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Yongfeng Yang

Publications and source records attributed to Yongfeng Yang.

3 recordsLinked to original sources

Testing the physical reality of tidal bulges in the world's oceans

Persistent alternation of high and low water in coastal and oceanic regions has attracted human attention for millennia. This movement of water is generally explained through the double water bulge model. Although this model has been widely adopted in the scientific literature on tides since the 18th century, the physical existence of water bulges on the Earth's surface has yet to be verified. Herein, we establish a lunar angle phase-dependent statistical analysis of tide patterns at 362,370 oceanic locations spotted by Jason-3 satellite of AVISO in 2021 to address this issue. We show that during lunar angle phases of 0 degree-45 degree and 135 degree-180 degree, which spatially correspond to the water bulging regions expected in the double water bulge model, the number of low tides consistently exceeds that of high tides. Conversely, during lunar angle phase of 45 degree-135 degree, which spatially correspond to the water-depressing region expected in the model, high tides predominantly outnumber low tides. These findings evidently contradict the physical existence of two water bulges in the world's oceans, suggesting that the scientific community should pay additional attention to alternative explanations for tides, such as gravitational forcing mechanism and oceanic basin oscillation-generated driving mechanism.

physics.ao-ph

An oceanic basin oscillation-driving mechanism for tides

Tides represent the daily alternations of high and low waters along coastlines and in oceans, and the current theory (termed the gravitational forcing mechanism) explains them as a manifestation of the response of ocean water to the Moon's (Sun's) gravitational force. However, although the purely hydrodynamic models representing the current theory have been widely tested over global ocean,their tidal elevation accuracies are generally low. This implies an uncertainty as to whether the gravitational forcing mechanism is the best explanation for tides. In this study, we present a new theory (termed the oceanic basin oscillation-driving mechanism), in which tides are explained as a manifestation of oscillating ocean basin that is intricately linked to the elongated spinning solid Earth due to the Moon (Sun). Based on this new theory, we develop an algebraic tide model and test it using 11-year observations from 33 bottom pressure stations over the Pacific Ocean, the average Root Mean Square (RMS) deviation of tidal elevation predicted by this model against observation is 7.54 cm. Using a ratio of M2 elevation RMS of ocean tide model EOT11a and its total tidal elevation RMS as a reference, we estimate the total tidal elevation RMS of six purely hydrodynamic models (i.e.,Hallberg Isopycnal Model, OSU Tidal Inversion software-GN ,STORMTIDE model, OSU Tidal Inversion Software-ERB,STM-1B, and HYbrid Coordinate Ocean Model to be 59.93, 51.64, 57.05, 38.56, 86.92, and 53.56 cm, respectively.

physics.ao-ph

A rotational ellipsoid model for solid Earth tide with high precision

Solid Earth tide represents the response of solid Earth to the lunar (solar) gravitational force. The yielding solid Earth due to the force has been thought to be a prolate ellipsoid since the time of Lord Kelvin, yet the ellipsoid's geometry such as major semi-axis's length, minor semi-axis's length, and flattening remains unresolved. Additionally, the tidal displacement of reference point is conventionally resolved through a combination of expanded potential equations and given Earth model. Here we present a geometric model in which both the ellipsoid's geometry and the tidal displacement of reference point can be resolved through a rotating ellipse with respect to the Moon (Sun). We test the geometric model using 23-year gravity data from 22 superconducting gravimeter (SG) stations and compare it with the current model recommended by the IERS (International Earth Rotation System) conventions (2010), the average Root Mean Square (RMS) deviation of the gravity change yielded by the geometric model against observation is 6.47 \mu Gal (equivalent to 2.07 cm), while that yielded by the current model is 30.77 \mu Gal (equivalent to 9.85 cm). The geometric model will greatly contribute to many application fields such as geodesy, geophysics, astronomy, and oceanography.

physics.geo-ph