The present invention will be described in detail below in conjunction with specific embodiments.
 The invention provides a method for calculating the secondary tide distribution experience and tide graph based on relative admittance, including the following calculation steps:
 Step S1, for a certain main tidal component n, the admittance An is:
 among them H n And g n Are the corrected amplitude, amplitude and lag angle of the main tidal component, C n Is the tidal force coefficient (see Chen Zongyong, 1980 ; Fang Guohong et al., 1986  , Huang Zuke, Huang Lei, 2005  );
 Step S2, in the same tide family, define the relative admittance of the secondary tidal component m to the primary tidal component n as:
 among them,
 r m/n =g m -g n (4)
 H in formula (3) m /H n Is the amplitude ratio in traditional tidal science, g m -g n Is the late angle difference; if the amplitude ratio of the actual tidal component is the same as the ratio of the tidal force, then Equal to 1, the actual ocean It will not be exactly equal to 1, but it is close to 1 for most sea areas; if the delay angles of the two partial tides are equal, then r m/n Equal to zero, r in the actual ocean m/n Generally not equal to zero, for most sea areas, it is greater than zero (if m tidal angular velocity is greater than n tidal) or less than zero (if m tidal angular velocity is less than n tidal);
 In step S3, according to equations (3) and (4), the amplitude and delay angle of the secondary tidal component m are derived as:
 g m =r m/n +g n (6)
 Using the above-mentioned data, the same tide graph of small sub-tides can be drawn.
 Among them, the specific calculation steps of step S2 are as follows:
 Step S201, the main tidal component is M 2 , S 2 , K 1 , O 1 , The secondary component is N 2 , K 2 , P 1 , Q 1 ,
 Then the amplitude ratio is The delay angle difference is
 Suppose the amplitude ratio is H and the retardation angle difference is g, record A=Hsing, B=Hcosg;
 Step S202, if there are N tide gauge observation points in a certain sea area, they are represented by i (i=1, 2,...,N), and the latitude and longitude of each point is among them Use negative values for southern latitude, λ, In degrees, then H i And g i Is the amplitude ratio and delay angle difference of the observation points of each tide gauge station, and the distance from the observation station i to the other stations is:
 The weighted average of i points is:
 Among them, in formula (9) and formula (10), Represents the sum of all observation points, but does not include point i;
 Step S203, use the following steps to determine the relative admittance R of point i i :
 The water depth of each grid point m in and around the sea area is Dm, and the latitude and longitude of point m is m=1,2...,M, the distance between grid point m and tide gauge station i is:
 Select all r im 6 m) points, average the water depth values of these points and record as Calculate the corresponding Kelvin wave velocity:
 Kelvin wave wavelength:
 L i = U i T (13)
 Among them, T is the tidal wave period, namely
 T=360°/ω (14)
 Among them, ω is the tidal wave angular velocity;
 Last selected
 R i =κL i (κ=1/4) (15);
 Step S204, according to step S402, calculate all points i=1, 2..., N with And calculate:
 Root mean square deviation
 δ i ≥mσ (18)
 It is considered that the data at the i-th point may be abnormal, then R i Round it down, m takes 2;
 In step S205, each grid point is set in the sea area according to a predetermined resolution, and the serial number of each grid point is k (k=1, 2...), and the corresponding latitude and longitude is Calculate the distance from point k to each observation point i as
 Find the weighted average of k points
 Step S206, calculate R according to the algorithm of step S403 k , And discard data abnormal values according to the algorithm of step S404;
 The specific calculation steps of step S3 are as follows:
 Step S301, by with Inversely calculate the amplitude ratio of each grid point And late angle difference
 In step S302, after obtaining the relative admittance of m to n component, the harmonic constant of m component can be derived from the harmonic constant of n component according to equations (3) and (4):
 g m =r m/n +g n (6)
 Use the above data to draw the corresponding tide map.
 Further, verify that the remaining R after removing the outliers in step S204 i , And use the following steps:
 by with Inversely calculate the amplitude ratio of each observation point And late angle difference
 Then by
 Calculate the mean square error of the amplitude ratio and the delay angle difference
 After testing, the above amplitude ratio And late angle difference All are within the error range and meet the accuracy requirements.
 Using the relative admittance (equivalent to amplitude ratio and delay angle difference) between the secondary tidal component and the main tidal component to calculate the harmonic constant of the secondary tidal component can often obtain more accurate results (for example, Fang Guohong, 1974  ). Fang (1994  ) Also gives details of Bo, Huang, and Donghai S 2 Relative to M 2 And K 1 Relative to O 1 The distribution of amplitude ratio and delay angle difference.
 The present invention first uses the harmonic constants (amplitude and lag angle) of the coastal tide gauge stations to obtain the relative admittance distribution of the studied sea area, and then further uses the harmonic constants and relative admittances of the main tidal components in the sea area to give the secondary tidal components Distribution, can effectively reduce the relative error of the detection results, with high accuracy.
 The present invention is not limited to the above-mentioned best embodiment. Anyone should know that structural changes made under the enlightenment of the present invention, and any technical solutions that are the same or similar to the present invention, fall within the protection scope of the present invention.