http://hdl.handle.net/2117/1442 Sat, 18 May 2013 14:02:51 GMT 2013-05-18T14:02:51Z webmaster.bupc@upc.edu Universitat Politècnica de Catalunya. Servei de Biblioteques i Documentació no http://hdl.handle.net/2117/19340 Title: Stability of the MIRAS amplitude calibration Authors: Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; Martín Neira, Manuel Abstract: Efficient methods to characterize and mitigate long-and short- term drifts in SMOS data have been developed after careful analysis of the external and internal calibration parameters and by accurate modeling of the individual receiver front-ends. A method to characterize this drift has been successfully developed and used to reduce the measured antenna temperature variations. Fri, 17 May 2013 13:43:19 GMT http://hdl.handle.net/2117/19340 2013-05-17T13:43:19Z Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; Martín Neira, Manuel no Radiometer calibration, Accurate modeling, Amplitude calibration, Antenna temperature, Internal calibration, Radiometer calibration, Receiver front-ends Efficient methods to characterize and mitigate long-and short- term drifts in SMOS data have been developed after careful analysis of the external and internal calibration parameters and by accurate modeling of the individual receiver front-ends. A method to characterize this drift has been successfully developed and used to reduce the measured antenna temperature variations. http://hdl.handle.net/2117/19326 Title: Performance of a spatial error correction technique in SMOS brightness temperature images Authors: Wu, Lin; Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Duffo Ubeda, Núria; Martín Neira, Manuel Abstract: Soil Moisture and Ocean Salinity (SMOS) brightness temperature synthesized images are obtained after a comprehensive calibration and error correction procedure. However, the final images are still contaminated by small but non-negligible spatial errors: the so-called pixel bias. These errors have been found to be very stable in the SMOS Alias-Free Field of View (AF-FoV) and can be mitigated, to a large extent, by applying a multiplicative mask to the measured brightness temperatures at the antenna plane. This paper describes the procedure to upgrade this mask to cover SMOS Extended AF­ FoV. Fri, 17 May 2013 10:19:57 GMT http://hdl.handle.net/2117/19326 2013-05-17T10:19:57Z Wu, Lin; Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Duffo Ubeda, Núria; Martín Neira, Manuel no Performance of a spatial error correction technique in SMOS brightness temperature images Soil Moisture and Ocean Salinity (SMOS) brightness temperature synthesized images are obtained after a comprehensive calibration and error correction procedure. However, the final images are still contaminated by small but non-negligible spatial errors: the so-called pixel bias. These errors have been found to be very stable in the SMOS Alias-Free Field of View (AF-FoV) and can be mitigated, to a large extent, by applying a multiplicative mask to the measured brightness temperatures at the antenna plane. This paper describes the procedure to upgrade this mask to cover SMOS Extended AF­ FoV. http://hdl.handle.net/2117/19265 Title: Airborne wind retrieval using GPS delay-Doppler maps Authors: Zavorotny, Valery; Rodríguez, Nereida; Akos, D.M.; Camps Carmona, Adriano José Abstract: Global Navigation Satellite System Reflectometry (GNSSR) has emerged recently as a promising remote sensing tool to retrieve various geophysical parameters of Earth’s surface. GNSS-reflected signals, after being received and processed by the airborne or space-borne receiver, are available as delay correlation waveforms or as delay- Doppler maps. In the case of a rough ocean surface, those characteristics can be related to the RMS of L-band limited slopes of the surface waves, and from there to the surface wind speed. The raw GNSS-reflected signal can be processed either in real time by the receiver, or can be recorded and stored onboard and post-processed in a laboratory. The latter approach leveraging a software receiver allows more flexibility while processing the raw data. This work analyzes Delay Doppler Maps (DDM) obtained as a result of processing of the data collected by the GPS data logger/software receiver onboard the NOAA Gulfstream-IV jet aircraft. Thereafter, the DDMs were used to retrieve surface wind speed employing several different metrics that characterize the DDM extent in the Doppler frequency-delay domain. In contrast to previous works in which winds have been retrieved by fitting the theoretically modeled curves into measured correlation waveforms, here we do not rely on any model for the