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Estuaries and coasts runoff plays a crucial role in the dynamics of the ocean system. However, the current emphasis on synthetic aperture radar (SAR) retrieved current velocities has been on studying strong boundary currents and large-scale ocean circulation, resulting in relatively limited observational research on estuarine current velocities. This study aims to observe the current velocities in the Yangtze River estuary area using Sentinel-1A SAR data. The findings indicate a high agreement between the current velocities retrieved by Sentinel-1A and those observed at hydrographic stations, showcasing the characteristics of current velocity distribution associated with seafloor topography. This highlights the significant potential of SAR in observing estuarine current velocities, contributing to the analysis of benthic topography and the statistics of river runoff. [ABSTRACT FROM AUTHOR]

This study quantitatively analyzes how cross-track phase interference affects sea surface current inversion accuracy in ATI. It then suggests a calculation method for this phase over the ocean, enhancing ATI accuracy: RMSE 0.037 m/s using HYCOM data, 0.023 m/s with Himawari, compared to average buoy velocity of 0.131 m/s. [ABSTRACT FROM AUTHOR]

In this paper, the current field modulation is described using a solution of the wave action equation. Using an integrated equation model (IEM), a current field modulated scattering model is established. The sea surface backscattering coefficient decreases with increasing current speed. At high wind speeds, the change of backscattering coefficient under 1 m $ \cdot $ ⋅ s−1 current field modulation is about 1 dB. An increase of 60° in the angle between wind and current direction leads to a decrease of 1.5 dB in the modulation coefficient. Finally, the model is verified using satellite data. [ABSTRACT FROM AUTHOR]

The Wiener index is one of the most classic and widely used indicators in topology. It reflects the average distance of any node pair in the graph. It not only makes the boundaries of given graphs clearer but also continuously generates topological indices that are more suitable for new fields, such as the Gutman index. The Wiener index and Gutman index are two important topological indices, which are commonly used to describe the characteristics of molecular structure. They are closely related to the physical and chemical properties of molecular compounds. And they are widely used to predict the physical and chemical properties and biological activity of molecular compounds. In this paper, we study the vertex Gutman index and Gutman index and describe the structural characteristics of all cases of two simple cycles intersecting. We comprehensively analyze the Gutman index and vertex Gutman index in these cases in detail by means of classification discussion and analogical reasoning and characterize their maximum and minimum accordingly. [ABSTRACT FROM AUTHOR]

The Interferometric Imaging Radar Altimeter (InIRA) is alow-orbit single-frequency altimeter whose signals are subject to an ionospheric delay, which introduces measurement errors. Additionally, some difficulties, such as selecting the interpolation algorithm and intercepting the height scale, arise when applying the ionospheric correction model. Based on Sentinel-3A dual-frequency measurements, this paper suggests that linear variogram-based kriging is suitable for spatial interpolation, and the total electron content height scale coefficient calculated by the hierarchical IRI forecast model can be applied to the interpolated GIM intercept. When the improved GIM value is applied to four scenes of InIRA data, the obtained Ku-band ionospheric correction varies from 1.49cm to 1.57cm. [ABSTRACT FROM AUTHOR]