Anthropic Exposure Indicator for River Basins Based on Landscape Characterization and Fuzzy Inference

Water Resources - The objective of this study is to develop an anthropic exposure indicator for river basins using quantitative and qualitative aspects of the landscape and morphometric analysis...     

Physics‐based probabilistic seismic hazard and loss assessment in large urban areas: A simplified application to Istanbul

A set of 3D physics‐based numerical simulations (PBS) of possible earthquakes scenarios in Istanbul along the North Anatolian Fault (Turkey) is considered in this article to provide a comprehensive example of application of PBS to probabilistic seismic hazard (PSHA) and loss assessment in a large urban area. To cope with the high‐frequency (HF) limitations of PBS, numerical results are first postprocessed by a recently introduced technique based on Artificial Neural Networks (ANN), providing broadband waveforms with a proper correlation of HF and low‐frequency (LF) portions of ground motion as well as a proper spatial correlation of peak values also at HF, that is a key feature for the seismic risk application at urban scale. Second, before application to PSHA, a statistical analysis of residuals is carried out to ensure that simulated results provide a set of realizations with a realistic within‐ and between‐event variability of ground motion. PBS results are then applied in a PSHA framework, adopting both the “generalized attenuation function” (GAF) approach, and a novel “footprint” (FP)‐based approach aiming at a convenient and direct application of PBS into PSHA. PSHA results from both approaches are then compared with those obtained from a more standard application of PSHA with empirical ground motion models. Finally, the probabilistic loss assessment of an extended simplified portfolio of buildings is investigated, comparing the results obtained adopting the different approaches: (i) GMPE, (ii) GAF, and (iii) FP. Only FP turned out to have the capability to account for the specific features of source and propagation path, while preserving the proper physically based spatial correlation characteristics, as required for a reliable loss estimate on a building portfolio spatially distributed over a large urban area.     

Influence of the Sonic Anemometer Temperature Calibration on Turbulent Heat-Flux Measurements

The speed of sound in moist air is discussed and a more accurate value for the coefficient of the linear dependence of sonic temperature on specific humidity is proposed. An analysis of speed-of-sound data measured by three sonic anemometers in a climate chamber and in the field shows that the temperature response of each instrument significantly influences not only the determination of sonic temperature, but also its fluctuations. The corresponding relative contribution to the error in the evaluation of the temperature fluctuations and the turbulent heat fluxes can be as high as 40%. The calibration procedure is discussed and a method of correction is proposed.     

Economic impacts of climate change in Europe: sea-level rise

This paper uses two models to examine the direct and indirect costs of sea-level rise for Europe for a range of sea-level rise scenarios for the 2020s and 2080s: (1) the DIVA model to estimate the physical impacts of sea-level rise and the direct economic cost, including adaptation, and (2) the GTAP-EF model to assess the indirect economic implications. Without adaptation, impacts are quite significant with a large land loss and increase in the incidence of coastal flooding. By the end of the century Malta has the largest relative land loss at 12% of its total surface area, followed by Greece at 3.5% land loss. Economic losses are however larger in Poland and Germany (483 and483 and 391 million, respectively). Coastal protection is very effective in reducing these impacts and optimally undertaken leads to protection levels that are higher than 85% in the majority of European states. While the direct economic impact of sea-level rise is always negative, the final impact on countries’ economic performances estimated with the GTAP-EF model may be positive or negative. This is because factor substitution, international trade, and changes in investment patterns interact with possible positive implications. The policy insights are (1) while sea-level rise has negative and huge direct economic effects, overall effects on GDP are quite small (max −0.046% in Poland); (2) the impact of sea-level rise is not confined to the coastal zone and sea-level rise indirectly affects landlocked countries as well (Austria for instance loses −0.003% of its GDP); and (3) adaptation is crucial to keep the negative impacts of sea-level rise at an acceptable level.     

