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The only remote sensing technique capable of obtaining sea ice thickness on basin-scale are satellite altimeter missions, such as the 2010 launched CryoSat-2. It is equipped with a Ku-Band radar altimeter which measures the height of the ice surface above the water level. This method requires highly accurate range measurements. During the CryoSat Validation Experiment (CryoVEx) 2011 in the Lincoln Sea Cryosat-2 underpasses were accomplished with two aircraft which carried an airborne laser scanner, a radar altimeter and an electromagnetic induction device for direct sea ice thickness retrieval. Both aircraft flew in close formation at the same time of a CryoSat-2 overpass. This is a study about the comparison of the sea-ice freeboard distribution of laser scanner and radar altimeter measurements with the CryoSat-2 product within the multi-year sea ice region of the Lincoln Sea in spring, with respect to the penetration of the Ku-Band signal into the snow and the effect of surface roughness on the radar range retrieval.

Cryosat2 Level 1B SAR data can be processed using different empirical retrackers to determine the sea surface height and its variations in the Arctic Ocean. Two improved retrackers based on the combination of OCOG (Offset Centre of Gravity), Threshold methods and Leading Edge Retrieval is used to estimate the sea surface height in the Arctic Region. This sea surface height determination is to be compared with the Level2 sea surface height components available in the Cryosat2 data. Further a comparison is done with the marine gravity field for retracker performance evaluation.

Due to the impact of higher and higher frequencies in a lot of applications, the Shielding Effectiveness (SE) characterisation of materials is expanding from LF up to frequencies well above 1 GHz. Additionally, requirements with respect to energy-efficiency necessitate the use of light-weight shielding materials such as composites, especially in aerospace applications. A typical concern about composite materials is their internal homogeneity, which may result in a nearly isotropic up to a full anisotropic material type. This paper gives an overview of (semi)-standardized measurement methodologies from Low Frequencies (LF) up to the µWave (µW) region, including discussions on different SE values obtained by different methodologies ispartof: pages:1-5 ispartof: PROCEEDINGS OF 2016 ESA WORKSHOP ON AEROSPACE EMC (AEROSPACE EMC) pages:1-5 ispartof: ESA Workshop on Aerospace EMC (Aerospace EMC) location:Valencia: SPAIN date:23 May - 25 May 2016 status: published

Most recent SAR sensors use wide band signals to achieve metric range resolution. One can also take advantage of wide band to split it into sub-bands and generate several lower-resolution images, centered on slightly different frequencies, from a single acquisition. This process, named Multi Chromatic Analysis (MCA) corresponds to performing a spectral analysis of SAR images. Split-Band SAR interferometry (SBInSAR) is based on spectral analysis performed on each image of an InSAR pair, yielding a stack of sub-band interferograms. Scatterers keeping a coherent behaviour in each subband interferogram show a phase that varies linearly with the carrier frequency, the slope being proportional to the absolute optical path difference. This potentially solves the problems of phase unwrapping on a pixelperpixel basis. In this paper, we present an SBInSAR processor and its application using TanDEM-X data over the Nyiragongo volcano.

The current synthetic aperture radar (SAR) theory makes a quite restrictive assumption – linearity – in the SAR imaging model, for the convenience of mathematical derivation. That is to say the imaged area is considered as an ensemble of individual point scatterers whose scattered fields and, hence, their responses in the SAR image superimpose linearly [1]. This is the so called the first Born approximation. However, the reality is, for sure, more complicated than such approximation. This work presents a step towards a better understanding of the scattering mechanism of different objects, and the occurrence of single scatterer, as well as multiple scatterers within a resolution cell. We back trace individual SAR scatterer to high resolution optical images where we can analyze the geometry, material, and other properties of the imaged object. The proposed approach consists of the following steps: 1. Retrieve the 3D positions of the scatterers’ positions from SAR images, i.e. a tomographic SAR inversion. 2. Co-register the 3D point cloud of the SAR scatterers with a reference 3D model, due to the relative position of the SAR point cloud to the reference point. 3. Co-register high resolution optical image with the reference 3D model, so that each scatterer can be traced in the optical image. 4. Classify the optical image pixels based on its semantic meaning, e.g. geometry, material, and so on. 5. Analyze the semantic meaning of the scatterers, especially those multiple scatterers within the same resolution cell. Currently, this work is finished till step three. The algorithm for step four and five are under development. We will present the findings in final full paper.

