The primary objective of the European Space Agency's 7 th Earth Explorer mission, BIOMASS, is to determine the worldwide distribution of forest above-ground biomass (AGB) in order to reduce the major uncertainties in calculations of carbon stocks and fluxes associated with the terrestrial biosphere, including carbon fluxes associated with Land Use Change, forest degradation and forest regrowth. To meet this objective it will carry, for the first time in space, a fully polarimetric P-band synthetic aperture radar (SAR). Three main products will be provided: global maps of both AGB and forest height, with a spatial resolution of 200 m, and maps of severe forest disturbance at 50 m resolution (where "global" is to be understood as subject to Space Object tracking radar restrictions). After launch in 2022, there will be a 3-month commissioning phase, followed by a 14-month phase during which there will be global coverage by SAR tomography. In the succeeding interferometric phase, global polarimetric interferometry Pol-InSAR coverage will be achieved every 7 months up to the end of the 5-year mission. Both Pol-InSAR and TomoSAR will be used to eliminate scattering from the ground (both direct and double bounce backscatter) in forests. In dense tropical forests AGB can then be estimated from the remaining volume scattering using non-linear inversion of a backscattering model. Airborne campaigns in the tropics also indicate that AGB is highly correlated with the backscatter from around 30 m above the ground, as measured by tomography. In contrast, double bounce scattering appears to carry important information about the AGB of boreal forests, so ground cancellation may not be appropriate and the best approach for such forests remains to be finalized. Several methods to exploit these new data in carbon cycle calculations have already been demonstrated. In addition, major mutual gains will be made by combining BIOMASS data with data from other missions that will measure forest biomass, structure, height and change, including the NASA Global Ecosystem Dynamics Investigation lidar deployed on the International Space Station after its launch in December 2018, and the NASA-ISRO NISAR Land S-band SAR, due for launch in 2022. More generally, space-based measurements of biomass are a core component of a carbon cycle observation and modelling strategy developed by the Group on Earth Observations. Secondary objectives of the mission include imaging of sub-surface geological structures in arid environments, generation of a true Digital Terrain Model without biases caused by forest cover, and measurement of glacier and icesheet velocities. In addition, the operations Here Eff denotes fossil fuel emissions; Elb is net land biospheric emissions, comprising both Land Use 94 Change and ecosystem dynamics, and including alterations to biomass stocks linked to process 95 responses to climate change, nitrogen deposition and rising atmospheric CO2; ΔCatmos is the change in 96 atmospheric CO2; and Uland and Uocean are net average uptake by t...

Ice crystal orientation fabric (COF) records information about past ice-sheet deformation and influences the present-day flow of ice. Polarimetric radar sounding provides a means to infer anisotropic COF patterns due to the associated birefringence of polar ice. Here we develop a polarimetric coherence (phase-based) method to determine horizontal properties of the COF. The method utilizes the azimuth and depth-dependence of the vertical gradient of the hhvv coherence phase to infer the dielectric principal axes and birefringence which are then related to the second order fabric orientation tensor. Specifically, under the assumption that one of the orientational eigenvectors is vertical, we can determine the horizontal eigenvectors and the difference between the horizontal eigenvalues (a measure of horizontal fabric asymmetry). The method exploits single-polarized data acquired with varying antenna orientation. It applies to ground-based 'multi-polarization' surveys and is demonstrated using data acquired by CReSIS (Center for Remote Sensing of Ice Sheets) using MCRDs (Multi Channel Coherent Radar Depth Sounder) from the NEEM ice core region in Greenland. The analysis is validated using a combination of polarimetric matrix backscatter simulations and comparison with COF data from the NEEM ice core. The results are consistent with a conventional model of ice deformation at an ice divide where a lateral tension component is present, with minor horizontal COF asymmetry and the greatest horizontal concentration of crystallographic axes orientated near-parallel to the ice divide.

Abstract-Data driven classification algorithms have proven to do well for Automatic Target Recognition (ATR) in Synthetic Aperture Radar (SAR) data. Collecting datasets suitable for these algorithms is a challenge in itself as it is difficult and expensive. Due to the lack of labelled datasets with real SAR images of sufficient size, simulated data plays a big role in SAR ATR development, but the transferability of knowledge learned on simulated data to real data remains to be studied further.In this paper we show the first study of Transfer Learning between a simulated dataset and a set of real SAR images. The simulated dataset is obtained by adding a simulated object radar reflectivity to a terrain model of individual point scatters, prior to focusing. Our results show that a Convolutional Neural Network (Convnet) pre-trained on simulated data has a great advantage over a Convnet trained only on real data, especially when real data is sparse. The advantages of pre-training the models on simulated data show both in terms of faster convergence during the training phase and on the end accuracy when benchmarked on the MSTAR dataset. These results encourage SAR ATR development to continue the improvement of simulated datasets of greater size and complex scenarios in order to build robust algorithms for real life SAR ATR applications.

Abstract-EMISAR is a high-resolution (2 2 2 2 2 m), fully polarimetric, dual-frequency (L-and C-band) synthetic aperture radar (SAR) system designed for remote-sensing applications. The SAR is operated at high altitudes on a Gulfstream G-3 jet aircraft. The system is very well calibrated and has low sidelobes and low cross-polar contamination. Digital technology has been utilized to realize a flexible and highly stable radar with variable resolution, swath width, and imaging geometry. Thermal control and several calibration loops have been built into the system to ensure system stability and absolute calibration. Accurately measured antenna gains and radiation patterns are included in the calibration. The processing system is developed to support data calibration, which is the key to most of the current applications. Recent interferometric enhancements are important for many scientific applications.

Abstract-Natural media like cold-land ice, vegetation, and dry sand are subject to a substantial penetration at microwave frequencies. For such media, the synthetic aperture radar (SAR) phase center is located below the surface, and consequently, the surface elevation determined with SAR interferometry (InSAR) is biased downward. For infinitely deep uniform volumes, the elevation bias is often equated with the penetration depth, but in this paper, it is shown that the two quantities generally differ. The interferometric bias is approximately equal to the two-way power-penetration depth if the latter is small compared to the ambiguity height, but for increasing penetration depth, the bias approaches one quarter of the ambiguity height. Consequently, no phase wrapping results even if the penetration depth exceeds the ambiguity height. The ratio of the InSAR elevation bias to the ambiguity height depends only on the ratio of the penetration depth to the ambiguity height, and the bias can be expressed in terms of the InSAR coherence magnitude, which makes it possible to correct the InSAR surface elevation for the bias. The volume depth can be considered infinite if it exceeds the penetration depth by a factor of two to five and if the surface scattering from the top and the bottom of the volume is negligible.