A novel ozone sensor for direct eddy flux measurements

A small, lightweight (1.5 kg) and fast-response ozone sensor for direct eddy flux measurements has been built. The basis for detection is the chemiluminescence of an organic dye adsorbed on dry silica gel in the reaction with ozone. The chemiluminescence is monitored with a cheap and small blue-sensitive photomultiplier. At a flow rate of 100 l min^-1 the ozone sensor has a 90% response time of significantly better than 0.1 s with a detection limit lower than 50 ppt at S/N=3. There are no interferences from other atmospheric trace gases like NO_x, H₂O₂ and PAN. Water vapour and SO₂ enhance the chemiluminescence efficiency of the ozone sensor. Since their response times are 22 seconds and 30 minutes, respectively, no correlation between rapid ozone fluctuations and those of these two trace gases is noticed by the ozone sensor when operating at a frequency of 10 Hz.The ozone sensor was tested for several weeks in continuous measurements of ozone fluxes and deposition velocities over different croplands using the eddy correlation technique. Good agreement was found between ozone dry deposition velocities derived from profile measurements and by eddy correlation.     

The transition from peraluminous to peralkaline granitic melts: Evidence from melt inclusions and accessory minerals

Fractional crystallization of peraluminous F- and H₂O-rich granite magmas progressively enriches the remaining melt with volatiles. We show that, at saturation, the melt may separate into two immiscible conjugate melt fractions, one of the fractions shows increasing peraluminosity and the other increasing peralkalinity. These melt fractions also fractionate the incompatible elements to significantly different degrees. Coexisting melt fractions have differing chemical and physical properties and, due to their high density and viscosity contrasts, they will tend to separate readily from each other. Once separated, each melt fraction evolves independently in response to changing T/P/X conditions and further immiscibility events may occur, each generating its own conjugate pair of melt fractions. The strongly peralkaline melt fractions in particular are very reactive and commonly react until equilibrium is attained. Consequently, the peralkaline melt fraction is commonly preserved only in the isolated melt and mineral inclusions.

We demonstrate that the differences between melt fractions that can be seen most clearly in differing melt inclusion compositions are also visible in the composition of the resulting ore-forming and accessory minerals, and are visible on scales from a few micrometers to hundreds of meters.     

Nullschichteffekt und Frontalzonen

Zusammenfassung In früheren Untersuchungen wurde etwa 1 km unterhalb der Tropopause eine Schicht gefunden, in der im Mittel die Vertikalbewegungen in hochreichenden Druckgebilden Null sind (Nullschicht). Diese Nullschicht erweist sich als der Hauptsitz des vom Tief zum Hoch erfolgenden ageostrophischen Massenflusses, der als primär gegenüber den druckausgleichenden Vorgängen in der Grundschicht angesehen werden muß. Setzt man als Arbeitshypothese die Stärke dieses Massenflusses zum Hoch (Nullschichteffekt) proportional zum horizontalen Druckgradienten an, so läßt sich hieraus die Existenz der Nullschicht folgern, ihre etwas unterhalb der Tropopause gelegene Höhe sowie die Drängung der Isohypsen in den Frontalzonen. Der Nullschichteffekt als aktiver Vorgang liefert weiter eine Erklärung für die Aufrechterhaltung der drei atmosphärischen Systeme Hoch/Tief, Frontalzone und planetarische Westdrift. Er stellt die erforderliche Wärmepumpe für diese drei nach dem Prinzip der Kältemaschine wirkenden atmosphärischen Systeme dar; sein Zustandekommen ist noch ungeklärt.Die Methode der Verwendung der mittleren interdiurnen Temperaturänderungen, mit der die Nullschicht gefunden wurde, liefert ein Schema der vertikalen und ageostrophisch-horizontalen Zirkulation in einer Frontalzone. Nach diesem entspricht die Dynamik einer Frontalzone völlig der eines Paares hochreichender Hoch- und Tiefdruckgebiete.

---

Summary In several earlier papers a layer 1000 meters below the tropopause was discussed where vertical motion in high reaching pressure formations averages zero (zero layer). The zero layer proves to be the principal region of ageostrophic mass flow from Low to High that is to be considered primary in relation to pressure levelling processes in the ground layer. Assuming, as a working hypothesis, that the strength of that mass flow towards the High (zero layer effect) is proportional to the horizontal pressure gradient, it is possible to conclude hereof the existence of a zero layer, its height slightly below the tropopause, and the concentration of contour lines in the frontal zones. The zero layer effect as an active process also furnishes an explanation for the maintenance of the three atmospherical systems: High/Low, frontal zone, and planetary west drift. It provides the necessary heat pump for these three atmospherical systems acting in accordance with the principle of a refrigerating machine. Its origin is still unknown.The method of utilizing mean interdiurnal changes of temperature, by which the zero layer was found, provides a vertical and ageostrophic-horizontal circulation pattern in a frontal zone. Accordingly, the dynamics of a frontal zone corresponds perfectly to that of a couple of high-reaching high and low pressure areas.

