Spin vectors in the Koronis family: comprehensive results from two independent analyses of 213 rotation lightcurves

Observations of Koronis asteroid family members (158) Koronis, (277) Elvira, (311) Claudia, (321) Florentina, and (720) Bohlinia made during the period 1998-2001 yielded 61 new individual rotation lightcurves to augment previous surveys (R.P. Binzel, 1987, Icarus 72, 135-208; S.M. Slivan, R.P. Binzel, 1996, Icarus 124, 452-470) and allow determination of the senses of rotation and spin vector orientations for these objects. Spin vector reductions were performed on these five objects and also on family members (167) Urda, (208) Lacrimosa, (534) Nassovia, and (1223) Neckar using both a combination of amplitude-magnitude and epoch methods and a convex inversion method. A total of 213 individual lightcurves were analyzed to determine sidereal rotation periods, pole solutions and obliquities, associated photometric parameters, and model shapes for each object. We checked our methods and results using the (243) Ida Master Dataset of lightcurves (R. P. Binzel et al., 1993, Icarus 105, 310-325) and found that the true pole determined from the Galileo fly by of this irregularly shaped member of the Koronis family falls just at the edge of the estimated uncertainty of our own solution. Our findings for the spin vector distribution of 10 members within the Koronis family represent the first systematic study of spin states within a well-established Hirayama family, and provide observational constraints for models of the physics of family formation and spin vector evolution in the main belt.     

Characterization of subsurface fluxes at the plot scale during flash floods in the Valescure catchment,France

This study focuses on a 10-m² plot within a granitic hillslope in Cevennes mountainous area in France, in order to study infiltration and subsurface hydrological processes during heavy rainfalls and flash floods. The monitoring device included water content at several depths (0–70 cm for the shallow soil water; 0–10 m for the deep water) during both intense artificial and natural rainfall events, chemical and physical tracers, time-lapse electrical resistivity tomography. During the most intense events, the infiltrated water was estimated to be some hundreds of millimetres, which largely exceeds the topsoil capacity (≤40 cm deep in most of the cases). The weathered/fractured rock area below the soil clearly has an active role in the water storage and sub-surface flow dynamics. Vertical flow was dominant in the first 0–10 m, and lateral flow was effective at 8–10 m depth, at the top of the saturated area. The speed of the vertical flow was estimated between 1 and 10 m/hr, whereas it was estimated between 0.1 and 1 m/hr for the lateral flow. The interpretation of the experiments might lead to a local pattern of the 2D-hydrological processes and profile properties, which could be generic for most of the mountainous catchments under Mediterranean climate. It suggests that fast triggering of floods at the catchment scale cannot be explained by a mass transfer within the hillslope, but should be due to a pressure wave propagation through the bedrock fractures, which allows exfiltration of the water downstream the hillslope.     

Risk‐based seismic design for collapse safety

Risk‐based seismic design, as introduced in this paper, involves the use of different types of analysis in order to satisfy a risk‐based performance objective with a reasonable utilization rate and sufficient reliability. Differentiation of the reliability of design can be achieved by defining different design algorithms depending on the importance of a structure. In general, the proposed design is iterative, where the adjustment of a structure during iterations is the most challenging task. Rather than using automated design algorithms, an attempt has been made to introduce three simple guidelines for adjusting reinforced concrete frames in order to increase their strength and deformation capacity. It is shown that an engineer can design a reinforced concrete frame in a few iterations, for example, by adjusting the structure on the basis of pushover analysis and checking the final design by means of nonlinear dynamic analysis. A possible variant of the risk‐based design algorithm for the collapse safety of reinforced concrete frame buildings is proposed, and its application is demonstrated by means of an example of an eight‐storey reinforced concrete building. Four iterations were required in order to achieve the risk‐based performance objective with a reasonable utilization rate. Copyright © 2016 John Wiley & Sons, Ltd.     

Local Imbalance of Turbulent Kinetic Energy in the Surface Layer

We utilize experimental data collected in 2002 over an open field in Hanford, Washington, USA, to investigate the turbulent kinetic energy (TKE) budget in the atmospheric surface layer. The von Kármán constant was determined from the near-neutral wind profiles to be 0.36 ± 0.02 rather than the classical value of 0.4. The TKE budget was normalized and all terms were parameterized as functions of a stability parameter z/L, where z is the distance from the ground and L is the Obukhov length. The shear production followed the Businger–Dyer relation for −2 < z/L < 1. Contrary to the traditional Monin–Obukhov similarity theory (MOST), the shear, buoyancy and dissipation terms were found to be imbalanced due to a non-zero vertical transport over all stabilities. Motivated by this local imbalance, modified parameterizations of the dissipation and the turbulent transport were attempted and generated good agreement with the experimental data. Assuming stationarity and horizontal homogeneity, the pressure transport was estimated from the residual of the TKE budget.     

