Magnetic anomalies across Campbell Plateau,New Zealand

Magnetic measurements over the Campbell Plateau, New Zealand, show the existence of a linear positive anomaly belt which extends for 900 km along an approximately east-west trend. This anomaly belt is considered to be a continuation of the Stokes Magnetic Anomaly occurring through New Zealand and associated with rocks of the New Zealand Geosyncline. If this is so, a transcurrent fault with a dextral displacement of about 330 km and aligned in a northeast-southwest direction must occur between the eastern end of the Stokes Magnetic Anomaly and the western end of the anomaly belt across Campbell Plateau.     

Desert isotope hydrology: Water sources of the Sinai Desert

The isotopic composition of groundwater sources of the Sinai Desert was surveyed. The results are characterized by a large spread in the oxygen-18 and deuterium abundances, compared to equivalent systems from less arid climates. The variability reflects differences in the altitude at which precipitation occurred, the evaporation from stagnant surface waters prior to their infiltration into the ground and admixtures of waters which are not of meteoric or recent origin. It is difficult to distinguish between water sources recharged by direct infiltration and others recharged through the intermediary of flood waters, on the basis of their isotope composition. The isotopio composition enables a clearcut distinction, however, between paleowaters and more recently recharged groundwaters. Among the conclusions: paleowaters play a central role in the deep aquifers of desert areas; direct rain recharge to aquifers is widespread; surface waters which have undergone extensive evaporation contribute their water to local perched aquifers which are found along their route.     

Binarity of the red-rectangle and other extremely fe-poor (post?)-AGB stars

We present radial velocity measurements proving the binary nature of all the known extremely Fe-deficient Post-ABG stars including HD 44179, the central star of the well known but poorly understood Red-Rectangle nebula. With the observed orbital parameters, it is more likely that the stars represent a particular stage in binary evolution, rather than a typical post-AGB evolutionary stage.     

Meteorologische und statistische Betrachtungen über die interdiurne Veränderlichkeit

Zusammenfassung Praktische Fragen über die interdiurnen Veränderungen der Temperatur und der Feuchtigkeit haben uns gezwungen, die interdiurne Veränderlichkeit (I. V.) eingehender als gewöhnlich zu studieren. Vor allem wurde untersucht, welche Größe die I. V. am besten charakterisieren könnte. Die I. V. zeigte sich stark von der Lage der Station abhängig und sie weist auch einen gut ausgeprägten Jahresgang auf. Für Zuverlässigkeitsbetrachtungen war die numerische Kenntnis der Autokorrelationen in den Zeitreihen der täglichen Werte der Temperatur und der Feuchtigkeit notwendig. Es wurden Autokorrelationskoeffizienten bis zur sechsten Ordnung berechnet. Die Zeitreihe der I. V. erwies sich als negativ autokorreliert. Damit schnell und genügend genau Fragen aus der Praxis beantwortet werden könnten, wurde ein Nomogramm konsruiert. Ein zweites Nomogramm ermöglicht u. a. die Abschätzung der minimalen Länge der Grundperiode, damit man mit Hilfe des ersten Nomogramms Angaben mit vorgegebener Zuverlässigkeit machen kann.

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Summary Practical questions as to the interdiurnal variations of temperature and humidity forced us to make a thorough study of the interdiurnal variability (I. V.). First of all we examined which quantity could represent the I. V. best. The I. V. proved to depend on the situation of the station and to possess a highly pronounced annual variation. Considerations of reliability required numerical knowledge of the autocorrelation of the time series of the daily values of temperature and humidity. Coefficients of autocorrelation of orders 1 up to and including 6 were computed. The time series of the I. V. shows negative autocorrelation. In order to facilitate answering to practical problems, a nomogram was constructed. A second nomogram enables to estimate, for instance, the minimum length of the basic period required in order that the answer found by the help of the first nomogram possesses a prescribed reliability.

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Résumé Ce sont des questions pratiques concernant les variations interdiurnes de la température et de l'humidité qui nous ont forcés à étudier la variabilité interdiurne (V. I.) plus profondément que d'habitude. On a examiné quelle quantité peut represénter la V. I. de la meilleure façon. On a constaté que la V. I. dépend de la situation de la station et posséde un variation annuelle significative. En examinant la significativité statistique, il faut connaître l'autocorrélation dans les séries des valeurs quotidiennes de la température et de l'humidité; ces séries montrent une autocorrélation négative et on a calculé des facteurs d'autocorrélation jusqu'au sixième ordre. Pour pouvoir répondre rapidement et avec une précision suffisante aux questions de la pratique, on a construit un nomograme. Un second nomogramme permet d'estimer, par exemple, la durée minima de la période de base pour pouvoir donner, à l'aide du premier nomogramme, des réponses avec une exactitude désirée.

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Deuterium content of humic acids from marine and non-marine environments

Deuterium values obtained for humic acids isolated from marine sediments from the NE Pacific are in the range of $\text{δ}\text{D}\text{= (?105 ± 5)‰}$, corresponding to values obtained for marine plankton from the same area. Soil humic acids have a much broader range of δD values (?57 to ?97‰), depending on the isotopic values of the precipitation and the isotopic composition of the parent plant precursor.Data obtained on hydrogen isotope distribution confirms previous hypotheses based on chemical analysis and on carbon isotopes, which indicated the authigenic nature of marine humates.     