---

Résumé Des recherches antérieures ont démontré l'existence d'une couche atmosphérique située à environ 1 km au-dessous de la tropopause dans laquelle les mouvements verticaux sont en moyenne nuls (couche neutre). Cette couche serait le siège principal du flux de masse non géostrophique dirigé de l'aire de basse pression vers celle de haute pression et que l'on doit considérer comme primaire par rapport aux échanges de pression dans la couche de base. Si l'on admet que l'intensité de ce flux de masse est proportionnelle au gradient horizontal de pression, on en peut déduire l'existence de la couche à mouvement vertical nul (couche neutre), son altitude un peu inférieure à celle de la tropopause ainsi que le resserrement des isohypses dans les zones frontales. L'existence de cette couche neutre explique en outre le maintien des trois systèmes fondamentaux de l'atmosphère: centres de basse et de haute pression, zones frontales et courant planétaire d'Ouest. Il constitue la pompe à chaleur de ces systèmes atmosphériques fonctionnant selon le principe de la machine frigorifique; son origine n'est pas encore expliquée.L'usage des varaitions interdiurnes moyennes de température qui a conduit à la découverte de la couche neutre en question fournit un schéma des circulations verticales et horizontales non géostrophiques dans une zone frontale d'après lequel la dynamique d'une telle zone correspond exactement à celle d'un couple d'aires de basse et de haute pression atteignant la haute atmosphère.

---

---

Mit 12 Textabbildungen.     

Shale basins,sulfur-deficient ore brines and the formation of exhalative base metal deposits

The massive sulfide deposits of the Iberian Pyrite Belt are interbedded with felsic volcanic rocks and shale, and underlain by several thousand meters of siliciclastic sedimentary rocks known as the PQ Group. Isotope geochemistry and regional geology are both consistent with equilibration of the ore-forming fluids with the PQ Group, prior to ore deposition near the former seafloor. The average Cu:Zn:Pb ratio of the PQ Group rocks (ca. 26:55:19) is similar to the weighted average of all the massive sulfide orebodies combined (ca. 25:52:23).The genetic relationship between massive sulfide deposits and a siliciclastic sedimentary metal source is explained here by a thermodynamic model, proposing that mildly reducing redox conditions imposed by equilibration with the sedimentary rocks are most critical for the formation of an effective ore-forming fluid. Relatively metal-rich but organic-poor pyrite-bearing shale undergoing dewatering of saline pore fluids is an effective source for the generation of sulfur-deficient but relatively iron and base metal-rich brines. Thus, we propose that the giant deposits of the Iberian Pyrite Belt owe their existence not to exceptionally metal-enriched (e.g., magmatic) fluids, but to the existence of a fairly ordinary but large metal source in reactive siliciclastic sediments, combined with an underlying igneous heat source and a particularly efficient mechanism of sulfide precipitation by mixing with H₂S-rich fluids at or near the seafloor.Essentially similar mineral equilibria are imposed when saline fluids are buffered by typical continental basement rocks. Leaching of retrograde minerals and possibly residual salts from their magmatic or metamorphic prehistory is expected to generate similar, variably metal-rich but relatively sulfide-deficient fluids. Thus, the existence of mildly reducing rocks can be the dominant chemical control in the source of fluids generating many volcanogenic, Irish-type or sedex deposits, many of which are known to precipitate their metal load in response to biogenic sulfide addition at the ore deposition site.     

Europrobe seismic reflection profiling across the eastern Middle Urals and West Siberian Basin

New deep seismic reflection data provide images of the crust and uppermost mantle underlying the eastern Middle Urals and adjacent West Siberian Basin. Distinct truncations of reflections delineate the late-orogenic strike-slip Sisert Fault extending vertically to ∼28 km depth, and two gently E-dipping reflection zones, traceable to 15–18 km depth, probably represent normal faults associated with the opening of the West Siberian Basin. A possible remnant Palaeozoic subduction zone in the lower crust under the West Siberian Basin is visible as a gently SW-dipping zone of pronounced reflectivity truncated by the Moho. Continuity of shallow to intermediate-depth reflections suggest that Palaeozoic accreted island-arc terranes and overlying molasse sequences exposed in the hinterland of the Urals form the basement for Triassic and younger deposits in the West Siberian Basin. A highly reflective lower crust overlies a transparent mantle at about 43 km depth along the entire 100 km long seismic reflection section, suggesting that the lower crust and Moho below the eastern Middle Urals and West Siberian Basin have the same origin.     

