Earth Tides and Lense–Thirring Effect     

Lorenzo Iorio 《Celestial Mechanics and Dynamical Astronomy》2001,79(3):201-230

The general relativistic Lense—Thirring effect can be measured by inspecting a suitable combination of the orbital residuals of the nodes of LAGEOS and LAGEOS II and the perigee of LAGEOS II. The solid and ocean Earth tides affect the recovery of the parameter by means of which the gravitomagnetic signal is accounted for in the combined residuals. Thus an extensive analysis of the perturbations induced on these orbital elements by the solid and ocean Earth tides is carried out. It involves the l=2 terms for the solid tides and the l=2,3,4 terms for the ocean tides. The perigee of LAGEOS II turns out to be very sensitive to the l=3 part of the ocean tidal spectrum, contrary to the nodes of LAGEOS and LAGEOS II. The uncertainty in the solid tidal perturbations, mainly due to the Love number k ₂, ranges from 0.4% to 1.5%, while the ocean tides are uncertain at 5–15% level. The obtained results are used in order to check in a preliminary way which tidal constituents the Lense-Thirring shift is sensitive to. In particular it is tested if the semisecular 18.6-year zonal tide really does not affect the combined residuals. It turns out that, if modeled at the level of accuracy worked out in the paper, the l=2,4 m=0 and also, to a lesser extent, the l=3, m=0 tidal perturbations cancel out.This revised version was published online in October 2005 with corrections to the Cover Date.  相似文献   

The Impact of the Static Part of the Earth's Gravity Field on Some Tests of General Relativity with Satellite Laser Ranging     

Lorenzo Iorio 《Celestial Mechanics and Dynamical Astronomy》2003,86(3):277-294

In this paper we calculate explicitly the classical secular precessions of the node and the perigee of an Earth artificial satellite induced by the even zonal harmonics of the static part of the geopotential up to degree l = 20. Subsequently, their systematic errors induced by the mismodelling in the even zonal spherical harmonics coefficients J _l are compared to the general relativistic secular gravitomagnetic and gravitoelectric precessions of the node and the perigee of the existing laser-ranged geodetic satellites and of the proposed LARES. The impact of the future terrestrial gravity models from CHAMP and GRACE missions is discussed as well. Preliminary estimates with the recently released EIGEN-1S gravity model including the first CHAMP data are presented.  相似文献   

A numerical and statistical investigation of a seiche oscillation of the Ligurian Sea     

Lorenzo Papa 《Ocean Dynamics》1981,34(1):15-25

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A statistical analysis of upper and lower limits of earthquake magnitude     

Lorenzo Casertano 《Pure and Applied Geophysics》1982,120(4):840-849

The relationship between frequency and magnitude in homogeneous series of earthquakes is studied. The linear relation of Gutenberg and Richter between the logarithm of frequency and the magnitude is found to be applicable only in a restricted range of magnitudes.The plots of the cumulative number of earthquakes versus magnitude for 20 different series (the total number of events in a single series ranging from about 50 to more than 3000) clearly indicate the presence of vertical asymptotes. This fact suggests that upper and lower limits could exist for the magnitude of a single event, i.e. for the energy that can be released in an earthquake. From the position of the vertical asymptotes it is possible to obtain the upper and lower bounds of magnitude for each series of earthquakes. The empirical shape of the cumulative number-magnitude distribution can be well represented by equilateral hyperbolas. A least ² method has been used to obtain the best-fitting hyperbolas and corresponding the minimum and maximum magnitudes for each series.The shape of the frequency-magnitude relationship is discussed in lesser detail. It is found, however, that after suitable rescaling the earthquakes in each series follow much the same law, with a comparatively small scatter.  相似文献   

A Critical Analysis of a Recent Test of the Lense–Thirring Effect with the LAGEOS Satellites     

