Monitoring spring phenology in Mediterranean beech populations through in situ observation and Synthetic Aperture Radar methods

2020 ◽  
Vol 248 ◽  
pp. 111978
Author(s):  
Roberta Proietti ◽  
Serena Antonucci ◽  
Maria Cristina Monteverdi ◽  
Vittorio Garfì ◽  
Marco Marchetti ◽  
...  
Keyword(s):  
Synthetic Aperture Radar ◽  
Synthetic Aperture ◽  
In Situ Observation ◽  
Spring Phenology ◽  
Aperture Radar

scholarly journals Assessment of DUACS Sentinel-3A Altimetry Data in the Coastal Band of the European Seas: Comparison with Tide Gauge Measurements

2020 ◽  
Vol 12 (23) ◽  
pp. 3970
Author(s):  
Antonio Sánchez-Román ◽  
Ananda Pascual ◽  
Marie-Isabelle Pujol ◽  
Guillaume Taburet ◽  
Marta Marcos ◽  
...  
Keyword(s):  
Synthetic Aperture Radar ◽  
Tide Gauge ◽  
Synthetic Aperture ◽  
Altimetry Data ◽  
Radar Altimeter ◽  
Long Wave ◽  
Tide Gauge Measurements ◽  
European Seas ◽  
Aperture Radar

The quality of the Data Unification and Altimeter Combination System (DUACS) Sentinel-3A altimeter data in the coastal area of the European seas is investigated through a comparison with in situ tide gauge measurements. The comparison was also conducted using altimetry data from Jason-3 for inter-comparison purposes. We found that Sentinel-3A improved the root mean square differences (RMSD) by 13% with respect to the Jason-3 mission. In addition, the variance in the differences between the two datasets was reduced by 25%. To explain the improved capture of Sea Level Anomaly by Sentinel-3A in the coastal band, the impact of the measurement noise on the synthetic aperture radar altimeter, the distance to the coast, and Long Wave Error correction applied on altimetry data were checked. The results confirmed that the synthetic aperture radar altimeter instrument onboard the Sentinel-3A mission better solves the signal in the coastal band. Moreover, the Long Wave Error processing contributes to reduce the errors in altimetry, enhancing the consistency between the altimeter and in situ datasets.

scholarly journals DESCRIPCIÓN DEL PROYECTO DE TESIS DOCTORAL: APLICACIÓN DE LA TECNOLOGIA DINSAR A LA PREVENCION DE LOS RIESGOS GEOLOGICOS NATURALES E INDUCIDOS EN CIUDADES E INFRAESTRUCTURAS PRIORITARIAS DE CENTROAMÉRICA

2021 ◽  
Author(s):  
Carlos García-Lanchares ◽  
Miguel Marchamalo ◽  
Candela Sancho
Keyword(s):  
Costa Rica ◽  
Synthetic Aperture Radar ◽  
El Salvador ◽  
Synthetic Aperture ◽  
Earth Surface ◽  
Differential Interferometry ◽  
Surface Monitoring ◽  
Aperture Radar

Este documento presenta la formulación y primeros pasos de un proyecto de Doctorado Industrial, desarrollado en elmarco del proyecto Kuk ahpán que tiene como objetivo comprender, monitorear y modelar procesos tectónicos a escalalitosférica en Centroamérica. Para ello, un equipo internacional de seis países (Nicaragua, Costa Rica, El Salvador,Guatemala, Noruega y España) trabaja integrando la investigación en diversas técnicas e ingenierías Geofísicas, con elobjetivo de actualizar los Mapas de Riesgo Sísmico de la Región, un insumo crítico. para los códigos de seguridad yconstrucción. El proyecto de doctorado propuesto se enmarca en la investigación y desarrollo de tecnologías para prevenirlos riesgos geológicos naturales e inducidos que afectan a ciudades e infraestructuras en países altamente vulnerables,utilizando la tecnología DInSAR (Differential Interferometry with Synthetic Aperture Radar) optimizada por la startupDetektia Earth Surface Monitoring en colaboración con la Universidad Politécnica de Madrid. La interferometría diferencialde radar de apertura sintética es una técnica basada en el procesamiento y análisis de series largas de imágenes de radarde apertura sintética. Esta tecnología proporciona registros (desde 1992) y movimientos actualizados en cualquiersuperficie en cualquier parte del mundo sin necesidad de instrumentación terrestre, con precisiones de alrededor de 1 mm/ año (velocidad). En este contexto, el radar satelital proporciona información valiosa sobre áreas muy grandes quecomplementan el trabajo de campo y la instrumentación in situ. Primero, comenzamos integrando datos DInSAR condiversos datos geofísicos como batimetría, geomagnetismo, gravimetría, perfiles sísmicos… para mapear completamentela falla Swan sobre Honduras y Guatemala. Usamos esta tecnología para abordar el riesgo sísmico sobre la falla y áreascercanas. En un segundo paso, aplicaremos esta evaluación de riesgo sísmico (incluyendo amenazas naturales yantropogénicas) en ciudades e infraestructuras críticas en Centroamérica.

