排序方式： 共有38条查询结果，搜索用时 765 毫秒
21.
Caterina Gozzi Roberta Sauro Graziano Francesco Frondini Antonella Buccianti 《Environmental Earth Sciences》2018,77(16):579
Chemical reactions in aqueous geochemical systems are driven by nonequilibrium conditions, and their dynamics can be deduced through the distributional analysis (identification of probability laws) of complex compositional indices. In this perspective, compositional data analysis offers the possibility to investigate the behavior of the composition as a whole instead of isolated chemical species, with the awareness that multispecies systems are characterized by the simultaneous interactions among all their parts. We addressed this problem using D???1 isometric log-ratio coordinates describing the D compositional dataset of the river chemistry of the Alpine region (D number of variables), thus working in the \({{\mathbb{R}}^{D - 1}}\) statistical sample space. The D???1 coordinates were chosen using the decreasing variance criterion so that each one could provide information about different space–time properties for the investigated geochemical system. Coordinates dominated by heterogeneity appear to be able to capture regime shifts only on a long-time period and monitor processes on a very wide scale. On the other hand, coordinates characterized by lower variability present multimodality, thus capturing the presence of alternative states in the analyzed spatial domain also for the current time. Further developments are needed to determine the ranges of conditions for which variability and other statistics can be useful indicators of regime shifts on different time–space scales in geochemical systems. 相似文献
22.
23.
P. Calosi S.P.S. Rastrick M. Graziano S.C. Thomas C. Baggini H.A. Carter J.M. Hall-Spencer M. Milazzo J.I. Spicer 《Marine pollution bulletin》2013
To reduce the negative effect of climate change on Biodiversity, the use of geological CO2 sequestration has been proposed; however leakage from underwater storages may represent a risk to marine life. As extracellular homeostasis is important in determining species’ ability to cope with elevated CO2, we investigated the acid–base and ion regulatory responses, as well as the density, of sea urchins living around CO2 vents at Vulcano, Italy. We conducted in situ transplantation and field-based laboratory exposures to different pCO2/pH regimes. Our results confirm that sea urchins have some ability to regulate their extracellular fluid under elevated pCO2. Furthermore, we show that even in closely-related taxa divergent physiological capabilities underlie differences in taxa distribution around the CO2 vent. It is concluded that species distribution under the sort of elevated CO2 conditions occurring with leakages from geological storages and future ocean acidification scenarios, may partly be determined by quite subtle physiological differentiation. 相似文献
24.
S. Businger T. M. Graziano M. L. Kaplan R. A. Rozumalski 《Meteorology and Atmospheric Physics》2005,88(1-2):65-90
Summary On 24–25 February 1989 a storm brought high winds and moderate to heavy snow to the U.S. East Coast. The storm is noteworthy for its rapid mesoscale development within a polar air mass at relatively low latitudes and for the difficulty experienced by operational NWP models and forecasters in predicting the storms impact. This paper investigates the mesoscale structure and evolution of the cold-air cyclone through analysis of enhanced data sets collected during the
xperiment on
apidly
ntensifying
yclones over the
tlantic (ERICA). Results are presented from numerical sensitivity studies of the impact of diabatic heating on storm structure and track using the Mesoscale Atmospheric Simulation System (MASS) model.The following conclusions are drawn from the research. Differential surface fluxes in the vicinity of the Gulf Stream led to the development of a well-defined baroclinic zone at low levels that extended parallel to the axis of the Gulf-Stream front. The baroclinic zone strengthened and assumed the characteristics of a shallow warm front as the cyclone matured. Enhanced cyclonic vorticity, moisture-flux convergence, clouds, and precipitation accompanied the front. Early in the event a series of shallow, thermally forced vortices of small wavelength (200km) formed along the baroclinic zone in the area of maximum surface-heat fluxes offshore of the Carolinas. Baroclinic instability associated with a vigorous short-wave trough aloft resulted in the outbreak of deep convection surrounding and rapid intensification of the northernmost vortex.Numerical sensitivity experiments were conducted to investigate the nonlinear response of the mass field to the convection. The results show that latent heating in deep convection surrounding the surface low produced a mesoscale height perturbation aloft. The subsequent acceleration of the flow aloft substantially increased the integrated mass divergence above the surface cyclone, leading to deepening on the scale observed. The observed track of the low followed the axis of the warm front, which in turn followed the axis of maximum SST gradient associated with the Gulf-Stream front. Accurate simulation of the storm track required a high-resolution, full-physics run that included high-resolution SST data in the initial condition and moisture nudging during the early hours of the simulation.Current affiliation: NWS Office of Climate, Water, and Weather Services, 1325 East-West Highway, Silver Spring, MD 20910.Current affiliation: NWS UCAR/COMET, Boulder, CO 80307-3000. 相似文献
25.