Stream response to precipitation variability: a spectral view based on analysis and modelling of hydrological cycle components

Hydrological processes commonly exhibit long‐term persistence, also known as the ‘Hurst phenomenon’. Here, we examine long‐term precipitation and streamflow time series from the Elbe River Basin to quantify differences in the spectral properties and in the Hurst parameter estimates () of the individual hydrological cycle components. Precipitation‐runoff modelling is performed for the Elbe River sub‐catchment Striegis using the Soil and Water Assessment Tool (SWAT). For 38 daily 50 years long streamflow time series from the Elbe River Basin, baseflow separation and spectral analysis is performed. The results show a spectral shift towards low‐frequency scales (>2 years) from precipitation to baseflow, with a parallel increase of from 0.52 (precipitation) to 0.65 (baseflow). The SWAT model is able to reproduce both, the main low‐frequency mode (≈7 yr.) and the (0.62) of the observed Striegis River flow time series. The baseflow appears to be the main component which shapes the low‐frequency response and of streamflow in the Elbe River Basin to the input precipitation. This conclusion is further confirmed through PMWIN‐MODFLOW groundwater modelling of a hypothetic phreatic stream‐connected aquifer system that consists of various soils (sand, loamy sand and silt). A power shift towards lower frequencies and an increase of for the hydraulic heads is obtained, as the aquifer's lateral dimensions increase and its hydraulic conductivity decreases. The average of the groundwater heads is 0.80, 0.90 and 1.0 for sand, loamy sand and silt aquifers, respectively. Copyright © 2014 John Wiley & Sons, Ltd.     

Dynamical seasonal prediction using the global environmental multiscale model with a variable resolution modeling approach

In this work we evaluate seasonal forecasts performed with the global environmental multiscale model (GEM) using a variable resolution approach and with a high-resolution region over different geographical locations. Therefore, using two grid positions, one over North America and the other over the tropical Pacific-eastern Indian Ocean, we compare the seasonal predictions performed with the variable resolution approach with seasonal forecast performed with the uniform grid GEM model. For each model configuration, a ten-member ensemble forecast of 4?months is performed starting from the first of December of selected ENSO winters between 1982 and 2000. The sea surface temperature anomaly of the month preceding the forecast (November) is persisted throughout the forecast period. There is not enough evidence to indicate that a Stretch-Grid configuration has a clear advantage in seasonal prediction compared to a Uniform-Grid configuration. Forecasts with highly resolved grids placed over North America have more accurate seasonal mean anomalies and more skill in representing near surface temperature over the North American continent. For 500-hPa geopotential height, however, no configuration stands out to be consistently superior in forecasting the ENSO related seasonal mean anomalies and skill score.     

Analytical modelling of wintertime coastal jets in the Adriatic Sea

Two diagnostic models, reproducing circulation generated in a marginal sea by variable density, have been developed. The models’ domain is a 2D transverse section for which analytical solutions have been obtained. They describe the winter situation in the northern Adriatic, with a strong vertical mixing present and the density maximum dominating the centre of the basin. Both models employ Boussinesq-type parametrisation of friction and linear slip at the bottom. The first model allows for frictional departure from hydrostatic equilibrium and includes vertical friction only. The second one is hydrostatic but allows for lateral friction as well. The results obtained by the two models are similar and to some extent dependent on the vertical and bottom friction. They reproduce several well known characteristics of the Adriatic circulation (cyclonic surface flow, downwelling in the central and larger part of the basin compensated by upwelling in the coastal zone) but also predict some phenomena that are still not well understood. A conspicuous feature of the model results are coastal jets, which were observed in the Adriatic on several occasions. The present models show that the distance of jets from the coasts depends on lateral friction: it is found to vary from 1 up to 10 km on the Italian side and between 2 and 15 km on the Croatian side. Both models reproduce the west–east asymmetry, with the wider current on the east side of the basin. The asymmetry is a subject on which conflicting empirical results exist in the Adriatic. In the two models cyclonic flow occupies the whole water column, which disagrees with some recent theoretical findings of the near-bottom anticyclonic flow and thus leaves the issue open.     

A ~565 Ma old glaciation in the Ediacaran of peri-Gondwanan West Africa

International Journal of Earth Sciences - In the Cadomian orogen of the NE Bohemian Massif and of SW Iberia, a post-Gaskiers glacial event dated at c. 565&nbsp;Ma has been detected. Such...