The Chinese HY-2C satellite was launched on Sep. 21, 2020, carrying the new Ku-band scatterometer (HSCAT-C). Different from the other currently operating scatterometers, the HSCAT-C is in a nonsun-synchronous orbit and as such it will be useful for the cross-calibration of sea surface wind products from current space-borne scatterometers and radiometers. In this article, the HSCAT-C wind products are validated by comparing to collocated winds from buoys, European Centre for Medium-Range Weather Forecasts model, and several other scatterometers. The results show that the quality of HSCAT-C winds is very good: in comparison with buoy winds, the wind speed standard deviation and direction root-mean-square error are 1.03 m/s and 15.9°, respectively. The HSCAT-C winds show very good agreements with the HSCAT-B winds, especially in the range of [4, 17] m/s. In addition, as HSCAT-C is a rotating pencil-beam scatterometer, some common error characteristics are also clearly found in the wind products. Based on the validation results and existing scatterometer application experience, it is believed that the availability of the HSCAT-C wind product would greatly benefit the scientific and user community.

Estuarine wetlands have experienced a variety of ecological and environmental problems caused by natural and anthropogenic factors. China has proposed a series of measures and made great efforts to control coastal degradation; however, decision makers still urgently need to know which measures to implement and how they will influence the estuarine environment and functions. This study used field observations, a hydrodynamic model, and statistical methods to investigate the effects of potential restoration scenarios on hydrodynamic conditions in the tidal-influenced estuarine wetland system, Liaodong Bay (China). Results reveal that the average total phosphorus, organic carbon, available phosphorus, pH, total nitrogen content, and moisture content in the soil and sediment environment were 0.04 ± 0.003%, 0.84 ± 0.25%, 16.3 ± 4.7 mg/kg, 8.3 ± 0.1, 0.07 ± 0.02%, and 44 ± 2%, respectively, exhibiting an overall trend of degradation. A series of restoration scenarios in regards to hydrodynamic regulation and tidal inputs were used to preserve the ecological value of the estuarine wetland. Model simulations indicate that the significant improvement of hydrodynamic fields (inundation depth and flow velocity) is more likely to occur when the tidal amplitudes reach around 2 m, while relatively weak responses can be observed when the tidal levels are lower than 1 m. Additionally, the construction of floodgates may play a key role in determining the tidal inputs and flowpaths across the wetland. The modifications in micro-topography of the wetland may play a complementary role in enhancing the connectivity condition via increased creek depth of 0.5 m and width up to around 20 m. This work represents a first attempt in exploring hydrodynamic effects of restoration scenarios for a tidal-dominated wetland. An improved understanding of the estuarine system also highlights that the design and implementation of wetland restoration projects should use more comprehensive measures to achieve long-term landscape management, connectivity planning, and ecological sustainability.

The China France Oceanography Satellite (CFOSAT) and Haiyang‐2B (HY‐2B) satellites were successively launched in China on the 29^th and 25^th of October 2018, respectively. HY‐2B carries the second Chinese radar altimeter along with three other microwave sensors, whereas CFOSAT contains the first Surface Waves Investigation and Monitoring (SWIM) instrument and a fan beam rotating scatterometer. As missions for measuring the dynamic marine environment, both satellites can measure the nadir significant wave height (SWH). For data obtained from a newly launched satellite to be utilized with confidence, the quality of SWH from the two satellites requires validation. In this study, the HY‐2B altimeter and CFOSAT nadir SWHs have been validated against the National Data Buoy Center (NDBC) buoys and the Jason‐3 altimeter SWH data, respectively, which resulted in CFOSAT nadir SWH having the best accuracy and HY‐2B having the best precision. The SWHs of the two missions are also calibrated by Jason‐3 and NDBC buoys. Following calibration, the root mean square error (RMSE) of CFOSAT and HY‐2B are 0.21 and 0.27 cm, respectively, when compared to Jason‐3, and 0.23 and 0.30 cm, respectively, compared to the buoys. Our results show that the two missions can provide good‐quality SWH and can be relied upon as a new data resource of global SWH.

This paper reports Ku-band normalized radar cross section (NRCS) at low incidence angles ranging from 0° to 18° and in the wind speed range from 6 to 70 m/s. The precipitation radar onboard the tropical rainfall measuring mission and Jason-1 and 2 have provided 152 hurricanes observations between 2008 and 2013 that were collocated with stepped-frequency microwave radiometer measurements. It is found that the NRCS decreases with increasing incidence angle. The decrease is more dramatic in the 40–70 m/s range of wind speeds than in the 6–20 m/s range, indicating that the NRCS is very sensitive to low incidence angles under extreme wind conditions and insensitive to the extreme wind speed. Consequently, the sea surface appears relatively “smooth” to Ku-band electromagnetic microwaves. This phenomenon validates the observed drag coefficient reduction under extreme wind conditions, from a remote sensing viewpoint. Using the NRCS dependence on incidence angle under extreme wind conditions, we also present an empirical linear relationship between NRCS and incidence angles, which may assist future-satellites missions operating at small incidence angles to measure sea surface wind and wave field.

The total mean square slope (mss) of large-scale (in comparison with the scale of radar wavelengths) ocean waves can describe the roughness of the ocean surface. This important parameter has found many applications and can be determined by the dependence of large-scale mss on azimuthal angles. The Surface Waves Investigation and Monitoring instrument onboard the China France Oceanography Satellite (CFOSAT) can provide a 2-D normalized backscattering radar cross section (NRCS) for 2-D global ocean-surface wave detection. In this article, the 2-D NRCS is used to calculate the total large-scale mss via two methods. The first method is constructed from regression, while the second scheme is derived from a three-solution method. Finally, the total large-scale mss is calculated using these methods, and the map of the distribution of the global total mss is presented for the first time. Our results show that the two sources of total large-scale mss obtained are consistent with each other. CFOSAT can provide a 2-D total large-scale mss map and be used as a new data resource for global applications.