Abstract Volcanic and earthquake research, glaciology and ice sheet monitoring as well as monitoring land subsidence due to mining and gas, oil and water withdrawal are processes of great importance on a global level due to the fact that the result of those processes can act extremely destructive on land. It was demonstrated by the early missions that Synthetic Aperture Radar (SAR) is able to reliably map the Earth’s surface and acquire information about physical properties of the backscattering layer. The use of spaceborne SARs interferometers (InSAR) represents a unique method for detection and mapping of surface displacement over large temporal and special scales. Since the atmosphere, particularly due to the high water vapor spatial and temporal variability, introduces an unknown delay in the signal propagation, the tropospheric contribution to the SAR interferogram, the so called Atmospheric Phase Screen is examined in this work. More precisely, this tropospheric contribution is obtained from two different processing techniques, FreeSAR and PSBAS (Parallel Small Baseline Subset). Therefore, the goal of this work is comparison of two techniques in obtaining and representing the difference in delay of the wave propagation through the atmosphere (APS). To reach our goals, firstly, the region of interest (Northern Italy) is determined in order to obtain the data available on Sentinel Data Hub. Raw data are processed at the same time by author in FreeSAR processing software founded by Aresys (Advanced Remote Sensing Systems), while the raw data of the same area on the other hand were processed by Consiglio Nazionale delle Richerche, Napoli (CNR), in commercial SBAS software. Once the APS acquisition from both techniques was completed data were further processed in Matlab. The results are compared in the final step of the project where also the accuracy and reliability of solutions are discussed. Both techniques proved that are capable for generation of APS which are suitable for further investigations depending on the purpose and accuracy that is relevant for research.
Sommario La ricerca vulcanica e sismica, la glaciologia e il monitoraggio delle calotte polari oltre al monitoraggio della subsidenza terrestre a causa dell'estrazione mineraria e del ritiro di gas, petrolio e acqua sono processi di grande importanza a livello globale in quanto il risultato di tali processi può essere estremamente distruttivo sbarcare. È stato dimostrato dalle prime missioni che Synthetic Aperture Radar (SAR) è in grado di mappare in modo affidabile la superficie terrestre e acquisire informazioni sulle proprietà fisiche dello strato di backscattering. L'uso di interferometri SAR spaziali (InSAR) rappresenta un metodo unico per il rilevamento e la mappatura dello spostamento di superficie su grandi scale temporali e speciali. Poiché l'atmosfera, in particolare a causa dell'elevata variabilità spaziale e temporale del vapore d'acqua, introduce un ritardo sconosciuto nella propagazione del segnale, il contributo troposferico all'interferogramma SAR, in questo lavoro viene esaminato il cosiddetto schermo della fase atmosferica. Più precisamente, questo contributo troposferico è ottenuto da due diverse tecniche di elaborazione, FreeSAR e PSBAS (Parallel Small Baseline Subset). Pertanto, l'obiettivo di questo lavoro è il confronto di due tecniche per ottenere e rappresentare la differenza nel ritardo della propagazione dell'onda attraverso l'atmosfera (APS). Per raggiungere i nostri obiettivi, in primo luogo, viene determinata la regione di interesse (Nord Italia) al fine di ottenere i dati disponibili su Sentinel Data Hub. I dati grezzi sono elaborati contemporaneamente dall'autore nel software di elaborazione FreeSAR fondato da Aresys (Advanced Remote Sensing Systems), mentre i dati grezzi della stessa area sono stati elaborati dal Consiglio Nazionale delle Richerche di Napoli (CNR), in software SBAS commerciale. Una volta completata l'acquisizione di APS da entrambe le tecniche, i dati sono stati ulteriormente elaborati in Matlab. I risultati vengono confrontati nella fase finale del progetto in cui vengono discusse anche l'accuratezza e l'affidabilità delle soluzioni. Entrambe le tecniche hanno dimostrato che sono in grado di generare APS che sono adatte per ulteriori indagini a seconda dello scopo e della precisione rilevanti per la ricerca.
Water vapor from synthetic aperture radar : preliminary comparison between FreeSAR and PSBAS atmospheric phase screens
DANICIC, JELENA
2016/2017
Abstract
Abstract Volcanic and earthquake research, glaciology and ice sheet monitoring as well as monitoring land subsidence due to mining and gas, oil and water withdrawal are processes of great importance on a global level due to the fact that the result of those processes can act extremely destructive on land. It was demonstrated by the early missions that Synthetic Aperture Radar (SAR) is able to reliably map the Earth’s surface and acquire information about physical properties of the backscattering layer. The use of spaceborne SARs interferometers (InSAR) represents a unique method for detection and mapping of surface displacement over large temporal and special scales. Since the atmosphere, particularly due to the high water vapor spatial and temporal variability, introduces an unknown delay in the signal propagation, the tropospheric contribution to the SAR interferogram, the so called Atmospheric Phase Screen is examined in this work. More precisely, this tropospheric contribution is obtained from two different processing techniques, FreeSAR and PSBAS (Parallel Small Baseline Subset). Therefore, the goal of this work is comparison of two techniques in obtaining and representing the difference in delay of the wave propagation through the atmosphere (APS). To reach our goals, firstly, the region of interest (Northern Italy) is determined in order to obtain the data available on Sentinel Data Hub. Raw data are processed at the same time by author in FreeSAR processing software founded by Aresys (Advanced Remote Sensing Systems), while the raw data of the same area on the other hand were processed by Consiglio Nazionale delle Richerche, Napoli (CNR), in commercial SBAS software. Once the APS acquisition from both techniques was completed data were further processed in Matlab. The results are compared in the final step of the project where also the accuracy and reliability of solutions are discussed. Both techniques proved that are capable for generation of APS which are suitable for further investigations depending on the purpose and accuracy that is relevant for research.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/138906