In this study, we investigated the ability of deriving cyclic/annual motion information from Persistent Scatterers Interferometric (PSI) Time Series. One of the potential applications of such information is to characterize and map motion related to clay Swelling/Shrinking phenomena. Such an application could become particularly interesting with the development of nation/continent wide service based on PSI (such as EGMS from Copernicus). We identified biases affecting the PSI data limiting the approach that must be investigated in further works.

The Earth Observation is proven to be extremely useful in the management of the aftermaths of tsunami and earthquakes. ESA-Disaster Risk Reduction (DRR) is a project within the Earth Observation for Sustainable Development (EO4SD) program aiming to demonstrate on large scale in developing countries the usefulness of Earth Observation to reduce disaster risks and to support the management of the post-event rehabilitation and reconstructions. Among the activities of the project, the ESA-DRR team, following the dramatic event of the Sulawesi earthquake (28 September 2018) supported the Indonesian authorities, through the cooperation with the Asian Development Bank (ADB), the reconstruction and rehabilitation of Palu area. The provided EO services are presented.

We are communicating recent integration of the SNAPPING surface motion mapping service for Sentinel-1 mission on the GEP platform in support to the scientific community as well as EO practitioners. The service is built on ESA SNAP and StaMPS packages that have already demonstrated numerous successful investigations of geohazard phenomena. SNAPPING is well-tailored in terms of EO data manipulation and parallelization on cloud resources, enabling users to respond to the ever increasing volume of satellite data and high computational requirements. The service generates average motion rate maps and full displacement time series at reduced spatial resolution, making it suitable not only for various research application domains, but also when rapid and low cost inspection of an area is of interest.

An effort is made herein to demonstrate advanced terrain motion products obtained via operational SAR interferometric services running on the Geohazards Exploitation Platform to support the World Bank's City Resilience Program. The objective is to highlight the validity of medium resolution terrain motion products for the provision of systematic terrain motion analysis to operational teams, allowing for the prompt identification of potential hazardous phenomena over wide areas. The challenge is to inform the City Resilience Program and its connected operational teams about urban hazards in a rapid manner in order to capably guide their investment plans in resilience. Such services, combined with tailored capacity building activities, pave the way for the use of a platform-based InSAR solution directly by EO practitioners and end-users for the purpose of monitoring cities according to various concerns. The introduction of online tools expands and scales the skills of technical staff of local authorities and relevant agencies while increasing their acceptance of Earth Observation and its solutions.

ESA's Geohazards Exploitation Platform (GEP) is a cloud-based environment providing a set of processing tools and services that allow mapping hazard prone land surfaces and monitoring terrain deformation. The platform is continuously expanding through its early adopter programme to include a broad range of on-demand and systematic products and services, currently available or under development on cloud processing resources to support EO practitioners and other users to better understand geohazards and their impact. The present work is introducing several of these services as well as other innovative concepts such as GEP's e-collaboration environment.

The systematic availability of data from the Copernicus Sentinel-1 mission, allows redundancy of pairs considered during interferometric processing. In the present work the effect of DInSAR pairs' selection on the interferometric estimates, especially for the case of relatively fast moving landslides, is investigated. Interferometric findings over a well-monitored site are validated by in-situ geodetic measurements. It was documented that significant underestimation of motion occurs for DInSAR solutions utilizing pairs covering larger temporal spans, while displacement patterns are generally maintained. The above fact is attributed mainly to the magnitude of cumulated motion at temporally long interferograms, exceeding the physical limit of SAR interferometric techniques, with pronounced underestimation issues introduced. The need for an a priori knowledge of the expected motion rates for the optimum selection of interferometric combinations for measuring ground displacements is underlined.

This paper presents a method for deriving shallow to intermediate (1m to 50m) coastal bathymetry from space-borne multispectral data taking advantage of the short time-lag between sensors' bands. The idea is to quantify local waves' characteristics (wavelengths and celerities) that are related to the water depths using optical data: local spectral analysis can provide the significant wavelengths and inter-band offset-tracking and the corresponding celerities (knowing the inter-band time-lag). Such an approach was firstly described in [1]. However, for an application to extended areas and using large data sets (as possible with the Sentinel-2 archive), a faster technique is required: the ability of processing large areas and data acquired at different dates is required for actual operational uses. The approach we propose here is based on Fast Fourier Transform analysis in order to simultaneously extract the wavelengths and celerities.

