During the last years at the Matera Space Geodesy Center (ASI/CGS) space geodesy activities relat... more During the last years at the Matera Space Geodesy Center (ASI/CGS) space geodesy activities related to atmospheric applications have grown up. In particular, studies on the troposphere for meteorological applications using GPS signal, started in 1999, have been developed in the framework of national and international context (MAGIC EC project, COST 716 Action). Presently, at CGS, the data of 35 European stations are analysed on hourly basis to produce tropospheric Total Zenith path Delay (ZTD), results being continuously available on: geodaf.mt.asi.it. To carry on the fruitful research on the use of GPS derived tropospheric parameters for meteorological applications and climate research and the experiences of assimilation of GPS PWV into the MM5 non hydrostatic modeling, the Italian Space Agency, Università de L'Aquila and Parco Scientifico e Tecnologico d'Abruzzo (PSTdA) decided to start a new dedicated project, installing 10 new permanent GPS stations in Basilicata regio...
2019 Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum (EFTF/IFC)
In these last decades scientific activities by Global Navigation Satellite Systems (GNSS) were de... more In these last decades scientific activities by Global Navigation Satellite Systems (GNSS) were developed covering a wide spectrum of topics. We will focus on two scientific areas: Fundamental Physics Experiments (FP), and atmosphere remote sensing by GALILEO. On August 22nd 2014, two Galileo satellites (GSAT5-6) were launched on wrong very high eccentric orbits (e=.156). The two satellites have provided the unique opportunity to perform investigations in the field of General Relativity and Gravitation (GR). Dark matter (DM) makes up about 85% of all matter in the Universe and nothing is known about its nature. There is a growing interest in finding candidates alternative to Weakly Interacting Mass Particles (WIMP). Some models provide DM in the form of spatially large objects, such as Topological Defects (TD), of the same order of Earth that can cause anomalies in atomic clocks.The transit of TD induce changes in Fundamental Constants such as: the fine structure constant, the ratio of the light quark mass to the quantum chromodynamics energy-scale, and the electron and proton masses. GALILEO clocks can be suitable to detect the DM. Gamma ray bursts (GRB) are caused by extremely energetic events in the very distant universe. They have durations from seconds to minutes and cover the entire electromagnetic spectrum. The challenge is their detection and location in the sky in real-time allowing detailed follow-up observations of these exotic events within minutes by dedicated satellites and earthbound telescopes. A GNSS constellation like Galileo is the ideal detector for GRB. We have a radio occultation event when a Low Earth Orbit satellite (LEO) equipped with a spaceborne receiver, catches signals when a GNSS satellite is eclipsing/rising behind Earth. In this geometry configuration GNSS signals propagate tangentially through Earth’s atmosphere. From the received signal is possible to retrieve very accurate Temperarture, Pressure and Humidity profiles of the atmosphere as well as its ionosphere structure.
Nine years of VLBI data acquired within the EUROPE campaign have been analysed to estimate the mo... more Nine years of VLBI data acquired within the EUROPE campaign have been analysed to estimate the motion of the stations participating to this campaign. The estimated site velocities and baseline time series are compared to those obtained from the GPS solution carried out at CGS as contribution to EUREF. Both the solutions have been expressed in the ITRF96 reference frame
The Italian Space Agency (ASI) is very active in the field of Atmospheric Sounding by using the G... more The Italian Space Agency (ASI) is very active in the field of Atmospheric Sounding by using the GNSS Radio Occultation Technique since several years. The main activities in this field are essentially : · the development and the manufacturing of a Proto Flight Model of the first GNSS Receiver for Geodetic application: Lagrange, installed on the Argentinean SAC-C satellite. This program was co-funded with the Italian Company Laben. · the development and the manufacturing of the Proto Flight Model of a GNSS Receiver for Radio Occultation called Lagrange RO . The activities of the Phase C/D of this instrument have been assigned to an industrial team composed by Laben (as prime contractor and with the responsibility of the receiver and the full payload) and to Alenia Spazio (responsible of the Radio Occultation Antennas). ASI plans to embark this payload on the Argentinian SAOCOM or SAC D satellite. The payload will be delivered to ASI for the first half of the 2004. In same time ASI is ...
