Zur Entwicklung der luftelektrischen Grundanschauung     

H. Israël 《Meteorology and Atmospheric Physics》1951,3(3-4):356-356

Ohne Zusammenfassung  相似文献   

Luftelektrische Tagesgänge und Massenaustausch im Hochgebirge der Alpen     

Israël  H.  Kasemir  H. W.  Wienert  K. 《Meteorology and Atmospheric Physics》1951,3(5):357-381

Zusammenfassung Es wird über die Ergebnisse luftelektrischer Untersuchungen auf dem Jungfraujoch (Schweiz) und ihre Deutung berichtet. Während zweier Meßperioden von je mehrwöchiger Dauer wurden das luftelektrische Potentialgefälle und der vertikale Leitungsstrom registriert; bearbeitet sind zunächst die Tagesgänge an klaren Tagen mit Hochdruckwetter. Die Tagesvariationen der drei luftelektrischen Elemente: Potentialgefälle, Vertikalstrom und Leitfähigkeit zeigen, daß auf dem Jungfraujoch im Sommer und im Herbst zwei ganz verschiedene Typen des luftelektrischen Verhaltens zu erkennen sind: Im Sommer herrscht auch an dieser Höhenstation der von den Tieflandstationen bekannte Typ vor, bei dem das Potentialgefälle angenähert invers zur Leitfähigkeit und zum Vertikalstrom verläuft. Im Herbst dagegen verlaufen Potentialgefälle und Vertikalstrom im wesentlichen gleichsinnig bei gegensinniger, aber schwächer ausgeprägter Tagesvariation der Leitfähigkeit. Im Sommer herrscht also auch in Jungfrauhöhe in den Alpen derkontinentale Typ, während sich im Herbst die Verhältnisse demozeanischen Typ annähern. Eine genauere Analyse ergibt, daß im Sommer die Tagesvariation desSäulenwiderstandes (columnar resistance) über dem Jungfraujoch in enger Korrelation zum örtlichen Widerstand der Luft an der Meßstelle (Reziprokwert der Leitfähigkeit) steht, während dies im Herbst nicht mehr der Fall ist.Zur Deutung dieser Feststellungen ist folgendes anzunehmen: Im Hochsommer wirkt die Tagesschwankung des vertikalen Massenaustausches aerosolverändernd bis in die Höhe des Alpenkammes, erkennbar daran, daß die Steuerung der luftelektrischen Tagesvariationen im wesentlichen von den unteren Schichten her erfolgt. Im Herbst dagegen ist dieser Einfluß in Kammhöhe der Alpen nahezu geschwunden; die Austauschvariation dringt nicht mehr bis in diese Höhen vor. Die verbleibenden Variationen der Leitfähigkeit deuten auf advektiven Luftaustausch hin. Das Verhalten des Dampfdruckes auf dem Jungfraujoch im Sommer und Herbst stützt diese Deutung.

---

Summary The present paper gives an account of researches on atmospheric electricity carried out at Jungfraujoch (Switzerland). During two periods of several weeks each the potential gradient and the vertical air-earth current have been recorded. In the first place the diurnal variations on fine days at high pressure weather situation are elaborated. The daily variations of the three elements: potential gradient, vertical current, and conductivity, show that in summer and autumn two different types of the conditions of atmospheric electricity can be discerned: In summer the well-known type of the lowland stations is predominating also at this high altitude station, the type where the potential gradient is very nearly inverse to conductivity and vertical current. In autumn on the contrary the potential gradient and the vertical current are essentially parallel since the conductivity shows a slight diurnal variation in contrary sense. Thus, in summer prevails at the altitude of Jungfraujoch in the Alps thecontinental type, whilst in autumn the conditions approach to theoceanic type. It results from a rigorous analysis that in summer the diurnal variation of thecolumnar resistance on Jungfraujoch is in close correlation to the local air resistance (the reciprocal figure of conductivity) at the measuring point, whereas in autumn this is no longer the case.To explain these results we must assume as follows: In midsummer the diurnal variation of vertical mass exchange produces alterations of the aerosol up to the altitude of the crest of the Alps, which is perceptible from the fact that diurnal variations of atmospheric electricity start essentially from the lower layers. In autumn this influence has almost disappeared in the summit altitude of the Alps, as the daily variation of exchange does not advance to this altitude. The remaining variations of the conductivity point at an advective exchange of air. The behaviour of vapour pressure in summer and autumn at Jungfraujoch gives support to this interpretation.

