TanDEM-X: A Satellite Formation for High-Resolution SAR Interferometry

Krieger, Gerhard; Moreira, Alberto; Fiedler, Hauke; Hajnsek, Irena; Werner, Marian; Younis, Marwan; Zink, Manfred

doi:10.1109/tgrs.2007.900693

Cited by 1,374 publications

(793 citation statements)

References 64 publications

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“…S1 in the Supplement) of the TanDEM-X mission (Krieger et al, 2007), in which the TerraSAR-X and TanDEM-X satellites image the surface simultaneously from different viewing angles. This allows us to infer topography interferometrically without the need to correct for ice flow.…”

Section: Surface Elevationsmentioning

confidence: 99%

Detecting high spatial variability of ice shelf basal mass balance, Roi Baudouin Ice Shelf, Antarctica

et al. 2017

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Abstract. Ice shelves control the dynamic mass loss of ice sheets through buttressing and their integrity depends on the spatial variability of their basal mass balance (BMB), i.e. the difference between refreezing and melting. Here, we present an improved technique -based on satellite observations -to capture the small-scale variability in the BMB of ice shelves. As a case study, we apply the methodology to the Roi Baudouin Ice Shelf, Dronning Maud Land, East Antarctica, and derive its yearly averaged BMB at 10 m horizontal gridding. We use mass conservation in a Lagrangian framework based on high-resolution surface velocities, atmosphericmodel surface mass balance and hydrostatic ice-thickness fields (derived from TanDEM-X surface elevation). Spatial derivatives are implemented using the total-variation differentiation, which preserves abrupt changes in flow velocities and their spatial gradients. Such changes may reflect a dynamic response to localized basal melting and should be included in the mass budget. Our BMB field exhibits much spatial detail and ranges from −14.7 to 8.6 m a −1 ice equivalent. Highest melt rates are found close to the grounding line where the pressure melting point is high, and the ice shelf slope is steep. The BMB field agrees well with on-site measurements from phase-sensitive radar, although independent radar profiling indicates unresolved spatial variations in firn density. We show that an elliptical surface depression (10 m deep and with an extent of 0.7 km × 1.3 km) lowers by 0.5 to 1.4 m a −1 , which we tentatively attribute to a transient adaptation to hydrostatic equilibrium. We find evidence for elevated melting beneath ice shelf channels (with melting being concentrated on the channel's flanks). However, farther downstream from the grounding line, the majority of ice shelf channels advect passively (i.e. no melting nor refreezing) toward the ice shelf front. Although the absolute, satellite-based BMB values remain uncertain, we have high confidence in the spatial variability on sub-kilometre scales. This study highlights expected challenges for a full coupling between ice and ocean models.

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Section: Surface Elevationsmentioning

confidence: 99%

Detecting high spatial variability of ice shelf basal mass balance, Roi Baudouin Ice Shelf, Antarctica

et al. 2017

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“…This allowed us to compute kinematic orbits and gravity fields for several satellites which are not originally dedicated to the study of Earth's gravity field. We used data from the satellite missions Swarm (Friis-Christensen et al 2006), TerraSAR-X (Werninghaus et al 2007), Tandem-X (Krieger et al 2007), MetOpA, MetOpB (Edwards et al 2006) and Cosmic (Rocken et al 2000). For each satellite, the previously described work flow was used to generate kinematic orbits.…”

Section: Other Satellite Missionsmentioning

confidence: 99%

Precise orbit determination based on raw GPS measurements

Zehentner

Mayer‐Gürr

2015

J Geod

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Precise orbit determination is an essential part of the most scientific satellite missions. Highly accurate knowledge of the satellite position is used to geolocate measurements of the onboard sensors. For applications in the field of gravity field research, the position itself can be used as observation. In this context, kinematic orbits of low earth orbiters (LEO) are widely used, because they do not include a priori information about the gravity field. The limiting factor for the achievable accuracy of the gravity field through LEO positions is the orbit accuracy. We make use of raw global positioning system (GPS) observations to estimate the kinematic satellite positions. The method is based on the principles of precise point positioning. Systematic influences are reduced by modeling and correcting for all known error sources. Remaining effects such as the ionospheric influence on the signal propagation are either unknown or not known to a sufficient level of accuracy. These effects are modeled as unknown parameters in the estimation process. The redundancy in the adjustment is reduced; however, an improvement in orbit accuracy leads to a better gravity field estimation. This paper describes our orbit determination approach and its mathematical background. Some examples of real data applications highlight the feasibility of the orbit determination method based on raw GPS measurements. Its suitability for gravity field estimation is presented in a second step. B Norbert Zehentner

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“…The interference phase has ambiguity constrained to a value between -π~π. The measure of this is Hamb in Fig .4, which stands for Height Ambiguity [19]. It indicates ambiguity index of height value.…”

Section: Phase Interferogram and Coherencementioning

confidence: 99%

A Study on Optimal D-InSAR Filtering Technique According to Landform Relief

Youm¹,

Hongsic²,

Kwangbae³

et al. 2017

Preprint

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Abstract:The InSAR technique measures the displacement of an indicator using SAR image interference. The technique of interfering two SAR images among InSAR techniques is called Differential InSAR (D-InSAR). In the process of D-InSAR, the filtering technique is used in the Unwrapped Mask, usually using the GoldStein method. However, since the Goldstein method removes the noise on the path, it is difficult to derive the displacement value in the agricultural area where the relative coherence is low. In Korea, more than 50% of the whole country consists of mountainous regions and agricultural regions, so it is difficult to use the Goldstein technique polysynthetically. In this study, we set the test-bed for the urban area and the agricultural area based on Coherence, and introduce Goldstein and Boxcar Filter, one of the Goldstein and LSM techniques. Through this process, we want to draw the conclusion which is displacement values in the agricultural area.

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TanDEM-X: A Satellite Formation for High-Resolution SAR Interferometry

Cited by 1,374 publications

References 64 publications

Detecting high spatial variability of ice shelf basal mass balance, Roi Baudouin Ice Shelf, Antarctica

Detecting high spatial variability of ice shelf basal mass balance, Roi Baudouin Ice Shelf, Antarctica

Precise orbit determination based on raw GPS measurements

A Study on Optimal D-InSAR Filtering Technique According to Landform Relief

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