The upcoming launch of the L-band Synthetic Aperture Radar (SAR) satellite mission Radar Observing System for Europe L-band SAR (ROSE-L) will enable multi-frequency SAR observations when combined with existing C-band satellite missions (e.g., Sentinel-1). Due to the different penetration depths of the SAR signals, multi-frequency SAR offers great potential for field-scale agricultural monitoring and the estimation of soil and plant parameters. The SARSense campaign, conducted between June and August 2019 at the Selhausen agricultural test site near Jülich, Germany, has yielded a comprehensive dataset that includes both air- and space-borne C- and L-band SAR data, extensive in-situ field measurements of soil and plant parameters as well as unmanned aerial systems (UAS)-based multispectral and thermal infrared measurements and cosmic neutron sensing observations. The study provides both, an insight into the strengths and limitations of the acquired dataset as well as an analysis of the different behaviour of C- and L-band backscattering on changing soil moisture and plant parameters for taproot crops and cereals.

With the upcoming L-band Synthetic Aperture Radar (SAR) satellite mission Radar Observing System for Europe L-band SAR (ROSE-L) and its integration into existing C-band satellite missions such as Sentinel-1, multi-frequency SAR observations with high temporal and spatial resolution will become available. The SARSense campaign was conducted between June and August 2019 to investigate the potential for estimating soil and plant parameters at the agricultural test site in Selhausen (Germany). It included C- and L-band air- and space-borne observations accompanied by extensive in situ soil and plant sampling as well as unmanned aerial system (UAS) based multispectral and thermal infrared measurements. In this regard, we introduce a new publicly available SAR data set and present the first analysis of C- and L-band co- and cross-polarized backscattering signals regarding their sensitivity to soil and plant parameters. Results indicate that a multi-frequency approach is relevant to disentangle soil and plant contributions to the SAR signal and to identify specific scattering mechanisms associated with the characteristics of different crop type, especially for root crops and cereals.

This paper presents our latest bistatic SAR interferograms obtained from our airborne systems at L-band, acquired under the scope of the BelSAR project. The results are obtained after applying a multisquint-based approach to remove the phase errors caused by clock-drift and baseline inaccuracies. We observe that the phase induced by the clock drift are not range-dependent as the baseline error. Therefore, we estimate from the spectral diversity phase a non-range dependent phase profile along cross-range dimension and afterwards we estimate the two components of the baseline errors. The implemented multisquint is integrated with the actual backprojection processor used to focus the bistatic data. First results show that we are able to remove both the mis-synchronization errors and baseline errors and generate fully synchronized interferometric data from our non-cooperative airborne bistatic system and support future campaigns for non-cooperative bistatic SAR constellations.

This paper presents three recent (2017–2019) campaigns performed by the MetaSensing SAR system over different frequencies, in order to support the development of emerging applications. The L-band campaign data set are related to the full-polarimetric Bistatic SAR campaign at L-band, in Belgium, to allow investigations on agriculture monitoring and crop growth. The C-band campaign data set are related to single-pass monostatic InSAR at C-band in Norway to support further use in the carbon stock estimation context. The X-band campaign data set are related to full polarimetric high resolution single-look-complex SAR imagery at X-band acquired every hour over same area of Rotterdam to support potential applications with high revisit imagery rate.

In late 2019, the Lombardia region in Italy awarded the NOCTUA programme, aiming at monitoring ground infrastructure and natural hazards by means of a dedicated Synthetic Aperture Radar satellite. MetaSensing is providing the StarSAR-X, its phased array X-band SAR payload together with the SAR Ground Processing Facility. The SAR Payload will be hosted on the ION2 platform built by D-Orbits resulting in a small high-performance SAR satellite designed for repeat pass Differential interferometry at X-band. This paper describes the design and development status of the StarSAR-X.

In summer 2019 the SARSense campaign was held in Jülich, Germany, to provide insights into the potentials and specifications of the ESA Copernicus candidate mission ROSE-L (Radar Observation System for Europe). ROSE-L will consist of two satellites that carry a polarimetric L-band SAR. Since the L-band signal can penetrate through many natural materials such as vegetation, dry snow and ice, the mission will provide additional information that cannot be gathered by the Copernicus Sentinel-1 C-band SAR mission. The overall objective of the SARSense 2019 campaign is to analyze the mission design concerning its potential for agricultural monitoring services including target applications such as soil moisture monitoring, irrigation management, crop type discrimination, food security and precision farming. The SARSense in situ measurements of soil moisture, soil temperature, vegetation properties, UAS-based multispectral and thermal mapping, as well as the airborne SAR observations are presented as well as strategies for soil moisture retrieval and first analysis.