Vincenza Tornatore

Vincenza Tornatore
Politecnico di Milano | Polimi · Department of Civil and Environmental Engineering

Astronomy

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63
Publications
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300
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Publications

Publications (63)
Article
Full-text available
The atmospheric humidity in the Polar Regions is an important factor for the global budget of water vapour, which is a significant indicator of Earth’s climate state and evolution. The Global Navigation Satellite System (GNSS) can make a valuable contribution in the calculation of the amount of Precipitable Water Vapour (PW). The PW values retrieve...
Article
Full-text available
This paper presents a comparison of the vertical total electron content (vTEC) estimated over Italy using two different approaches: the GPS Global Ionosphere Maps (GIMs) and the so-called “calibration technique” developed by Ciraolo in 2007. The study has been carried out at a regional level by considering three Italian dual-frequency stations of t...
Article
Full-text available
We assess the performance of different break detection methods on three sets of benchmark datasets, each consisting of 120 daily time series of integrated water vapor differences. These differences are generated from the Global Positioning System (GPS) measurements at 120 sites worldwide, and the numerical weather prediction reanalysis (ERA‐Interim...
Article
Full-text available
In recent years, the measurement of dam displacements has benefited from a great improvement of existing technology, which has allowed a higher degree of automation. This has led to data collection with an improved temporal and spatial resolution. Robotic total stations and GNSS (Global Navigation Satellite System) techniques, often in an integrate...
Presentation
Full-text available
Detecting breaks in tropospheric data is indispensable, since these breaks directly affect the trend estimates from Zenith Total Delay (ZTD) series or Integrated Water Vapor (IWV) records. Various algorithms have been already employed to report the exact epochs of break points during the entire time span of ZTD or IWV series. This procedure is know...
Article
Full-text available
Global Navigation Satellite Systems (GNSS) receivers are nowadays commonly used in monitoring applications, e.g., in estimating crustal and infrastructure displacements. This is basically due to the recent improvements in GNSS instruments and methodologies that allow high-precision positioning, 24 h availability and semiautomatic data processing. I...
Preprint
GNSS receivers are nowadays commonly used in monitoring applications, e.g., in estimating crustal and infrastructure deformations. This is basically due to the recent improvements in GNSS instruments and methodologies that allow high precision positioning, 24 h availability and semiautomatic data processing. In this paper, GNSS estimated deformatio...
Conference Paper
The Project proposal “Using Regional GNSS Networks to Strengthen Severe Weather Prediction” has been selected by The Scientific and Research Council of Turkey to be funded under “1001 - Scientific and Technological Research Projects Funding Program”. The project received a three-year grant of 304.685,60 TL. The project team consist of one manager,...
Conference Paper
Integrated water vapour (IWV) is calculated from processing of GNSS data and IWV time series are produced. IWV time series analysis is important to monitoring of climate changes.Inhomogeneities caused by earthquakes, changes in hardware or equipment etc., can affect actual trends and seasonal variability in time series. This work presents non-parame...
Conference Paper
Time series of any climatic variables, e.g., precipitation, may be affected by non-climatic factors, which may alter the climatic signals. Homogeneous climatic time series are important for climate change studies. Inhomogeneities caused by station relocation and instrumentation changes, etc., can mask actual trends and seasonal variability in time...
Article
Full-text available
In this paper station coordinate time series from three space geodesy techniques that have contributed to the realization of the International Terrestrial Reference Frame 2014 (ITRF2014) are compared. In particular the height component time series extracted from official combined intra-technique solutions submitted for ITRF2014 by DORIS, VLBI and G...
Conference Paper
Full-text available
Seasonal components in the ZTD (Zenith Tropospheric Delay) and IWV (Integrated Water Vapour) time series are important and provide information about weather conditions in a given region. The main purpose of this research is to analyze linear trends and seasonal components of ZTD’s and IWS’s in GPS reprocessing campaign at selected stations in Europ...
Conference Paper
Full-text available
In this work we have compared the Up component time series reprocessed in view of the new ITRF2014. The solutions that we have considered are the combinations of individual submissions of the Operational Analysis Centers (ACs) as official IVS, IGS and IDS products. We have modelled time series as discrete-time Marcov processes, we have detected and...
Conference Paper
Full-text available
The topic VLBI tracking of GNSS satellites has lately emerged as a new way for linking the dynamic reference frame realized by GNSS satellites to the ICRF. Recently, a few related experiments and studies have been carried out to test and further develop this technique. In this contribution we present preliminary results of post-correlation with the...