Lorenzo Iorio 《Journal of Geodesy》2006,80(3):128-136

In this paper, we quantitatively discuss the impact of the current uncertainties in the even zonal harmonic coefficients J _l of the Newtonian part of the terrestrial gravitational potential on the measurement of the general relativistic Lense–Thirring effect. We use a suitable linear combination of the nodes Ω of the laser-ranged LAGEOS and LAGEOS-II satellites. The one-sigma systematic error due to mismodelling of the J _l coefficients ranges from ~ 4% for the EIGEN−GRACE02S gravity field model to ~ 9% for the GGM02S model. Another important source of systematic error of gravitational origin is represented by the secular variations j _l of the even zonal harmonics. While the relativistic and J _l signals are linear in time, the shift due to j _l is quadratic. We quantitatively assess their impact on the measurement of the Lense–Thirring effect with numerical simulations obtaining a 10−20% one-sigma total error over 11 years for EIGEN-GRACE02S. Ciufolini and Pavlis (Nature 431:958–960, 2004) claim a total error of 5% at the one-sigma level.  相似文献   

Can Sea Fog be Inferred from Operational GEM Forecast Fields?     

Lorenzo de la Fuente  Yves Delage  Serge Desjardins  Allan MacAfee  Garry Pearson  Harold Ritchie 《Pure and Applied Geophysics》2007,164(6-7):1303-1325

Three cases of widespread sea fog in Lunenburg Bay, Nova Scotia were used to evaluate the suitability of operational regional GEM forecast fields for inferring advection fog occurrences. Verification scores suggest that the objective analyses contain significant departures from observations that will affect model accuracy, given the sensitivity of fog condensation microphysics. Dew point depression (ES) scores show larger differences compared to temperature, with both influenced by surface characteristics. For objective analyses and GEM forecasts ES < 2 C seems to match fog satellite images better than the physical threshold ES ≤ 0 C. In addition the GEM forecasts show a general tendency towards drier conditions near the surface, therefore reconfiguring GEM to better represent condensation in the boundary layer is proposed.  相似文献   

Wetland Plant Diversity in a Coastal Nature Reserve in Italy: Relationships with Salinization and Eutrophication and Implications for Nature Conservation     

Renato Gerdol  Lisa Brancaleoni  Lorenzo Lastrucci  Giovanni Nobili  Mauro Pellizzari  Michele Ravaglioli  Daniele Viciani 《Estuaries and Coasts》2018,41(7):2079-2091

Wetlands are important centers of biodiversity. Coastal wetlands are subject to anthropogenic threats that can lead to biodiversity loss and consequent negative effects on nature conservation. We investigated relationships between wetland vegetation and habitat conditions in a coastal Nature Reserve in Northern Italy that has undergone seawater intrusion and eutrophication for several decades. The wetland vegetation in the Nature Reserve consisted of nine communities of hygrophytic and helophytic vegetation and five communities of waterplant vegetation. The hygrophytic and helophytic communities were arranged according to a salinity gradient, from salt-free habitats to strongly saline habitats. The saline habitats had high nutrient levels, due to the influx of nitrate-rich saltwater from an adjacent lagoon. The waterplant communities were all typical of freshwater habitats. Water-table depth and concentration of dissolved nutrients in the water were the main factors structuring waterplant vegetation. The main driver of future changes in the wetland vegetation of the Nature Reserve is the ongoing increase in salinity levels which may enhance expansion of halophilic species and communities, thus outcompeting locally rare freshwater species. If nutrient, especially nitrate, load further increases in the next future, this may exert negative effects on wetland species and communities preferring nutrient-poor habitats.  相似文献   

Regional thermo-rheological field related to granite emplacement in the upper crust: implications for the Larderello area (Tuscany,Italy)     

Federica Rochira  Alfredo Caggianelli  Salvatore de Lorenzo 《Geodinamica Acta》2018,30(1):225-240

