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In letzten Jahren ist das Interesse an der Radarinterferometrie für die Bodenbewegungserfassung stark gewachsen und kommerzielle und behördliche Dienste ste-hen zur Verfügung. Das Ziel des neuen DIN-Normungsverfahrens ist es, vereinheitlichte Be-griffe, validierte Verfahren und Standards bei den Vermessungsprodukten und der Qualitäts-sicherung zu etablieren und damit fachkundig und rechtssicher für die betriebliche und be-hördliche Praxis einsetzbar zu machen. Dieser Beitrag beschreibt den Kontext der Initiative, den Stand der bisherigen Validierungen und Standardisierungen und Beispiele von aktuellen Bodenbewegungsdiensten und Corner-Reflektoren.

Troposphere effect mitigation based on numerical weather prediction (NWP) is an actual research topic in SAR interferometry (InSAR) and especially in persistent scatterer interferometry (PSI). This is the reason, a scientific troposphere effect mitigation processing system has been developed. The objective of this paper is to provide the methodology of four developed algorithms, demonstrate application examples, discuss the methods characteristic and recommend techniques for operational systems.

The Ems Estuary enters the North Sea between the Netherlands and Germany. The Estuary has vast tidal flats consisting of fine-grained sediment. It is highly modified e.g. for land reclamation, coastal protection and navigability. Thus, the tidal behavior changed and natural sediment sinks vanished. The latter is identified as the most important reason for the substantial increase in suspended sediment concentration (SSC) from the 1990s onwards. Extensive research is being done to better understand the hydraulic and morphodynamic systems in order to keep the area in a stable state while balancing different concerns and interests, including future sea-level rise. Therefore, sediment budget calculations and morphodynamic modellings are carried out, taking into account all known sediment sinks and sources, such as dredging, land reclamation and fairway deepening. An additional sediment sink, which is hardly considered today, can be caused by the offshore subsidence due to hydrocarbon extraction. So the onshore subsidence above the huge Groningen natural gas field west of the Ems estuary is well known. In this study, we estimate the offshore extension of the subsiding area to the seafloor of the Ems Estuary. To do so, we apply Persistent Scatterer Interferometry (PSI) to generate around the Ems estuary a Wide Area Product (WAP) of interferometric ground motion information. We combined information about the extension of Dutch and German natural gas fields, the WAP-PSI-derived subsidence onshore east and west of the estuary and verified with Global Navigation Satellite Systems (GNSS) Stations including those mounted on tide gauges offshore in the estuary. Interpretation with further thematic data led to the identification and volume estimation of a new significant sediment sink in the Outer Ems. Starting in 1992, the offshore subsidence of the seafloor is estimated. Between 1992 and 2001 a maximum subsidence of 42 mm is detected. An area of approximately 200 km^2 is affected by a subsidence rate > 2 mm/a. The subsidence volume in the 9-year period from 1992 to 2001 adds up to approximately 5.5 Mil. m^3. The resulting average annual volume change of ca. 0.6 Mil. m^3/a is in the same order of magnitude as the estimated annual sediment sink of the total Ems Estuary between 1994 and 2015. With the data of the PSI-based BBD, up-to-date sedimentation volumes can be evaluated. We suggest to take this sediment sink and in general, the subsidence of the seafloor and tidal flats due to natural gas and oil extraction into account in future sediment budget calculations and morphodynamic modelling approaches. The politically decided end of natural gas extraction from the Groningen gas field will also put an end to a huge sediment sink in the Ems estuary probably increasing SSC further.

Troposphere effect mitigation based on numerical weather prediction (NWP) is an actual research topic in SAR interferometry (InSAR) and especially in persistent scatterer interferometry (PSI). This is the reason, a scientific troposphere effect mitigation processing system has been developed. The objective of this paper is to provide the methodology of four developed algorithms, demonstrate application examples, discuss the methods characteristic and recommend techniques for operational systems.

This technical note (TN) focuses on the assessment of the atmospheric effects and their compensation in SAR interferometry and especially in persistent scatterer interferometry (PSI). Different strategies to reduce atmospheric effects exist for mountainous areas. In principle, the topographically-correlated atmospheric phase can be estimated • directly from the data, • from global coarse grid GPS zenith path delay data and • from numerical weather prediction models (NWP). These methods are compared and the related assessment is described in this technical note. The output is a recommendation how to implement the atmosphere mitigation in mountainous areas and an error propagation assessment of the NWP method.

