F-SAR - recent upgrades and campaign activities

Horn, Ralf; Jaeger, Marc; Keller, Martin; Limbach, Markus; Nottensteiner, Anton; Pardini, Matteo; Reigber, Andreas; Scheiber, Rolf

doi:10.23919/irs.2017.8008092

Cited by 18 publications

(10 citation statements)

References 3 publications

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“…Moreover, these instruments operating in the microwave domain are independent of external illumination, such as daylight. The SAR sensor F‐SAR of the German Aerospace Center (DLR) has been in operation aboard a Dornier Do228‐212 aircraft since November 2006, and details on the current status of the system are reported in Horn et al (). It features simultaneous data acquisition at multiple wavelengths (X, C, S, L, and P bands) and with four complex‐valued polarization channels ( S H H , S H V , S V H , and S V V ).…”

Section: Methods and Datamentioning

confidence: 99%

“…The spatial resolution of the sensor ranges from 1.5–2.25 m at P band down to 0.2–0.3 m at X band. In addition, the radiometric resolution is at least 0.5 dB per channel with a noise equivalent sigma zero of −30 dB or better (Horn et al, ). The side‐looking, slant range acquisition geometry of the polarimetric sensor implies that raw data are acquired while flying in the so‐called azimuth direction and recording along the range direction.…”

Section: Methods and Datamentioning

confidence: 99%

See 1 more Smart Citation

Synergies for Soil Moisture Retrieval Across Scales From Airborne Polarimetric SAR, Cosmic Ray Neutron Roving, and an In Situ Sensor Network

Fersch

Jagdhuber

Schrön

et al. 2018

Water Resources Research

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The consistent determination of soil moisture across scales is a persistent challenge in hydrology. Several measurement methods exist at distinct scales, each of which is challenging in terms of data processing, removal of vegetation and surface effects, and calibration. While in situ measurements are trusted at the point scale, distributed sensor networks extend the areal representation to the field scale. At this scale, also cosmic ray neutron sensing (CRNS) has become an established method to derive volume‐averaged, root zone soil moisture over several tens of hectometers, but the signal is often biased due to biomass water. With airborne synthetic aperture radar (SAR) remote sensing, it is possible to cover regional scales, but the method is limited to the topmost soil layer and sensitive to vegetation parameters. In this study, the performance and synergistic potential of these complementary methods is investigated for the determination of soil moisture within a 55 km2 Alpine foothill river catchment in Southern Germany. The individual approaches are evaluated and brought into synergy for a 9 ha grassland and several other locations within the catchment. The results indicate that the sensor network data provide valuable information to calibrate the mobile CRNS rover, and to optimize the vegetation removal within the polarimetric SAR retrieval algorithm. The root‐mean‐square errors for polarimetric SAR soil permittivity are 9.32 with the standard agriculture approach, 4.29 with the semi‐stand‐alone approach, and 0.31 with the sensor network optimized approach. Furthermore, the CRNS soil moisture product was improved by considering the remotely sensed cross‐polarized backscatter product as a biomass water proxy.

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Section: Methods and Datamentioning

confidence: 99%

Section: Methods and Datamentioning

confidence: 99%

Synergies for Soil Moisture Retrieval Across Scales From Airborne Polarimetric SAR, Cosmic Ray Neutron Roving, and an In Situ Sensor Network

Fersch

Jagdhuber

Schrön

et al. 2018

Water Resources Research

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show abstract

“…Moreover, soil moisture sensing is also a topic of discussion for airborne microwave RS working on resolutions that are valid for habitat research and precision farming and capable of retrieving soil moisture patterns with a high spatial resolution (<100 m). On airborne platforms joint active-passive remote-sensing instrument constellations include PLMR (polarimetric L-band multibeam radiometer) [178,297,298] (Figure 7c) and F-SAR sensors [299,300] (Figure 7d), also referred to as multi-sensor platforms.…”