---

Résumé L'article traite des résultats de recherches d'électricité atmosphérique au Jungfraujoch (Suisse) et de leur interprétation. Deux périodes de mesures de plusieurs semaines chacune ont été consacrées à l'enregistrement du gradient de potentiel et du courant vertical. On décrit tout d'abord la variation diurne lors des jours sereins de temps anticyclonique. On distingue an Jungfraujoch en été et en automne respectivement deux types très différents de la marche diurne du gradient de potentiel, du courant vertical et de la conductibilité. En été le type bien connu des stations de plaine pour lequel le gradient de potentiel varie à peu près inversement à la conductibilité et au courant vertical s'observe aussi au Jungfraujoch. Par contre en automne le gradient de potentiel et le courant vertical varient en général dans le même sens, tandis que la conductibilité varie, elle, en sens contraire, bien que faiblement. Il y a donc à l'altitude du Jungfraujoch en été le «type continental», alors qu'en automne les conditions se rapprochent du «type océanique». Une analyse plus détaillée montre qu'en été la variation diurne de la «résistance tubulaire» (columnar resistance) au-dessus du Jungfraujoch est en liaison étroite avec la résistance locale de l'air au point de mesure (inverse de la conductibilité), tandis qu'en automne ce n'est plus le cas.Pour interpréter ces résultats il faut admettre ce qui suit: En été la variation diurne de l'échange vertical turbulent modifie les aérosols jusqu'au niveau de la crête alpine, ce que l'on reconnaît au fait que les variations diurnes des phénomènes d'électricité atmosphérique sont largement conditionnés par les couches basses. En automne par contre cet effet a disparu sur les Alpes, car la variation de l'échange turbulent n'a plus d'influence à ce niveau. La variation de la conductibilité qui subsiste suggère un échange d'air par advection. L'allure de la pression de vapeur d'eau au Jungfraujoch en été et en automne confirme cette hypothèse.

---

---

Mit 11 Textabbildungen.  相似文献   

Buchbesprechungen     

F. Steinhauser  H. Israël 《Meteorology and Atmospheric Physics》1949,2(1):144-162

Ohne Zusammenfassung  相似文献   

Buchbesprechungen     

F. Steinhauser  H. Israël 《Meteorology and Atmospheric Physics》1952,5(1):120-128

Ohne Zusammenfassung  相似文献   

Méthode de comparaison des régimes pluviaux en météorologie synoptique     

M. Bouët 《Meteorology and Atmospheric Physics》1948,1(1):100-107

Résumé On développe une méthode basée sur le dénombrement des jours de pluite communs à deux stations données et sur l'écart avec leur probabilité. Une formule simple définit l'indice de similitude de deux régimes pluviaux, indice qui peut varier de –1 à +1 et qui caractérise la plus ou moins grande similitude des distributions chronologiques de la pluie en deux endroits quelconques. L'application de la méthode conduit à établir une loi de décroissance de l'indice avec la distance séparant les stations comparées. Dans la région alpine cette loi présente une anomalie résultant de l'effet orographique.

---

Summary A method of obtaining a synoptic view of the distribution of precipitation (rain- and snowfall) is developed. It is based on the number of days on which precipitation occurs at both of two places more or less distant from each other. A mathematical definition is given of an index of similarity, which latter varies between –1 and +1. These, limiting, figures signify in the case of –1 that precipitation is least likely to occur on any one day at both of two different places, in the case of +1 that it is most likely to occur, and that when the index of similarity is 0 no relation at all can be established for the likelihood of precipitation at both places on the same day. The index shows a sharp decline as the distance between places increases. In general it shows less relationship in regard to the simultaneous occurrence of rain-and snowfall between places lying on opposite sides of the Alps than between places on the same side, showing once more how the Alps act as a weather partition. The results, based on observations at 9 places in Switzerland and 8 in other European countries, are valid for the Temperate Zone; for other climatic regions they may be different.

---

Zusammenfassung Von der Anzahl der gleichzeitigen Niederschlagstage an zwei Beobachtungsstationen und von der Abweichung ihrer Wahrscheinlichkeit ausgehend, wird eine Methode zum Vergleiche der Niederschlagstypen im synoptischen Sinne entwickelt. Der sogenannte Ähnlichkeitsindex, der zwischen –1 und +1 variieren kann, wird mathematisch definiert. Je nach dem Wert desselben ist die zeitliche Verteilung der Niederschlagstage an zwei Orten gleich (+1), indifferent (0) oder entgegengesetzt (–1). Bei der Anwendung der Methode tritt eine gesetzmäßige Abnahme des Index mit der Entfernung auf. Ein entgegengesetztes Verhalten des Ähnlichkeitsindex beiderseits der Alpen veranschaulicht die Rolle, welche die Alpen bekanntlich als Wetterscheide spielen.