Large fractions (15-40%) of the Arctic and Subarctic land surface are covered by lakes and rivers, e.g. in the Lena Delta in Northern Siberia more than 30%. The timing and duration of ice-onset is a relevant climate signal since it is strongly driven by the air temperature. Remote sensing provides a means for obtaining regional information in the high Arctic where ground-based data networks are sparse. Space-borne imaging radar is a suitable tool for the detection of freeze processes, as the backscattering of radar waves is highly dependent on the dielectric properties of the surface. As radar operates independently from sunlight and cloud cover, data retrieval is possible on a regular basis. Radar systems can monitor the earth surface at comparatively high spatial resolutions (on the order of 1 to 20 m), which allows to detect small-scale surface characteristics like ice-onset on small lakes and narrow river channels, which are often present in permafrost environments. For this study, a time series of high resolution TerraSAR-X images was analyzed. The images, recorded during fall and winter 2012, cover several lakes and river channels located in the central Lena Delta, North Siberia, Russia. Images are available every five to six days. After geocoding and multilooking, the pixel size is 13.2 m in azimuth and range direction. In 2012, ice-on is first visible in the SAR images at October 6th on the lakes and narrow river channels. The main channels of the Lena River were partly ice-free until October 12th and frozen from October, 17th on. These results were achieved via visual inspection by an experienced user. Automatic detection, however, is difficult, as the backscattering intensities are similar for calm water surfaces and thin ice without air inclusions or cracks. Thus the often used threshold-based method might miss the ice-onset. In addition, threshold-based methods can get confused with open water affected by wind, as the radar intensity scattered from a rough water surface at higher wind speeds is larger than the intensity from calm water and similar to the intensity of thicker ice. A lake or river channel with a thin ice cover might be characterized by low backscattering intensities on average, which is similar to ice-free water bodies, but can show surface features such as thin cracks, displayed by higher backscatter values. These features are clearly detectable via visible inspection. Techniques like edge detection or other gradient-based methods can help to visualize structures within the ice and ice-water boundaries. The presence of strong radar intensity gradients over lakes and rivers can be taken as a signal for the presence of ice. Later in winter, when the ice thickens and air bubbles, e.g. from methane emissions, are trapped in the ice, or the surface roughens due to break-up and refreeze, these features vanish and the backscatter rises to values close to 0 dB (HH-polarization). The main reflection of the radar waves now occurs at the ice-water boundary. As soon as the ice is frozen to the ground, the backscatter drops again. Thus it is possible to determine from SAR images whether the whole water column is frozen. In the Lena Delta, several lakes and river channels freeze to the ground, whereas others don't. Thus a map partitioning shallow water bodies from deep ones can be established on the base of space-borne SAR observations during winter.

The topic of this paper is the work carried out in Work Package 2.3-2 of the EU network ACE. This work package is concerned with the modelling of the surfaces of modern reflector antennas. In particular the problems associated with homogenisation are described together with an application example. Fast, but approximate, methods are compared to rigorous solutions for realistic strip grid configurations. A new, fast and very efficient interpolation technique for frequency selective surfaces is introduced.

