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The Yellow Sea is a strongly tidally-driven and highly stratified shallow sea due to the presence of the Yellow Sea Cold Water Masses. Observations show that the near-inertial event sustains for 10 days with a peak near-inertial velocity of 0.15m/s, which accounts for 30% of the total velocity during the passage of a cyclone. Near-inertial velocity is dominated by the first baroclinic mode with one zero-crossing at the depth of the maximum stratification and two velocity peaks in the mixed layer and below the thermocline, respectively. Combined with numerical simulation analysis, it was found that the two velocity peaks are controlled by stratification and tides. In the mixed layer, the near-inertial peak is induced by wind stress, but the strong stratification constrains the downward propagation of the near-inertial energy. With respect to the near-inertial peak below the thermocline, it is associated with a barotropic wave generated at the coast and propagating offshore. However, the near-inertial flow within the bottom layer is reduced by the eddy viscosity of the tidal currents. Within the thermocline, the pronounced vertical convection due to velocity shear weakens the intensity of the near-inertial flow.

Currently micro/nano satellites have become the protagonists in most formation flying missions, and there is an urgent demand to propose a reliable approach for quick fuel estimation of multiple-impulsive scheme on-board to achieve formation reconfiguration problems. This paper presents an optimal control approach based on multiple impulses for satellite formation in-plane reconfiguration issue in near circular orbit. Based on initial small deviation in the cylindrical coordinates system, a relative orbit motion expression is investigated, and a time-varying propagate system without perturbation is presented in this paper, which is suitable to calculate the solution of relative orbital maneuver by multiple impulses. The formation reconfiguration problem of this relative orbit motion is considered, and orbital motion equations with initial deviations are presented for relative orbital transfer calculation. Through different combinations of method from normal four-impulsive solution, the optimal three-impulsive method for relative orbital transfer in plane is obtained by analysis solution based on graphical and numerical way. In the end of paper, the effectivity and optimality of method is validated, and fuel consumption is analyzed through simulations of assumptive different formation reconfiguration missions.

Numerical simulations of the eight major tidal constituents (M2, S2, K1, O1, N2, K2, P1, and Q1) in the Bohai, Yellow and East China Seas (BYES) were conducted using the Regional Ocean Modeling System (ROMS) based on altimeter products from X-TRACK. Tidal harmonic constants and two-dimensional tidal current data with a spatial resolution of 1/12° were obtained. To validate the simulation results (SRs), harmonic constants from altimeters and tide gauges, two sea level anomaly time series, and velocity observations from 12 current meters were utilized. Additionally, data from five tidal models were used for comparison. The validation and comparison results demonstrated the accuracy of SR, especially when compared with coastal tide gauge data where SR performs exceptionally well. The cotidal charts and tidal current ellipses obtained through SR exhibited good continuity and consistency with the previous studies, effectively reflecting the tidal characteristics of the BYES. The SR can serve as a valuable reference and support for tidal-related fields in the BYES, including the supplement and verification of ocean measurements and the calculation of reference planes for ocean engineering.