CN109557594A - Gravity datum figure time-varying modification method and system based on gravity anomaly time-varying - Google Patents
Gravity datum figure time-varying modification method and system based on gravity anomaly time-varying Download PDFInfo
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- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
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Abstract
The invention discloses a kind of gravity datum figure time-varying modification method and system based on gravity anomaly time-varying.The gravimetric data obtained is resolved by GRACE satellite data first, a moon gravity field model is calculated, choosing certain month gravity field model is background gravity field model, the two asks difference to obtain the gravity anomaly variation formula under background gravitational field, and is filtered to this formula to eliminate the influence of north and south band error；Then gravitational field time-varying influence factor classify being abstracted to sum by influence principle and obtain gravity anomaly fitting formula, and filtered gravity anomaly variation formula is combined to obtain gravity anomaly change in long term rate, prediction of the realization to gravity anomalous variation；The gravity anomaly time-varying formula that current time is finally determined according to gravity anomaly change in long term rate, for obtaining time-varying amendment gravity datum figure, reducing the error hiding rate of gravity datum figure to the progress time-varying amendment of initial data used in gravity datum figure is prepared.
Description
Technical field
The present invention relates to control theory field is belonged to, pushed away at any time mainly for existing gravity datum figure navigation matching precision
The problem of shifting can reduce, and propose a kind of gravity datum figure time-varying modification method and system based on gravity anomaly time-varying.
Background technique
Intuitively think, remove outside the influence of factors such as earthquake, earth gravitational field be it is static constant, do not occur at any time
Variation, this is also the key point and basic point of departure that gravity value can be used as a kind of passive assisting navigation Matching Elements.
Progress with gravimetric technique and the further investigation to earth gravitational field, materials on the earth changes in distribution cause
The phenomenon that gravitational field changes at any time is found.Meanwhile with the sequential transmissions of Gravity Satellite, study Time-variable gravity at
For reality.Fig. 1 show the same area 2002 and local gravity anomaly schematic diagram in 2006, can significantly see the area
The GRAVITY ANOMALIES in domain is changed.
Currently, the prior art can be with the gravimetric data of precise measurement global range, precision is higher, but does not have time-varying
Property, only by repeatedly measurement just it can be found that gravity is changing.So, the weight drawn is removed by measuring obtained gravimetric data
Power reference map does not have time variation yet, in navigation and in the case where initial navigation works well, since timeliness lacks,
After preparing gravity datum figure, if the long period does not carry out time-varying amendment to it, when carrying out navigation matching again, just it will appear larger
Error, positioning accuracy is substantially reduced.
Summary of the invention
The object of the present invention is to provide a kind of gravity datum figure time-varying modification method and system based on gravity anomaly time-varying,
Gravity anomaly fitting formula is obtained by the way that the influence factor classification for causing gravity anomaly to change is abstract, and combines and eliminates north and south item
Gravity anomaly with error changes formula, obtains gravity anomaly time-varying formula, and is used for the time-varying amendment of gravity datum figure,
Reduce the error hiding rate of gravity datum figure.
To achieve the above object, the present invention provides following schemes:
A kind of gravity datum figure time-varying modification method based on gravity anomaly time-varying, the gravity datum figure time-varying amendment side
Method includes:
It is resolved according to GRACE satellite data and obtains gravimetric data, and according to the gravimetric data, obtain a moon gravitational field mould
Type；
Choosing any one month gravity field model is background gravity field model, and by the expression formula of the moon gravity field model
Difference calculating is carried out with the expression formula of the background gravity field model, the gravity anomaly variation obtained under the background gravitational field is public
Formula；
Space smoothing processing is carried out to gravity anomaly variation formula, determines smoothed out gravity anomaly variation formula；
Classification fitting is carried out to gravitational field time-varying influence factor, obtains gravity anomaly fitting formula；
According to the smoothed out gravity anomaly variation formula and the gravity anomaly fitting formula, determine that gravity anomaly is long
Phase change rate；
According to the gravity anomaly change in long term rate, the gravity anomaly time-varying formula at current time is determined；
According to the gravity anomaly time-varying formula, the GRAVITY ANOMALIES at current time is calculated；
According to the GRAVITY ANOMALIES, time-varying amendment is carried out to initial data used when preparing gravity datum figure, is obtained
Positive G of then turning revisionism reference map.