  相似文献   

A Time Monte Carlo method for addressing uncertainty in land-use change models     

Ahmed Mustafa  Ismaïl Saadi  Mario Cools  Jacques Teller 《International journal of geographical information science》2018,32(11):2317-2333

One of the main objectives of land-use change models is to explore future land-use patterns. Therefore, the issue of addressing uncertainty in land-use forecasting has received an increasing attention in recent years. Many current models consider uncertainty by including a randomness component in their structure. In this paper, we present a novel approach for tuning uncertainty over time, which we refer to as the Time Monte Carlo (TMC) method. The TMC uses a specific range of randomness to allocate new land uses. This range is associated with the transition probabilities from one land use to another. The range of randomness is increased over time so that the degree of uncertainty increases over time. We compare the TMC to the randomness components used in previous models, through a coupled logistic regression-cellular automata model applied for Wallonia (Belgium) as a case study. Our analysis reveals that the TMC produces results comparable with existing methods over the short-term validation period (2000–2010). Furthermore, the TMC can tune uncertainty on longer-term time horizons, which is an essential feature of our method to account for greater uncertainty in the distant future.  相似文献   

Momentum- and Heat-Flux Parametrization at Dome C,Antarctica: A Sensitivity Study     

Etienne Vignon  Christophe Genthon  Hélène Barral  Charles Amory  Ghislain Picard  Hubert Gallée  Giampietro Casasanta  Stefania Argentini 《Boundary-Layer Meteorology》2017,162(2):341-367

An extensive meteorological observational dataset at Dome C, East Antarctic Plateau, enabled estimation of the sensitivity of surface momentum and sensible heat fluxes to aerodynamic roughness length and atmospheric stability in this region. Our study reveals that (1) because of the preferential orientation of snow micro-reliefs (sastrugi), the aerodynamic roughness length \(z_{0}\) varies by more than two orders of magnitude depending on the wind direction; consequently, estimating the turbulent fluxes with a realistic but constant \(z_{0}\) of 1 mm leads to a mean friction velocity bias of \(24\,\%\) in near-neutral conditions; (2) the dependence of the ratio of the roughness length for heat \(z_{0t}\) to \(z_{0}\) on the roughness Reynolds number is shown to be in reasonable agreement with previous models; (3) the wide range of atmospheric stability at Dome C makes the flux very sensitive to the choice of the stability functions; stability function models presumed to be suitable for stable conditions were evaluated and shown to generally underestimate the dimensionless vertical temperature gradient; as these models differ increasingly with increases in the stability parameter z / L, heat flux and friction velocity relative differences reached \(100\,\%\) when \(z/L > 1\); (4) the shallowness of the stable boundary layer is responsible for significant sensitivity to the height of the observed temperature and wind data used to estimate the fluxes. Consistent flux results were obtained with atmospheric measurements at heights up to 2 m. Our sensitivity study revealed the need to include a dynamical parametrization of roughness length over Antarctica in climate models and to develop new parametrizations of the surface fluxes in very stable conditions, accounting, for instance, for the divergence in both radiative and turbulent fluxes in the first few metres of the boundary layer.  相似文献   

Separation of rifting and lithospheric folding signatures in the NW-Alpine foreland   总被引：2，自引：0，他引：2  

O. Bourgeois  M. Ford  M. Diraison  C. Le Carlier de  Veslud  M. Gerbault  R. Pik  N. Ruby  S. Bonnet 《International Journal of Earth Sciences》2007,96(6):1003-1031