scholarly journals Evaluation of the Performances of Radar and Lidar Altimetry Missions for Water Level Retrievals in Mountainous Environment: The Case of the Swiss Lakes

2021 ◽  
Vol 13 (11) ◽  
pp. 2196
Author(s):  
Frédéric Frappart ◽  
Fabien Blarel ◽  
Ibrahim Fayad ◽  
Muriel Bergé-Nguyen ◽  
Jean-François Crétaux ◽  
...  
Keyword(s):  
Synthetic Aperture Radar ◽  
Water Level ◽  
Open Loop ◽  
Water Levels ◽  
Synthetic Aperture ◽  
Low Resolution ◽  
Radar Altimetry ◽  
Constant Bias ◽  
Aperture Radar

Radar altimetry is now commonly used to provide long-term monitoring of inland water levels in complement to or for replacing disappearing in situ networks of gauge stations. Recent improvements in tracking and acquisition modes improved the quality the water retrievals. The newly implemented Open Loop mode is likely to increase the number of monitored water bodies owing to the use of an a priori elevation, especially in hilly and mountainous areas. The novelty of this study is to provide a comprehensive evaluation of the performances of the past and current radar altimetry missions according to their acquisition (Low Resolution Mode or Synthetic Aperture Radar) and tracking (close or open loop) modes, and acquisition frequency (Ku or Ka) in a mountainous area where tracking losses of the signal are likely to occur, as well as of the recently launched ICESat-2 and GEDI lidar missions. To do so, we evaluate the quality of water level retrievals from most radar altimetry missions launched after 1995 over eight lakes in Switzerland, using the recently developed ALtimetry Time Series software, to compare the performances of the new tracking and acquisition modes and also the impact of the frequency used. The combination of the Open Loop tracking mode with the Synthetic Aperture Radar acquisition mode on SENTINEL-3A and B missions outperforms the classical Low Resolution Mode of the other missions with a lake observability greater than 95%, an almost constant bias of (−0.17 ± 0.04) m, a RMSE generally lower than 0.07 m and a R most of the times higher than 0.85 when compared to in situ gauge records. To increase the number of lakes that can be monitored and the temporal sampling of the water level retrievals, data acquired by lidar altimetry missions were also considered. Very accurate results were also obtained with ICESat-2 data with RMSE lower than 0.06 and R higher than 0.95 when compared to in situ water levels. An almost constant bias (0.42 ± 0.03) m was also observed. More contrasted results were obtained using GEDI. As these data were available on a shorter time period, more analyses are necessary to determine their potential for retrieving water levels.

Der Multi-Purpose Airborne Sensor Carrier MASC-V

2021 ◽  
Author(s):  
Ines Weber ◽  
Andreas Platis ◽  
Kjell zum Berge ◽  
Martin Schön ◽  
Jakob Boventer ◽  
...  
Keyword(s):  
Synthetic Aperture Radar ◽  
Synthetic Aperture ◽  
Aperture Radar