Optionally, described that space smoothing processing is carried out to gravity anomaly variation formula, determine that smoothed out gravity is different
Often variation formula, specifically includes:
Isotropic Gaussian smoothing filter function is substituted into the gravity anomaly variation formula, is obtained smoothed out heavy
Power anomalous variation formula, existing north and south band error interference when eliminating using GRACE satellite data resolving gravimetric data.
Optionally, execute by isotropic Gaussian smoothing filter function substitute into gravity anomaly variation formula it
Before, further includes:
Determine the truncation order of gravity field model；
According to the truncation order, Gaussian smoothing radius is determined.
Optionally, the smoothed out gravity anomaly changes formula are as follows:
Wherein, f is universal gravitational constant, and M is earth quality, and r is distance of the observation point to earth centroid, aeIt is ellipse for the earth
Ball major radius, λ,The longitude and latitude of observation point are corresponded respectively to, l, m are the l rank of Time-variable gravity model spheric harmonic expansion, m
It is secondary, WlFor Gaussian smoothing filter function,For moon gravity field model and background gravity field model spherical harmonic coefficient it
Difference,For complete normalized association Legnedre polynomial.
Optionally, the gravity anomaly fitting formula is
Wherein, Δ t is the difference of the time of decimal system moon gravity field model and the time of background gravity field model, and A is normal
Value is similar to the constant value of straight line fitting, and B is gravity anomaly change in long term rate, and i=1 represents variation annual period item, and i=2 represents half
Annual period changes item, then the amplitude of year variation isI=3 indicates 161 days periodic terms relevant to S2 semidiurnal wave, ωi
Angular rate of change when to be specifically fitted, SIN function and cosine function are fitted a change rate when curve, and ξ indicates noise and mistake
Difference influences, and belongs to indeterminate.
Optionally, the gravity anomaly time-varying formula is
Wherein, t0=2003.0 be the benchmark time,For the GRAVITY ANOMALIES of benchmark time,
For the GRAVITY ANOMALIES of t moment.
Optionally, described according to the GRAVITY ANOMALIES, initial data used when preparing gravity datum figure is carried out
Time-varying amendment obtains time-varying amendment gravity datum figure, specifically includes:
According to the GRAVITY ANOMALIES, time-varying amendment is carried out to initial data used in gravity datum figure is prepared, when obtaining
It turns revisionism correction data；
Data are corrected according to the time-varying, carry out gridding drawing using interpolation algorithm, obtain time-varying amendment gravity datum
Figure.
The present invention also provides a kind of gravity datum figure time-varying update the system based on gravity anomaly time-varying, the gravity base
Quasi- figure time-varying update the system includes:
Month gravity field model obtains module, obtains gravimetric data for resolving according to GRACE satellite data, and according to described
Gravimetric data obtains a moon gravity field model；
Gravity anomaly variation formula obtains module, is background gravitational field mould for choosing any one month gravity field model
Type, and the expression formula of the moon gravity field model and the expression formula of the background gravity field model are subjected to difference calculating, it obtains
Gravity anomaly under the background gravitational field changes formula；
Smoothed out gravity anomaly changes formula determining module, flat for carrying out space to gravity anomaly variation formula
Sliding processing determines smoothed out gravity anomaly variation formula；
Gravity anomaly fitting formula obtains module, for carrying out classification fitting to gravitational field time-varying influence factor, obtains weight
Power exception fitting formula；
Gravity anomaly change in long term rate determining module, for according to the smoothed out gravity anomaly variation formula and described
Gravity anomaly fitting formula determines gravity anomaly change in long term rate；
Gravity anomaly time-varying formula determining module, for determining current time according to the gravity anomaly change in long term rate
Gravity anomaly time-varying formula；
Current time GRAVITY ANOMALIES computing module, for calculating current time according to the gravity anomaly time-varying formula
GRAVITY ANOMALIES；
Time-varying amendment gravity datum obtains module, for according to the GRAVITY ANOMALIES, to preparing gravity datum figure when institute
The initial data of use carries out time-varying amendment, obtains time-varying amendment gravity datum figure.
