment. Comparison with aggregated surface flux data revealed good agreement for the sensible heat flux but larger discrepancies and a higher statistical uncertainty for the latent heat flux     

Climate change effects on hydrological system conditions influencing generation of storm runoff in small Alpine catchments

Floods and debris flows in small Alpine torrent catchments (<10 km²) arise from a combination of critical antecedent system state conditions and mostly convective precipitation events with high precipitation intensities. Thus, climate change may influence the magnitude–frequency relationship of extreme events twofold: by a modification of the occurrence probabilities of critical hydrological system conditions and by a change of event precipitation characteristics. Three small Alpine catchments in different altitudes in Western Austria (Ruggbach, Brixenbach and Längentalbach catchment) were investigated by both field experiments and process‐based simulation. Rainfall–runoff model (HQsim) runs driven by localized climate scenarios (CNRM‐RM4.5/ARPEGE, MPI‐REMO/ECHAM5 and ICTP‐RegCM3/ECHAM5) were used in order to estimate future frequencies of stormflow triggering system state conditions. According to the differing altitudes of the study catchments, two effects of climate change on the hydrological systems can be observed. On one hand, the seasonal system state conditions of medium altitude catchments are most strongly affected by air temperature‐controlled processes such as the development of the winter snow cover as well as evapotranspiration. On the other hand, the unglaciated high‐altitude catchment is less sensitive to climate change‐induced shifts regarding days with critical antecedent soil moisture and desiccated litter layer due to its elevation‐related small proportion of sensitive areas. For the period 2071–2100, the number of days with critical antecedent soil moisture content will be significantly reduced to about 60% or even less in summer in all catchments. In contrast, the number of days with dried‐out litter layers causing hydrophobic effects will increase by up to 8%–11% of the days in the two lower altitude catchments. The intensity analyses of heavy precipitation events indicate a clear increase in rain intensities of up to 10%.