Some Statistics of the Temperature Structure Parameter in the Convective Boundary Layer Observed by Sodar     

Igor Petenko  Giangiuseppe Mastrantonio  Angelo Viola  Stefania Argentini  Ilaria Pietroni 《Boundary-Layer Meteorology》2014,150(2):215-233

The characteristics of the temporal and height variations of the temperature structure parameter $C_\mathrm{T}^{2}$ in strongly convective situations derived from the sodar echo-signal intensity measurements were analyzed for the first 100 m. It was corroborated that the probability density function (pdf) of the logarithm of $C_\mathrm{T}^{2}$ in the lower convective boundary layer is markedly non-Gaussian, whereas turbulence theory predicts it to be normal. It was also corroborated that the sum of two weighted Gaussians, which characterize the statistics of $C_\mathrm{T}^{2}$ within convective plumes and in their environment and the probability of plume occurrence, well approximates the observed pdfs. It was shown that the height behaviour of the arithmetic mean of $ C_\mathrm{T}^{2}$ (both total and within plumes) follows well a power law $C_\mathrm{T}^{2} (z) \sim z^{-q}$ with the exponent $q$ close to the theoretically predicted value of 4/3. But for the geometrical means of $C_\mathrm{T}^{2}$ (both total and within the plumes), $q$ is close to 1. The difference between arithmetically and geometrically averaged $C_\mathrm{T}^{2}$ profiles was analyzed. The vertical profiles of the standard deviation, skewness and kurtosis of $\hbox {ln}C_\mathrm{T}^{2}$ pdfs were analyzed to show their steady behaviour with height. The standard deviations of the logarithm of $C_\mathrm{T}^{2}$ within the plumes and between them are similar and are 1.5 times less than the total standard deviation. The estimate of the variability index $F_\mathrm{T}$ and its height behaviour were obtained, which can be useful to validate some theoretical and modelling predictions. The vertical profiles of the skewness and kurtosis show the negative asymmetry of pdfs and their flatness, respectively. The spectra of variations in $\hbox {ln}C_\mathrm{T}^{2}$ are shown to be satisfactorily fitted by the power law $f^{-\gamma } $ in the frequency range 0.02 and 0.2 Hz, with the average exponent $\approx $ 1.27  $\pm $  0.22.  相似文献   

Local Circulation Diurnal Patterns and Their Relationship with Large-Scale Flows in a Coastal Area of the Tyrrhenian Sea   总被引：1，自引：0，他引：1  

Igor Petenko  Giangiuseppe Mastrantonio  Angelo Viola  Stefania Argentini  Lucia Coniglio  Paolo Monti  Giovanni Leuzzi 《Boundary-Layer Meteorology》2011,139(2):353-366

In order to characterise the local low-level circulation in the Tyrrhenian Sea coastal area near Rome, the wind field observed by conventional anemometers, Doppler sodar, and rawinsonde has been analysed. The prevailing diurnal behaviour of wind speed and direction as a function of season was highlighted, and the existence of two different patterns of the local circulation, mainly due to land and sea breezes and to the drainage flow from the mouth of the Tiber valley, revealed. The comparison between the low-level circulation and synoptic flow allowed us to determine the influence of the large-scale flow on nocturnal currents that are observed at the Pratica di Mare site and the way that wind direction evolves during the day. Numerical simulations are consistent with experimental data and depict the main features of the low-level wind field in the area.  相似文献   

Groundwater contamination risk assessment: initial methodology for highly developed areas. Case study in the Province of Milan (Italy)     

Tullia Bonomi  Angelo Cavallin  Paolo Cerutti  Giuseppe Rotondaro 《地学学报》1994,6(2):195-201

Maps of factors contributing to groundwater contamination risk have been produced for a sector of the province of Milan to support decision-making in land planning and management.
Risk assessment has considered factors related to: natural vulnerability, hazard due to human activities and costs resulting from pollution. In order to evaluate existing hazard, a specific census was carried out over the area and industrial, agricultural and quarrying activities were mapped. Industrial activities were first divided into 4 groups according to national waste type regulation.
The number of data and the density of mapped factors necessitated the use of a land information system for data storage and management and map design.  相似文献   