The specific embodiment provided according to the present invention, the invention discloses following technical effects:
The present invention provides a kind of gravity datum figure time-varying modification method and system based on gravity anomaly time-varying, comprising:
Acquisition gravimetric data is resolved by GRACE satellite data first, a moon gravity field model is calculated, chooses any one month gravitational field
Model is background gravity field model, and the expression formula of moon gravity field model and the expression formula of background gravity field model is carried out difference
The gravity anomaly variation formula under background gravitational field is calculated, then space smoothing processing is carried out to gravity anomalous variation formula,
Existing north and south band error interference when eliminating using GRACE satellite data resolving gravimetric data；When then to gravitational field
Change influence factor carries out classification fitting and obtains gravity anomaly fitting formula, and according to smoothed out gravity anomaly variation formula and again
Power exception fitting formula determines gravity anomaly change in long term rate, realizes the prediction to gravity anomalous variation；It is finally different according to gravity
Normal change in long term rate determines the gravity anomaly time-varying formula at current time, calculates the GRAVITY ANOMALIES at current time, to preparation weight
Used initial data carries out time-varying amendment when power reference map, obtains time-varying amendment gravity datum figure, reduces gravity datum figure
Error hiding rate.
Detailed description of the invention
It in order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, below will be to institute in embodiment
Attached drawing to be used is needed to be briefly described, it should be apparent that, the accompanying drawings in the following description is only some implementations of the invention
Example, for those of ordinary skill in the art, without creative efforts, can also obtain according to these attached drawings
Obtain other attached drawings.
Fig. 1 is 2002 and 2006 local gravity anomaly figures of the present invention；
Fig. 2 is the flow diagram of gravity datum of embodiment of the present invention figure time-varying modification method；
Fig. 3 is the earth gravitational field variation diagram that the present invention is influenced by north and south band error；
Fig. 4 is degree variance of gravity anomaly of the present invention and the relational graph that order is truncated；
Fig. 5 is the non-tidal fluctuations schematic diagram of gravity of the present invention；
Fig. 6 is the structural schematic diagram of gravity datum of embodiment of the present invention figure time-varying update the system.
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation description, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on
Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts every other
Embodiment shall fall within the protection scope of the present invention.
The object of the present invention is to provide a kind of gravity datum figure time-varying modification method and system based on gravity anomaly time-varying,
To correct for the time-varying of gravity datum figure, the error hiding rate of gravity datum figure is reduced.
In order to make the foregoing objectives, features and advantages of the present invention clearer and more comprehensible, with reference to the accompanying drawing and specific real
Applying mode, the present invention is described in further detail.
Innovative part of the present invention includes first, in the solution of gravity anomaly fitting formula, generates variation to gravity anomaly
Influence factor realize that Mathematical Fitting is crucial.Cause the factor of Gravity changer various, and mechanism is different, therefore in fact
It is now fitted, to carry out classification fitting by the principle difference of influence.Reasonable analysis is carried out to the mechanism of every one kind first, takes out number
The expression formula of fitting is learned, existing gravimetric data data is secondly utilized, solution obtains unknown parameter, and then obtains fitting expression
Formula finally sums items to get gravity anomaly fitting formula is arrived.
Second, gravity anomaly time-varying formula is obtained, gravity anomaly fitting formula and gravity anomaly time-varying formula are not only needed
It is combined solution, it is also necessary to which the gravity anomaly time-varying formula solved to satellite data is filtered, and has eliminated north and south band mistake
The influence of difference, and then obtain gravity anomaly change in long term rate.Using gravity anomaly change in long term rate, in conjunction with background gravity field model
GRAVITY ANOMALIES, gravity anomaly time-varying formula can be derived by.
Fig. 2 is the flow diagram of gravity datum of embodiment of the present invention figure time-varying modification method, as shown in Fig. 2, of the invention
The gravity datum figure time-varying modification method that embodiment provides including the following steps:
Step 101: being resolved according to GRACE satellite data and obtain gravimetric data, and according to the gravimetric data, obtain moon weight
Force field model.
Step 102: choosing any one month gravity field model is background gravity field model, and by the moon gravity field model
Expression formula and the expression formula of the background gravity field model carry out difference calculating, the gravity obtained under the background gravitational field is different
Often variation formula.
Step 103: space smoothing processing being carried out to gravity anomaly variation formula, determines that smoothed out gravity anomaly becomes
Change formula.
Step 104: classification fitting being carried out to gravitational field time-varying influence factor, obtains gravity anomaly fitting formula.
Step 105: according to the smoothed out gravity anomaly variation formula and the gravity anomaly fitting formula, determining weight
Power exception change in long term rate.
Step 106: according to the gravity anomaly change in long term rate, determining the gravity anomaly time-varying formula at current time.
Step 107: according to the gravity anomaly time-varying formula, calculating the GRAVITY ANOMALIES at current time.
