Gaofen-3 (GF-3), the first Chinese spaceborne synthetic aperture radar (SAR) in C-band for civil applications, was launched on August 2016. Some studies have examined the use of GF-3 SAR data for ocean and coastal observations, but these studies generally focus on one particular application. As GF-3 has been in operation over two years, it is essential to evaluate its performance in ocean observation, a primary goal of the GF-3 launch. In this paper, we offer an overview demonstrating the capabilities of GF-3 SAR in ocean and coastal observations by presenting several representative cases, i.e., the monitoring of intertidal flats, offshore tidal turbulent wakes and oceanic internal waves, to highlight the GF-3’s full polarimetry, high spatial resolution and wide-swath imaging advantages. Moreover, we also present a detailed analysis of the use of GF-3 quad-polarization data for sea surface wind retrievals and wave mode data for sea surface wave retrievals. The case studies and statistical analysis suggest that GF-3 has good ocean and coastal monitoring capabilities, though further improvements are possible, particularly in radiometric calibration and stable image quality.

The Synthetic Aperture Radar (SAR) Wave Mode (WM) is an imaging mode dedicated to ocean surface wave observation. Since the first used in the ERS-1/SAR in 1991, this imaging mode has been continuously acquired by ERS-2, ENVISAT/ASAR, Sentinel-1A/1B and the GaoFen-3, and has been providing ocean wave observation data for almost 30 years. As the Envisat/ASAR has the longest archived WM data, we used a parametric model named CWAVE_ENV to retrieve ocean wave parameters of significant wave height (SWH) and mean wave period (MWP) from all the ASAR WM data in its lifetime from December 2002 to April 2012. By comparing with the ECMWF and NDBC buoy data, we found good agreements between the ASAR retrieved results and the buoy measurements. The retrieved ASAR integral wave parameters are further calibrated using the buoy measurements based on the Reduced Majored Axes (RMA) regression method. By calibration, the bias of SWH and MWP are improved from −0.06 m to 0.00 m and from −0.19 s to 0.00 s. Cross-validation of the calibrated ASAR wave parameters with the JASON-1 Radar Altimeter SWH also shows a good consistency, with the correlation coefficient of 0.93, the bias and RMSE of 0.18 m and 0.53 m, respectively. The proposed 10-year global wave product could be a good complementary to the Radar Altimeter product and possible good dataset for wave climate study. A preliminary result of using these data for global wave analysis is shown as well in this paper.