The Australia telescope 20 GHz survey: hardware, observing strategy, and scanning survey catalog

The Australia Telescope 20 GHz (AT20G) survey is a large area (2?? sr), sensitive (40 mJy), high frequency (20 GHz) survey of the southern sky. The survey was conducted in two parts: an initial fast scanning survey, and a series of more accurate follow-up observations. The follow-up survey catalog has been presented by Murphy et al. (MNRAS 402:2403, 2010). In this paper we discuss the hardware setup and scanning survey strategy as well as the production of the scanning survey catalog.     

GRS evidence and the possibility of paleooceans on Mars

The Gamma Ray Spectrometer (Mars Odyssey spacecraft) has revealed elemental distributions of potassium (K), thorium (Th), and iron (Fe) on Mars that require fractionation of K (and possibly Th and Fe) consistent with aqueous activity. This includes weathering, evolution of soils, and transport, sorting, and deposition, as well as with the location of first-order geomorphological demarcations identified as possible paleoocean boundaries. The element abundances occur in patterns consistent with weathering in situ and possible presence of relict or exhumed paleosols, deposition of weathered materials (salts and clastic minerals), and weathering/transport under neutral to acidic brines. The abundances are explained by hydrogeology consistent with the possibly overlapping alternatives of paleooceans and/or heterogeneous rock compositions from diverse provenances (e.g., differing igneous compositions).     

Stellar clusters in the nuclear regions of AGN with the Advanced Camera for Surveys

We explore the role of star clusters in the nuclear regions of galaxies through their connection with active galactic nuclei (AGN). Nuclear star clusters (NCs) are conspicuous in the centers of most nearby galaxies, all along the Hubble sequence. These clusters are probably the faint-end distribution of the central supermassive black holes (SMBHs) in massive bulges. On the other hand, star formation is known to be ongoing in the majority of Seyfert nuclei and in many low-luminosity active galactic nuclei (LLAGN). We study two samples of AGN galaxies (75 Seyferts and 26 LLAGN) in the near-ultraviolet with the Hubble Space Telescope’s Advanced Camera for Surveys. We aim to better understand the connection between the growing of the SMBH and the build-up of the bulge, and we also intend to make statistical progress and determine the properties of the population of NCs coexisting with growing SMBHs.     

Kinematics of gas and stars in circumnuclear star-forming regions of early-type spirals

We present high-resolution (R～20,000) spectra in the blue and the far red of circumnuclear star-forming regions (CNSFRs) in three early-type spirals (NGC3351, NGC2903 and NGC3310), which have allowed the study of the kinematics of the stars and the ionized gas in these structures and, for the first time, the derivation of their dynamical masses for the first two. In some cases, these regions, about 100 to 150 pc in size, are composed of several individual star clusters with sizes between 1.5 and 4.9 pc, estimated from Hubble Space Telescope images. The stellar dispersions have been obtained from the Calcium triplet (CaT) lines at λ λ 8494, 8542, 8662 Å, while the gas velocity dispersions have been measured by means of Gaussian fits to the Hβ and [Oiii]λ 5007 Å lines in the high-dispersion spectra. Values of the stellar velocity dispersions are between 30 and 68 km?s^?1. We apply the virial theorem to estimate dynamical masses of the clusters, assuming that systems are gravitationally bounded and spherically symmetric, and using previously measured sizes. The measured values of the stellar velocity dispersions yield dynamical masses of the order of 10⁷ to 10⁸ M_⊙ for the entire CNSFRs. Stellar and gas velocity dispersions are found to differ by about 20 to 30 km?s^?1, with the Hβ emission lines being narrower than both the stellar lines and the [Oiii]λ 5007 Å lines. The douby-ionized oxygen, on the other hand, exhibits velocity dispersions comparable to those of the stars or, in some cases, even larger. We have found indications of the presence of two different kinematical components in the ionized gas of the regions. We have mapped the velocity field in the central kpc of the spiral galaxies NGC3351 and NGC2903. For the first object, the radial velocity curve shows deviations from circular motions for the ionized hydrogen consistent with its infall towards the central regions of the galaxy, at a velocity of about 25 km?s^?1. For NGC3310, we present preliminary results for the velocity dispersions for one of the two observed slit position angles, two CNSFRs and the nucleus.