The Persistent Scatterer Interferometry Wide Area Product (PSI-WAP) based on ERS1 & ERS2 radar data has been used in the seismic active area of Atalanti Faulting Zone (Central Greece) to spatially and temporally study the ground deformation for the period 1992-2003. The observed LOS velocity field, with values ranging between -0.5 to -5.0 mm/yr, combined with small standard deviation velocity values reveals an almost linear type of ground deformation. The most intense subsidence was associated to alluvia deposits and man made activities (intense water pumping). Differential motions along the main faulting zones have also been clearly identified. GPS results reflected a similar pattern of motions (subsidence) with the identified interferometric image. The recorded seismicity in the area is not significant for the PSI-WAP period. The micro-seismic activity (M

Interferometric synthetic aperture radar (InSAR) measurements are merely sensitive to the deformation along the Line of Sight (LOS) direction of the sensor. To improve the geometrical sensitivity and retrieve the three-dimensional deformation, the integration of InSAR from non-coplanar acquisitions as well as fusion with resolution-scale SAR image shift measurements has become a standard approach. Using different statistical measures, we assess and compare the influence of different image acquisition strategies as well as data fusion on the performance of InSAR in 3D deformation retrieval. Integrating nominal InSAR acquisitions, i.e. a set of measurements from ascending and descending tracks acquired from right-looking geometry, a strong correlation between the retrieved 3D parameters in the local vertical-north plane is observable. This correlation is sought to be decreased by non-nominal acquisitions; i.e. left-looking or squinted observations. These acquisition strategies are discussed for consideration in the future L-band mission Tandem-L.

Long-term ground deformation monitoring using the Persistent Scatterer Interferometry Wide Area Product (PSI-WAP) technique for the period 1992-2003, combined with Differential GPS measurements and seismicity analysis has provided useful information about the tectonic motions of the tectonically complex area of Patras Gulf (Western Greece), and lead to new insights on the geotectonic regime of this region. Descending ERS radar images were used to compile the PSI-WAP product that has been calibrated using the absolute velocity field of available GPS stations in the area. It has been found that the deformation of the southern part of Patras Gulf near the coastline has been characterized by considerable subsidence (>-5mm/yr), where unconsolidated sediments usually prevail, compared to the northern part of the gulf. Significant subsidence has also been identified in areas along the down-throw side of possible faults, as well as areas where extensive ground water pumping has occurred for irrigation. These results correlate well with local GPS and seismicity data.

In PSI (Persistent Scatterer Interferometry) the PSs are implicitly assumed to have a stable phase throughout a stack of images so that all images can be used for estimation. However, PSs can fade due to changes in acquisition geometry where the elevation or azimuth response of the PS for different baselines or zero Doppler frequencies is imprinted on the return. Physical changes caused by construction or seasonal changes due to snow cover can also cause the sudden appearance or disappearance of a PS. Here, several parametric change point estimators are assessed for their suitability in detecting such events both through simulation and their application to an ERS stack over Hamburg.

The persistent scatterer interferometry (PSI) is a well established monitoring technique for urban areas. It has been updated in order to process wide areas with the accepted characteristics in precision and resolution. Of course, the covered processing area now includes rural areas with a low persistent scatterer (PS) density. In order to bridge forested areas and water bodies, low quality and more distant PSs need to be included into the reference network. The development of the wide area product (WAP) succeeded to cope with the resulting difficulties resulting in spatial error propagation. In this paper, the developed WAP system is described and a processing example is presented.

InSAR’s capabilities have been considerably improved by advanced processing techniques such as Persistent Scatterer Interferometry (PSI) and SAR Tomography (TomoSAR). However, complicated scattering situations (e.g. layover) need to be better resolved in urban areas. This paper presents a new technique for providing the 3D point scatterer location and the resolution cell configuration, based only on the amplitude of SAR images. The implemented method is based on the principle of radargrammetry and uses Bayesian inference. As com-pared to PSI and TomoSAR, the method is insensitive to temporal decorrelation, atmospheric phase screen (APS) and non-linear motion of point scatterers.

In the Persistent Scatterer Interferometry relative height and deformation updates are estimated between nearby persistent scatterers (PSs). In practice, a reference network is established and the absolute values are estimated by integration. However, PSs can be mis-detected and relative measurements mis-estimated. As a consequence, the integration result depends on the integration path. Therefore, inconsistent measurements need to be eliminated. This paper presents our implemented integration technique which is based on a multithreaded Singular Value Decomposition. An advantage of our method is the straight forward error propagation assessment. As a result, the actual network can be improved by removing inaccurate point scatterers.