<p>Das unbemannte Luftfahrtsystem (UAS) "Meteorological Airborne Sensor Carrier (MASC)" wird an der Universität Tübingen entwickelt und für meteorologische in-situ Messungen turbulenter Größen (Wind, Temperatur, Feuchte) und von Aerosolpartikeln in der unteren Atmosphäre genutzt. Die neueste UAS-Generation, MASC-V, wurde im September 2021 erstmals für Offshore Windmessungen außerhalb der Sichtweite eines Fernpiloten eingesetzt. MASC-V wurde in Zusammenarbeit mit der Firma ElevonX d.o.o. entwickelt und trägt das gleiche meteorologische Messsystem, wie das bewährte UAS MASC-3. Im Gegensatz zu MASC-3 ist MASC-V ein VTOL-UAS, es kann vollautomatisch senkrecht starten und landen und im Flächenflug weite Strecken von mehr als 100 Km zurücklegen. Dazu kommt ein Sicherheitskonzept mit zusätzlichen Redundanzen, insbesondere bei den Telemetriesystemen. Das neue Betriebskonzept schafft die Grundlagen die Betriebserlaubnis außerhalb der Sichtweite des Fernpiloten in der gesamten europäischen Union.<br />Nach der Systemvalidierung mithilfe eines meteorologischen Messturms am Observatorium Lindenberg des Deutschen Wetterdienstes wurde MASC-V für die Validierung von Windmessungen aus Satellite Synthetic-Aperture Radar Daten vom 13. bis 24. September 2021 über der Nordsee von der Hochseeinsel Helgoland am Testzentrum für maritime Technologien in Zusammenarbeit mit dem Fraunhofer Institut für Fertigungstechnik und angewandte Materialforschung eingesetzt. Synthetic-Aperture Radar Satellitendaten der Sentinel 1 - Formation können detaillierte Informationen über das Oberflächenwindfeld liefern. Die flächendeckende Validierung dieser Ergebnisse mit konventionellen Messmethoden ist schwierig, da in den geforderten niedrigen Höhen (unter 30 m) nur stationäre Messungen (Messtürme, Bojen) möglich sind, oder räumliche Messungen mit bemannten Messflugzeugen nur in größeren Höhen durchgeführt werden können. MASC-V kann dieses Anforderungsprofil erfüllen, da es große Messgebiete im Tiefflug in kurzer Zeit abdecken kann und keine Start- und Landebahn benötigt. Die neuen UAS-Messungen von Helgoland liefern nicht nur die erste flächendeckende Validierung einer SAR-Windmessung. Sie zeigen auch das Potenzial von UAS, die in einem Gelände ohne Start-und Landeinfrastruktur, außerhalb der Sichtweite betrieben werden können, für meteorologische Messungen auf Skalen von mehreren 10 Km oder für vertikale Sondierungen der Atmosphäre von bis einigen Kilometern über Grund.</p>

scholarly journals Perspectives on the Structural Health Monitoring of Bridges by Synthetic Aperture Radar

2020 ◽  
Vol 12 (23) ◽  
pp. 3852
Author(s):  
Filippo Biondi ◽  
Pia Addabbo ◽  
Silvia Liberata Ullo ◽  
Carmine Clemente ◽  
Danilo Orlando
Keyword(s):  
Synthetic Aperture Radar ◽  
Early Warning ◽  
Low Cost ◽  
Synthetic Aperture ◽  
Mode Shapes ◽  
Distributed Monitoring ◽  
Complete Procedure ◽  
Infrastructure Health ◽  
Aperture Radar

Large infrastructures need continuous maintenance because of materials degradation due to atmospheric agents and their persistent use. This problem makes it imperative to carry out persistent monitoring of infrastructure health conditions in order to guarantee maximum safety at all times. The main issue of early warning infrastructure fault detection is that expensive in-situ distributed monitoring sensor networks have to be installed. On the contrary, the use of satellite data has made it possible to use immediate and low-cost techniques in recent years. In this regard, the potential of spaceborne Synthetic Aperture Radar for the monitoring of critical infrastructures is demonstrated in geographically extended areas, even in the presence of clouds, and in really tough weather. A complete procedure for damage early-warning detection is designed, by using micro-motion (m-m) estimation of critical sites, based on modal proprieties analysis. Particularly, m-m is processed to extract modal features such as natural frequencies and mode shapes generated by vibrations of large infrastructures. Several study cases are here considered and the “Morandi” Bridge (Polcevera Viaduct) in Genoa (Italy) is analyzed in depth highlighting abnormal vibration modes during the period before the bridge collapsed.

