C-SAR instrument design for the Sentinel-1 mission

A Prototype Software Package to Retrieve Soil Moisture From Sentinel-1 Data by Using a Bayesian Multitemporal Algorithm

“…S-1 will ensure the continuity of the series of C-band SAR instruments that begun with ERS-1 and continued with ERS-2, ENVISAT/ASAR and RADARSAT. The two-satellite constellation will offer six days exact repeat [9] and is expected to provide coverage over Europe and Canada in 1-3 days [14]. The SAR sensors will operate in two main modes: Interferometric Wide Swath (IW) and Wave.…”

“…the limits of validity of the SEM and the expected range of variability of the target parameters ([0.03-0.4] for , [0. [2][3][4][5] cm for and [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] cm for ). The first condition encompasses the second one, except for the upper limit of which has been slightly extended up to 0.4 to account for the range of expected soil moisture values; this extension of the model validity has been however assessed in the literature, as previously discussed [7], [19].…”

“…This condition is found by using and cross-polarized data (when available) through the logical AND of the following conditions: (9) In order to apply the vegetation correction, only vegetated pixels which likely correspond to sparse vegetation without significant multiple scattering (SparseMask) can be retained. SparseMask basically includes pixels that verify (8), and do not verify (9).…”

“…This condition is found by using and cross-polarized data (when available) through the logical AND of the following conditions: (9) In order to apply the vegetation correction, only vegetated pixels which likely correspond to sparse vegetation without significant multiple scattering (SparseMask) can be retained. SparseMask basically includes pixels that verify (8), and do not verify (9). However, an additional test verifies that the co-polarized return is not too much higher than the average return from bare soils, in order to ensure that multiple scattering effects possibly caused by vegetation are actually negligible (i.e., vegetation is actually sparse).…”

“…Conversely, the use of high resolution Synthetic Aperture Radar (SAR) systems to retrieve allows for the generation of soil moisture products with resolution varying from hundreds of meters [7] to 1 km [8]. Although SAR temporal resolution has been generally considered as a critical aspect for soil moisture applications so far, the forthcoming European Space Agency (ESA) Sentinel-1 (S-1) mission, which is an element of the European Global Monitoring for Environment and Security (GMES) program, will provide C-band radar data characterized by short revisit time (the two-satellite constellation will offer six days exact repeat [9]). …”