Monsune und Tropenorkane im Witterungsklima und in der Groß-Zirkulation

Zusammenfassung In dem Ablauf des Jahresganges im Witterungsklima und der allgemeinen Zirkulation wirken sich monsunale Einflüsse aus. Das im Winter zeitweise auftretende ozeanwärts gerichtete Abströmen kontinental-arktischer Luft erfolgt in Zusammenhang mit Kaltlufthöhentrögen. Im Sommer bedingen die Nordwärtsverlagerung der nordatlantischen und nordpazifischen Hochdruckgebiete und der Aufbau von warmen Höhenhochdruckgebieten über Hochasien und Arizona dazwischenliegende Höhentröge, mit denen die monsunale Advektion maritimer Luftmassen in das Festland hinein verbunden ist. Auch das indische Monsuntief befindet sich in einem Höhentrog zwischen dem hochasiatischen Höhenhoch und dem nordwärts vorgerückten Hoch aus dem Südindischen Ozean. Die festländischen sommerlichen Höhenhochs üben eine blockierende Wirkung auf die Zirkulation aus. Der ebenfalls in die Großzirkulation eingreifende interhemisphärische Austausch von Masse und Moment tritt witterungsklimatisch am meisten dadurch in Erscheinung, daß die Entstehungsgebiete der tropischen Wirbelstürme den Trögen der jeweils anderen, winterlichen Halbkugel zugeordnet sind.

---

Witterungsklima (weather-climate) and general circulation considered in the light of monsoons and tropical storms

Summary The course of the annual variations of theWitterungs-klima and of the general circulation is subjected to monsoonal influences. The outflow of arctic air masses from the continent to the ocean occurring temporarily during the winter is related to upper air troughs of cold air. In summer, the northward displacement of the North Atlantic and the North Pacific anticyclones and the formation of warm upper air highs above Central Asia and Arizona cause intermediate air troughs to develop which, on their part, are related to the monsoonal advection of maritime air masses to the continent. The Indian monsoonal low is likewise located in an upper air trough between the upper air high above Central Asia and the high pressure area that advanced from the South Indian Ocean. In summer, the continental upper air highs exert a blocking action on the circulation. The interhemispheric exchange of mass and momentum which, too, reflects on the large scale circulation is mainly called into existence in its weather-climatic respect owing to the fact that the areas of origin of tropical storms (hurricanes, typhoons) are co-ordinated to the througs of the opposite winterly hemisphere.

---

Witterungsklima (climat du temps) et circulation générale considérés sous l'aspect des moussons et des cyclones tropicaux

Résumé Le cours des variations annuelles duWitterungsklima et de la circulation générale est sujet à des influences des moussons. Les écoulements à partir du continent vers l'océan des masses d'air arctiques, se produisant de temps en temps pendant l'hiver, sont reliés à des talwegs d'air froid en altitude. En été, le déplacement vers le nord des anticyclones de l'Atlantique Nord et du Pacifique Nord ainsi que la formation d'anticyclones en grande altitude au-dessus de l'Asie Centrale et d'Arizone causent la formation des hauts talwegs intercalés entre les anticyclones mentionnés ci-dessus. Ces talwegs ont rapport à l'advection de mousson des masses d'air maritime vers le continent. La dépression de mousson indien se trouve dans un talweg en altitude entre le haut anticyclone de l'Asie Centrale et l'anticyclone de l'océan Indien du Sud qui s'est déplacé vers le Nord. En été, les anticyclones continentaux en altitude ont un effet bloquant sur la circulation. L'échange interhémisphérique de masses et de moment qui réflète également sur la circulation générale se montre d'une manière la plus prononcée dans le «climat du temps» par suite du fait que les régions d'origine des cyclones tropicaux sont coordonnées à des trains de talwegs de l'hémisphère hivernal opposé.

---

---

Herrn Professor Dr. Gerhard Schott zum 90. Geburtstag gewidmet.     

Analytical Solution for Testing Debris Avalanche Numerical Models

—We present here the analytical solution of a one-dimensional dam-break problem over inclined planes. This solution is used to test a numerical model developed for debris avalanches. We consider a dam with infinite length in one direction where material is released from rest at the initial instant. We solve analytically and numerically the depth-averaged long-wave equations derived in a topography-linked coordinate system. The numerical and analytical solutions provide for a Coulomb-type friction law at the base of the flow. The analytical solution is obtained by using the method of characteristics and describes the flow over a constant slope, provided that the angle is higher than the friction angle. The numerical model utilizes a finite-difference method based on a Godunov-type scheme. Comparison between analytical and numerical results illustrates the remarkable stability and precision of the numerical method as well as its ability to deal with strong discontinuities.