determination. Instead, the approach is based on a linear regression between DDMs observables and the wind speeds obtained in simultaneous GPS dropsonde measurements. Wed, 15 May 2013 15:58:39 GMT http://hdl.handle.net/2117/19265 2013-05-15T15:58:39Z Zavorotny, Valery; Rodríguez, Nereida; Akos, D.M.; Camps Carmona, Adriano José no Bistatic radar, delay-Doppler mapping, global navigation satellite systems (GNSS), global positioning system (GPS), ocean surface, oceanography, reflected GPS, scatterometry Global Navigation Satellite System Reflectometry (GNSSR) has emerged recently as a promising remote sensing tool to retrieve various geophysical parameters of Earth’s surface. GNSS-reflected signals, after being received and processed by the airborne or space-borne receiver, are available as delay correlation waveforms or as delay- Doppler maps. In the case of a rough ocean surface, those characteristics can be related to the RMS of L-band limited slopes of the surface waves, and from there to the surface wind speed. The raw GNSS-reflected signal can be processed either in real time by the receiver, or can be recorded and stored onboard and post-processed in a laboratory. The latter approach leveraging a software receiver allows more flexibility while processing the raw data. This work analyzes Delay Doppler Maps (DDM) obtained as a result of processing of the data collected by the GPS data logger/software receiver onboard the NOAA Gulfstream-IV jet aircraft. Thereafter, the DDMs were used to retrieve surface wind speed employing several different metrics that characterize the DDM extent in the Doppler frequency-delay domain. In contrast to previous works in which winds have been retrieved by fitting the theoretically modeled curves into measured correlation waveforms, here we do not rely on any model for the determination. Instead, the approach is based on a linear regression between DDMs observables and the wind speeds obtained in simultaneous GPS dropsonde measurements. http://hdl.handle.net/2117/19216 Title: Laboratori docent d'ones de radiació i ones guiades Authors: Cardama Aznar, Ángel; Mallorquí Franquet, Jordi Joan; Romeu Robert, Jordi; Torres Torres, Francisco Tue, 14 May 2013 16:46:47 GMT http://hdl.handle.net/2117/19216 2013-05-14T16:46:47Z Cardama Aznar, Ángel; Mallorquí Franquet, Jordi Joan; Romeu Robert, Jordi; Torres Torres, Francisco no http://hdl.handle.net/2117/19164 Title: Field conjugation adaptive arrays for reliable satellite downlink coherent laser communications Authors: Belmonte Molina, Aniceto; Kahn, Joseph M. Abstract: We analyze the performance of adaptive field conjugation array receivers in satellite downlink coherent laser communications. We consider coherent fiber arrays consisting of multiple subapertures, with each subaperture interfaced to a single-mode fiber. We quantify how field conjugation processing improves performance in the presence of turbulence, as compared to a monolithic-aperture coherent receiver having an equal total cross-sectional area. In general, the performance of such a field conjugation adaptive should improve with an increasing number of subapertures and, given a fixed collecting area, the fiber array system can offer superior performance. Fri, 10 May 2013 13:58:38 GMT http://hdl.handle.net/2117/19164 2013-05-10T13:58:38Z Belmonte Molina, Aniceto; Kahn, Joseph M. no Free-space coherent optical communications, Channel-matched receivers, Satellite downlinks, Optical ground stations We analyze the performance of adaptive field conjugation array receivers in satellite downlink coherent laser communications. We consider coherent fiber arrays consisting of multiple subapertures, with each subaperture interfaced to a single-mode fiber. We quantify how field conjugation processing improves performance in the presence of turbulence, as compared to a monolithic-aperture coherent receiver having an equal total cross-sectional area. In general, the performance of such a field conjugation adaptive should improve with an increasing number of subapertures and, given a fixed collecting area, the fiber array system can offer superior performance. http://hdl.handle.net/2117/19157 Title: Snow monitoring using GNSS-R techniques Authors: Rodríguez Álvarez, Nereida; Aguasca Solé, Alberto; Valencia Domènech, Enric; Bosch Lluís, Xavier; Ramos Pérez, Isaac; Hyuk, Park; Camps Carmona, Adriano José; Vall-Llossera Ferran, Mercedes Magdalena Abstract: GNSS-R techniques are currently being studied to remotely sense a number of geophysical parameters over different types of surfaces [1-6]. The Interference Pattern Technique (IPT) is based on the measurement of the interference pattern