Triangulating Social Multimedia Content for Event Localization using Flickr and Twitter

The analysis of social media content for the extraction of geospatial information and event‐related knowledge has recently received substantial attention. In this article we present an approach that leverages the complementary nature of social multimedia content by utilizing heterogeneous sources of social media feeds to assess the impact area of a natural disaster. More specifically, we introduce a novel social multimedia triangulation process that uses both Twitter and Flickr content in an integrated two‐step process: Twitter content is used to identify toponym references associated with a disaster; this information is then used to provide approximate orientation for the associated Flickr imagery, allowing us to delineate the impact area as the overlap of multiple view footprints. In this approach, we practically crowdsource approximate orientations from Twitter content and use this information to orient Flickr imagery accordingly and identify the impact area through viewshed analysis and viewpoint integration. This approach enables us to avoid computationally intensive image analysis tasks associated with traditional image orientation, while allowing us to triangulate numerous images by having them pointed towards the crowdsourced toponym location. The article presents our approach and demonstrates its performance using a real‐world wildfire event as a representative application case study.     

Laboratory examination of linearity in rainfall–runoff relationships

ABSTRACT

Certain rainfall–runoff models, e.g. the unit hydrograph, assume linear relationships between the variables. These are proportionality of runoff discharges to (net) rainfall depth and linear summations of discharges resulting from (net) rainfalls during different time intervals or over different sectors of a watershed. This study examines the validity of these assumptions by use of an extensive two-dimensional laboratory experimentation. The results indicate that proportionality would be found under high rainfall intensity through a long duration. Spatial summations would more likely yield correct discharges in cases where rainfall duration is equal to, or is longer than, the time of concentration. Temporal summations may yield correct discharges when rainfall duration is longer than one half of the time of concentration. Here, the time of concentration is determined at the beginning of gradual approach of the discharge towards the equilibrium state.     

The geochemical evolution of the Pleistocene Lake Lisan-Dead Sea system

The geochemical history of Lake Lisan, the Pleistocene precursor of the Dead Sea, has been studied by geological, chemical and isotopic methods.Aragonite laminae from the Lisan Formation yielded (equivalent) Sr/Ca ratios in the range 0.5 × 10^?2?1 × 10^?2, Na/Ca ratios from 3.6 × 10^?3 to 9.2 × 10^?3, $\text{δ}{}^{18}\text{O}{}_{\mathrm{PDB}}$ values between 1.5 and 7%. and $\text{δ}{}^{13}\text{C}{}_{\mathrm{PDB}}$ from ?7.7 to 3.4%..The distribution coefficient of Na⁺ between aragonite and aqueous solutions, $\text{λ}{}^{\mathrm{A}}{}_{\mathrm{Na}}$, is experimentally shown to be very sensitive to salinity and nearly temperature independent. Thus, Na/Ca in aragonite serves as a paleosalinity indicator.Sr/Ca ratios and $\text{δ}{}^{18}\text{O}$ values in aragonite provide good long-term monitors of a lake's evolution. They show Lake Lisan to be well mixed, highly evaporated and saline. Except for a diluted surface layer, the salinity of the lake was half that of the present Dead Sea (15 vs 31%).Lake Lisan evolved from a small, yet deep, hypersaline Dead Sea-like, water body. This initial lake was rapidly filled-up to its highest stand by fresh waters and existed for about 40,000 yr before shrinking back to the present Dead Sea. The chemistry of Lake Lisan at its stable stand represented a material balance between a Jordan-like input, an original large mass of salts and a chemical removal of aragonite. The weighted average depth of Lake Lisan is calculated, on a geochemical basis, to have been at least 400, preferably 600 m.The oxygen isotopic composition of Lake Lisan water, which was higher by at least 3%. than that of the Dead Sea, was probably dictated by a higher rate of evaporation.Na/Ca ratios in aragonite, which correlate well with $\text{δ}{}^{13}\text{C}$ values, but change frequently in time, reflect the existence of a short lived upper water layer of varying salinity in Lake Lisan.     

Combining field and modelling techniques to assess rockfall dynamics on a protection forest hillslope in the European Alps

Adequate management of a mountain forest that protects downslope areas against impacts of rockfall requires insight into the dynamics of the hillslope environment. Therefore, we applied a combined approach, using field and modelling techniques, to assess the determining factors for rockfall source areas, rockfall tracks and rockfall runout zones on a forested slope in mountainous terrain. The first objective of this study was to understand why rockfall occurs in the study area. The second objective was to translate the knowledge obtained in the field into a model that simulates rockfall dynamics on a forested slope realistically. The third objective was to assess which hillslope characteristics primarily determine the distribution of active rockfall tracks. To achieve these objectives, we made a geomorphological map of the whole study area, and we measured the major discontinuity planes in the bedrock that are exposed in the rockfall source areas. Furthermore, a test site for simulation modelling within the larger study area was defined in which both a forest and a hillslope inventory were carried out. The available data and our developed rockfall simulation model allowed us to assess the slope characteristics that mainly determine the distribution of areas affected by rockfall. We found that in decreasing order of importance, both standing and felled trees, the surface roughness and rockfall resistant shrubs primarily determine the distribution of rockfall-affected areas. Simulation tests without a forest cover produced similar rockfall runout zones as fossil rockfall events identified in the field. We believe that the combined field and modelling approach is a prerequisite for understanding how forests can protect against rockfall.