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14 results on '"Parcharidis, Isaak"'

1. Hephaestus: A large scale multitask dataset towards InSAR understanding

Author

Bountos, Nikolaos Ioannis, Papoutsis, Ioannis, Michail, Dimitrios, Karavias, Andreas, Elias, Panagiotis, and Parcharidis, Isaak

Subjects
Computer Science - Computer Vision and Pattern Recognition, Astrophysics - Instrumentation and Methods for Astrophysics, Computer Science - Machine Learning
Abstract

Synthetic Aperture Radar (SAR) data and Interferometric SAR (InSAR) products in particular, are one of the largest sources of Earth Observation data. InSAR provides unique information on diverse geophysical processes and geology, and on the geotechnical properties of man-made structures. However, there are only a limited number of applications that exploit the abundance of InSAR data and deep learning methods to extract such knowledge. The main barrier has been the lack of a large curated and annotated InSAR dataset, which would be costly to create and would require an interdisciplinary team of experts experienced on InSAR data interpretation. In this work, we put the effort to create and make available the first of its kind, manually annotated dataset that consists of 19,919 individual Sentinel-1 interferograms acquired over 44 different volcanoes globally, which are split into 216,106 InSAR patches. The annotated dataset is designed to address different computer vision problems, including volcano state classification, semantic segmentation of ground deformation, detection and classification of atmospheric signals in InSAR imagery, interferogram captioning, text to InSAR generation, and InSAR image quality assessment., Comment: This work has been accepted for publication in EARTHVISION 2022, in conjuction with the Computer Vision and Pattern Recognition (CVPR) 2022 Conference

Published
2022

10. Sudden changes in nitrogen dioxide emissions over Greece due to lockdown after the outbreak of COVID-19.

Author

Koukouli, Maria-Elissavet, Skoulidou, Ioanna, Karavias, Andreas, Parcharidis, Isaak, Balis, Dimitris, Manders, Astrid, Segers, Arjo, Eskes, Henk, and van Geffen, Jos

Abstract

The unprecedented order, in modern peaceful times, for near-total lockdown of the Greek population, as means of protection against the Severe Acute Respiratory Syndrome CoronaVirus-2, commonly known as COVID-19, infection, has brought unintentional positive side-effects to the country's air quality levels. S5P/TROPOMI monthly mean tropospheric nitrogen dioxide (NO2) observations show an average decrease of -3 % to -26 % [-1 % to -27 %] with an average of -22 % [-11 %] for March and April 2020 respectively, compared to the previous year, over the six larger Greek metropolitan areas, attributable mostly to vehicular emission reductions. Furthermore, significant effects for shipping emissions over the Aegean Sea as well as the areas surrounding major Greek ports were observed, of approximately -12 % [-5 %]. For the capital city of Athens, weekly analysis was possible and it revealed a marked decline in NO2 load between -8 % and -43 % for seven of the eight weeks studied. Chemical transport modelling, provided by the LOTOS-EUROS CTM, shows that the magnitude of these reductions cannot solely be attributed to the difference in meteorological factors affecting NO2 levels during March and April 2020 and the equivalent time periods of the previous year. Taking this factor into account, the resulting decline was estimated to range between 0 % and -37 % for the five largest cities, with an average of ~ -10 %. As transport is the second largest sector that affects Greece's air quality, this occasion may well help policy makers in enforcing more targeted measures to aid Greece in further reducing emissions according to international air quality standards. [ABSTRACT FROM AUTHOR]

Published
2020
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13. Coseismic displacements from moderate-size earthquakes mapped by Sentinel-1 differential interferometry: The case of February 2017 Gulpinar Earthquake Sequence (Biga Peninsula, Turkey)

Author

Ganas, Athanassios, Kourkouli, Penelope, Briole, Pierre, Moshou, Alexandra, Elias, Panagiotis, and Parcharidis, Isaak

Subjects
InSAR, stress, 13. Climate action, earthquake, deformation, Aegean, sentinel, Biga peninsula, relocation
Abstract

We study the tectonic deformation from the February 2017 shallow earthquake sequence onshore Biga Peninsula (NW Turkey, NE Aegean region). We use InSAR interferograms (Sentinel-1 satellites) to identify the seismic fault (striking N110°E) and seismological data (parametric data and Moment Tensor solutions from NOA and KOERI catalogues) so as to refine its geometry and kinematics using inversion techniques. Despite the moderate magnitudes of the main events of the sequence (5.0 ≤ Mw ≤ 5.2), the total surface deformation is 2.2 fringes (or maximum 6.2 cm along LOS) and it is well visible with InSAR because of the shallow depth of the four main events (6–8 km) and the good coherence of the signal phase. Our geodetic inversion showed that the fault has normal-slip kinematics, dimensions of 6 by 6 km (length, width) and dips at 45°. The InSAR data are fitted by a uniform slip of 28 cm. In addition, 429 earthquakes were relocated with the HypoDD software and the use of a 1-D velocity model. The dip-direction of the fault is not retrievable from InSAR, but a south-dipping plane is clear from seismology and the aftershocks distribution. The spatial distribution of relocated events indicates the activation of one fault with a rupture zone length of about 10 km, a result of the occurrence of off-fault aftershocks along strike the main rupture. A stress inversion using 20 focal mechanisms (M ≥ 3.6; NOA solutions) indicates that faulting accommodates a N196°E extension. It is confirmed that moderate (5.0 ≤ M ≤ 5.2) shallow events can be traced in InSAR studies and can produce surface displacements that provide useful data in fault inversion., Remote Sensing, 10 (7), ISSN:2072-4292

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