Patti Graziano Grassi Sabrina Morreale Gabriele Corrao Mauro Imposa Sebastiano 《Natural Hazards》2021,108(3):2467-2492
Natural Hazards - The occurrence of strong and abrupt rainfall, together with a wrong land use planning and an uncontrolled urban development, can constitute a risk for infrastructure and... 相似文献
26.
Jonas V. Müller Christian Berg Jacqueline Détraz-Méroz Brigitta Erschbamer Noémie Fort Catherine Lambelet-Haueter Vera Margreiter Florian Mombrial Andrea Mondoni Konrad Pagitz Francesco Porro Graziano Rossi Patrick Schwager Elinor Breman 《山地科学学报》2017,14(4):806-810
Safeguarding plants as seeds in ex situ collections is a cost effective element in an integrated plant conservation approach. The European Alps are a regional centre of plant diversity. Six institutions have established a regional network covering the European Alps which will conserve at least 500 priority plant species and which will improve the conservation status of plant species in grassland communities in the subalpine, alpine and nival altitudinal belts. Targeted research will expand the knowledge of the ecology of target species. Public engagement activities will raise the awareness for the importance of specific conservation actions in the European Alps. 相似文献
27.
This paper presents a static equivalent approach to estimate the maximum kinematic interaction effects on piles subjected to lateral seismic excitation. Closed-form expressions are reported for the evaluation of the maximum free-field soil movements and for the computation of maximum pile shear force and bending moments. Firstly, modal analysis, combined with a suitable damped response spectrum, is used to evaluate the maximum free-field response. Secondly, the pile is schematised as a Winkler's beam subjected to equivalent static forces defined according to soil vibration modal shapes and amplitude. The method may be applied by using response spectra suggested by National Standards or those obtained with accelerograms. The procedure proposed may be conveniently implemented in simple spreadsheets or in commercial finite element programs and easily used by practicing engineers. Method accuracy is demonstrated by comparing the results with those obtained with a more rigorous model. Good results may be achieved by considering only the first soil vibration mode making the procedure straightforward for practical design purposes. 相似文献
28.
Mathematical Geosciences - Outliers are encountered in all practical situations of data analysis, regardless of the discipline of application. However, the term outlier is not uniformly defined... 相似文献
29.
30.
Di Franco A Graziano M Franzitta G Felline S Chemello R Milazzo M 《Marine pollution bulletin》2011,62(5):926-933
Many human activities add new structures to the marine landscape. Despite the fact that human structures cause some inevitable impacts, surprisingly little information exists on the effects of marina on natural marine assemblages. The aim of this paper is to assess habitat-specific response of benthic sessile organisms of rocky shores in relation to the presence of a small marina. Sampling was carried out at three coastal habitats (midshore, lowshore and subtidal) by means of visual censuses adopting an after-control-impact (ACI) experimental design. It appears that the marina affects the structure and composition of benthic communities of both the midshore and the lowshore. Little effect was evident on shallow subtidal assemblage structure. The results of the present study clearly show habitat-specific responses of coastal benthic assemblages to the presence of infrastructure. 相似文献