Step 108: according to the GRAVITY ANOMALIES, time-varying being carried out to initial data used when preparing gravity datum figure
Amendment obtains time-varying amendment gravity datum figure.
Step 101 specifically includes: resolving the gravimetric data obtained by GRACE satellite data can be calculated a moon gravitational field mould
Type.
Gravity anomaly Δ g at certain point can be expressed by formula (1): Δ g=g-g'(1).
In formula (1), g is A/W value, and g' is normal gravity.
And then it can be obtained by Bruns formula:
In formula (2), T is disturbing potential, and n is geoidal height.
Since the calculating of elevation h is along normal direction, positive direction is the direction of exterior normal, and it is big that this makes it possible to obtain physics
The fundamental differential of ground surveying, it may be assumed that
Gravity anomaly is calculated it can be seen from fundamental differential, first have to study disturbing potential.For
Simplify and calculate, it is assumed that the rotary shaft of normal ellipsoid, center are overlapped with the rotary shaft of the practical earth, mass center respectively, and the two has
Identical angular velocity of rotation with this condition discusses to the calculating of gravity disturbance position.
It can be obtained by assumed condition, for normal ellipsoid, potential of centrifugal force is equal to the potential of centrifugal force of the practical earth, then can obtain it
Disturbing potential are as follows: T=U-VH(4)。
In formula (4), U is gravitation potential of earth, VHIt is both harmonic function for normal gravitational potential, the humorous letter of ball can be used
Several levels number indicates are as follows:
In formula (5) and formula (6), f is universal gravitational constant, and M is earth quality, aeFor earth ellipsoid major radius,For l rank m times complete normalized spheric harmonic function coefficient,It is more for complete normalized association Legendre
Formula, r are distance of the observation point to earth centroid, λ,The longitude and latitude of observation point are corresponded respectively to,For normal gravitation
Potential coefficient, constant value, and normal ellipsoid relating to parameters,For 2l rank 0 time association Legnedre polynomial of standardizing completely.
Wherein, the second order zonal harmonic coefficient expression formula of normal gravitational potential are as follows:
In formula (7), e is the first eccentricity of ellipsoid, and e' is the second eccentricity of ellipsoid,For the earth from
Tarnsition velocity.By normal ellipsoid parameter, takeEllipsoid zonal harmonic coefficient and its gravitation position can be acquired.
Formula (5) and formula (6) formula are substituted into formula (4), the series expansion of disturbing potential spheric harmonic function are as follows:
In formula,
Meanwhile by the boundary condition under spheric approximation are as follows:
Formula (8) are substituted into formula (2), the humorous expression formula of ball of gravity anomaly, the table of front-month gravity field model can be obtained
Up to formula, are as follows:
In formula (10), f is universal gravitational constant, and M is earth quality, and r is distance of the observation point to earth centroid, ae
For earth ellipsoid major radius, l, m are the l rank of Time-variable gravity model spheric harmonic expansion, m times,WithIt is completely normalized
Spheric harmonic function coefficient,For l rank m times complete normalized spheric harmonic function coefficient,For complete normalized association
Legnedre polynomial, λ,Correspond respectively to the longitude and latitude of observation point.
Step 102 specifically includes: choosing certain month gravity field model is background gravity field model, and by moon gravity field model
Expression formula and the expression formula of background gravity field model carry out difference calculating, and the gravity anomaly variation under background gravitational field can be obtained
Formula, are as follows:
Wherein,For the difference of moon gravity field model and the spherical harmonic coefficient of background gravity field model.
Step 103 specifically includes:
Studies have shown that can have serious north and south band error interference, such as when being calculated using GRACE satellite data
Earth gravitational field variation diagram shown in Fig. 3 when being influenced by north and south band error.Therefore, it to extract effective gravimetric data, needs
Its variation characteristic is analyzed, space smoothing filtering processing is carried out.
For the influence for reducing higher order term error, earth gravitational field time-varying situation is accurately analyzed, the present invention is using each to same
The means that the Gaussian smoothing filter function of property is handled as space smoothing.Gaussian smoothing filter function is substituted into formula (11),
Smoothed out gravity anomaly variation formula can be obtained:
Wherein,For the difference of moon gravity field model and the spherical harmonic coefficient of background gravity field model, WlFor Gauss
Smoothing filter function.Isotropic Gaussian smoothing filter function are as follows:
In formula (13), γ is Ground PointWithBetween angular distance, meet relational expression:
Its recurrence formula are as follows:
Before Gaussian smoothing filter function is substituted into formula (11), it is also necessary to:
S1: the truncation order of gravity field model is determined.