We modelled thermo-rheological perturbations, related to the emplacement of a magmatic body in the upper crust. This approach was considered relevant for the areas characterized by elevated surface heat flow and chiefly for the geothermal fields. The numerical conductive thermal model applied to the Larderello geothermal area in Tuscany, allowed to constrain size, depth and timing of emplacement of the pluton. We inferred that the emplacement of a magmatic body, at a minimum depth of 3 km, having a horizontal extension of 14 km and a maximum thickness of 8 km, can reasonably reproduce the observed regional surface heat flow anomaly of the Larderello area, when 300 (± 100) kyr are elapsed from the magma emplacement. Even assuming an incremental growth, the first magma injection should not be older than 1 ± 0.3 Ma.

Results of the thermal model were used to set up a rheological model and to simulate the drifting of the brittle-ductile transition during the cooling of the pluton. A comparison with the K-horizon profile, a prominent seismic reflector in the Larderello area, was then performed. It was found that the K-horizon approximately corresponds with the pluton roof and with the current location of the brittle-ductile transition.  相似文献   

The wideband [0.001 Hz–100 kHz] interferometry project in Central Italy     

P. Palangio  F. Masci  C. Di Lorenzo  M. Di Persio 《Geophysical Prospecting》2009,57(4):729-737

We are reporting some results and future planning of the Magnetic and Electric fields Monitoring Project. The principal purpose of the project is to create a network of observatories for monitoring the electromagnetic signals in the 0.001 Hz–100 kHz frequency bands in Central Italy. These bands include both natural and artificial signals. The technological objectives of the project are the development of new instrumentation and the know-how transfer to the industry. These instruments were tested in the Geomagnetic Observatory of L'Aquila, the first station of the network. Here we show some examples of the developed electric and magnetic sensors. These instruments are designed for the automatic long-term recording of the electromagnetic fields in a wide band of frequency. The preliminary results of the first operating station of the network are shown taking into account, in the signal elaboration, the single station approach. Here we are reporting some examples concerning the calculation of the ground electric resistivity profile, the evaluation of the magnetic induction vectors and the study of the magnetic sources by the eigenvectors calculation. When all the stations of the network will be in operation, the use of an innovative technique, the wideband interferometry will be proposed. Combining the simultaneous observations of the electromagnetic field measured in each station, we will be able to obtain detailed information about the investigated electromagnetic sources.  相似文献   

Bed material transport estimate in large gravel‐bed rivers using the virtual velocity approach          下载免费PDF全文

Luca Mao  Lorenzo Picco  Mario A. Lenzi  Nicola Surian 《地球表面变化过程与地形》2017,42(4):595-611

This paper reports on a first attempt of using the virtual velocity approach to assess sediment mobility and transport in two wide and complex gravel‐bed rivers of northern Italy. Displacement length and virtual velocity of spray‐painted tracers were measured in the field. Also, the thickness of the sediment active layer during floods was measured using scour chains and post‐flood morphological changes as documented by repeated survey of channel cross‐sections. The effects of eight and seven floods were studied on the Tagliamento and Brenta Rivers, where 259 and 277 spray‐painted areas were surveyed, respectively. In the Tagliamento River 36% of the spray‐painted areas experienced partial transport, whereas in the Brenta River this accounted for 20%. Whereas, full removal/gravel deposition was observed on 37% and 26% of these areas on the Tagliamento and Brenta Rivers, respectively. The mean displacement length of particles, the thickness of the active layer and the extent of partial transport are well correlated with the dimensionless shear stress. The virtual velocity approach allowed calculation of bed material transport over a wide range of flood magnitudes. Annual coarse sediment transport was calculated up to 150 for the Tagliamento, and 30 × 10³  m³ yr^?1 for the Brenta. The outcomes of this work highlight the relevance of partial transport condition, as it could represent more than 70% of the total bed material transported during low‐magnitude floods, and up to 40% for near‐bankfull events. Results confirm that bed material load tends to be overestimated by traditional formulas. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献