International Association of Geodesy Symposia, 1993
The main objective of the TYRGEONET (TYRrhenian GEOdetic NETwork) project is to perform a geodeti... more The main objective of the TYRGEONET (TYRrhenian GEOdetic NETwork) project is to perform a geodetic survey by means of the Global Positioning System technique in that region of the Mediterranean area where many geodynamical phenomena, that most influence the evolution of the basin are located. The project supports other researches regarding the detection of active deformation in the Central Mediterranean. The TYRGEONET is a collaborative project between many Italian and foreign Institutions, like the Centre Spatial de Toulose (F), the Institut de Physique du Globe, Paris (F), the Institut de la Meteorologie, Tunis (TN), the Institut Preparatoire Technique du Nabeul (TN), the Universities of Lubiana (YU) Thessaloniki (GR), and Zagabria (YU).
International Association of Geodesy Symposia, 1998
Taking into account the growing number of permanent GPS stations in Europe, the EUREF subcommissi... more Taking into account the growing number of permanent GPS stations in Europe, the EUREF subcommission decided in 1995 to coordinate the activities related to this network for the maintenance of the European Reference Frame.
IGARSS 2003. 2003 IEEE International Geoscience and Remote Sensing Symposium. Proceedings (IEEE Cat. No.03CH37477)
This paper concerns the validation of the atmospheric integrated precipitable water vapour (IPVW)... more This paper concerns the validation of the atmospheric integrated precipitable water vapour (IPVW) product of the MERIS instrument on board of ENVISAT satellite. The validation is performed both at specific locations and over an extended area. The first comparison is performed with respect to the measurements of ground based instruments (microwave radiometers, GPS receivers, radiosoundings). The second assessment is based
International Association of Geodesy Symposia, 2002
The FOURIER mission (Adriani et al. 2001) has been selected by the Italian Space Agency, together... more The FOURIER mission (Adriani et al. 2001) has been selected by the Italian Space Agency, together with other 4 projects, for a feasibility study. Within the current year one of these will be selected to fly within the next 4 years. The primary goal of FOURIER is the development of a systematic and objective observational test of the predictive capabilities of climate models, as proposed by Goody (1998). This requires long-term climate benchmark observations that differ from those presently available. High accuracy, demonstrable with respect to international standards, is the primary requirement. Other important features follow from this requirement. At least two types of space measurement satisfy these criteria: refractivity retrieved by GPS microwave occultation data; and calibrated, resolved, thermal radiances. In Fourier mission it is foreseen to put on board both a GPS-GLONASS receiver and a spectral radiometer (the Planetary Fourier Spectrometer —PFS-) to perform just such a test. In the paper will be discussed how to compare and validate data which will be obtained with both instruments for the future mission. Essentially the “main drawback” is that: while the PFS points to nadir direction, GNSS occultations are retrieved just along Earth grazing directions. So only the occultations that occur along the spacecraft velocity direction are selected and benchmarking for calibration purposes.
In the last decade the use of GPS radio occultations technique (GPS RO) has been deeply and widel... more In the last decade the use of GPS radio occultations technique (GPS RO) has been deeply and widely investigated for retrieving physical and chemical parameters of Earth atmosphere. The technique proved to be particularly precise in retrieving temperature profiles with an high vertical resolution (<1 Km). Temperature profiles are obtained for dry part of atmosphere solving for the system of
Physics and Chemistry of the Earth, Parts A/B/C, 2004
ABSTRACT The use of the GPS radio occultation technique (GPS RO) for retrieving physical and chem... more ABSTRACT The use of the GPS radio occultation technique (GPS RO) for retrieving physical and chemical parameters of the Earth&#39;s atmosphere has been deeply and widely investigated over the last decade. The technique has proved to be particularly precise in retrieving temperature profiles with high vertical resolution (&lt;1 km). Temperature profiles are obtained for the dry part of atmosphere solving for the system of two equations (Smith and Weintraub equation for refractivity and the hydrostatic equilibrium relationship) with two unknowns (hydrostatic pressure P and temperature T). The system cannot be solved for the lower troposphere because water vapor pressure is not negligible. This makes it necessary to include some additional external information, such as humidity computed from meteorological analyses available from the European Center for Medium-Range Weather Forecasting (ECMWF) or the National Center for Environmental Prediction (NCEP), or zenith troposphere delays estimated from GPS ground station measurements [IAG2001 Scientific Assembly (2001); J. Geophys. Res. 102(D21) (2001) 27,221]. This investigates the possibility of retrieving humidity using the refractivity profiles derived from GPS RO data only. In particular with the proposed method, the dry pressure profiles are obtained fitting the refractivity of the outer troposphere layers (from up to the stratopause) using the Hopfield dry atmosphere model [J. Geophys. Res. 74(18) (1969) 4487], in which ground pressure and temperature are the parameters to be estimated. In the second step humidity profiles are extracted by subtracting the dry refractivity given by the estimated Hopfield model from the values (wet + dry) retrieved by GPS RO. The refractivity profiles used in the work were retrieved from CHAMP GPS RO data [Geophys. Res. Lett. 28 (2001) 3263]. The humidity profiles obtained with the proposed technique have been compared and validated with profiles retrieved from radwinsonde observations (RAOB) over eight sites. The results are promising in that the new method seems to retrieve profiles comparable to those obtained using the method currently in use (TAO 11(1) (2000) 53).
Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy, 2001
... All rights reserved 1 Introduction During 1999, a cooperation among ASI CGS, UniversitA de L&... more ... All rights reserved 1 Introduction During 1999, a cooperation among ASI CGS, UniversitA de L&amp;#x27;Aquila (UNIAQ) and Fondazione Ugo Bordoni (FUB) allowed to ... J. Talaya, A. Rius, F. Vespe, R. Santangelo, X.-Y. Huang, J. Davila, M. Ge, A. Flores, H. Vedel, K. Mogensen and X ...
The Lense - Thirring effect is a very small shift of the orbit of a test particle due to the spin... more The Lense - Thirring effect is a very small shift of the orbit of a test particle due to the spin of a body. It may be described as an orbital drag due to the gravitomagnetic field generated by the spin of the central body. Gravitomagnetism, a fundamental weak-field prediction of Einstein's theory of general relativity, is generated by currents of mass and owes its name to its formal analogies with magnetism, generated by currents of electric charge. Then, according to general relativity, the Earth's spin should influence the motion of its orbiting satellites. Indeed, we have analysed the laser-ranging observations of the orbits of the satellites LAGEOS and LAGEOS II and have obtained the first direct measurement of the Lense - Thirring effect, or `frame-dragging', due to the Earth's spin. We measured 0264-9381/14/10/003/img8 and estimated the total error 0264-9381/14/10/003/img9, whereas the general relativistic value is 0264-9381/14/10/003/img10.
During the last years at the Matera Space Geodesy Center (ASI/CGS) space geodesy activities relat... more During the last years at the Matera Space Geodesy Center (ASI/CGS) space geodesy activities related to atmospheric applications have grown up. In particular, studies on the troposphere for meteorological applications using GPS signal, started in 1999, have been developed in the framework of national and international context (MAGIC EC project, COST 716 Action). Presently, at CGS, the data of 35 European stations are analysed on hourly basis to produce tropospheric Total Zenith path Delay (ZTD), results being continuously available on: geodaf.mt.asi.it. To carry on the fruitful research on the use of GPS derived tropospheric parameters for meteorological applications and climate research and the experiences of assimilation of GPS PWV into the MM5 non hydrostatic modeling, the Italian Space Agency, Università de L'Aquila and Parco Scientifico e Tecnologico d'Abruzzo (PSTdA) decided to start a new dedicated project, installing 10 new permanent GPS stations in Basilicata regio...
2019 Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum (EFTF/IFC)
In these last decades scientific activities by Global Navigation Satellite Systems (GNSS) were de... more In these last decades scientific activities by Global Navigation Satellite Systems (GNSS) were developed covering a wide spectrum of topics. We will focus on two scientific areas: Fundamental Physics Experiments (FP), and atmosphere remote sensing by GALILEO. On August 22nd 2014, two Galileo satellites (GSAT5-6) were launched on wrong very high eccentric orbits (e=.156). The two satellites have provided the unique opportunity to perform investigations in the field of General Relativity and Gravitation (GR). Dark matter (DM) makes up about 85% of all matter in the Universe and nothing is known about its nature. There is a growing interest in finding candidates alternative to Weakly Interacting Mass Particles (WIMP). Some models provide DM in the form of spatially large objects, such as Topological Defects (TD), of the same order of Earth that can cause anomalies in atomic clocks.The transit of TD induce changes in Fundamental Constants such as: the fine structure constant, the ratio of the light quark mass to the quantum chromodynamics energy-scale, and the electron and proton masses. GALILEO clocks can be suitable to detect the DM. Gamma ray bursts (GRB) are caused by extremely energetic events in the very distant universe. They have durations from seconds to minutes and cover the entire electromagnetic spectrum. The challenge is their detection and location in the sky in real-time allowing detailed follow-up observations of these exotic events within minutes by dedicated satellites and earthbound telescopes. A GNSS constellation like Galileo is the ideal detector for GRB. We have a radio occultation event when a Low Earth Orbit satellite (LEO) equipped with a spaceborne receiver, catches signals when a GNSS satellite is eclipsing/rising behind Earth. In this geometry configuration GNSS signals propagate tangentially through Earth’s atmosphere. From the received signal is possible to retrieve very accurate Temperarture, Pressure and Humidity profiles of the atmosphere as well as its ionosphere structure.