The complete Sentinel-1A (S1A) data set since autumn 2014 until September 2015 over two test sites of the EU FP7 project NorthState has been collected: Hallormsstaour in the north-east of Iceland of 50×50 km2 and Hyytiälä in southern Finland of 200×200 km2. The dense 20m-resolution dual-polarization S1A time series allow for a new level of forest land cover monitoring capabilities compared to ESA's former Envisat A(dvanced)SAR sensor. Temporal filtered dual-polarized mosaics clearly show different land covers that can be classified into forest land cover (FLC) products. Even single agricultural fields can be distinguished from these mosaics. The S1A data set also allowed the construction of a precise water mask for these sites. Results of S1A-based FLC based on two different approaches are compared to 2010 ALOS PALSAR derived FLC results and very high resolution (VHR) NDVI aerial photos. The forest land cover classes extracted are forest, disturbed forest, peatland, grassland, bare land, and settlements.

In November 2005 an ESA funded airborne campaign was conducted in Southern Tunisia to generate a data base of high resolution optical and radar data in support of science product development with respect to water management applications in semi-arid areas. Both the optical (AVIS of LMU) and radar sensor (E-SAR of DLR) were operated quasi-simultaneously from the same aircraft. In parallel a ground measurement campaign was conducted with the support of the Tunisian organisations CRDA (Commissariat Regional des Development Agricole) and IRA (Institut des Regiones Arides). This paper describes the acquired optical, radar, and ground reference data, the adopted processing methodologies as well as the results obtained in the frame of this project from the radar data.

The ACE project initiated the start of several integration activities between European institutions involved in electromagnetic modeling of antennas with planar or conformal topologies. The goal of the integration activities was / is not to create a global software package that integrates the software of all partners, but to initiate a long term process for antenna software integration activities within the European antenna community. During the first two years of ACE the integration activities were performed in several groups with a rather small number of partners in each group. The groups were formed by partners who wanted to integrate a specific approach developed by one partner into the software code of another partner. This allows increasing the capability and efficiency of a software code. In this paper a short overview of all integration activities is given.

This work aims to analyse red and far red sun-induced chlorophyll fluorescence (F) and biophysical variable patterns in a plain mixed forest (Forêt de Hardt, France) using ground measurements and airborne data. The airborne data were acquired using the novel airborne imaging spectrometer HyPlant developed by the Forschungszentrum Jülich in collaboration with SPECIM Spectral Imaging Ltd (Finland), covering the visible, near infrared and shortwave infrared spectral regions. The HyPlant sensor is the only currently available airborne imaging spectrometer with a subnanometer spectral resolution in the region from 670 to 780 nm, offering the opportunity to quantify F at the two fluorescence emission peaks (red and far-red). The hyperspectral images were used to obtain three different products: (i) a forest species composition map based on a classification approach (ii) red and far red F maps obtained applying the singular vector decomposition (SVD) method and (iii) maps of leaf chlorophyll content (Chl) and Leaf Area Index (LAI) produced by means of radiative transfer models. Ground data were collected in a field campaign that was conducted concurrently with the airborne data acquisition with the aim to evaluate the accuracy of all the products. The ground measurements were acquired in 22 elementary sampling units of 20 x 20 m spread over an extensive area and consisted on species composition and crown condition assessment, leaf sampling for pigment extraction, digital hemispherical photography acquisition for LAI estimation, and top of canopy F measurements for each of the main forest species (i.e., hornbeam (Carpinus betulus L.), oak (Quercus robur L.), linden (Tilia L.) and pine (Pinus L.)) with high-resolution spectroradiometers manually operated from a mobile hydraulic platform. The spatial variability of the biophysical variables (Chl and LAI) and F retrieved from the airborne data were compared and analysed in relation with species-specific patterns and forest structure. Moreover, the radiative transfer model for vegetation Soil-Canopy Observation of Photochemistry and Energy fluxes (SCOPE) was used to simulate the “potential” F emission expected over the forest setting the biophysical and environmental input variables to their real values and keeping the physiological parameters fixed. The simulated potential F was then compared to the one retrieved from field and airborne measurements to identify deviations between the expected and the observed values. The spatial distribution of these anomalies was analysed in relation to species composition and canopy density and greenness. In this contribution, we show for the first time F maps in both the red and far-red region over a mixed forest. The F maps show reliable ranges of variation when compared to ground canopy F measurements performed concurrently with the overflight. The analysis of the F maps shows that the F intensity depends on the variation of forest species composition, leaf Chl and vegetation density. However, the relationship between F and the biophysical variables (Chl and LAI) is not unique, suggesting that F can provide additional information, particularly in dense and green canopies. Thus, this study highlights the potential of retrieving F maps in combination with reflectance-derived biophysical variables to improve our understanding of F dynamics in complex ecosystems. This is the concept behind the European Space Agency’s (ESA’s) FLuorescence EXplorer (FLEX) mission currently under evaluation

