Variational Reconstruction and Simulation Experiments of Sea Surface Wind Field for Ocean Data Buoy

The sea surface wind field is an important physical parameter in oceanography and meteorology.With the continuous refinement of numerical weather prediction,air-sea interface materials,energy exchange,and other studies,three-dimensional(3D)wind field distribution at local locations on the sea surface must be measured accurately.The current in-situ observation of sea surface wind parameters is mainly achieved through the installation of wind sensors on ocean data buoys.However,the results obtained from this single-point measurement method cannot reflect wind field distribution in a vertical direction above the sea surface.Thus,the present paper proposes a theoretical framework for the optimal inversion of the 3D wind field structure variation in the area where the buoy is located.The variation analysis method is first used to reconstruct the wind field distribution at different heights of the buoy,after which theoretical analysis verification and numerical simulation experiments are conducted.The results indicate that the use of variational methods to reconstruct 3D wind fields is significantly effective in eliminating disturbance errors in observations,which also verifies the correctness of the theoretical analysis of this method.The findings of this article can provide a reference for the layout optimization design of wind measuring instruments in buoy observation systems and also provide theoretical guidance for the design of new observation buoys in the future.

Distribution law of rice pollen in the wind field of small UAV

The wind field produced by the rotor-wing UAV has a significant impact on the distribution of rice pollen,which directly influences hybrid rice breeding.This research aimed to explore the distribution law of rice pollen in the wind field of small UAV.Aviation Beidou Positioning System UB351 positions all sampling nodes for precise corresponding coordinates and spacing information,and draws UVA’s flying trajectories,thus providing accurate data for tests.Wireless sensor network measurement system was used to study the three-direction wind field produced by the rotor-wing UAV under various experimental factors and acquires wind field width and wind speed,and the data were compared with the area ratio and width of pollen distribution.Test of univariate normality was conducted through Shapiro-Wilk test and Kolmogorov-Smimov test.In order to figure out the appropriate flight speed for UAV’s pollination under pollen distribution law,it is also necessary to perform analysis of variances on regression model.The comparison of wind speed in longitudinal(X)and lateral(Y)direction show that as the major force of the horizontal wind field produced by the rotor-wing UAV,the wind from Y-direction forms the widest wind field.Moreover,flight speed mainly influences wind field width.To be specific,the width of horizontal wind field decreases as flight speed increases.Meanwhile,UAV flight speed also exerts significant impact on vertical wind field.Both the pollen distribution width of more than 5 pollen grains and the area ratio reached the maximum when the UAV flight was at 4.53 m/s,which was the most favorable speed to pollination.In addition,pollen quantity is closely associated with both horizontal and vertical wind field.With comparison of the pollen quantity of sampling nodes,it was found that the wind field produced by the rotor-wing UAV exerted asymmetrical impact on pollen distribution.Q-Q plot of SPSS verifies that pollen distribution is against normal distribution.The establishment of a multiple linear regression model of pollen distribution and wind speed in three directions indicates that pollen distribution quantity only shares positive linear relation with the wind field in X-direction.These findings provide a theoretical guidance for rice pollination by using agricultural UAVs.