of the GPS direct and reflected signals, after reflecting over the surface, as the GPS satellites move. This paper extends previous studies [7-11], in which water level was monitored [7] and land areas were observed retrieving soil moisture, topography and vegetation height for different kinds of crops (wheat, barley and maize) [8-10], to a snow- covered soils studies. Fri, 10 May 2013 11:59:51 GMT http://hdl.handle.net/2117/19157 2013-05-10T11:59:51Z Rodríguez Álvarez, Nereida; Aguasca Solé, Alberto; Valencia Domènech, Enric; Bosch Lluís, Xavier; Ramos Pérez, Isaac; Hyuk, Park; Camps Carmona, Adriano José; Vall-Llossera Ferran, Mercedes Magdalena no GNSS, Reflectometry, Snow, Thickness GNSS-R techniques are currently being studied to remotely sense a number of geophysical parameters over different types of surfaces [1-6]. The Interference Pattern Technique (IPT) is based on the measurement of the interference pattern of the GPS direct and reflected signals, after reflecting over the surface, as the GPS satellites move. This paper extends previous studies [7-11], in which water level was monitored [7] and land areas were observed retrieving soil moisture, topography and vegetation height for different kinds of crops (wheat, barley and maize) [8-10], to a snow- covered soils studies. http://hdl.handle.net/2117/19142 Title: PARIS interferometric technique proof of concept: sea surface altimetry measurements Authors: Rius, A.; Fabra Cervellera, Fran; Ribó, S.; Arco Fernandez, Juan Carlos; Oliveras, S.; Cardellach, Estel; Camps Carmona, Adriano José; Nogués Correig, O.; Kainulainen, J.; Rohue, E.; Martín Neira, Manuel Abstract: We report preliminary results of an aircraft experiment aimed to proof the PARIS Interferometric Technique. The experiment was performed in the Gulf of Finland during a two hours flight.We installed a PARIS Interferometric Receiver together with a GOLD-RTR instrument to collect reflected C/A, P(Y) and M-code GPS signals. The collected data has been analyzed to produce altimetric observables with both techniques. Wed, 08 May 2013 18:10:58 GMT http://hdl.handle.net/2117/19142 2013-05-08T18:10:58Z Rius, A.; Fabra Cervellera, Fran; Ribó, S.; Arco Fernandez, Juan Carlos; Oliveras, S.; Cardellach, Estel; Camps Carmona, Adriano José; Nogués Correig, O.; Kainulainen, J.; Rohue, E.; Martín Neira, Manuel no Aircraft, Antennas, Delay, Global Positioning System, Instruments, Receivers, Sea measurements We report preliminary results of an aircraft experiment aimed to proof the PARIS Interferometric Technique. The experiment was performed in the Gulf of Finland during a two hours flight.We installed a PARIS Interferometric Receiver together with a GOLD-RTR instrument to collect reflected C/A, P(Y) and M-code GPS signals. The collected data has been analyzed to produce altimetric observables with both techniques. http://hdl.handle.net/2117/19141 Title: Impact of the observation geometry on the GNSS-R direct descriptors used for sea state monitoring Authors: Valencia Domenech, Enric; Camps Carmona, Adriano José; Hyuk, Park; Rodriguez Alvarez, N.; Ramos Pérez, Isaac Abstract: In recent years GNSS-R has been proposed for ocean remote sensing, both for altimetry and scatterometry. For the later, two main approaches are available: fitting the measurements with a model, or using some observable from the measurements (either the waveform or the delay-Doppler Map) to be directly linked to ocean surface’s roughness. For groundbased and airborne experiments, several direct observables have been proposed to describe ocean surface’s roughness, and they have been used assuming that the observation geometry had little impact on them. However, it may not be true for a spaceborne scenario, since the dynamics are higher. In this work an extensive simulation study is performed, and the first results on how the observation geometry does impact different GNSS-R direct observables is presented. Wed, 08 May 2013 17:57:38 GMT http://hdl.handle.net/2117/19141 2013-05-08T17:57:38Z Valencia Domenech, Enric; Camps Carmona, Adriano José; Hyuk, Park; Rodriguez Alvarez, N.; Ramos Pérez, Isaac no Delay-Doppler Map (DDM), GNSS-R, ocean surface roughness, spaceborne In recent years GNSS-R has been proposed for ocean remote sensing, both for altimetry and scatterometry. For the later, two main approaches are available: fitting the measurements with a model, or using some observable from the measurements (either the waveform or the delay-Doppler Map) to be directly linked to ocean surface’s roughness. For groundbased and airborne experiments, several direct observables have been proposed to describe ocean surface’s roughness, and