An essential step in earthquake risk assessment consists in collecting information regarding buildings at risks in order to evaluate their vulnerability, and, ultimately, their expected damages for events of specific intensity. A number of building features can be retrieved by means of remote sensing, either directly (through direct observations of features such as their size or footprints) or indirectly (by appraising the expected building types, given features such as the shape of roads or roofs, and an a-priori knowledge of the urban landscape of interest). Here, we evaluate to which extent the accuracy of mean damage grade can be improved by means of remote sensing using the RISK-EU (2004) [1] assessment grid. The results show that if nothing is known regarding the building stocks in the city of interest, the uncertainty in average vulnerability can be reduced by half using remote sensing observations if adequate indirect proxies can be found.

Recent development by European Space Agency (ESA) involved the extension of the interferometric capabilities of the SentiNel Application Platform (SNAP) to enable SAR interferometric time series analysis through the Stanford Method of Persistent Scatterer (StaMPS) software package. In the current work, we demonstrate the enabled Persistent Scatterers Interferometry (PSI) processing of Copernicus Sentinel-1 mission data through SNAP-StaMPS integrated processing. A detailed overview of the processing steps involved as well as considerations and assumptions to exploit the SNAP-StaMPS synergy are presented. We intend to support the Earth Observation community by providing guidelines for Sentinel-1 TOPS data PSI processing using open source software packages. We demonstrate the SNAP functionality by processing two stacks of Sentinel-1 products over Mexico City (Mexico) and Rome (Italy).

At the beginning of 2011 Santorini volcano underwent a volcanic unrest, accompanied by an increase of the microseismic activity. The unrest that lasted for over a year, demonstrated substantial amounts of uplift, justifying the volcanic origin of the activity. The continuation of the deformation monitoring after the unrest event was deemed necessary, in order to validate the post-unrest state of the volcano and to recognize potential ground deformation signals. The Copernicus Sentinel-1 mission is profoundly promising towards this direction, due to its systematic acquisition and short revisit. A multi-temporal SAR interferometric analysis was deliberated in a way to avoid significant phase changes and to retain high coherence. In this paper, DInSAR analysis was applied over Santorini to retrieve the actual deformation state of the volcano during the repose period 2014-2017. The results indicate subsidence rates on Nea Kameni of about 8-9 mm/yr, implying a gradual deflation of the magma chamber, while the rest of the area appears almost stable with negligible deformation.

In the presented study our purpose is to show the interest of space-borne high-resolution L-band Synthetic Aperture Radar (SAR) images (ALOS-2/PALSAR2 data in SM1 mode) for mapping deformation of slow landslides. The methods we combined are sub-pixel correlation offset tracking techniques and differential SAR interferometry. Hell-bourg and Grand Ilet landslides (our test cases) are located on La Réunion Island in the Indian Ocean with motions up to about 1 m/y. The produced deformation maps resulted better than those obtained in previous studies with C or X band SAR data or with current Sentinel-1 data as L-band data are less affected by the vegetated cover than X- or C-band data. Finally, the possibility of deriving 3D mapping of the displacement by combining ascending and descending acquisitions (each one provides 2 components of the deformation: line of sight and azimuth) is investigated.

The Sentinel-1 Mission is the European Imaging Radar Observatory for the Copernicus joint initiative of the European Commission (EC) and the European Space Agency (ESA). The objective of the current paper is to provide a brief overview of the latest ESA activities, in the frame of the Scientific Exploitation of Operational Missions (SEOM) programme, aimed to facilitate the scientific exploitation of Sentinel-1 mission as well as discuss future opportunities for research.

