Spectroscopy Of Comet Hale-Bopp In The Visible/Near Infrared: Modeling Of Dust Properties     

Bellucci  G. 《Earth, Moon, and Planets》1997,78(1-3):305-311

Previous analysis of imaging spectroscopy data in the 0.4–1 μm spectral range of comet Hale-Bopp, have shown the presence of two regions on the sunward and antisunward sides of the nucleus exhibiting different continuum emission (Bellucci, 1998, hereafter paper I). In this work we present the modeling of the continuum emission in terms of size distribution and composition of the dust grains. The spectra are fitted by micron sized olvine grains. A mechanism to explain the spatial gradient is also proposed. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

OMEGA/Mars Express: Visual channel performances and data reduction techniques     

G. Bellucci  F. Altieri  Y. Langevin 《Planetary and Space Science》2006,54(7):675-684

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High-resolution CASSINI-VIMS mosaics of Titan and the icy Saturnian satellites     

R. Jaumann  K. Stephan  B.J. Buratti  T.B. McCord  F. Capaccioni  P. Cerroni  G. Bellucci  M. Combes  P. Drossart  Y. Langevin  R.M. Nelson  B. Sicardy  L.A. Soderbloom  K.-D. Matz  F. Scholten 《Planetary and Space Science》2006,54(12):1146-1155

The Visual Infrared Mapping Spectrometer (VIMS) onboard the CASSINI spacecraft obtained new spectral data of the icy satellites of Saturn after its arrival at Saturn in June 2004. VIMS operates in a spectral range from 0.35 to 5.2 μm, generating image cubes in which each pixel represents a spectrum consisting of 352 contiguous wavebands.As an imaging spectrometer VIMS combines the characteristics of both a spectrometer and an imaging instrument. This makes it possible to analyze the spectrum of each pixel separately and to map the spectral characteristics spatially, which is important to study the relationships between spectral information and geological and geomorphologic surface features.The spatial analysis of the spectral data requires the determination of the exact geographic position of each pixel on the specific surface and that all 352 spectral elements of each pixel show the same region of the target. We developed a method to reproject each pixel geometrically and to convert the spectral data into map projected image cubes. This method can also be applied to mosaic different VIMS observations. Based on these mosaics, maps of the spectral properties for each Saturnian satellite can be derived and attributed to geographic positions as well as to geological and geomorphologic surface features. These map-projected mosaics are the basis for all further investigations.  相似文献   

A multi‐temporal analysis of AMSR‐E data for flood and discharge monitoring during the 2008 flood in Iowa     

Marouane Temimi  Teodosio Lacava  Tarendra Lakhankar  Valerio Tramutoli  Hosni Ghedira  Riadh Ata  Reza Khanbilvardi 《水文研究》2011,25(16):2623-2634

The objective of this work is to demonstrate the potential of using passive microwave data to monitor flood and discharge conditions and to infer watershed hydraulic and hydrologic parameters. The case study is the major flood in Iowa in summer 2008. A new Polarisation Ratio Variation Index (PRVI) was developed based on a multi‐temporal analysis of 37 GHz satellite imagery from the Advanced Microwave Scanning Radiometer (AMSR‐E) to calculate and detect anomalies in soil moisture and/or inundated areas. The Robust Satellite Technique (RST) which is a change detection approach based on the analysis of historical satellite records was adopted. A rating curve has been developed to assess the relationship between PRVI values and discharge observations downstream. A time‐lag term has been introduced and adjusted to account for the changing delay between PRVI and streamflow. Moreover, the Kalman filter has been used to update the rating curve parameters in near real time. The temporal variability of the b exponent in the rating curve formula shows that it converges toward a constant value. A consistent 21‐day time lag, very close to an estimate of the time of concentration, was obtained. The agreement between observed discharge downstream and estimated discharge with and without parameters adjustment was 65 and 95%, respectively. This demonstrates the interesting role that passive microwave can play in monitoring flooding and wetness conditions and estimating key hydrologic parameters. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Evidence of a full West Antarctic Ice Sheet back to the early Oligocene: insight from double dating of detrital apatites in Ross Sea sediments.          下载免费PDF全文

Valerio Olivetti  Maria Laura Balestrieri  Federico Rossetti  Stuart N. Thomson  Franco M. Talarico  Massimiliano Zattin 《地学学报》2015,27(3):238-246