In this paper novel ultra wideband (UWB) antenna designs suitable for ceiling-mount base station and small terminal applications are presented. Two different designs of antenna arrays employing two triangular radiators above a ground plane have been investigated. In the first design, triangular unipoles are settled parallel one to each other at the distance of a half wavelength at the 3 GHz. In the second design the same radiators are tilted to form a conical like structure. The in-phase excitation of the unipoles was performed by a section of the microstrip line which is centrally fed by a coaxial probe from the opposite side of the ground plane. The input impedance and radiation patterns of both antennas are simulated and measured. In the frequency range 0.8?5 GHz the VSWR was less than 2. have shown mobile base station and small terminal applications.

Planar printed antennas, are often required to be fed by parallel feed-networks, which, when printed on the same substrate as the radiating elements, create mutual coupling, spurious radiation and excite surface waves. This considerably affects the array efficiency. Numerous architectures were proposed in the past ; some of them use the multilayer structure (which by itself exhibits low efficiency), or perpendicularly fed structures. The latter consist of a substrate for the radiating element and another substrate which for the feed-network. The paper reviews some of the basic configurations proposed until now, and shows the specific improvements introduced by the proposed architecture.

With the globally decreasing amount of in-situ stations, satellite altimetry based water levels are an important supplement to obtain continuous time series of the worlds inland water. In this study we demonstrate two new services, that are related to inland water and altimetry. The first is Altimetry for inland water (AltWater), which is a new open service, that provides altimetry based time series for inland water. Currently, the service includes data from cryoSat- 2, but we intend to add other missions in future versions. The second,tsHydro, is a software package, that is implemented in the open source environment "R". The package enables the user to easily construct water level time series for lakes and rivers based on along-track altimetry data.

ERS-1 and ASAR imagery were used for mapping and monitoring the forest area of French Guiana for 1992/1993, 2003/2004, and 2006/2007. Imagery was ortho-rectified using the SRTM DEM. A least square algorithm was used to improve the residual geometric inaccuracies. For the ERS data, significantly better geometric performance could be achieved using the PGS processor (the so called Envisat processor) data than with the standard VMP processor. The image analysis used three SAR based features, which were computed of two to five acquisitions from the same location. The most effective feature in change detection is annual average amplitude. The planned future operative system uses annual SAR data acquisitions and sample point inventory using high-resolution optical data twice in decade. The study was part of the GMES (Global Monitoring for the Environment and Security) Service Element Forest Monitoring.

Taking advantage of the mobile platforms to interact with the HICOD2000 system has been the motivation for the work described in this paper. Regardless of the limited resources available in mobile platforms the authors demonstrate that using the features of the HICOD2000 system the mobile device might be of major assistance in the field where satellite imagery may have an important and useful role. This paper describes an extension of the HICOD2000 system, available to the public through the ESA Service Support Environment. The EO JPEG2000 compressed products have achieved good compression ratios, minimizing both storage space and bandwidth. Regarding security to sensitive data the system enforces user access rights via a digital rights management platform called OpenSDRM. The mobile device has been endowed with the implementation of the JPIP protocol to optimize network bandwidth as well as the necessary components to interface with the OpenSDRM platform and decode JPSEC protected images: the OpenSDRM wallet and the protection tool. info:eu-repo/semantics/publishedVersion