The contribution focuses on the current status of the ESA study entitled “InSARAP Sentinel-1 Constellation Study”, which investigates the interferometric performance of the S1A/S1B units. General aspects like the interferometric compatibility in terms of common range and Doppler bandwidth and the burst synchronization are addressed. Besides the first interferometric results with both units, time series results over the pilot sites combining both satellites are also shown, as well as some investigations with fast moving (i.e., glaciers) scenarios.

ESA's Scientific Exploitation of Operational Missions (SEOM) programme represents a pathfinder for science and innovation addressing the needs and requirements of the Earth system science community in terms of providing novel observations, new algorithms and products that will be a driver for new and innovative scientific discoveries. The current paper aims to provide a brief overview of the various SEOM activities relevant to the first Copernicus Sentinel 1 mission and to present the main achievements and discuss future opportunities for research.

This paper presents results of the Sentinel-1 sensor in the interferometric wide-swath (IW) mode encompassing the first two years of operation of the mission. The paper focuses on persistent scatterer interferometric results and their validation. Further applications and investigations are also addressed, e.g., earthquakes, volcanoes and tomography.

This contribution reports on the performance investigations of the interferometric wide swath (IW) mode of Sentinel-1, which is implemented using the terrain observation by progressive scans (TOPS) mode. The key aspects of the TOPS mode that need to be considered for accurate interferometric processing will be presented, and first analyses with Sentinel-1 time series will be shown. The results focus on the pilot sites of Campi Flegrei/Vesuvius and Mexico City, as well as Greenland glaciers. Other aspects related to the interferometric performance are also presented, like the burst synchronization, the pointing accuracy, or the considerations when evaluating non-stationary scenes.

A discrete scattering model, based on the radiative-transfer theory, is used to simulate the backscattering of burned pine canopies at C-band. The model is first parameterized either with direct field measurements on a selected burned area in Greece or with proper estimations of the required variables, for which direct measurements were not possible. The simulated backscatter at VV polarization was compared against European Remote Sensing 2 (ERS-2) observations. The comparison was based on the observed backscattering of nine burned plots, during four different postfire acquisitions $(n=36)$ . In general, the model provides satisfying estimations of the backscattering with a root-mean-square error of 1.01 dB. The copolar signal for both HH and VV showed a mild decrease with increasing fire impacts and was considerably affected by the incidence angle. From the experiments performed in the simulated environment, it is concluded that the SAR copolar (C-band) backscatter varies with respect to certain fire impact levels. Other important acquisition- or stand-dependent variables (such as incidence angle and snag age) were also found to impact the relationship between backscatter and fire impacts. Finally, the backscattering variability on increasing volumetric soil moisture (VSM) and snag moisture was examined. The increase of VSM from 20% to 30% amplified the signal in both copolarized bands by 1.2–1.5 dB. This amplification was more apparent on VV polarization than in HH polarization. Instead, the HH signal proved to be more sensitive on the increase of snag moisture, which was tested under a stable dry soil.

The northern part of Athens Basin was subjected to human induced lowering of groundwater table due to over-pumping. The prolonged drought from late 1980's to early 1990's and the increased water demand resulted in significant settlement. Advanced SAR interferometric techniques were applied to investigate the time dependent ground displacements, focusing mainly on the non-linear component of motion, by utilizing ERS and ENVISAT satellite archive data. It has been shown that high displacement rates (up to -22.7 mm/yr) observed until 1995 were reduced when these areas were integrated to the national water supply system and groundwater extraction was abandoned. After 2002 large percent of the area is undergoing uplift indicating that the system is under a state of physical rebound.

In this study SAR interferometry technique has been applied over Kos Island (Hellenic Volcanic Arc) in order to detected pre-, coand post-seismic deformation and to compare with the deformation detected in Nisyros Island for the same period using the same interferometric pairs. The seismic unrest activity observed in Nisyros volcano (1996-1999) could produce crustal deformation in the adjacent island of Kos. The results of the interferometric processing show that coand post-seismic deformation was not possible to be detected due to the obtained low coherence. Contrary the results of the interferometric pair of the pre-seismic unrest period show two fringes of deformation in the southwest part of the island, the same amount of deformation was observed in Nisyros island.