Nine years of VLBI data acquired within the EUROPE campaign have been analysed to estimate the mo... more Nine years of VLBI data acquired within the EUROPE campaign have been analysed to estimate the motion of the stations participating to this campaign. The estimated site velocities and baseline time series are compared to those obtained from the GPS solution carried out at CGS as contribution to EUREF. Both the solutions have been expressed in the ITRF96 reference frame
The Italian Space Agency (ASI) is very active in the field of Atmospheric Sounding by using the G... more The Italian Space Agency (ASI) is very active in the field of Atmospheric Sounding by using the GNSS Radio Occultation Technique since several years. The main activities in this field are essentially : · the development and the manufacturing of a Proto Flight Model of the first GNSS Receiver for Geodetic application: Lagrange, installed on the Argentinean SAC-C satellite. This program was co-funded with the Italian Company Laben. · the development and the manufacturing of the Proto Flight Model of a GNSS Receiver for Radio Occultation called Lagrange RO . The activities of the Phase C/D of this instrument have been assigned to an industrial team composed by Laben (as prime contractor and with the responsibility of the receiver and the full payload) and to Alenia Spazio (responsible of the Radio Occultation Antennas). ASI plans to embark this payload on the Argentinian SAOCOM or SAC D satellite. The payload will be delivered to ASI for the first half of the 2004. In same time ASI is ...
International Association of Geodesy Symposia, 1993
The main objective of the TYRGEONET (TYRrhenian GEOdetic NETwork) project is to perform a geodeti... more The main objective of the TYRGEONET (TYRrhenian GEOdetic NETwork) project is to perform a geodetic survey by means of the Global Positioning System technique in that region of the Mediterranean area where many geodynamical phenomena, that most influence the evolution of the basin are located. The project supports other researches regarding the detection of active deformation in the Central Mediterranean. The TYRGEONET is a collaborative project between many Italian and foreign Institutions, like the Centre Spatial de Toulose (F), the Institut de Physique du Globe, Paris (F), the Institut de la Meteorologie, Tunis (TN), the Institut Preparatoire Technique du Nabeul (TN), the Universities of Lubiana (YU) Thessaloniki (GR), and Zagabria (YU).
International Association of Geodesy Symposia, 1998
Taking into account the growing number of permanent GPS stations in Europe, the EUREF subcommissi... more Taking into account the growing number of permanent GPS stations in Europe, the EUREF subcommission decided in 1995 to coordinate the activities related to this network for the maintenance of the European Reference Frame.
IGARSS 2003. 2003 IEEE International Geoscience and Remote Sensing Symposium. Proceedings (IEEE Cat. No.03CH37477)
This paper concerns the validation of the atmospheric integrated precipitable water vapour (IPVW)... more This paper concerns the validation of the atmospheric integrated precipitable water vapour (IPVW) product of the MERIS instrument on board of ENVISAT satellite. The validation is performed both at specific locations and over an extended area. The first comparison is performed with respect to the measurements of ground based instruments (microwave radiometers, GPS receivers, radiosoundings). The second assessment is based
International Association of Geodesy Symposia, 2002
The FOURIER mission (Adriani et al. 2001) has been selected by the Italian Space Agency, together... more The FOURIER mission (Adriani et al. 2001) has been selected by the Italian Space Agency, together with other 4 projects, for a feasibility study. Within the current year one of these will be selected to fly within the next 4 years. The primary goal of FOURIER is the development of a systematic and objective observational test of the predictive capabilities of climate models, as proposed by Goody (1998). This requires long-term climate benchmark observations that differ from those presently available. High accuracy, demonstrable with respect to international standards, is the primary requirement. Other important features follow from this requirement. At least two types of space measurement satisfy these criteria: refractivity retrieved by GPS microwave occultation data; and calibrated, resolved, thermal radiances. In Fourier mission it is foreseen to put on board both a GPS-GLONASS receiver and a spectral radiometer (the Planetary Fourier Spectrometer —PFS-) to perform just such a test. In the paper will be discussed how to compare and validate data which will be obtained with both instruments for the future mission. Essentially the “main drawback” is that: while the PFS points to nadir direction, GNSS occultations are retrieved just along Earth grazing directions. So only the occultations that occur along the spacecraft velocity direction are selected and benchmarking for calibration purposes.