The West Antarctic Ice Sheet is the most unstable component of the Antarctic cryosphere. Its fluctuations are well documented since the Pliocene, but its behaviour over the last 35 Ma is more controversial, particularly during periods of past high global pCO₂ values similar to those predicted in future global climate scenarios. Here, we present new U–Pb dating of detrital apatite grains (previously dated by the fission‐track method) from Cape Roberts Project Oligocene to Pliocene marine sediments in the Ross Sea. Two past ice‐flow patterns were identified: one formed by outlet glaciers sourcing short‐travelled apatites and one, northerly directed, bringing far‐travelled apatite grains. The latter provides the first robust physical evidence for the presence and repeated expansion of an Oligocene West Antarctic Ice Sheet.  相似文献   

The Non-Gravitational Perturbations impact on the BepiColombo Radio Science Experiment and the key rôle of the ISA accelerometer: direct solar radiation and albedo effects     

David M. Lucchesi  Valerio Iafolla 《Celestial Mechanics and Dynamical Astronomy》2006,96(2):99-127

The paper is focused on the estimate of the impact of the non-gravitational perturbations on the orbit of the Mercury Planetary Orbiter (MPO), one of the two spacecrafts that will be placed in orbit around the innermost planet of the solar system by the BepiColombo space mission. The key rôle of the Italian Spring Accelerometer (ISA), that has been selected by the European Space Agency (ESA) to fly on-board the MPO, is outlined. In the first part of the paper, through a numerical simulation and analysis we have estimated, over a time span of several years, the long-period behaviours of the disturbing accelerations produced by the incoming direct solar radiation pressure, and the indirect effects produced by Mercury’s albedo. The variations in the orbital parameters of the spacecraft, together with their spectral contents, have been estimated over the analysed period. The direct solar radiation pressure represents the strongest non-gravitational perturbation on the MPO in the very complex radiation environment of Mercury. The order-of-magnitude of this acceleration is quite high, about 10^?6 m/s², because of the proximity to the Sun and the large area-to-mass ratio of the spacecraft. In the second part of the paper, we concentrated upon the short-period effects of direct solar radiation pressure and Mercury’s albedo. In particular, the disturbing accelerations have been compared with the ISA measurement error and the advantages of an on-board accelerometer are highlighted with respect to the best modelling of the non-gravitational perturbations in the strong radiation environment of Mercury. The readings from ISA, with an intrinsic noise level of about $10^{-9}\,m/s^{2}/\sqrt{Hz}The paper is focused on the estimate of the impact of the non-gravitational perturbations on the orbit of the Mercury Planetary Orbiter (MPO), one of the two spacecrafts that will be placed in orbit around the innermost planet of the solar system by the BepiColombo space mission. The key r?le of the Italian Spring Accelerometer (ISA), that has been selected by the European Space Agency (ESA) to fly on-board the MPO, is outlined. In the first part of the paper, through a numerical simulation and analysis we have estimated, over a time span of several years, the long-period behaviours of the disturbing accelerations produced by the incoming direct solar radiation pressure, and the indirect effects produced by Mercury’s albedo. The variations in the orbital parameters of the spacecraft, together with their spectral contents, have been estimated over the analysed period. The direct solar radiation pressure represents the strongest non-gravitational perturbation on the MPO in the very complex radiation environment of Mercury. The order-of-magnitude of this acceleration is quite high, about 10⁻⁶ m/s², because of the proximity to the Sun and the large area-to-mass ratio of the spacecraft. In the second part of the paper, we concentrated upon the short-period effects of direct solar radiation pressure and Mercury’s albedo. In particular, the disturbing accelerations have been compared with the ISA measurement error and the advantages of an on-board accelerometer are highlighted with respect to the best modelling of the non-gravitational perturbations in the strong radiation environment of Mercury. The readings from ISA, with an intrinsic noise level of about in the frequency band of 3·10⁻⁵–10⁻¹ Hz, guarantees a very significant reduction of the non-gravitational accelerations impact on the space mission accuracy, especially of the dominant direct solar radiation pressure.  相似文献   

A quantitative approach for the evaluation of rockfall risk on buildings     

De Biagi  Valerio  Napoli  Maria Lia  Barbero  Monica 《Natural Hazards》2017,88(2):1059-1086

Natural Hazards - A quantitative rockfall risk analysis at local scale is a complex and difficult task because it should consider both the randomness in the natural phenomenon and the variability...  相似文献   

