PHOENIX-2: A New Broadband Spectrometer for Deci- metric and Microwave Radio Bursts – First Results

A broadband radio spectrometer has been put into operation at Bleien, Switzerland, to register the flare emission of the full Sun. In the frequency range of operation, 0.1 to 4.0 GHz, both modes of circular polarization are recorded continuously. The new system, Phoenix-2, has been developed from the experience with the previous Phoenix spectrometer. Improved, computer-controlled focal hardware allows now a complete daily calibration, a more sophisticated calibration procedure, and monitoring of all essential instrumental and environmental parameters. Calibrated data are now usually available the day after observation and are accessible through the Internet. The scientific improvements include a larger frequency range of observation, a larger number of completely recorded events due to full-day registration, more accurate measurements, particularly in circular polarization, and more reliable operation. First observations are presented and quantitative results comparing the calibration with single frequency instruments are reported. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1005194314845     

Relationships between lightning activity and various thundercloud parameters: satellite and modelling studies

The lightning frequency model developed by Baker et al. [Baker, M.B., Christian, H.J., Latham, J., 1995. A computational study of the relationships linking lightning frequency and other thundercloud parameters, Q. J. R. Meteorol. Soc., 121, 1525–1548] has been refined and extended, in an effort to provide a more realistic framework from which to examine computationally the relationships that might exist between lightning frequency f (which is now being routinely measured from a satellite, using the NASA/MSFC Optical Transient Detector (OTD)) and a variety of cloud physical parameters. Specifically, superior or more comprehensive representations were utilised of: (1) glaciation via the Hallett–Mossop (H–M) process; (2) the updraught structure of the model cloud; (3) the liquid-water-content structure of the model cloud; (4) the role of the reversal temperature T_rev in influencing lightning characteristics; (5) the critical breakdown field for lightning initiation; and (6) the electrical characteristics of the ice crystal anvil of the model cloud. Although our extended studies yielded some new insights into the problem, the basic pattern of relationships between f and the other parameters was very close to that reported by Baker et al. (1995). The more elaborate treatment of T_rev restricted somewhat the range of conditions under which reverse-polarity lightning could be produced if the cloud glaciated via H–M, but confirmed the earlier conclusion that such lightning would not occur if the glaciation was of the Fletcher type. The computations yielded preliminary support for the hypothesis that satellite measurements of f might be used to determine values of the ice-content of cumulonimbus anvils: a parameter of climatological importance. The successful launch and continuing satisfactory functioning of the OTD [Christian, H.J., Goodman, S., 1992. Global observations of lightning from space, Proc. 9th Int. Conf. on Atmospheric Electricity, St. Petersburg, pp. 316–321; Christian, H.J., Blakesee, R.J., Goodman, S.J., 1992. Lightning imaging sensor (LIS) for the earth observing system. NASA Tech. Memorandum, 4350] make it possible—with a high degree of precision—to measure lightning location, occurrence time and frequency f over extensive areas of the Earth's surface. Measured global distributions of lightning and associated lightning stroke radiance demonstrate that: lightning activity is particularly pronounced over the tropics, much greater over land than over the oceans, and exhibits great seasonal variability; lightning radiance tends to be greater over the oceans, less when lightning activity is high, and greater in the Northern Hemisphere winter than summer.     

Naturnahe Abwasserreinigung: Interdisziplinäre Zusammenarbeit von Naturwissenschaftler und Ingenieur

Sewage from scattered villages is often treated in septic tanks whose removal efficiency of biodegradable components amounts to about 35%. Viewed from the standpoint of water protection such a performance provides an insufficient prevention of water pollution. It is worth aspiring to more extensive sewage treatment, i.e. oxidation of organic matter and nitrogen compounds. This particularly applies to rural regions if scattered villages are situated in ecologically sensitive regions such as watersheds of small brooks. Here, it is resonable to emply natural methods of treating sewage such as constructed wetlands and lagoons up to a size of 1,000 population equivalents. Constructed wetlands and lagoons provide an excellent field of cooperation between biologist and engineer, because the complexity of the microbial communities and the influence of the physico-chemical and geological conditions upon the microorganisms are not yet well understood. Further interdisciplinary research work has to be done for instance in regard to the relationship between helophytes and bacteria in the biofilm on the rhizomes of the need or focussing upon effluent polishing of lagoons.     

