Thomas Börner

Measurement and Characterization of Entropy and Degree of Polarization of Weather Radar Targets

To date, few polarimetric weather radars have exhibited the capability to measure full scattering matrices. In contrast, in the synthetic aperture radar (SAR) community, considerable experience has been gained in dealing with complete scattering matrices and their statistical behavior. This paper aims to place weather radar parameters in a wider context in order to exploit more general concepts like target decomposition theorems and polarization basis transformations. Entropy, which is a fully polarimetric variable derived from the Cloude-Pottier decomposition, and the degree of polarization, which is derived from Wolfs coherence matrix, are the subject of this paper. The theoretical analysis carried out in the first part is checked against fully polarimetric data from POLDIRAD, which is the german aerospace center research weather radar. The entropy and the degree of polarization are compared with the copolar correlation coefficient in order to understand whether they can add value to radar meteorological investigations. Because the degree of polarization is available to conventional dual-polarization coherent systems, it is important to assess its potential for operational use.

Concept design of a near-space radar for tsunami detection

Off-shore detection of tsunami waves is a critical component of an effective tsunami warning system (TWS). Even more critical is the off-shore detection of local tsunamis, namely tsunamis that strike coastal areas within minutes from the triggering quake. In this paper we propose a new concept for tsunami detection. NESTRAD (Near-Space Tsunami Radar) consists of a real aperture radar accommodated inside a stationary stratospheric airship providing continuous monitoring of tsunamigenic oceanic trenches.

Signal: SAR for ice, glacier and global dynamics

SIGNAL is an innovative earth exploration mission proposal with the main objective to estimate accurately and repeatedly topography and topographic changes associated with mass change or other dynamic effects on glaciers, ice caps and polar ice sheets. Elevation measurements are complemented with glacier velocity measurements, providing valuable additional information for a better understanding of the hydrology of glacierized basins and of the Arctic and Antarctic water cycle. SIGNAL is capable of monitoring all critical regions with a high spatial resolution and an adequate revisit time. This paper gives an overview about the actual mission design status and provides a brief description of the topography (DEM - digital elevation map) self-calibration strategy and the estimated global interferometric performance.

ALOS PALSAR products verification

ALOS, an enhanced successor of the Japanese Earth Resources Satellite 1 (JERS-1), was launched from JAXAs Tanegashima Space Center in January 2006. An important contribution to the ALOS mission is the verification of PALSAR products to be distributed by the European ADEN node using the PALSAR processor developed by JAXA. A total of 28 ALOS PALSAR products have been analysed with respect to radiometric, geometric and polarimetric quality (including effects of Faraday rotation caused by the ionosphere) and a summary of the results is shown in this paper.

BIOMASS end-to-end mission performance simulator

This paper discusses the implementation of an end-to-end simulator for the BIOMASS mission. An overview of the system architecture is provided along with a functional description of the modules that comprise the simulator.

Biomass End-to-End mission performance assessment

This paper provides an overview of the BIOMASS Mission End-to-End simulator (BEES) and of the mission performance analysis performed with it. The end-to-end performance, in terms of biomass estimates error, is close to the 20% error goal set for the mission. The main sources of errors are temporal decorrelation and the limited available bandwidth, while system induced errors have a negligible impact on the final performance.

Degree of polarization for weather radars

Future operational weather radars are likely to implement hybrid polarization, an operating mode that involves transmitting 45deg slant polarization and receiving the horizontal and vertical components of the backscattered field. In this work, the degree of polarization at slant send is theoretically considered and experimentally evaluated from fully polarimetric signatures in order to assess its potential for use in next generation operational weather radars.

Development of a coherent scattering model for polarimetric SAR interferometry applications

Presents a stochastic coherent polarimetric scattering model, which can be used for interferometric simulation. The author gives a brief description of the capabilities of the model regarding the simulation of natural targets and the physical interpretation of the scattering processes. Two important features of the model are the simulation of temporal and volume decorrelation. These effects occur particularly over vegetated areas, such as forests. In order to validate the predictions of the model the author compares them with full polarimetric and interferometric L-band SAR data from DLRs ESAR sensor over a forested area at the Oberpfaffenhofen (Germany) test site. The results show that it is possible to relate the interferometric coherence to the height distribution of the illuminated scatterers and thus the tree heights.

On the performance of baseline self-calibration using intersecting interferometric SAR acquisitions

In this paper a baseline (height) self-calibration concept is introduced and applied to simulations of two different single-pass interferometric SAR systems with a single-swath and a dual-swath configuration. The results will show that the general performance is very promising and that, by simultaneously acquiring two separated swathes, accuracies in the sub-decimetric range can be reached.