The tandem-L mission proposal: Monitoring earth's dynamics with high resolution SAR interferometry

Abstract

Tandem-L is a proposal for an innovativeinterferometric and polarimetric radar mission that enables the systematic monitoring of dynamic processes on the Earth surface. Important mission objectives are global forest height and biomass inventories, large scale measurements of millimetric displacements due to tectonic shifts, and systematic observations of glacier movements. The innovative mission concept and the high data acquisition capacity of Tandem-L provide a unique data source to observe, analyze and quantify the dynamics of a wide range of mutually interacting processes in the bio-, litho-, hydro-and cryosphere. By this, Tandem-L will be an essential step to advance our understanding of the Earth system and its intricate dynamics.This paper provides an overview of the Tandem-L mission concept and its main application areas. Performance predictions show the great potential of Tandem-L to acquire a wide range of bio-and geophysical parameters with high accuracy on a global scale. Innovative aspects like the employment of advanced digital beamforming techniques to improve performance and coverage are discussed in detail.

Validation of Spaceborne and Modelled Surface Soil Moisture Products with Cosmic-Ray Neutron Probes

“…The importance of footprint-scale soil moisture reference data will increase in near future due to downscaled global soil moisture products such as those by Merlin et al [65], Das et al [66], Piles et al [67], Rüdiger et al [68], high resolution radar soil moisture retrievals [69][70][71], or future satellite missions such as Tandem-L [72,73]. Therefore, in this study a more in-depth analysis and comparison of different currently available soil moisture products from SMOS, SMAP, AMSR-2, ASCAT and the Global Land Data Assimilation System Version 2 (GLDAS2) simulation with CRNP time series is performed to find out how useful cosmic-ray soil moisture data can be.…”

Wavelet Based Analysis of TanDEM-X and LiDAR DEMs across a Tropical Vegetation Heterogeneity Gradient Driven by Fire Disturbance in Indonesia

“…Higher penetration from LiDAR compared to TanDEM-X has been observed in dense tropical forest in the Amazon [61]. TanDEM-X phase conversion to a DSM is limited by the penetration depth at X-band, with the availability of future missions such as TanDEM-L [79], penetration depth into the canopy will be greater as this increases with wavelength [51]. This will provide a similar kind of information on ground topography similarly to a DTM generated from LiDAR returns and the possibility to generate CHMs using a combination of TanDEM-X/-L over a wide areal coverage [80].…”

Recent Trend and Advance of Synthetic Aperture Radar with Selected Topics

“…Currently, a new generation of spaceborne SAR systems is being planned to provide a wide-swath coverage without loosing spatial resolution using a digital beam forming (DBF) technique (for DBF, see Section 2.7). TanDEM-L, for example, will cover a swath width of 350 km with spatial resolution of 10 m, and the revisit time will be 8 days [22,158].…”

“…A basic design of achieving high resolution in wide swath is DBF on receive with the conventional analogue beam forming on transmit, where a wide swath is illuminated using either a small part of an antenna or a small separate antenna, and the scattered signal is received by multiple independent sub-apertures; these signals are then processed independently to produce images of multiple swaths and to produce a wide-swath image by combining them. Several different approaches have been proposed, including a squinted geometry, a displace phase center antenna technique, both of which use sub-apertures aligned in the azimuth direction, a quad-element rectangular array system, and a high-resolution wide-swath (HRWS) system employing multiple sub-aperture elements split into both the azimuth and range directions [192][193][194][197][198][199], as well as the use of a large reflector antenna with feed arrays [158,200,201]. As mentioned in Section 2.2, Tandem-L will have 10 m resolution covering 350 km swath with repeat cycle of 8 days [22,158].…”

“…Several different approaches have been proposed, including a squinted geometry, a displace phase center antenna technique, both of which use sub-apertures aligned in the azimuth direction, a quad-element rectangular array system, and a high-resolution wide-swath (HRWS) system employing multiple sub-aperture elements split into both the azimuth and range directions [192][193][194][197][198][199], as well as the use of a large reflector antenna with feed arrays [158,200,201]. As mentioned in Section 2.2, Tandem-L will have 10 m resolution covering 350 km swath with repeat cycle of 8 days [22,158]. A new different approach to the DBF-based HRWS SAR system has also been proposed using a staggered illumination by continuously varying pulse repetition frequency with a full aperture on both transmission and reception [198,202,203].…”