Mode Mixing by a Shallow Sunspot

Sunspots are strong absorbers of f and p modes. A possible absorption mechanism is direct conversion to slow magnetoacoustic waves. Calculations based on vertical magnetic field models show that this works well for f modes, but is inadequate for p modes. Using a very simple shallow spot model, in which the effects of the magnetic field are accounted for solely by a surface condition, we investigate the possibility that p modes first scatter into f modes inside the spot, which are then more susceptible to conversion to slow modes. We find that the coupling between an incident p mode and the internal f mode is unlikely to be strong enough to account for the observed absorption, but that the incident modes do couple strongly to the acoustic jacket in some cases, leading to a region immediately around the sunspot where a significant fraction of the surface velocity is due to the jacket modes.     

Die Bedeutung der Süddeutschen Großscholle in der Geodynamik Westeuropas

The crustal plate of Southern Germany models, in a highly instructive way, the real behaviour of continental crustal plates in the immediate foreland of an active orogenic mountain belt. The frontier line between alpidic and outer-alpine strain pattern crossed this first order tectonic unit. During Upper Tertiary times, the crustal plate of Southern Germany shows an anticlockwise rotation of the direction of maximal principal stress (from NNE/SSW through NNW/SSE to NW/SE), nearly contemporaneous to the transition from alpine Flysch-to Molasse-to postorogenic sedimentation. From prae-Upper Cretaceous to Oligocene, NNE-SSW-plate movement follows a direction more or less parallel — not perpendicular — to the North Atlantic midocean ridge. Since the Pliocene, the axis of tectonic transport (a in rock fabrics nomenclature) turns to a more northwesterly-southeasterly position, so nearly becoming to the well known sea-floor spreading concept. But, at that time, alpine orogenesis comes to an end. Today, neither in the Alps nor in their foreland, any adequate subduction zone to counterbalance the opening of the North Atlantic (as supposed by means of paleomagnetic data) still exists. Since early Pliocene time, the Southern Germany crustal plate shows, in spite of the overburden by thick Molasse sediments, neither any subsidence nor underthrusting the Alps, but, on the contrary, uplifting in a magnitude up to more than fivehundred meters, while the opening of the North Atlantic seems to continue. So we find some serious inconsistencies between the so called new global tectonics and the tectonic evolution of the Southern Germany crustal plate.     

Cosmology and cosmogony in a cyclic universe

In this paper we discuss the properties of the quasi-steady state cosmological model (QSSC) developed in 1993 in its role as a cyclic model of the universe driven by a negative energy scalar field. We discuss the origin of such a scalar field in the primary creation process first described by F. Hoyle & J. V. Narlikar forty years ago. It is shown that the creation processes which take place in the nuclei of galaxies are closely linked to the high energy and explosive phenomena, which are commonly observed in galaxies at all redshifts. The cyclic nature of the universe provides a natural link between the places of origin of the microwave background radiation (arising in hydrogen burning in stars), and the origin of the lightest nuclei (H, D, He³ and He⁴). It also allows us to relate the large scale cyclic properties of the universe to events taking place in the nuclei of galaxies. Observational evidence shows that ejection of matter and energy from these centers in the form of compact objects, gas and relativistic particles is responsible for the population of quasi-stellar objects (QSOs) and gamma-ray burst sources in the universe. In the later parts of the paper we briefly discuss the major unsolved problems of this integrated cosmological and cosmogonical scheme — the understanding of the origin of the intrinsic redshifts, and the periodicities in the redshift distribution of the QSOs.     

Import of coastally-derived chlorophylla to South Slough, Oregon

Material transfer between estuaries and the nearshore zone has long been of interest, but information on the processes affecting Pacific Northwest estuaries has lagged behind other areas. The west coast of the U.S. is a region of seasonally variable upwelling that results in enhanced phytoplankton production in the nearshore zone. We examined estuarine-nearshore links over time by measuring physical oceanographic variables and chlorophylla concentration from an anchor station in South Slough, Oregon. Data was collected during 24-h cruises conducted at approximately weekly intervals during summer 1996 and spring 1997. The results demonstrate that the physical oceanography of this estuarine site was strongly influenced by the coastal ocean. Marine water reached the estuarine site on every sampled tide, and chlorophylla was clearly advected into the estuary with this ocean water. In contrast, phytoplankton concentrations were comparatively reduced in the estuarine water. There were, however, large fluctuations in the import of chlorophyll over the course of the summer. These variations likely reflect upwelling-generated phytoplankton production in the coastal ocean and subsequent cross-shelf transport to the estuary. Suspension feeding organisms in South Slough likely depend on the advection of this coastally-derived phytoplankton. The large allochthonous chlorophyll input measured for this system appears dissimilar from most estuaries studied to date. Previous investigations have focused on the outwelling and inwelling of materials in estuaries. We must now consider the influence of coastal upwelling and downwelling processes on estuarine material exchange.     

Arcanite from Fumarole Exhalations of the Tolbachik Volcano (Kamchatka,Russia) and Its Crystal Structure

The crystal structure (R = 0.0194) of arcanite β-K₂SO₄ was studied on a single crystal from exhalations of the Arsenatnaya fumarole, Tolbachik Volcano (Kamchatka, Russia). The mineral crystallizes at a temperature of ≥350–430°C and associates with langbeinite, aphthitalite, hematite, tenorite, johillerite, and others. Arcanite is orthorhombic, Pnma, a = 7.4763(2) Å, b = 5.77262(16) Å, c = 10.0630(3) Å, V = 434.30(2) ų, Z = 4. Its structure contains isolated SO₄ tetrahedra, whereas K cations center ten- and nine-fold polyhedra.     

Diurnal trends in reflectance of bare soil surfaces in Southern Tunisia

In an area in southern Tunisia diurnal trends of bare soil surfaces have been investigated. The study area comprises two main parts: the footslopes and the playas.

The diurnal variation of the bidirectional reflectance factor (BRF) in nadir direction on the footslopes is dominated by the effect of roughness. Maximum BRF is found with small solar zenith angles due to decrease in shadow related to surface roughness. For Landsat overpass it implies that the normal ground reflectance for a bare surface on the footslopes at identical surface conditions is up to 10% lower in December (solar zenith angle 63 degrees) than in June (28 degrees). Band ratios on the footslopes hardly change with variation of zenith angle.

The diurnal variation in the playas is dominated by moisture. Asymmetric daily curves, with the lowest reflectance in the morning have been found. Four phenomena are reported which can be held responsible for this effect. This daily effect of moisture is weather dependent and may obscure long time changes of TM signal. In band ratios even with TM band 7 the diurnal moisture change can hardly be detected.