they have been used assuming that the observation geometry had little impact on them. However, it may not be true for a spaceborne scenario, since the dynamics are higher. In this work an extensive simulation study is performed, and the first results on how the observation geometry does impact different GNSS-R direct observables is presented. http://hdl.handle.net/2117/18993 Title: Validation and experimental tests of the PAU-synthetic aperture radiometer Authors: Ramos Pérez, Isaac; Forte Veliz, Giuseppe Francesco; Camps Carmona, Adriano José; Bosch Lluís, Xavier; Rodríguez Álvarez, Nereida; Valencia Domènech, Enric; Hyuk, Park; Vall-Llossera Ferran, Mercedes Magdalena Abstract: This paper presents calibration and the radiometric performance of the Passive Advanced Unit Synthetic Aperture (PAU-SA) in order to verify the instrument's characterization. Thu, 25 Apr 2013 17:19:22 GMT http://hdl.handle.net/2117/18993 2013-04-25T17:19:22Z Ramos Pérez, Isaac; Forte Veliz, Giuseppe Francesco; Camps Carmona, Adriano José; Bosch Lluís, Xavier; Rodríguez Álvarez, Nereida; Valencia Domènech, Enric; Hyuk, Park; Vall-Llossera Ferran, Mercedes Magdalena no interferometric radiometer, Microwave radiometry, synthetic aperture radiometry This paper presents calibration and the radiometric performance of the Passive Advanced Unit Synthetic Aperture (PAU-SA) in order to verify the instrument's characterization. http://hdl.handle.net/2117/18992 Title: PAU instrument aboard INTA MicroSAT-1: initial results of the FM model from an airborne experiment Authors: Alonso Arroyo, Alberto; Camps Carmona, Adriano José; Pascual Biosca, Daniel; Hyuk, Park; Alcayde Egea, Antonio; Chavero, Sergio; Martinez, Pedro; Crespo, Luis; Angulo, Manuel; Rius, Antonio Abstract: This work presents the PAU instrument aboard the satellite INTA MicroSAT-1. The PAU instrument is a combination of a Radiometer and a GNSS Reflectometer designed to study the relationship GNSS-R observables (Delay Doppler Maps) and the L-Band brightness temperature measurements to improve the Sea Surface Salinity (SSS) retrievals. This work describes an airborne experiment conducted to preliminary test the PAU instrument GNSS-R observables sensibility to sea state and to explore other applications of the instrument Thu, 25 Apr 2013 16:16:10 GMT http://hdl.handle.net/2117/18992 2013-04-25T16:16:10Z Alonso Arroyo, Alberto; Camps Carmona, Adriano José; Pascual Biosca, Daniel; Hyuk, Park; Alcayde Egea, Antonio; Chavero, Sergio; Martinez, Pedro; Crespo, Luis; Angulo, Manuel; Rius, Antonio no Delay-Doppler Map (DDM), Global Navigation Satellite System Reflectometry (GNSS-R), Microwave Radiometry, Sea Surface Salinity (SSS), Sea-state, Experiments, Ocean currents, Reflection, Reflectometers, Salinity measurement, Temperature measurement, Global positioning system This work presents the PAU instrument aboard the satellite INTA MicroSAT-1. The PAU instrument is a combination of a Radiometer and a GNSS Reflectometer designed to study the relationship GNSS-R observables (Delay Doppler Maps) and the L-Band brightness temperature measurements to improve the Sea Surface Salinity (SSS) retrievals. This work describes an airborne experiment conducted to preliminary test the PAU instrument GNSS-R observables sensibility to sea state and to explore other applications of the instrument http://hdl.handle.net/2117/18857 Title: A downscaling approach to combine SMOS multi-angular and full-polarimetric observations with MODIS VIS/IR data into high resolution soil moisture maps Authors: Piles Guillem, Maria; Vall-Llossera Ferran, Mercedes Magdalena; Laguna, Laia; Camps Carmona, Adriano José Abstract: A downscaling algorithmfor SMOS which combines MODIS Visible/Infrared data and SMOS horizontal brightness temperatures at 42.5◦ incidence angle into high-resolution soil moisture maps has been shown to nicely reproduce soil moisture dynamics at a 1 km spatial scale. The core of this algorithm is a linking model that depicts the synergy between SMOS and MODIS observations and their sensitivity to soil moisture. In this work, the impact of adding SMOS observations at horizontal and vertical polarizations and at multiple incidence angles to this linking model has been evaluated using 6 months of observations over the Murrumbidgee catchment, South-East Australia, and a robust alternative formulation is proposed. Results show that adding SMOS observations at multiple incidence angles and both polarizations the algorithm is more stable over time and its minimization error is reduced. By comparing with in situ data, a remarkable improvement of the linear regression between downscaled and in situ data is