The solar temperature reversal and convective motions     

Angelo James Skalafuris 《Astrophysics and Space Science》1974,29(1):L9-L17

Given an equation of State, the three equations of mass, momentum and energy conservation determine the vortex free flow fields in a star. The solar data processed by Athay (1966) is a measure of the dissipation of the fluid, while the use of an empirical temperature profile (BCA, 1968) permits values for the gradients in the equations of fluid flow rendering them algebraic, with solutions independent of boundary conditions. This approach serves as a consistency check on the methods with which data have been processed by inquiring to what degree the basic conservation laws have been satified, and by directly implying a velocity field which can be scrutinized for its observational consequences. We find that the most consistent interpretation to this data is that the temperature minimum should not be coincident with flux maximum as the BCD model photosphere is, and that the temperature profile must rise higher at the 1500 km. region above optical depth one. Furthermore, more emissions must occur in the U-V metals at this region to support such a temperature increase, but at least an order of magnitude decrease in H^? emission should also be expected, as well as some suppression of the Balmer. As a theoretical consequence horizontal stratification of the velocity field occurs, suggesting either cellular motions or differential rotation with surface velocities as high as 60 km s^?1, but on the average near 30 to 40 km s^?1, across the solar surface.  相似文献   

Laboratory plasmas and the galactic spiral arms     

Joseph C. Cataldo  Angelo James Skalafuris 《Astrophysics and Space Science》1975,32(1):L11-L14

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Temporal Changes in Seawater Carbonate Chemistry and Carbon Export from a Southern California Estuary     

May-Linn Paulsen  Andreas J. Andersson  Lihini Aluwihare  Tyler Cyronak  Sydney D’Angelo  Charlie Davidson  Hany Elwany  Sarah N. Giddings  Heather N. Page  Magali Porrachia  Stephen Schroeter 《Estuaries and Coasts》2018,41(4):1050-1068

Estuaries are important subcomponents of the coastal ocean, but knowledge about the temporal and spatial variability of their carbonate chemistry, as well as their contribution to coastal and global carbon fluxes, are limited. In the present study, we measured the temporal and spatial variability of biogeochemical parameters in a saltmarsh estuary in Southern California, the San Dieguito Lagoon (SDL). We also estimated the flux of dissolved inorganic carbon (DIC) and total organic carbon (TOC) to the adjacent coastal ocean over diel and seasonal timescales. The combined net flux of DIC and TOC (F_DIC?+?TOC) to the ocean during outgoing tides ranged from ??1.8±0.5?×?10³ to 9.5±0.7?×?10³?mol C h^?1 during baseline conditions. Based on these fluxes, a rough estimate of the net annual export of DIC and TOC totaled 10±4?×?10⁶?mol C year^?1. Following a major rain event (36 mm rain in 3 days), F_DIC?+?TOC increased and reached values as high as 29.0 ±?0.7?×?10³?mol C h^?1. Assuming a hypothetical scenario of three similar storm events in a year, our annual net flux estimate more than doubled to 25 ±?4?×?10⁶?mol C year^?1. These findings highlight the importance of assessing coastal carbon fluxes on different timescales and incorporating event scale variations in these assessments. Furthermore, for most of the observations elevated levels of total alkalinity (TA) and pH were observed at the estuary mouth relative to the coastal ocean. This suggests that SDL partly buffers against acidification of adjacent coastal surface waters, although the spatial extent of this buffering is likely small.  相似文献   

Geospatial web services pave new ways for server-based on-demand access and processing of Big Earth Data     

Julia Wagemann  Oliver Clements  Ramiro Marco Figuera  Angelo Pio Rossi  Simone Mantovani 《International Journal of Digital Earth》2018,11(1):7-25

ABSTRACT

Big Earth Data has experienced a considerable increase in volume in recent years due to improved sensing technologies and improvement of numerical-weather prediction models. The traditional geospatial data analysis workflow hinders the use of large volumes of geospatial data due to limited disc space and computing capacity. Geospatial web service technologies bring new opportunities to access large volumes of Big Earth Data via the Internet and to process them at server-side. Four practical examples are presented from the marine, climate, planetary and earth observation science communities to show how the standard interface Web Coverage Service and its processing extension can be integrated into the traditional geospatial data workflow. Web service technologies offer a time- and cost-effective way to access multi-dimensional data in a user-tailored format and allow for rapid application development or time-series extraction. Data transport is minimised and enhanced processing capabilities are offered. More research is required to investigate web service implementations in an operational mode and large data centres have to become more progressive towards the adoption of geo-data standard interfaces. At the same time, data users have to become aware of the advantages of web services and be trained how to benefit from them most.  相似文献   