Using GRACE satellite data restore gravity field model order be it is conditional, when the spherical harmonic coefficient of use is more than
When 90 rank, the error of gravity field model can be increased rapidly.
Therefore, suitable truncation order is chosen in the calculating of Yao Jinhang degree variance to the extent permitted by the error.Degree variance
Calculation formula is
Between 53 totally months gravimetric datas calculate 04 month in December, 2006 in 2002, when having obtained different rank
The distribution situation of Gravity changer clearly reflects degree variance of gravity anomaly and the relationship of order is truncated, chooses and cut when to calculate
Faulted-stage number provides reference, as shown in Figure 4.Calculating gravity field model used is the GRACE month gravity field model that CSR is provided.
S2: the determination of Gaussian smoothing radius.
Reasonable Gaussian smoothing radius is chosen, interference can be effectively reduced, has important shadow to the calculating of Time-variable gravity
It rings, so suitable Gaussian smoothing radius b should be chosen.Again because when Gaussian smoothing radius b is excessive, gravitational field variable signal
Loss is serious.Therefore, the selection of Gaussian smoothing radius should be determined after truncation order determines.
Studies have shown that Gaussian smoothing can be calculated according to the order of gravity field model and the relational expression of Gaussian smoothing radius b
Radius b；The order of gravity field model and the relational expression of Gaussian smoothing radius b areN is Time-variable gravity model
Order.
Step 104 specifically includes:
Studies have shown that the factor for causing gravity to change over time is more, mainly caused by the changes in distribution of earth quality,
It is broadly divided into tidal fluctuations and non-tidal fluctuations, influence factor includes air quality variation, seawer tide, hydrologic(al) regime variation
And the natural causes such as earthquake, volcanic eruption.The non-tidal fluctuations schematic diagram of gravity is as shown in Figure 5.
The above influence factor, removing can be observed periodically outer, and there are still some uncontrollable factors, cannot achieve system
One mathematical expression.When therefore carrying out analysis quantization for gravitational field time-varying influence factor, do not realized linearly using simple
Fitting will carry out division fitting by class in conjunction with the specific nature of its influence factor.The present invention cause gravitational field time-varying influence because
Element is divided into 3 classes and is fitted, specifically:
1) linear fit item, what is mainly reflected is gravitational field at any time long-term slowly varying, is specifically fitted to constant value, table
Show the change in long term rate of gravity at any time.
2) periodic term, main includes the influence factor periodically observe for causing VARIATION OF GRAVITY FIELD, and utilization is just remaining
String function is combined, and realizes fitting.
3) random entry, the influence factor that can not be predicted and be expressed including error, noise etc., is indicated by ξ.
The gravity anomaly fitting formula obtained from are as follows:
In formula (16), Δ t is the difference of the time of decimal system moon gravity field model and the time of background gravity field model
Value, A is constant value, is similar to the constant value of straight line fitting, and B is gravity anomaly change in long term rate, and i=1 represents variation annual period item, i
=2 represent half a year mechanical periodicity item, then the amplitude of year variation isI=3 is indicated 161 days relevant to S2 semidiurnal wave
Periodic term, ωiAngular rate of change when to be specifically fitted, SIN function and cosine function are fitted a change rate when curve, ξ table
Show that noise and error influence, belongs to indeterminate.
Step 105 specifically includes: obtaining moon gravimetric data in conjunction with being resolved by GRACE satellite data, area needed for choosing part
The moon gravimetric data in domain, and by formula (12) calculate after, the gravity in some a series of period of available regional area
The variable quantity of value, i.e., (δ g, Δ t) value, these values reflect the variation of certain month gravity anomaly and background moon gravity anomaly and time
Relationship.
In conjunction with formula (12) and formula (16), available gravity anomaly change in long term rate B.It is long-term using the gravity anomaly
Change rate B realizes the prediction to gravity anomalous variation.
Step 106 specifically includes:
Gravity anomaly time-varying formula when t based on gravity anomaly change in long term rate B are as follows:
In formula (17), t0=2003.0 be the benchmark time,For the GRAVITY ANOMALIES of benchmark time.