Altimetry-derived tide model for improved tide and water level forecasting along the European continental shelf

Ocean Dynamics - With the continued rise in global mean sea level, operational predictions of tidal height and total water levels have become crucial for accurate estimations and understanding of...     

Municipal Wastewater Treatment Using Moringa oleifera Seed and Press Cake Powder: A Comparative Analysis

Moringa oleifera (MO), also known as drumstick tree, has gained worldwide attention among researchers and policy makers, for showing its remarkable potential in environmental management. Recently, MO seed or press cake (a by-product of oil extraction industry) powder has also emerged as an alternative and promising coagulant for environmental remediation. In this view, attempts have been made in this study to evaluate the efficacy of MO seed and press cake powder (MSP & PCP) for the treatment of municipal wastewater. Both MSP and PCP are characterized by using swelling ratio, scanning and transmission electron microscopy analysis. The effect of various operational parameters such as coagulation–flocculation pH (2–10), coagulant dosage (0.1–1 g L⁻¹), and sedimentation time (0–180 min), etc., is investigated to understand the potential of MSP and PCP. At optimized operational conditions, sedimentation kinetics is also performed suggesting that the treatment process is being governed by the second-order kinetic model. The chemical and biological oxygen demand removals at optimized conditions are observed as follows: ≈38 and ≈73% for MSP and ≈47 and ≈85% for PCP. Overall, the results of the present study elucidated that PCP can be employed as a promising alternative of MSP for municipal wastewater with improved treatment efficiencies.     

Visual characterization technique for gravel‐cobble river bed surface sediments; validation and environmental applications Contribution to the programme of CIRSA (Centre Interuniversitaire de Recherche sur le Saumon Atlantique)

This paper presents an evaluation of the feasibility and the reliability of a visual characterization technique for gravel–cobble river bed surface substrate. Based on principal axis regressions, using phi scale (ϕ), comparisons of visual estimation and grid sampling techniques show that useful predictive relations (R² = 0·78–0·88) exist between visual estimates of the surface d₁₆, d₅₀ and d₈₄ and estimates obtained for the same percentiles with the grid sampling technique. Comparisons of visual estimation and the surface‐bulk sampling technique also indicate a predictive relation (R² = 0·70) between the d₅₀ of the two methods. Trained operators can visually estimate gravel–cobble bed surface d₁₆ to uncertainties of 41 per cent, d₅₀ to 15 per cent and d₈₄ to 11 per cent (for example, there is a 5·5 mm error on a d₈₄ size of 50 mm). Furthermore, evidence shows that if operators are properly trained, a calibration relation for each percentile can be applied independently of operators. This visual characterization allows effective detailed mapping of spatial patterns in substrate size distribution along extensive reaches of gravel‐bed rivers. The technique can be very useful in creating terrain models for various geomorphological, hydrological and biological applications such as the determination of entrainment thresholds, hydraulic roughness and substrate suitability for benthic insects or salmonid habitat. Copyright © 2001 John Wiley & Sons, Ltd.     

Let-It-Rain: a web application for stochastic point rainfall generation at ungaged basins and its applicability in runoff and flood modeling

We present a web application named Let-It-Rain that is able to generate a 1-h temporal resolution synthetic rainfall time series using the modified Bartlett–Lewis rectangular pulse (MBLRP) model, a type of Poisson stochastic rainfall generator. Let-It-Rain, which can be accessed through the web address http://www.LetItRain.info, adopts a web-based framework combining ArcGIS Server from server side for parameter value dissemination and JavaScript from client side to implement the MBLRP model. This enables any desktop and mobile end users with internet access and web browser to obtain the synthetic rainfall time series at any given location at which the parameter regionalization work has been completed (currently the contiguous United States and Republic of Korea) with only a few mouse clicks. Let-It-Rain shows satisfactory performance in its ability to reproduce observed rainfall mean, variance, auto-correlation, and probability of zero rainfall at hourly through daily accumulation levels. It also shows a reasonably good performance in reproducing watershed runoff depth and peak flow. We expect that Let-It-Rain can stimulate the uncertainty analysis of hydrologic variables across the world.     

