Letzte Erinnerung an Wilhelm Salomon-Calvi (1868–1941)

Ohne Zusammenfassung     

Die Stellung der nordalpinen Flyschzone im Rahmen der Ostalpen

Ohne Zusammenfassung     

Submicron dust and the collision of comet SL-9 with Jupiter

Sub-micron sized dust grains released from the several fragments of the comet Shoemaker-Levy 9 could produce significant observable effects on the colour of the Jovian surface. Analysis of photometric data could lead to important insights into the nature and quantity of the dust, as well as the release mechanisms involved.     

Magnetic fields and the temperature structure of the chromosphere-corona interface

The temperature structure of the transition region between the chromosphere and corona is discussed in the context of current ideas about magnetic fields in these layers. Magnetic channeling of the downward conductive heat flow from the corona into the regions of enhanced field at the supergranulation boundaries is proposed as a mechanism for explaining the measured intensities of solar ultraviolet emission lines which originate in layers with temperatures below 10⁵ °K. It is shown that nearly all of the observed ultraviolet line emission originates in interspicule regions, and that this emission plays an important part in the energy balance of the cooler layers of the transition region. It is suggested that certain motions observed in the upper chromosphere may represent the earliest visual evidence for conversion of inflowing conduction energy into kinetic motions.On leave from the Observatory Sonnenborgh at Utrecht, The Netherlands.     

Die Berechnung der Frontgeschwindigkeit in einem einachsig inhomogenen Körper aus seismischen Refraktionsmessungen

Zusammenfassung Es wird gezeigt wie man seismische Refraktionmessungen, unter der Voraussetzung, dass die zur Frontgeschwindigkeit c(z) inverse Funktion z=(c) schichtweise in eine Potenzreihe entwickelbar ist, direkt interpretieren kann. Abschliessend wird die neue Theorie mit der bekannten vonHerglotz-Wiechert undSlichter verglichen.

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Summary The theory of the interpretation of seis mic travel-time surfaces for refracted rays in parallel structures is treated in a new manner, under the assumption that the depth-velocity function of any bed can be expanded in a power serie.

     

Warming but not thawing of the cold permafrost in northern Alaska during the past 50 years

Climate warming has not resulted in measurable thawing of the cold (-5°C to -10°C) permafrost in northern Alaska during the last half century. The maximum depths of summer thaw at five locations near Barrow, Alaska, in 2005 were within the ranges of the depths obtained at those same locations during the early 1950s. However, there has been a net warming of about 2°C, after a cooling of 0.4°C during 1953-1960, at the upper depths of the permafrost column at two of the locations. Thawing of permafrost from above (increase in active layer thickness) is determined by the summer thawing index for the specific year; any warming, or cooling, of the upper permafrost column results from the cumulative effect of changes in the average annual air temperatures over a period of years, assuming no change in surface conditions. Theoretically, thawing from the base of permafrost should be negligible even in areas of thin (about 100-200 m) permafrost in northern Alaska. The reported shoreline erosion along the northern Alaska coast is a secondary result from changes in the adjacent ocean ice coverage during the fall stormy period, and is not directly because of any "thawing" of the permafrost.