Conference Paper
Full-text available
The topic VLBI tracking of GNSS satellites has lately emerged as a new way for linking the dynamic reference frame realized by GNSS satellites to the ICRF. Recently, a few related experiments and studies have been carried out to test and further develop this technique. In this contribution we present preliminary results of post-correlation with the...
Data
Very Long Baseline Interferometry (VLBI) is a primary space-geodetic technique for determining precise coordinates on the Earth, for monitoring the variable Earth rotation and orientation with highest precision, and for deriving many other parameters of the Earth system. The International VLBI Service for Geodesy and Astrometry (IVS, http://ivscc.g...
Chapter
Full-text available
We describe an experiment carried out to observe signals emitted by GLONASS (GLObal NAvigation Satellite System) satellites using the Very Long Baseline Interferometry (VLBI) technique. This test was performed on a single baseline and had as its primary goal to evaluate the capability of the VLBI system to observe GNSS (Global Navigation Satellite...
Article
Monitoring Earth-surface deformations with surveying instruments plays a key role in the knowledge of dynamics and the evolution of geophysical phenomena. During this stage, it is important to adopt an appropriate check of the statistical significance of point displacements. We verified the advantages of using a statistical Bayesian approach with a...
Article
As a preparation for future possible orbit determination of GNSS satellites by VLBI observations an initial three-station experiment was planned and performed in January 2009. The goal was to get first experience and to verify the feasibility of using the method for accurate satellite tracking. GNSS orbits related to a satellite constellation can b...
Article
Radio sources to observe are not natural radio sources but six satellites of GPS (Global Positioning System) and three of GLONASS (GLObal NAvigation Satellite System) constellations. Frequency signals are L1 (1575.25 MHz) and L2 (1227.6 MHz) for GPS, GLONASS have individual frequencies around G1 (1600 MHz) and G2 (1250 MHz). We want first evaluate...
Article
Full-text available
The Bayesian approach to significance testing, that makes use of prior information, has been studied in the last years, particularly to allow the detection of deformations which are small with respect to measurement errors from repeated surveys. Some investigations showed up to now that, under particular conditions concerning both the parameters of...
Article
Full-text available
Use of GPS-aided inertial navigation systems is continuously in-creasing thanks to the remarkable evolution of sensor technology and data pro-cessing methods. Several algorithms are developed to realize an INS/GPS (In-ertial Navigation System/Global Positioning System) software to post-process navigation data. Navigation equations are analytically...
Article
Full-text available
In this study, we investigate the coordinate time series of the radio telescopes which regularly take part in IVS-R1 and-R4 sessions. Firstly, we determine the linear trend (velocity vectors of the antenna coordinates) due to e.g. plate tectonics. The trends of the coordinate time series are estimated by Least Squares (LS), fitting the coefficients...
Article
Full-text available
One interesting aspect for the development of the VLBI2010 system would be to have the possibility to observe Global Navigation Satellite System (GNSS) signals. This might allow to improve the integration and combination of these techniques, which is an important aspect for the Global Geodetic Observing System (GGOS) of the International Associatio...
Conference Paper
Full-text available
Space Very Long Baseline Interferometry (SVLBI) is an important space technology for geodesy and geodynamics to a very high accuracy level. At present, the SVLBI mathematical model of geodetic parameters does not consider nutation parameters. In this paper the nutation parameters will be added to the rotation matrix, and the mathematical model of S...
Conference Paper
Full-text available
GNSS (Global Navigation Satellite System) is a global navigation satellite system consisting of different satellite constellations that transmit ranging signals used for positioning and navigation anywhere around the globe. In this work we present first investigations on the possibility to observe GNSS signals using the VLBI technique with the main...
Conference Paper
Full-text available
Space Very Long Baseline Interferometry (SVLBI) is an important space technology for geodesy and geodynamics to a very high accuracy level. At present, the SVLBI mathematical model of geodetic parameters does not consider nutation parameters. In this paper the nutation parameters will be added to the rotation matrix, and the mathematical model of S...
Article
Full-text available
The concept of reference system is changing because the number of regional GNSS networks for real time positioning on the national area is increasing. Nowadays, surveys are carried out, not only into a 'static' reference system, whose coordinates stay unchanged for several years, but also respect to a dynamic reference system realized by GPS perman...
Article
European geodetic very long baseline interferometry (VLBI) sessions (also known as EUROPE sessions) have been carried out on a regular basis for the past 15years to study relative crustal motions within Europe. These sessions are based on observations of extragalactic radio sources, which serve as distant fiducial marks to establish an accurate and...
