Simulation of Sentinel-1A observations and constraint of water cloud model at the regional scale using a discrete scattering model

Effective calibration of microwave scattering model and accurate simulation of backscattering coefficient (σo) at the regional scale are essential for improving soil moisture retrieval based on active microwave remote sensing. This study investigates the potential of simulating the Sentinel-1A observations and constraining the coefficients of the water cloud model (WCM) at the regional scale based on a theoretical microwave scattering model named Tor Vergata model. The Tor Vergata discrete scattering model is firstly calibrated at both site- and regional-scale to find a single set of model parameters for capturing the Sentinel-1A observations at the regional scale. Subsequently, the coupled WCM and Oh model is calibrated at the regional scale based on three strategies, i.e., using either the calibrated Tor Vergata simulations or the Sentinel-1A observations, or with the assumption that the σo only comes from the vegetation contribution during the peak growth period. The investigation is conducted in a Tibetan meadow ecosystem configured with a long-term regional-scale soil moisture monitoring network.