Step 108 specifically includes:
GRAVITY ANOMALIES when using the t acquiredTo initial data used when preparing gravity datum figure
Time-varying amendment is carried out, time-varying amendment data are obtained, obtains time-varying amendment gravity datum figure.
Specifically: input time t calculates decimal system time t', correspondence is calculated using formula (17)Weight
Power exceptional valueAccording to GRAVITY ANOMALIESGridding drawing is carried out using interpolation algorithm, obtains time-varying
Correct gravity datum figure.
To achieve the above object, the gravity datum figure time-varying amendment based on gravity anomaly time-varying that the present invention also provides a kind of
System.
Fig. 6 is the structural schematic diagram of gravity datum of embodiment of the present invention figure time-varying update the system, as shown in fig. 6, of the invention
Embodiment provide the gravity datum figure time-varying update the system include:
Month gravity field model obtains module 1, obtains gravimetric data for resolving according to GRACE satellite data, and according to institute
Gravimetric data is stated, a moon gravity field model is obtained.
Gravity anomaly variation formula obtains module 2, is background gravitational field mould for choosing any one month gravity field model
Type, and the expression formula of the moon gravity field model and the expression formula of the background gravity field model are subjected to difference calculating, it obtains
Gravity anomaly under the background gravitational field changes formula.
Smoothed out gravity anomaly changes formula determining module 3, for carrying out space to gravity anomaly variation formula
Smoothing processing determines smoothed out gravity anomaly variation formula.
Gravity anomaly fitting formula obtains module 4, for carrying out classification fitting to gravitational field time-varying influence factor, obtains weight
Power exception fitting formula.
Gravity anomaly change in long term rate determining module 5, for according to the smoothed out gravity anomaly variation formula and institute
Gravity anomaly fitting formula is stated, determines gravity anomaly change in long term rate.
Gravity anomaly time-varying formula determining module 6, for determining current time according to the gravity anomaly change in long term rate
Gravity anomaly time-varying formula.
Current time GRAVITY ANOMALIES computing module 7, for calculating current time according to the gravity anomaly time-varying formula
GRAVITY ANOMALIES.
Time-varying amendment gravity datum obtains module 8, for according to the GRAVITY ANOMALIES, to preparing gravity datum figure when institute
The initial data of use carries out time-varying amendment, obtains time-varying amendment gravity datum figure.
The research achievement of present invention combination satellite Time-variable gravity carries out quantitative study and close to the time-varying phenomenon of gravitational field
Like fitting, shifts onto obtain gravity anomaly time-varying formula, be obtained after being fitted using gravity anomaly time-varying formula to data used
The newest gravimetric data at a certain moment corrects the time-varying of gravity reference map to realize, and then it is higher that navigation accuracy is made
Gravity datum figure.
Each embodiment in this specification is described in a progressive manner, the highlights of each of the examples are with other
The difference of embodiment, the same or similar parts in each embodiment may refer to each other.
Used herein a specific example illustrates the principle and implementation of the invention, and above embodiments are said
It is bright to be merely used to help understand method and its core concept of the invention；At the same time, for those skilled in the art, foundation
Thought of the invention, there will be changes in the specific implementation manner and application range.In conclusion the content of the present specification is not
It is interpreted as limitation of the present invention.
Claims (8)
1. a kind of gravity datum figure time-varying modification method based on gravity anomaly time-varying, which is characterized in that the gravity datum figure
Time-varying modification method includes:
It is resolved according to GRACE satellite data and obtains gravimetric data, and according to the gravimetric data, obtain a moon gravity field model；
Choosing any one month gravity field model is background gravity field model, and by the expression formula of the moon gravity field model and institute
The expression formula for stating background gravity field model carries out difference calculating, obtains the gravity anomaly variation formula under the background gravitational field；
Space smoothing processing is carried out to gravity anomaly variation formula, determines smoothed out gravity anomaly variation formula；
Classification fitting is carried out to gravitational field time-varying influence factor, obtains gravity anomaly fitting formula；
According to the smoothed out gravity anomaly variation formula and the gravity anomaly fitting formula, determine that gravity anomaly becomes for a long time
Rate；
According to the gravity anomaly change in long term rate, the gravity anomaly time-varying formula at current time is determined；
According to the gravity anomaly time-varying formula, the GRAVITY ANOMALIES at current time is calculated；
According to the GRAVITY ANOMALIES, time-varying amendment is carried out to initial data used when preparing gravity datum figure, when obtaining
Positive G of turning revisionism reference map.