Isochron‐burial dating of glaciofluvial deposits: First results from the Swiss Alps

In this study, we use isochron‐burial dating to date the Swiss Deckenschotter, the oldest Quaternary deposits of the northern Alpine Foreland. Concentrations of cosmogenic ¹⁰Be and ²⁶Al in individual clasts from a single stratigraphic horizon can be used to calculate an isochron‐burial age based on an assumed initial ratio and the measured ²⁶Al/¹⁰Be ratio. We suggest that, owing to deep and repeated glacial erosion, the initial isochron ratio of glacial landscapes at the time of burial varies between 6.75 and 8.4. Analysis of 22 clasts of different lithology, shape, and size from one 0.5 m thick gravel bed at Siglistorf (Canton Aargau) indicates low nuclide concentrations: <20 000 ¹⁰Be atoms/g and <150 000 ²⁶Al atoms/g. Using an ²⁶Al/¹⁰Be ratio of 7.6 (arithmetical mean of 6.75 and 8.4), we calculate a mean isochron‐burial age of 1.5 ± 0.2 Ma. This age points to an average bedrock incision rate between 0.13 and 0.17 mm/a. Age data from the Irchel, Stadlerberg, and Siglistorf sites show that the Higher Swiss Deckenschotter was deposited between 2.5 and 1.3 Ma. Our results indicate that isochron‐burial dating can be successfully applied to glaciofluvial sediments despite very low cosmogenic nuclide concentrations. Copyright © 2017 John Wiley & Sons, Ltd.     

Sediment transport in high‐speed flows over a fixed bed: 2. Particle impacts and abrasion prediction

Single bed load particle impacts were experimentally investigated in supercritical open channel flow over a fixed planar bed of low relative roughness height simulating high‐gradient non‐alluvial mountain streams as well as hydraulic structures. Particle impact characteristics (impact velocity, impact angle, Stokes number, restitution and dynamic friction coefficients) were determined for a wide range of hydraulic parameters and particle properties. Particle impact velocity scaled with the particle velocity, and the vertical particle impact velocity increased with excess transport stage. Particle impact and rebound angles were low and decreased with transport stage. Analysis of the particle impacts with the bed revealed almost no viscous damping effects with high normal restitution coefficients exceeding unity. The normal and resultant Stokes numbers were high and above critical thresholds for viscous damping. These results are attributed to the coherent turbulent structures near the wall region, i.e. bursting motion with ejection and sweep events responsible for turbulence generation and particle transport. The tangential restitution coefficients were slightly below unity and the dynamic friction coefficients were lower than for alluvial bed data, revealing that only a small amount of horizontal energy was transferred to the bed. The abrasion prediction model formed by Sklar and Dietrich in 2004 was revised based on the new equations on vertical impact velocity and hop length covering various bed configurations. The abrasion coefficient k_v was found to be vary around k_v ~ 10⁵ for hard materials (tensile strength f_t > 1 MPa), one order of magnitude lower than the value assumed so far for Sklar and Dietrich's model. Copyright © 2017 John Wiley & Sons, Ltd.     

The probabilistic seismic hazard assessment of Germany—version 2016, considering the range of epistemic uncertainties and aleatory variability

The basic seismic load parameters for the upcoming national design regulation for DIN EN 1998-1/NA result from the reassessment of the seismic hazard supported by the German Institution for Civil Engineering (DIBt). This 2016 version of the national seismic hazard assessment for Germany is based on a comprehensive involvement of all accessible uncertainties in models and parameters and includes the provision of a rational framework for integrating ranges of epistemic uncertainties and aleatory variabilities in a comprehensive and transparent way. The developed seismic hazard model incorporates significant improvements over previous versions. It is based on updated and extended databases, it includes robust methods to evolve sets of models representing epistemic uncertainties, and a selection of the latest generation of ground motion prediction equations. The new earthquake model is presented here, which consists of a logic tree with 4040 end branches and essential innovations employed for a realistic approach. The output specifications were designed according to the user oriented needs as suggested by two review teams supervising the entire project. Seismic load parameters, for rock conditions of \(v_{S30}\) = 800 m/s, are calculated for three hazard levels (10, 5 and 2% probability of occurrence or exceedance within 50 years) and delivered in the form of uniform hazard spectra, within the spectral period range 0.02–3 s, and seismic hazard maps for peak ground acceleration, spectral response accelerations and for macroseismic intensities. Results are supplied as the mean, the median and the 84th percentile. A broad analysis of resulting uncertainties of calculated seismic load parameters is included. The stability of the hazard maps with respect to previous versions and the cross-border comparison is emphasized.