Speleogenesis of an exhumed hydrothermal sulphuric acid karst in Cambrian carbonates (Mount San Giovanni,Sardinia)     

Jo De Waele  Paolo Forti  Angelo Naseddu 《地球表面变化过程与地形》2013,38(12):1369-1379

In the past few years the systematic study of caves intercepted by mine workings in southwest Sardinia has permitted us to observe morphologies due to rare speleogenetic and minerogenetic processes related to ancient hydrothermal activity. These relic morphologies are slowly being overprinted by recent speleogenetic processes that tend to obscure the hypogene origin of these caves. A combined geomorphological and mineralogical investigation has permitted a fairly detailed reconstruction of the various phases of evolution of these caves. Cave formation had already started in Cambrian times, but culminated in the Carboniferous, when most of the large voids still accessible today were formed. A key role in carbonate dissolution was played by sulphuric acid formed by the oxidation of the polymetallic ores present in the rocks since the Cambrian. During the Quaternary a variety of minerals formed inside the caves: calcite and aragonite, that yielded sequences of palaeo‐environmental interest, and also barite, phosgenite, hydrozincite, hemimorphite and many others. These minerals are in part due to a phreatic thermal hypogenic cave forming phase, and in part to later epigene overprinting in an oxidizing environment rich in polymetallic ores. Massive gypsum deposits, elsewhere typical of this kind of caves, are entirely absent due to dissolution during both the phreatic cave formation and the later epigenic stage. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Ground motion amplification due to shallow cavities in nonlinear soils   总被引：2，自引：0，他引：2  

Stefania Sica  Angelo Dello Russo  Federica Rotili  Armando Lucio Simonelli 《Natural Hazards》2014,71(3):1913-1935

Subsurface cavities or stiff inclusions represent mechanical discontinuities for seismic waves propagating in soils. They modify the propagation pattern of seismic waves and alter soil response in correspondence to the ground level or building foundations. In the literature, different analytical and numerical solutions have been proposed to account for the effect of underground cavities or inclusions on the motion generated by P, S or R waves. In these former studies, the subsoil was assimilated to a homogeneous, isotropic and linear elastic halfspace containing one or more cavities. In the present study, the effect of subsurface cavities on ground motion amplification has been analysed accounting for soil stiffness degradation and associated damping increase with increasing levels of shear strains, a fundamental aspect of soil behaviour under earthquakes. The analysed model was inspired to a real case represented by the village of Castelnuovo (Italy), which during the 2009 Abruzzo earthquake suffered huge damage. The main shock (6 April 2009) caused the collapse of 50 % of the whole built environment. The historical centre of Castelnuovo rises on a hill. In its subsoil, there are many cavities with roofs 2–3 m below the ground level. The longitudinal NW–SE section of the hill has been investigated by 2D nonlinear site response analyses. A preliminary site response analysis was performed without modelling cavities, to identify ground motion amplification due to mere stratigraphic and topographic factors. The numerical model was later refined inserting: (1) a single cavity below the hilltop, (2) multiple cavities placed below the ground surface of the hill and (3) multiple cavities filled with concrete (inclusions). The performed study highlights the important role exerted by underground cavities on the ground motion computed at the hill surface. This effect should be properly considered for both microzonation studies and the correct determination of the seismic actions on specific buildings.  相似文献   

A two-phase model for fast geomorphic shallow flows   总被引：1，自引：0，他引：1  

Massimo GRECO  Michele IERVOLINO  Angelo LEOPARDI  Andrea VACCA 《国际泥沙研究》2012,27(4):409-425

The paper introduces a 2D shallow water model based on a two-phase formulation for the analysis of fast geomorphic transients occurring in the context of river morphodynamics.Mass and momentum conservation principles are separately imposed for both phases.The model naturally accounts for non-equilibrium solid transport,since neither instantaneous adaptation hypothesis nor any lag equation is employed to represent sediment dynamics.The hyperbolic character of the proposed model is shown to be preserved independently on the flow conditions.Results from numerical simulations of both 1D and 2D test-cases are compared with literature experimental data and with available numerical solutions.  相似文献