In the last decade the use of GPS radio occultations technique (GPS RO) has been deeply and widel... more In the last decade the use of GPS radio occultations technique (GPS RO) has been deeply and widely investigated for retrieving physical and chemical parameters of Earth atmosphere. The technique proved to be particularly precise in retrieving temperature profiles with an high vertical resolution (<1 Km). Temperature profiles are obtained for dry part of atmosphere solving for the system of
Physics and Chemistry of the Earth, Parts A/B/C, 2004
ABSTRACT The use of the GPS radio occultation technique (GPS RO) for retrieving physical and chem... more ABSTRACT The use of the GPS radio occultation technique (GPS RO) for retrieving physical and chemical parameters of the Earth&#39;s atmosphere has been deeply and widely investigated over the last decade. The technique has proved to be particularly precise in retrieving temperature profiles with high vertical resolution (&lt;1 km). Temperature profiles are obtained for the dry part of atmosphere solving for the system of two equations (Smith and Weintraub equation for refractivity and the hydrostatic equilibrium relationship) with two unknowns (hydrostatic pressure P and temperature T). The system cannot be solved for the lower troposphere because water vapor pressure is not negligible. This makes it necessary to include some additional external information, such as humidity computed from meteorological analyses available from the European Center for Medium-Range Weather Forecasting (ECMWF) or the National Center for Environmental Prediction (NCEP), or zenith troposphere delays estimated from GPS ground station measurements [IAG2001 Scientific Assembly (2001); J. Geophys. Res. 102(D21) (2001) 27,221]. This investigates the possibility of retrieving humidity using the refractivity profiles derived from GPS RO data only. In particular with the proposed method, the dry pressure profiles are obtained fitting the refractivity of the outer troposphere layers (from up to the stratopause) using the Hopfield dry atmosphere model [J. Geophys. Res. 74(18) (1969) 4487], in which ground pressure and temperature are the parameters to be estimated. In the second step humidity profiles are extracted by subtracting the dry refractivity given by the estimated Hopfield model from the values (wet + dry) retrieved by GPS RO. The refractivity profiles used in the work were retrieved from CHAMP GPS RO data [Geophys. Res. Lett. 28 (2001) 3263]. The humidity profiles obtained with the proposed technique have been compared and validated with profiles retrieved from radwinsonde observations (RAOB) over eight sites. The results are promising in that the new method seems to retrieve profiles comparable to those obtained using the method currently in use (TAO 11(1) (2000) 53).
Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy, 2001
... All rights reserved 1 Introduction During 1999, a cooperation among ASI CGS, UniversitA de L&... more ... All rights reserved 1 Introduction During 1999, a cooperation among ASI CGS, UniversitA de L&amp;#x27;Aquila (UNIAQ) and Fondazione Ugo Bordoni (FUB) allowed to ... J. Talaya, A. Rius, F. Vespe, R. Santangelo, X.-Y. Huang, J. Davila, M. Ge, A. Flores, H. Vedel, K. Mogensen and X ...
The Lense - Thirring effect is a very small shift of the orbit of a test particle due to the spin... more The Lense - Thirring effect is a very small shift of the orbit of a test particle due to the spin of a body. It may be described as an orbital drag due to the gravitomagnetic field generated by the spin of the central body. Gravitomagnetism, a fundamental weak-field prediction of Einstein's theory of general relativity, is generated by currents of mass and owes its name to its formal analogies with magnetism, generated by currents of electric charge. Then, according to general relativity, the Earth's spin should influence the motion of its orbiting satellites. Indeed, we have analysed the laser-ranging observations of the orbits of the satellites LAGEOS and LAGEOS II and have obtained the first direct measurement of the Lense - Thirring effect, or `frame-dragging', due to the Earth's spin. We measured 0264-9381/14/10/003/img8 and estimated the total error 0264-9381/14/10/003/img9, whereas the general relativistic value is 0264-9381/14/10/003/img10.
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Papers by F. Vespe