CN108120424A - A kind of zone digit height datum Model Calculating Method - Google Patents

Abstract

The present invention relates to a kind of zone digit height datum Model Calculating Methods, belong to electronic information field, take into account between 1985 state height benchmark and global elevation datum on the basis of vertical missing, joint GOCE Dir5 building global gravitational field models and EGM08 building global gravitational field models, using the computational methods for taking ellipsoid difference into account, the computational methods of the unified zone digit height datum model to CGCS2000 ellipsoids of structure.Advantage is, reference ellipsoid for triones navigation system is CGCS2000 ellipsoids, consider the influence that ellipsoid difference, vertical missing etc. are brought, structure adapts to the zone digit height datum model of China's elevation system, and precision, which can improve precision, can improve 40% to 60%.

Description

A kind of zone digit height datum Model Calculating Method

Technical field

The present invention relates to a kind of zone digit height datum Model Calculating Methods, belong to electronic information field.

Background technology

Beidou navigation terminal is the important carrier that triones navigation system serves the development of the national economy, by the city of more than ten years Field is cultivated, and ownership goal is progressively clear and definite with demand, and application market has been started up, and is just stepping into the fast of commercial applications now Fast developing period.At present, using GNSS location location technology, navigation terminal realizes the real-time acquisition of horizontal level, but measures Elevation be geodetic height.Defect is that satellite navigation application market is desirable for absolute elevation, i.e., normal high rather than geodetic height. Therefore the high-precision three-dimensional coordinate of measuring point is if desired obtained, including geodetic latitude, geodetic longitude, normal height, it is necessary to which joint carries out GNSS is measured and the measurement of the level.Therefore there is an urgent need for establishing global or national geoid's model, with geoid mould Offset replaces traditional measurement of the level value, realizes conventional measurement mode to the transformation for modernizing measurement pattern.

In the commercial navigations data processing software such as GrafNav, EGM2008 geoid's models are commonly used as benchmark Calculate absolute elevation.But EGM2008 geoid's models are what the reference ellipsoid based on EGM2008 gravity field models was built, And the reference ellipsoid of triones navigation system is CGCS2000 ellipsoids, the parameter of the two is different, as the major semiaxis of CGCS2000 is 6378137 meters, and the reference ellipsoid of EGM gravity field models is 6378136.3 meters, directly applies EGM2008 geoid moulds Error caused by type will bring reference ellipsoid inconsistent into Beidou navigation terminal；EGM2008 gravity field models only with A small amount of Satellite gravity data are not so good as the GOCE gravity based on the structure of Satellite gravity data for many years in the precision of middle long wavelength part Field model.The height above sea level in China exists using 1985 Huanghai Sea height datums as start of calculation face with global geoid's model Nearly 30 centimetres of system deviation.Therefore, it is necessary to consider ellipsoid in the acquisition of Beidou navigation terminal high-precision absolute elevation The influence that difference, vertical missing etc. are brought, structure adapt to the zone digit height datum model of China's elevation system.

The content of the invention

It is an object of the invention to provide a kind of zone digit height datum Model Calculating Method, so as to overcome the prior art Deficiency.

The invention is realized by the following technical scheme, takes into account vertical between 1985 state height benchmark and global elevation datum On the basis of deviation, combine GOCE-Dir5 building global gravitational field models and EGM08 building global gravitational field models, it is poor using ellipsoid is taken into account Different computational methods, the computational methods of the unified zone digit height datum model to CGCS2000 ellipsoids of structure.

Step 1, combine GOCE-DIR5 and EGM2008 and calculate geoid,

Geoid is calculated according to gravity field modelFormula is：

In formula,It is to calculate the earth's core of point to footpath, colatitude and longitude respectively,For reference ellipsoid major radius,For The product of universal gravitational constant and earth gross mass,It is m potential coefficient of standardizing completely of n ranks, For associate Legendre functions,It is top step number；

Step 2, take ellipsoid difference into account to unify geoid to CGCS2000 ellipsoids,

It is inconsistent in view of the corresponding reference ellipsoid parameter of gravity field model of different tissues issue, therefore by gravitational field potential coefficient It is unified to arrive CGCS2000 ellipsoids,