also observed (slope of 0.95). Wed, 17 Apr 2013 16:20:32 GMT http://hdl.handle.net/2117/18857 2013-04-17T16:20:32Z Piles Guillem, Maria; Vall-Llossera Ferran, Mercedes Magdalena; Laguna, Laia; Camps Carmona, Adriano José no MODIS, SMOS, Soil moisture, brightness temperatures, downscaling A downscaling algorithmfor SMOS which combines MODIS Visible/Infrared data and SMOS horizontal brightness temperatures at 42.5◦ incidence angle into high-resolution soil moisture maps has been shown to nicely reproduce soil moisture dynamics at a 1 km spatial scale. The core of this algorithm is a linking model that depicts the synergy between SMOS and MODIS observations and their sensitivity to soil moisture. In this work, the impact of adding SMOS observations at horizontal and vertical polarizations and at multiple incidence angles to this linking model has been evaluated using 6 months of observations over the Murrumbidgee catchment, South-East Australia, and a robust alternative formulation is proposed. Results show that adding SMOS observations at multiple incidence angles and both polarizations the algorithm is more stable over time and its minimization error is reduced. By comparing with in situ data, a remarkable improvement of the linear regression between downscaled and in situ data is also observed (slope of 0.95). http://hdl.handle.net/2117/18856 Title: Impact of doppler frequency compensation errors on spaceborne GNSS-R altimetry Authors: Hyuk, Park; Camps Carmona, Adriano José; Valencia Domenech, Enric Abstract: The compensation of the Doppler frequency error is important to accurately estimate the sea height in spaceborne GNSSR altimetry. This work presents the impact of the residual Doppler error on the altimetric performance. The GNSS-R altimetric observables (waveforms) are simulated with various observation parameters, and the degradation is analyzed vs. the Doppler errors. It is shown that the Doppler error causes a bias, a decrease of the waveform value, and consequently the altimetric performance degradation in accuracy and precision. Wed, 17 Apr 2013 16:12:59 GMT http://hdl.handle.net/2117/18856 2013-04-17T16:12:59Z Hyuk, Park; Camps Carmona, Adriano José; Valencia Domenech, Enric no Doppler compensation error, GNSS reflectometry, altimetry, altimetry waveform The compensation of the Doppler frequency error is important to accurately estimate the sea height in spaceborne GNSSR altimetry. This work presents the impact of the residual Doppler error on the altimetric performance. The GNSS-R altimetric observables (waveforms) are simulated with various observation parameters, and the degradation is analyzed vs. the Doppler errors. It is shown that the Doppler error causes a bias, a decrease of the waveform value, and consequently the altimetric performance degradation in accuracy and precision. http://hdl.handle.net/2117/18793 Title: Cross-correlation waveform mode: a critical review Authors: Martín Alemany, Francisco; Hyuk, Park; Camps Carmona, Adriano José; D'addio, Salvatore; Martín Neira, Manuel Abstract: Earth-reflected Global Navigation Satellite System (GNSS) signals have become an attractive tool for remote sensing. Recently it has been proposed as an alternative to the conventional altimetry to estimate the surface height However GNSS-R altimetry offers lower bandwidths and signals power compared to radar altimeters. This implies a poorer altimetry precision, accuracy and resolution per pulse.Also the altimetry precision will be impacted by the impact of the thermal, and speckle noise mainly. This paper gives a critical review of the cross-correlation waveform model. Mon, 15 Apr 2013 13:30:51 GMT http://hdl.handle.net/2117/18793 2013-04-15T13:30:51Z Martín Alemany, Francisco; Hyuk, Park; Camps Carmona, Adriano José; D'addio, Salvatore; Martín Neira, Manuel no GNSS-R, altimetry, thermal noise, speckle noise, Woodward Ambiguity, function Earth-reflected Global Navigation Satellite System (GNSS) signals have become an attractive tool for remote sensing. Recently it has been proposed as an alternative to the conventional altimetry to estimate the surface height However GNSS-R altimetry offers lower bandwidths and signals power compared to radar altimeters. This implies a poorer altimetry precision, accuracy and resolution per pulse.Also the altimetry precision will be impacted by the impact of the thermal, and speckle noise mainly. This paper gives a critical review of the cross-correlation waveform model. http://hdl.handle.net/2117/18761 Title: PAU instrument aboard INTA MicroSat-1: flight model tests Authors: Alonso González, Alberto; Camps Carmona, Adriano José; Pascual Biosca, Daniel; Hyuk, Park; Alcayde