Article
Full-text available
The IVS (International VLBI Service for Geodesy and Astrometry) Analysis Centers (BKG (Federal Agency for Cartography and Geodesy), NASA GSFC (Goddard Space Flight Center), DGFI (Deutsches Geodaetisches Forschungsinstitut), SHA (Shanghai Astronomical Observatory), USNO (U.S. Naval Observatory), MAO (Main Astronomical Observatory), AUS (Geoscience A...
Conference Paper
Full-text available
Parole chiave > Filtro di Kalman, Minimi quadrati, Navigazione, solu-zione geodetica Riassunto > Da sempre si è ritenuto il filtro di Kalman un'ottima alter-nativa alle soluzioni minimi quadrati anche per stime richieste non in tempo reale: ciò è principalmente dovuto all'insostenibile carico nume-rico che la soluzione minimi quadrati necessariamen...
Article
Full-text available
Working Group on Measurements and Methods of Hight Precision Space Geodesy - ASI Research (1998-1999-2000)
Article
Full-text available
Working Group on Measurements and Methods of Hight Precision Space Geodesy - ASI Research (1998-1999-2000)
Article
Full-text available
The ITALGEO99 quasi-geoid estimate is presented. This gravimetric quasi-geoid has been computed in the area 36° ≤ φ ≤ 47°, 6° ≤ λ ≤ 19° on a 2′ × 2′ regular geographical grid. With respect to the previous ITALGEO95 estimate, new gravity data have been included in the gravity data base (Slovenia area) and a completely revised DTM has been used for t...
Conference Paper
This paper reports experimental results carried out in the central part of Italy, from March to April 2000, in order to monitor main features of integrated precipitable water vapour (IPWV) horizontal distribution by means of a specific GPS network with five receivers and a scanning microwave ground-based radiometer (WVR-1100). A comparison of IPWV...
Article
Three satellite missions to evaluate on a global scale the earth gravity field have been recently inserted in the programs of some of the most important international spatial agencies. The launches of the satellites related to each mission will be carried out in few years starting from the first months of 2000. This paper describes the problems rel...
Article
This paper discusses preliminary results related to the comparison of long baselines obtained from GPS and VLBI data processing in Europe. This comparison was carried out with the aim to check the agreement of the crustal deformation fields derived by the two techniques. An approach based on the theory of stationary and ergodic stochastic processes...
Article
Most of the quasars or BL Lac objects regularly observed during geodetic VLBI experiments show extended spatial structures at the milliarcsecond scale. For high precision geodetic VLBI analysis source structure effects have to be accounted for. The proper correction of source structure effects is possible when brightness distributions of sources ar...
Article
Full-text available
This paper follows another one by the same authors ([7]), where the principle of a stochasticprobabilistic approach to the problem of cluster analysis was illustrated both from the theoretical point of view and by means of simulated and real-case examples. In the above cited paper the mono-dimensional case was treated (see also f8g), whereas we wan...
Article
Full-text available
We propose a new method to model a non-stationary and slowly variable phenomenon. The case of a one-dimensional stochastic process is presented. Particular care is taken in order to prove that the condition of positive definiteness of the covariance function is satisfied. The estimate of the covariance function is afterwards obtained by means of lo...
Article
Full-text available
Cluster analysis can be seen as a set of procedures which allow to subdivide sets of data into groups with homogeneous characteristics. From our point of view, it is mostly fruitful to use a statistical model for the data. This means that the problem of cluster analysis can be defined in the following way: to estimate a distribution which is a «mix...
Article
Full-text available
The relative orientation of a homogeneous sample of 92 compact groups of galaxies taken from Hickson's catalog is investigated. No evidence is found for these groups of galaxies to be aligned with either their nearest neighbors or with Abell clusters. However, a weak indication of alignment is found for groups connected in large structures such as...
Article
In the years 1988–1990 Europe has seen a rapid expansion of its geodetic VLBI network with the establishment of several new stations in the Mediterranean area. Now one of the world’s most densely spaced VLBI networks of fixed stations has started a campaign of regular measurements in order to determine regional crustal motions in an area where stro...
Article
Compact groups are small, relatively isolated systems of galaxies with projected separations comparable to the diameters of the galaxies themselves. The most recent, and largest, survey of compact groups is that of Hickson (1982) who visually inspected all the red POSS prints, covering about 67% of the sky. These groups have apparent space densitie...
