SARSense: Technical Assistance for Airborne Measurements during the SAR Sentinel Experiment

The SARSense campaign in the Jülich area (Germany) in summer 2019 was performed to support the ESA Copernicus high priority mission ROSE-L. Airborne SAR signals in C- and L-band, drone imagery, in situ soil and plant parameters, as well as biophysical variables in the lab were measured to provide a comprehensive data set to study details of the mission design for agricultural applications. Although an in depth analysis will be performed soon, the preliminary outcome of the dry summer example campaign is as follows: - An L-band SAR monitoring in the Copernicus program will provide an added value to the existing C-band capacities of Sentinel-1 (A/B). - Simultaneous C- and L-band observations may help to disentangle the different processes in the plant and the soil. Single frequency observations may tend to be misinterpreted. The main objectives of SARSense are: - investigate the use of L & C-band SAR data for soil moisture retrieval at high resolution (i.e., 0.1-1.0 km). Both the case of temporally collocated L & C-band SAR time series and that of independent acquisitions will be investigated. - extend the existing airborne SAR programme to new test sites (Jülich, Germany) and acquire reference L- and C-band airborne SAR datasets collocated in time and space over different well-defined land-cover including agricultural and forested regions. - document the added value of L-band SAR in addressing current EO measurement gaps (soil moisture, vegetation biomass, etc.) and enhanced continuity together with other missions such as Sentinel-1. - support specification of the time interval/latency between Sentinel-1 and L-band SAR coverage for time-critical application products such as soil moisture. - support trade-off and definition of other key missions parameters in Phase-A/-B1 (noise floor, resolution). The objectives shall be addressed through the design of the campaign acquisitions, the data acquisition, processing and documentation and preliminary analyses to provide first answers to key mission design needs. The later includes documenting the unique value of L-band SAR and trade-offs on the C- and L-band time-latency between acquisitions. The flight configuration is 2 fully polarimetric L- and C-band SAR on 1 aircraft. The SARSense campaign will cover a number of vegetation types focussing on agricultural and forest areas in order to satisfy all of the campaign objectives.