The development of the Alpine mountain belt has been governed by the convergence of the African and European plates since the Late Cretaceous. During the Cenozoic, this orogeny was accompanied with two major kinds of intraplate deformation in the NW-European foreland: (1) the European Cenozoic Rift System (ECRIS), a left-lateral transtensional wrench zone striking NNE-SSW between the western Mediterranean Sea and the Bohemian Massif; (2) long-wavelength lithospheric folds striking NE and located between the Alpine front and the North Sea. The present-day geometry of the European crust comprises the signatures of these two events superimposed on all preceding ones. In order to better define the processes and causes of each event, we identify and separate their respective geometrical signatures on depth maps of the pre-Mesozoic basement and of the Moho. We derive the respective timing of rifting and folding from sedimentary accumulation curves computed for selected locations of the Upper Rhine Graben. From this geometrical and chronological separation, we infer that the ECRIS developed mostly from 37 to 17 Ma, in response to north-directed impingement of Adria into the European plate. Lithospheric folds developed between 17 and 0 Ma, after the azimuth of relative displacement between Adria and Europe turned counter-clockwise to NW–SE. The geometry of these folds (wavelength = 270 km; amplitude = 1,500 m) is consistent with the geometry, as predicted by analogue and numerical models, of buckle folds produced by horizontal shortening of the whole lithosphere. The development of the folds resulted in ca. 1,000 m of rock uplift along the hinge lines of the anticlines (Burgundy–Swabian Jura and Normandy–Vogelsberg) and ca. 500 m of rock subsidence along the hinge line of the intervening syncline (Sologne–Franconian Basin). The grabens of the ECRIS were tilted by the development of the folds, and their rift-related sedimentary infill was reduced on anticlines, while sedimentary accumulation was enhanced in synclines. We interpret the occurrence of Miocene volcanic activity and of topographic highs, and the basement and Moho configurations in the Vosges–Black Forest area and in the Rhenish Massif as interference patterns between linear lithospheric anticlines and linear grabens, rather than as signatures of asthenospheric plumes.

O. BourgeoisEmail:

  相似文献   

Tectonic significance of an earthquake sequence in the Zacoalco half-graben, Jalisco, Mexico     

Javier F. Pacheco  Carlos A. Mortera-Gutirrez  Hugo Delgado  Shri K. Singh  Raúl W. Valenzuela  Nicolai M. Shapiro  Miguel A. Santoyo  Alejandro Hurtado  Ricardo Barrn  Esteban Gutirrez-Moguel 《Journal of South American Earth Sciences》1999,12(6):55

We studied a sequence of small earthquakes that occurred during the months of April and May of 1997, in Jalisco, southwestern Mexico. The earthquakes were located along a set of active faults that form the Zacoalco half-graben (La Lima fault system), west of Lake Chapala, within the rift–rift–rift triple junction. A total of 33 events were located, with magnitudes ranging from 1.5 to 3.5, recorded by a portable array of broadband seismographs. We identified two groups of events: one corresponding to a shallow normal fault, synthetic to La Lima fault system, and another group associated with a deeper fault. The events that occurred on the synthetic fault show normal faulting oriented on a NW–SE plane, dipping shallowly towards the SW. The other group of mechanisms showed either a normal fault oriented NW–SE and dipping steeply to the NE, or a very shallow-dipping normal fault, dipping to the SW. Earthquake distribution and fault plane solutions suggest that the Zacoalco half-graben developed from blocks that rotate as slip occurs on listric faults. These mechanisms could represent the type of motion expected for larger earthquakes in the area, like the one that occurred in 1568.  相似文献   

Helophyte zonation in two regulated estuarine areas in the Netherlands: Vegetation analysis and relationships with hydrological factors     

Hugo Coops  Noël Geilen  Gerard van der Velde 《Estuaries and Coasts》1999,22(3):657-668

The relationship between hydrological conditions and riparian helophyte vegetation was studied in two freshwater estuaries that differed in tidal regulation in order to assess the effects of large-scale hydrological regulation on the fringe vegetation. Vegetation and environmental variables were sampled for 206 sites in the Rhine-Meuse estuary (146 sites) and the IJsselmeer region (60 sites) in the Netherlands. These samples were classified into 10 vegetation types, all of which were dominated by tall helophytes. The most common vegetation types were dominated byPhragmites australis andTypha angustifolia, which formed both monospecific stands and mixtures. Tall Cyperaceae dominated three vegetation types (dominated individually bySchoenoplectus lacustris, Bolboschoenus maritimus, andSchoenoplectus tabernaemontani).Acorus calamus. Principal components analysis of the species composition of vegetation fringing open-water areas and associated environmental data revealed complex gradients incorporating differences in water depth, water-level fluctuation, were exposure, and sedimentation and/or erosion. The composition of the helophyte belts varied among the areas as the result of the differing times at which regulation occurred. Based on historical data, hydrological regulation of the estuaries has resulted in deterioration of intertidalSchoenoplectus andBolboschoenus stands, due to erosion and predation.P. australis stands have been invaded by terrestrial plant species or have been replaced byT. angustifolia. A scheme is presented of helophyte vegetation development under the influence of changes in the hydrological regime.  相似文献