Measurements of Turbulence and Dispersion in Three Idealized Urban Canopies with Different Aspect Ratios and Comparisons with a Gaussian Plume Model

Water-tunnel measurements of velocity, turbulence and scalar concentration for three model urban canopies with aspect ratios A _r of building height-to-width of 0.25, 1 and 3 are presented. The measurements for the canopies with A _r = 1 and 3 are new, while the measurements for A _r = 0.25 were previously published. A passive scalar was continuously released from a near-ground point source, and the concentration was measured at several distances from the source and at different heights above the ground. Plume spreads, concentration and distance from the source were non-dimensionalized using length, time and velocity scales reflecting the geometry of the buildings. The scaling collapses the data for all aspect ratios and is valid when the vertical extent of the plume is smaller than the canopy height. The observed plume spreads are compared with analytical relations, which predict linear growth in both transverse and vertical directions. The observed mean concentration is compared with a Gaussian dispersion model that predicts a ?2 power-law decay with distance from the source.     

Detecting WIMPs in the microwave sky

The hierarchical clustering observed in cold dark matter simulations results in highly clumped galactic halos. If the dark matter in our halo is made of weakly interacting massive particles (WIMPs), their annihilation products should be detectable in high density and nearby clumps. We consider WIMPs to be neutralinos and calculate the synchrotron flux from their annihilation products in the presence of the Galactic magnetic field. We derive a self-consistent emission spectrum including pair annihilation, synchrotron self-absorption, and synchrotron self-Compton reactions. The resulting radiation spans microwave frequencies that can be observed over the anisotropies in the cosmic microwave background. These synchrotron sources should be identifiable as WIMP clumps by their spatial structure and their distinctive radio spectrum.     

Groundwater flow analysis using different geothermal constraints: The case study of Acqui Terme area,northwestern Italy

We review some analytical techniques that use underground thermal data as tracers of groundwater flow. These techniques allow the evaluation of the Darcy velocity in shallow aquifers of mid-low permeability and the evaluation of heat gain/loss by conduction in deeper aquifers. Examples of application are then given for the Acqui Terme hydrothermal system, located in the Tertiary Piedmont Basin (northwestern Italy). The analysis of borehole temperatures allowed the inference of the hydraulic features of the sedimentary cover of the hydrothermal system. The results show the presence of a relatively weak flow, with upward and horizontal components, only in conglomerates occurring at the base of the marly impermeable cover. The analysis of the heat transported in the deep parts of the hydrothermal system was approached by splitting the water path into different sections, each with given shape, slope and hydraulic properties. The recharge area is situated in the upland, south of the discharge area. Meteoric water initially descends and then flows horizontally within the fractured metamorphic basement of the basin, heating by conduction. Finally, from a reservoir positioned at intermediate depths, hot water reaches rapidly the surface through a sub-vertical fault. This scheme of deep water flow is constrained by the regional surface heat flow and the local geothermal gradient, and it is consistent with data of rock–water equilibrium temperature.     

The occultation of Mariner 10 by Mercury

An analysis of the Mariner 10 dual frequency radio occultation recordings has yielded new information on the radius and atmosphere of Mercury. The ingress measurements which were conducted near 1.1° North latitude and 67.4° East longitude on the night side of the planet, gave a value for the radius of 2439.5 ± 1 km. Egress near 67.6° North latitide and 258.4° East longitude in the sunlit side yielded a radius of 2439.0 ± 1 km. The atmospheric measurements showed the electron density to be less than 10³ cm^?3 on both sides of the planet. From the latter result one may infer an upper limit to the dayside surface gas density of 10⁶ molecules per cm³.     

Relations between climatic–geomorphological parameters and sediment yield in a mediterranean semi-arid area (Sicily,southern Italy)

In the present work on-going research is discussed whose primary goal is to test some statistical methods to estimate the average yearly area-specific sediment yield (SSY). Using geomorphological and climatic parameters various multiple regression formulae have been set up based on SSY observed data from 16 catchments of Sicily. Three distinct techniques were adopted to select the parameters to be used in the equations: simple correlation, stepwise regression analysis and a supervised geomorphological–statistical correlation. The comparison of the results showed the effectiveness of the stepwise analysis, which led to a regression equation with a coefficient of determination (r ²) of 0.87. Nevertheless, even this methodology showed some elements of uncertainty that have caused, in some cases, appreciable differences between observed and predicted values (mean percentage error equal to 26%). These differences are likely either due to the hydraulic regime of most of Sicilian watercourses (typical of semi-arid regions) or to hidden factors (e.g., topography, human impact and concentrated erosion), which can greatly affect the processes of sediment production and transport. The study has pointed out the need to take into account a larger number of observations and to perform the analysis of relations between suitable variables and SSY at a more detailed time resolution.     

Building a European geothermal information network using a distributed e-Infrastructure

Geothermal data are published using different IT services, formats and content representations, and can refer to both regional and global scale information. Geothermal stakeholders search for information with different aims. E-Infrastructures are collaborative platforms that address this diversity of aims and data representations. In this paper, we present a prototype for a European Geothermal Information Platform that uses INSPIRE recommendations and an e-Infrastructure (D4Science) to collect, aggregate and share data sets from different European data contributors, thus enabling stakeholders to retrieve and process a large amount of data. Our system merges segmented and national realities into one common framework. We demonstrate our approach by describing a platform that collects data from Italian, French, Hungarian, Swiss and Icelandic geothermal data providers.