Egea, Antonio; Chavero, Sergio; Martinez, Pedro; Crespo, Luis; Angulo, Manuel; Rius, Antonio Abstract: This work presents the PAU instrument aboard the satellite INTA MicroSAT-1. The PAU instrument is a combination of a Radiometer and a GNSS Reflectometer designed to study the relationship GNSS-R observables (Delay Doppler Maps) and the L-Band brightness temperature measurements to improve the Sea Surface Salinity (SSS) retrievals. This work describes an airborne experiment conducted to preliminary test the PAU instrument GNSS-R observables sensibility to sea state and to explore other applications of the instrument. Wed, 10 Apr 2013 16:04:42 GMT http://hdl.handle.net/2117/18761 2013-04-10T16:04:42Z Alonso González, Alberto; Camps Carmona, Adriano José; Pascual Biosca, Daniel; Hyuk, Park; Alcayde Egea, Antonio; Chavero, Sergio; Martinez, Pedro; Crespo, Luis; Angulo, Manuel; Rius, Antonio no Delay-Doppler Map (DDM), Global Navigation Satellite System Reflectometry (GNSS-R), Microwave Radiometry, Sea Surface Salinity (SSS), Sea-state, Geology, Microwave devices, Ocean currents, Reflectometers, Remote sensing, Salinity measurement This work presents the PAU instrument aboard the satellite INTA MicroSAT-1. The PAU instrument is a combination of a Radiometer and a GNSS Reflectometer designed to study the relationship GNSS-R observables (Delay Doppler Maps) and the L-Band brightness temperature measurements to improve the Sea Surface Salinity (SSS) retrievals. This work describes an airborne experiment conducted to preliminary test the PAU instrument GNSS-R observables sensibility to sea state and to explore other applications of the instrument. http://hdl.handle.net/2117/18760 Title: Submeter ocean altimetry with GPS L1 C/A signal Authors: Carreño Luengo, Hugo; Hyuk, Park; Camps Carmona, Adriano José; Fabra Cervellera, Fran; Rius, Antonio Abstract: The ultimate accuracy and precision of conventional1 and interferometric2 Global Positioning Satellite System Rerflectometry (GNSS-R) techniques for mesoscale ocean altimetry are still a matter of debate in the scientific community. The results obtained depend on the techniques used to identify the point of the specular delay in the waveform, and to perform the different delay corrections to derive the geometric delay. Also, the geometric model assumed for the scenario determines the accuracy of the altimeter range. This work presents the results of two ESA-sponsored airborne experiments using conventional GNSS-R showing subdecimeter altimetric precision with the Global Positioning System (GPS) L1 C/A code only. The Relative Mean Dynamic Topography (RMDT) obtained in both experiments is compared with results derived from traditional radar altimetry provided by Jason 2. The Root Mean Square (RMS) of the RMDT difference between both measurement systems is 48 cm for the first flight, and 198 cm for the second flight. Additionally, results from the second flight experiment show the capability of the proposed technique to retrieve sea slope measurements by superposing the ground track with EM96 geoid undulations. Wed, 10 Apr 2013 15:59:40 GMT http://hdl.handle.net/2117/18760 2013-04-10T15:59:40Z Carreño Luengo, Hugo; Hyuk, Park; Camps Carmona, Adriano José; Fabra Cervellera, Fran; Rius, Antonio no altimetry, GNSS-R, Jason 2, precision, sea slope, Geology, Global positioning system, Radio altimeters, Remote sensing, Salinity measurement, Space flight The ultimate accuracy and precision of conventional1 and interferometric2 Global Positioning Satellite System Rerflectometry (GNSS-R) techniques for mesoscale ocean altimetry are still a matter of debate in the scientific community. The results obtained depend on the techniques used to identify the point of the specular delay in the waveform, and to perform the different delay corrections to derive the geometric delay. Also, the geometric model assumed for the scenario determines the accuracy of the altimeter range. This work presents the results of two ESA-sponsored airborne experiments using conventional GNSS-R showing subdecimeter altimetric precision with the Global Positioning System (GPS) L1 C/A code only. The Relative Mean Dynamic Topography (RMDT) obtained in both experiments is compared with results derived from traditional radar altimetry provided by Jason 2. The Root Mean Square (RMS) of the RMDT difference between both measurement systems is 48 cm for the first flight, and 198 cm for the second flight. Additionally, results from the second flight experiment show the capability of the proposed technique to retrieve sea slope measurements by superposing the ground track with EM96 geoid undulations.