Specific formula for calculation is：

In formula,It is the corresponding gravitational constant of gravity field model, length respectively Semiaxis and potential coefficient,It is that CGCS2000 reference ellipsoids are corresponding respectively Parameter；

Step 3, vertical missing structure zone digit height datum model is taken into account,

By the use of GPS/ levels eyeball as the standard that checks, the geoid that EGM2008 gravity field models calculate is in the essence in the whole world Spend for 13 centimetres, using the long wavelength component of GOCE-DIR5 model refinement EGM2008 gravity field models, precision can improve 40% to 60%。

The principle of the present invention is, for the geoid that building global gravitational field model EGM2008 is calculated in low-frequency range essence The problem of degree is not high, the present invention propose the spherical harmonic coefficient of joint GOCE_DIR5 gravity field models and EGM2008 gravity field models Geoid is calculated, to improve the precision of EGM2008 geoid digital models；For building global gravitational field model and the Big Dipper The problem of reference ellipsoid of navigation system is inconsistent using the computational methods for taking ellipsoid difference into account, will be based on earth's gravity field mould The geoid that type calculates is unified onto CGCS2000 reference ellipsoids where triones navigation system；Take 1985 state height bases into account Vertical missing between accurate and global elevation datum, establishes reduction to the zone digit height datum of 1985 state height benchmark of China Model.

It is an advantage of the current invention that the reference ellipsoid for triones navigation system is CGCS2000 ellipsoids, consider ellipse The influence that spherical aberration is different, vertical missing etc. is brought, structure adapt to the zone digit height datum model of China's elevation system, precision energy Improve 40% to 60%.

Description of the drawings

Fig. 1 is zone digit height datum illustraton of model.

Specific embodiment

Elevation information is the important component of space-time position, and it is mapping navigation information to obtain high-precision height above sea level in real time One of committed step.Beidou navigation terminal can quickly and efficiently measure geodetic height, the digital elevation benchmark model of combined high precision, Accurate absolute elevation can be obtained in real time.Taking the basis of vertical missing between 1985 state height benchmark and global elevation datum into account On, the unified zone digit height datum model to CGCS2000 ellipsoids is constructed based on GOCE+EGM08 gravity field models, it should Model scope corresponds to the coverage of Big Dipper area navigation, i.e. 55 degree of south latitude arrives east longitude 180 degree to 55 degree of north latitude, 55 degree of east longitude, Model accuracy is better than meter level, meets the application demand of Beidou navigation terminal-pair height above sea level.

1 pair of the preferred embodiment of the present invention is described further below in conjunction with the accompanying drawings：Take into account 1985 state height benchmark with Between global elevation datum on the basis of vertical missing, combine GOCE-Dir5 building global gravitational field models and EGM08 earth's gravity fields Model, using the computational methods for taking ellipsoid difference into account, the unified zone digit height datum model to CGCS2000 ellipsoids of structure Computational methods.

The present invention includes the following steps：

Step 1, combine GOCE-DIR5 and EGM2008 and calculate geoid,

Geoid is calculated according to gravity field modelFormula is：

In formula,It is to calculate the earth's core of point to footpath, colatitude and longitude respectively,For reference ellipsoid major radius,For The product of universal gravitational constant and earth gross mass,It is m potential coefficient of standardizing completely of n ranks, For associate Legendre functions,It is top step number.

The spheric harmonic expansion order number of EGM2008 gravity field models is 2159, and provides and expand to 2190 ranks, the expansion of 2159 times Open up coefficient；There are GRACE Satellite gravities data, Altimetry Data and high-resolution in the key data source that gravity field model uses Terrain data and high-precision ground gravity data etc.；GOCE-DIR5 models are published on 2014, and highest order is 300, the mould Data are GOCE, the GRACE and laser geodynamic satellite on October 2nd, 1 day 1 November in 2009 used by type The observation data of LAGEOS, valid data duration 42 totally months.The geoid precision of current GOCE models is after 200 ranks It is also less high, accumulated error less stable, and the geoid that EGM2008 gravity field models calculate is tired after 200 ranks Product error but gradually tends towards stability.In view of DIR5 gravity field models model and EGM2008 gravity field models in different frequency range Characteristic, this patent calculate the earth level using EGM2008 gravity field models of the 200 rank DIR5 gravity field models plus 2160 ranks Face.