scholarly journals Mapping Water Surface Elevation and Slope in the Mississippi River Delta Using the AirSWOT Ka-Band Interferometric Synthetic Aperture Radar

2019 ◽  
Vol 11 (23) ◽  
pp. 2739 ◽  
Author(s):  
Michael Denbina ◽  
Marc Simard ◽  
Ernesto Rodriguez ◽  
Xiaoqing Wu ◽  
Albert Chen ◽  
...  
Keyword(s):  
Synthetic Aperture Radar ◽  
Mississippi River ◽  
Water Surface ◽  
Surface Elevation ◽  
Synthetic Aperture ◽  
Ka Band ◽  
Water Surface Elevation ◽  
Phase Calibration ◽  
Aperture Radar

AirSWOT is an airborne Ka-band synthetic aperture radar, capable of mapping water surface elevation (WSE) and water surface slope (WSS) using single-pass interferometry. AirSWOT was designed as a calibration and validation instrument for the forthcoming Surface Water and Ocean Topography (SWOT) mission, an international spaceborne synthetic aperture radar mission planned for launch in 2022 which will enable global mapping of WSE and WSS. As an airborne instrument, capable of quickly repeating overflights, AirSWOT enables measurement of high frequency and fine scale hydrological processes encountered in coastal regions. In this paper, we use data collected by AirSWOT in the Mississippi River Delta and surrounding wetlands of coastal Louisiana, USA, to investigate the capabilities of Ka-band interferometry for mapping WSE and WSS in coastal marsh environments. We introduce a data-driven method to estimate the time-varying interferometric phase drift resulting from radar hardware response to environmental conditions. A system of linear equations based on AirSWOT measurements is solved for elevation bias and time-varying phase calibration parameters using weighted least squares. We observed AirSWOT WSE uncertainty of 12 cm RMS compared to in situ water level measurements when averaged over an area of 0.5 km 2 at incidence angles below 15 ∘ . At higher incidence angles, the observed AirSWOT elevation bias is possibly due to residual phase calibration errors or radar backscatter from vegetation. Elevation profiles along the Wax Lake Outlet river channel indicate AirSWOT can measure WSS over a 24 km distance with uncertainty below 0.3 cm/km, 8% of the true water surface slope as measured by in situ data. The data analysis and results presented in this paper demonstrate the potential of AirSWOT to measure water surface elevation and slope within highly dynamic and spatially complex coastal environments.

scholarly journals Validation of Sentinel-1 offshore winds and average wind power estimation around Ireland

2020 ◽  
Vol 5 (3) ◽  
pp. 1023-1036 ◽  
Author(s):  
Louis de Montera ◽  
Tiny Remmers ◽  
Ross O'Connell ◽  
Cian Desmond
Keyword(s):  
Wind Speed ◽  
Synthetic Aperture Radar ◽  
Wind Power ◽  
Surface Wind ◽  
Synthetic Aperture ◽  
Synthetic Aperture Radar Data ◽  
Average Wind ◽  
Level 2 ◽  
Aperture Radar

Abstract. In this paper, surface wind speed and average wind power derived from Sentinel-1 Synthetic Aperture Radar Level 2 Ocean (OCN) product were validated against four weather buoys and three coastal weather stations around Ireland. A total of 1544 match-up points was obtained over a 2-year period running from May 2017 to May 2019. The match-up comparison showed that the satellite data underestimated the wind speed compared to in situ devices, with an average bias of 0.4 m s−1, which decreased linearly as a function of average wind speed. Long-term statistics using all the available data, while assuming a Weibull law for the wind speed, were also produced and resulted in a significant reduction of the bias. Additionally, the average wind power was found to be consistent with in situ data, resulting in an error of 10 % and 5 % for weather buoys and coastal stations, respectively. These results show that the Sentinel-1 Level 2 OCN product can be used to estimate the wind resource distribution, even in coastal areas. Maps of the average and seasonal wind speed and wind power illustrated that the error was spatially dependent, which should be taken into consideration when working with Sentinel-1 Synthetic Aperture Radar data.

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