Article
Full-text available
The VLBI software packages for the data analysis which are used by different IVS (International VLBI Service for Geodesy and Astrometry) Analysis Centers applying various statistical methods. These statistical methods are the Least-Squares (LSQ) method, the Kalman filter (KF) method, the Square-Root Information Filter (SRIF) and the Least-Squares C...
Article
Full-text available
Several tests to observe signals transmitted by GLONASS (GLObal NAvigation Satellite System) satellites have been performed using the VLBI (Very Long Baseline Interferometry) technique. The radio telescopes involved in these experiments are Medicina and Onsala. The satellites transmit artificial radio signals that were considered in a similar way a...

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Projects

Projects (3)
Archived project
To measure the geometry , space orietation and gravity field of the planets of the solar system and to study the orbit of the spacecraft.
Project
The first aim of the project, to determine of atmospheric water vapor distribution by GNSS meteorology and GNSS tomography software developed by ourselves using observation data of network designed with 2 new constructed GNSS reference station, SAM1 CORS-TR (Continuously Operating Reference Stations Turkey) station 10-20km apart from Samsun rawisonde station and to compare of independent techniques derived water vapor distribution. Within the project, water vapor distribution derived by GNSS meteorology and GNSS tomography will be compared with water vapor distributions derived by independent techniques such as rawisonde and numerical weather models (NWM). Therefore, it is targeted to perform accuracy analysis of water vapor distributions derived by GNSS meteorology and GNSS tomography. Additionally, GNSS tomography model applied in Samsun test region will be applied in a small network designed by TRAB GNSS station, TRBN CORS-TR station and a new constructed GNSS station near to those stations in Trabzon. Water vapor distribution results calculated from GNSS tomography will be compared with of NWM. So, it is targeted to investigate generalization of model by applying in a different test area. The second aim of the project, to compare water vapor distributions derived by GNSS tomography with those derived by rawinsonde and NWM (MM5, ALADIN, ECMWF, etc.) at dates which severe weather events recorded according to Turkish State Meteorological Service data. Therefore, it is targeted to evaluate possible contribution of GNSS tomography to prediction of hydrological hazards and taking precautions. The third aim of the project, to determine near real time water vapor for near real time observations by modified version of GNSS tomography software developed by ourselves. For this aim, near real time water vapor distributions will be determined with near real time observation data obtained from networks composed of Turkish IGS (International GNSS Service) stations and some other GNSS stations established within private projects. Near real time water vapor distribution will be determined by Trop-NET (URL3) software installed at Analysis Center of Karadeniz Technical University (KTU) Department of Geomatics Engineering within a collaboration with Geodetic Observatory Pecny (Czech Republic) within COST Action ES1206 (Advanced Global Navigation Satellite Systems Tropospheric Products for Monitoring Severe Weather Events and Climate-GNSS4SWEC) to provide support The EUMETNET EIG GNSS water vapor programme (E-GVAP). Water vapor distribution derived with two software will be compared. Therefore, it is targetted to test GNSS tomography software for near real time observation data. It is targeted to evaluate the possible contribution of GNSS tomography to predict severe weather events by monitoring near real time water vapor distribution. There have not been found any research work on GNSS tomography in Turkey. Within this context, this study is original due to its contribution to literature of GNSS meteorology and GNSS tomography in Turkey; and to meteorological predictions in w.r.t. hydrological hazard evaluations in Turkey.
Project
We have derived the kinematical motions of Ny-Ålesund, Svalbard, comparing recently published ITRF2014 coordinate time series from VLBI, GPS, and DORIS. Earlier studies have revealed inconsistent results between different observing techniques, mainly due to non coherent processing strategies and different detection, handling and estimation strategy of the discontinuities. Offset detection and estimation still remain a critical issue in order to further reduce offset-related velocity biases. The harmonic analysis shows also some differences in the detected periodic signals frequency, phase and amplitude, that are clearly of non geophysical origin. The adopted analysis method models time series as discrete-time Markov processes. This approach is particularly well suited to better describe the long-term signal, particularly in case of nonlinearities in the time series when also the multilinear velocity models are not adequate. Time series offsets and long-term trends were estimated to obtain the quasi-cyclostationary residuals needed to conduct the harmonic analysis. Documented first-order discontinuities were assumed a priori as candidate discontinuity epochs, whereas other discontinuities were detected, thus adding dedicated variables to the original state–space model of the time series. The coordinate offsets were estimated and tested for statistical meaningfulness.