Step 2, take ellipsoid difference into account to unify geoid to CGCS2000 ellipsoids,

It is inconsistent in view of the corresponding reference ellipsoid parameter of gravity field model of different tissues issue, therefore by gravitational field potential coefficient It is unified to arrive CGCS2000 ellipsoids,

Specific formula for calculation is：

In formula,It is the corresponding gravitational constant of gravity field model, length respectively Semiaxis and potential coefficient,It is that CGCS2000 reference ellipsoids are corresponding respectively Parameter；

Step 3, vertical missing structure zone digit height datum model is taken into account,

The currently employed local height datum in China, is referred to as 1985 state height benchmark, and start of calculation face is based on Qingdao huge port tidal observation It stands from 1952 to 1979 the mean sea level of the tidal observation material computation year obtained.The height datum is only in Qingdao huge port institute of tidal station Huang Hai mean sea level overlap, so the grid DEM face measured using the point as starting point is not big on traditional concept Ground-level.Domestic scholars using the GPS/ leveling datas of China mainland are distributed in, calculate 1985 state height benchmark with it is complete The vertical missing of ball geoid is 26 ± 5.0 centimetres.This patent is based on the local height datum of country and global the earth level Face vertical missing achievement builds zone digit height datum model.

Cover Asia-Pacific most area in view of Big Dipper service range（55 degree of south latitude arrives east to 55 degree of north latitude, 55 degree of east longitude Through 180 degree）, the scope of the digital elevation benchmark model constructed by this patent is the region, as shown in Figure 1.With GPS/ levels Eyeball is as the standard that checks, and precision of the geoid that EGM2008 gravity field models calculate in the whole world is 13 centimetres, at me The precision in state continent is 20 centimetres；Utilize the long wavelength component of GOCE-DIR5 model refinement EGM2008 gravity field models, precision energy Improve 40% to 60%.And the raising of this precision is for this field, has been a kind of significant progress and prominent substance Feature, particularly this patent conversion formula between ellipsoid in strict accordance with Gravity coefficients, by GOCE+EGM2008 gravitational field moulds Type potential coefficient is unified to the CGCS2000 ellipsoid consistent with triones navigation system, at the same account for 1985 state height benchmark with it is complete Vertical missing between ball height datum, therefore it is better than rice on the Precision Theory of the zone digit elevation model constructed by this patent Grade meets the application demand of Beidou navigation terminal.

Claims (2)

1. a kind of zone digit height datum Model Calculating Method, it is characterized in that：

Take into account between 1985 state height benchmark and global elevation datum on the basis of vertical missing, the joint GOCE-Dir5 whole world Gravity field model and EGM08 building global gravitational field models, using the computational methods for taking ellipsoid difference into account, structure is unified to CGCS2000 The computational methods of the zone digit height datum model of ellipsoid.

2. a kind of zone digit height datum Model Calculating Method according to claim 1, feature include the following steps：

Step 1, combine GOCE-DIR5 and EGM2008 and calculate geoid,

Geoid is calculated according to gravity field modelFormula is：

In formula,It is to calculate the earth's core of point to footpath, colatitude and longitude respectively,For reference ellipsoid major radius,For The product of universal gravitational constant and earth gross mass,It is m potential coefficient of standardizing completely of n ranks, For associate Legendre functions,It is top step number；

Step 2, take ellipsoid difference into account to unify geoid to CGCS2000 ellipsoids,

It is inconsistent in view of the corresponding reference ellipsoid parameter of gravity field model of different tissues issue, therefore by gravitational field potential coefficient It is unified to arrive CGCS2000 ellipsoids,

Specific formula for calculation is：

In formula,It is the corresponding gravitational constant of gravity field model, length respectively Semiaxis and potential coefficient,It is the corresponding parameter of CGCS2000 reference ellipsoids respectively；

Step 3, vertical missing structure zone digit height datum model is taken into account,

By the use of GPS/ levels eyeball as the standard that checks, the geoid that EGM2008 gravity field models calculate is in the essence in the whole world Spend for 13 centimetres, using the long wavelength component of GOCE-DIR5 model refinement EGM2008 gravity field models, precision can improve 40% to 60%。