2. gravity datum figure time-varying modification method according to claim 1, which is characterized in that described to the gravity anomaly
Change formula and carry out space smoothing processing, determines smoothed out gravity anomaly variation formula, specifically include:
Isotropic Gaussian smoothing filter function is substituted into the gravity anomaly variation formula, it is different to obtain smoothed out gravity
Often variation formula, existing north and south band error interference when eliminating using GRACE satellite data resolving gravimetric data.
3. gravity datum figure time-varying modification method according to claim 2, which is characterized in that will be isotropic executing
Gaussian smoothing filter function substitutes into before the gravity anomaly variation formula, further includes:
Determine the truncation order of gravity field model；
According to the truncation order, Gaussian smoothing radius is determined.
4. gravity datum figure time-varying modification method according to claim 1, which is characterized in that the smoothed out gravity is different
Often variation formula are as follows:
Wherein, f is universal gravitational constant, and M is earth quality, and r is distance of the observation point to earth centroid, aeIt is long for earth ellipsoid
Radius, λ,The longitude and latitude of observation point are corresponded respectively to, l, m are the l rank of Time-variable gravity model spheric harmonic expansion, m times, Wl
For Gaussian smoothing filter function,For the difference of moon gravity field model and the spherical harmonic coefficient of background gravity field model,For complete normalized association Legnedre polynomial.
5. gravity datum figure time-varying modification method according to claim 4, which is characterized in that the gravity anomaly fitting is public
Formula is
Wherein, Δ t is the difference of the time of decimal system moon gravity field model and the time of background gravity field model, and A is constant value, closely
It is similar to the constant value of straight line fitting, B is gravity anomaly change in long term rate, and i=1 represents variation annual period item, and i=2 represents week half a year
Phase changes item, then the amplitude of year variation isIndicate 161 days periodic terms relevant to S2 semidiurnal wave, ωiFor
Angular rate of change when specific fitting, SIN function and cosine function are fitted a change rate when curve, and ξ indicates noise and error
It influences, belongs to indeterminate.
6. gravity datum figure time-varying modification method according to claim 5, which is characterized in that the gravity anomaly time-varying is public
Formula is
Wherein, t0=2003.0 be the benchmark time,For the GRAVITY ANOMALIES of benchmark time,When for t
The GRAVITY ANOMALIES at quarter.
7. gravity datum figure time-varying modification method according to claim 1, which is characterized in that described different according to the gravity
Constant value carries out time-varying amendment to initial data used when preparing gravity datum figure, obtains time-varying amendment gravity datum figure, tool
Body includes:
According to the GRAVITY ANOMALIES, time-varying amendment is carried out to initial data used in gravity datum figure is prepared, is turned revisionism when obtaining
Correction data；
Data are corrected according to the time-varying, carry out gridding drawing using interpolation algorithm, obtain time-varying amendment gravity datum figure.
8. a kind of gravity datum figure time-varying update the system based on gravity anomaly time-varying, which is characterized in that the gravity datum figure
Time-varying update the system includes:
Month gravity field model obtains module, obtains gravimetric data for resolving according to GRACE satellite data, and according to the gravity
Data obtain a moon gravity field model；
Gravity anomaly variation formula obtains module, is background gravity field model for choosing any one month gravity field model, and
The expression formula of the moon gravity field model and the expression formula of the background gravity field model are subjected to difference calculating, obtain the back
Gravity anomaly under scape gravitational field changes formula；
Smoothed out gravity anomaly changes formula determining module, for carrying out at space smoothing to gravity anomaly variation formula
Reason determines smoothed out gravity anomaly variation formula；
Gravity anomaly fitting formula obtains module, and for carrying out classification fitting to gravitational field time-varying influence factor, it is different to obtain gravity
Normal fitting formula；
Gravity anomaly change in long term rate determining module, for according to the smoothed out gravity anomaly variation formula and the gravity
Abnormal fitting formula determines gravity anomaly change in long term rate；
Gravity anomaly time-varying formula determining module, for determining the weight at current time according to the gravity anomaly change in long term rate
Power exception time-varying formula；
Current time GRAVITY ANOMALIES computing module, for calculating the weight at current time according to the gravity anomaly time-varying formula
Power exceptional value；
Time-varying amendment gravity datum obtains module, for being used to when preparing gravity datum figure according to the GRAVITY ANOMALIES
Initial data carry out time-varying amendment, obtain time-varying amendment gravity datum figure.
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