GGR Critical Review of Analytical Developments in 2008–2009: An Introduction     

Janet M. Hergt  Ricardo Arevalo Jr  L. Paul Bèdard  Jeremy Bellucci  Jacinta Enzweiler  Klaus Peter Jochum  Kathryn L. Linge  William F. McDonough  Regina Mertz-Kraus  Michael Wiedenbeck  Xiaohong Wang  Jon D. Woodhead 《Geostandards and Geoanalytical Research》2010,34(4):325-326

This collection of articles represents the fourth in a series of reviews in which authors have aimed at capturing the key advances in a range of analytical fields ( Hergt et al. 2005, 2006, 2008 ). The publication period under review is 2008–2009 and the intention here is to provide readers with a summary of the most influential developments published during this period, across a broad range of topics appropriate to the Earth and environmental sciences. Most authors comment on the ways in which the emphases of research in their specific fields of examination have changed over time. All note an increase in rigour and focus on data quality. Whether advances have taken place in instrumentation, sample manipulation or data deconvolution, there are a large number of dedicated scientists out there contributing to the high quality of geochemical data employed in geological and environmental research.  相似文献   

A new model for the formation of the Somma Caldera     

G. Rolandi  F. Bellucci  M. Cortini 《Mineralogy and Petrology》2004,80(1-2):27-44

Summary The evolution of the Mt. Somma caldera is reconstructed by means of volcanological, geological and geomorphologic data. The present caldera shape results from two caldera forming events: (a) break-up of the upper part of the older structure, which occurred between 17 and 8Kyr B.P. through a series of external volcaniclastic debris flow depositions and internal collapses into a cored-out vent. (b) W–SW directed sector collapse of the enlarged Mt. Somma crater, caused by excess vapour pressure generated during the Avellino eruption (3.5Kyr B.P.). At this time, the morphology of the Mt. Somma crater probably resembled the demolished crater formed in 1980 at Mt. St. Helens. Flank failure of Mt. Somma during the Avellino eruption was probably caused both by a migration of the vent to the west and a drastic change of the hydrogeological conditions at depth. Flank failure processes were extended to the S–SE sector of the Mt. Somma edifice during the 79 A.D. and 472 A.D. eruptions. After the 472 A.D. eruption interplinian activity during the Middle Ages resulted in the formation of the Vesuvius cone inside the Mt. Somma caldera.  相似文献   

Tectonic controls on the genesis of ignimbrites from the Campanian Volcanic Zone, southern Italy   总被引：2，自引：0，他引：2  

G. Rolandi  F. Bellucci  M. T. Heizler  H. E. Belkin  B. De Vivo 《Mineralogy and Petrology》2003,79(1-2):3-31

Summary ¶The Campanian Plain is an 80×30km region of southern Italy, bordered by the Apennine Chain, that has experienced subsidence during the Quaternary. This region, volcanologically active in the last 600ka, has been identified as the Campanian Volcanic Zone (CVZ). The products of three periods of trachytic ignimbrite volcanism (289–246ka, 157ka and 106ka) have been identified in the Apennine area in the last 300ka. These deposits probably represent distal ash flow units of ignimbrite eruptions which occurred throughout the CVZ. The resulting deposits are interstratified with marine sediments indicating that periods of repeated volcano-tectonic emergence and subsidence may have occurred in the past. The eruption, defined as the Campanian Ignimbrite (CI), with the largest volume (310km³), occurred in the CVZ 39ka ago. The products of the CI eruption consist of two units (unit-1 and unit-2) formed from a single compositionally zoned magma body. Slightly different in composition, three trachytic melts constitute the two units. Unit-1 type A is an acid trachyte, type B is a trachyte and type C of unit-2 is a mafic trachyte.The CI, vented from pre-existing neotectonic faults, formed during the Apennine uplift. Initially the venting of volatile-rich type A magma deposited the products to the N–NE of the CVZ. During the eruption, the Acerra graben already affected by a NE–SW fault system, was transected by E–W faults, forming a cross-graben that extended to the gulf of Naples. E–W faults were then further dislocated by NE–SW transcurrent movements. This additional collapse significantly influenced the deposition of the B-type magma of unit-1, and the C-type magma of unit-2 toward the E–SE and S, in the Bay of Naples. The pumice fall deposit underlying the CI deposits, until now thought to be associated with the CI eruption, is not a strict transition from plinian to CI-forming activity. It is derived instead from an independent source probably located near the Naples area. This initial volcanic activity is assumed to be a precursor to the CI trachytic eruptions, which vented along regional faults.Received October 23, 2002; revised version accepted July 29, 2003  相似文献