Section: Combining Active and Passive Microwave Sensorsmentioning

confidence: 99%

Linking Remote Sensing and Geodiversity and Their Traits Relevant to Biodiversity—Part I: Soil Characteristics

Lausch

Baade

Bannehr³

et al. 2019

Remote Sensing

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In the face of rapid global change it is imperative to preserve geodiversity for the overall conservation of biodiversity. Geodiversity is important for understanding complex biogeochemical and physical processes and is directly and indirectly linked to biodiversity on all scales of ecosystem organization. Despite the great importance of geodiversity, there is a lack of suitable monitoring methods. Compared to conventional in-situ techniques, remote sensing (RS) techniques provide a pathway towards cost-effective, increasingly more available, comprehensive, and repeatable, as well as standardized monitoring of continuous geodiversity on the local to global scale. This paper gives an overview of the state-of-the-art approaches for monitoring soil characteristics and soil moisture with unmanned aerial vehicles (UAV) and air- and spaceborne remote sensing techniques. Initially, the definitions for geodiversity along with its five essential characteristics are provided, with an explanation for the latter. Then, the approaches of spectral traits (ST) and spectral trait variations (STV) to record geodiversity using RS are defined. LiDAR (light detection and ranging), thermal and microwave sensors, multispectral, and hyperspectral RS technologies to monitor soil characteristics and soil moisture are also presented. Furthermore, the paper discusses current and future satellite-borne sensors and missions as well as existing data products. Due to the prospects and limitations of the characteristics of different RS sensors, only specific geotraits and geodiversity characteristics can be recorded. The paper provides an overview of those geotraits.

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“…Data have been provided in 2016 by Deutsches Zentrum für Luft-und Raumfahrt e.V. (DLR)'s fully polarimetric airborne system F-SAR in the framework of the AfriSAR campaign [17], [20], [34]. Central frequency is tuned on 435 MHz, signal and Doppler bandwidth are set to ensure 1.2 and 0.9 m of resolution in range and azimuth direction, respectively.…”

Section: Processed Data Setsmentioning

confidence: 99%

Digital Terrain Model Retrieval in Tropical Forests Through P-Band SAR Tomography

d’Alessandro

Tebaldini

2019

IEEE Trans. Geosci. Remote Sensing

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This paper focuses on the retrieval of terrain topography below dense tropical forests by means of synthetic aperture radar (SAR) systems. Low-frequency signals are needed to penetrate such a thick vegetation layer; however, this expedient alone does not guarantee proper retrieval. It is, here, demonstrated that the phase center of P-band backscatter may lie several meters above the ground, depending on the slope and incidence angle. SAR tomography is shown to overcome this problem and retrieves the actual topography even in the presence of dense trees up to 50 m tall. Digital terrain models returned by SAR tomography are, here, put in comparison with light detection and ranging (LiDAR) terrain models: the accuracy of radarderived maps is found to be at least comparable with the one offered by LiDAR systems. Moreover, the discrepancy between tomography and LiDAR is larger if large-footprint LiDAR is considered thus suggesting that, in this case, tomographic maps should be considered the reference height. Analyses are carried out by processing three data sets gathered over different tropical forests in western Africa. The robustness of the radar estimates is assessed with respect to both ground slope and treetop height.

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F-SAR - recent upgrades and campaign activities

Cited by 18 publications

References 3 publications

Synergies for Soil Moisture Retrieval Across Scales From Airborne Polarimetric SAR, Cosmic Ray Neutron Roving, and an In Situ Sensor Network

Synergies for Soil Moisture Retrieval Across Scales From Airborne Polarimetric SAR, Cosmic Ray Neutron Roving, and an In Situ Sensor Network

Linking Remote Sensing and Geodiversity and Their Traits Relevant to Biodiversity—Part I: Soil Characteristics

Digital Terrain Model Retrieval in Tropical Forests Through P-Band SAR Tomography

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