ETideLoad4.5 adopts the consistent geophysical models and same numerical standards to construct analytically compatible geodetic and geodynamic algorithms and then uniformly computes various tidal and non-tidal effects on various geodetic variations outside the solid Earth. ETideLoad4.5 can be employed to approach accurately global and regional load deformation field from surface load observations such as atmosphere, sea level, soil water, lakes and glaciers, and monitor collaboratively the land water, temporal gravity field, geological environment and ground stability variations by deep fusing of multi-source heterogeneous geodetic and surface load observations. (1) Using the consistent geophysical models and uniform numerical standards, and constructing analytic compatible geodetic and geodynamic algorithms, computes various tidal and non-tidal effects on various geodetic variations and then approaches and refines accurately global or regional surface load deformation field. (2) Strictly according to the principles of the geodesy and solid geodynamics, constrains and assimilates the deep fusion of multi-source heterogeneous geodetic and surface load observations to realize the collaborative monitoring of land water, temporal gravity field, geological environment and ground stability variations. (3) Provides a set of scientific and practical geodetic geodynamic computation tools for the construction of heterogeneous spatiotemporal geodetic frames, deep fusion of various heterogeneous Earth observations, collaborative monitoring of multi-geotechnologies, computation of solid Earth deformation, monitoring of surface hydrology environment and surveying of geological disasters.
(1) Using the scientific uniform numerical standards and analytic compatible geophysical algorithms, computes accurately the Earth tidal, ocean tidal load, surface atmosphere tidal load, permanent tidal, rotation polar shift and Earth’s mass centric variation effects on various geodetic variations, and forecast various tidal effects anytime and anywhere. (2) Approaches global or regional load deformation field from surface load observations such as atmosphere, sea level, soil water, lakes, rivers, glaciers and snow, and then collaboratively monitores the land water and temporal gravity field by deep fusing of various heterogeneous geodetic and surface load observations. (3) Constructs regional uniform spatiotemporal monitoring datum frames with high robustness to fuse the CORS, InSAR, and other geodetic variations. Proposes the criteria of the ground stability based on temporal geodetic field to realize quantitative monitoring of the ground stability spatiotemporal variations. ETideLoad4.5 is mainly based on the geophysical models and numerical standards recommended by IERS Conventions (2010). These geophysical models and numerical standards are stored in file form in the folder of C:\ETideLoad4.5_win64en\iers, which can be updated by the program [System Configs for the geophysical models and numerical standards]. Geophysical models and numerical standards in ETideLoad4.5 mainly include the surface atmosphere tidal load spherical harmonic coefficient model file, ocean tidal load spherical harmonic coefficient model file, Earth’s load Love number file, IERS Earth orientation parameter time series file, Earth mass centric variation time series file measured by SLR, ocean tidal constituent harmonic constant grid model files, JPL Moon and Planetary Ephemeris DE440 file, Love number correction file for frequency dependence and Desai ocean pole tide coefficient file. Geodetic variation in ETideLoad is defined as the difference between the geodetic element at the current epoch time and the mean of the elements over a period or the difference between the geodetic element at the current epoch time and that at a certain reference epoch time. The geodetic element may be a geodetic observation or parameter, and the geodetic variation refers to the difference in the geodetic element with time.
(1) Height anomaly or geoidal height variation in the unit of mm, ground gravity or gravity disturbance variation in the unit of μGal, and ground tilt or vertical deflection variation (vector) in the unit of mas namely 0.001ʺ. (2) Ground horizontal displacement in the unit of mm, ground radial displacement namely ground ellipsoidal height variation in the unit of mm, and ground normal or orthometric height variation in the unit of mm. (3) Gravity gradient variation in the unit of 10μE for global case, as well as in the unit of mE for regional case. (4) External geopotential perturbation in the unit of 0.1m²/s², gravity perturbation in the unit of μGal, and gravity gradient perturbation in the unit of 10μE. (5) Land equivalent water height variation (EWH) in the unit of cm, sea level variation in unit of cm, ocean tidal height in unit of cm, and atmosphere variation in unit of hPa (mbar).
(1) Ground tilt or vertical deflection variation vector (SW). The first component points to the south direction, and the second component points to the west direction, which forms a right-handed rectangular coordinate system with the ground gravity direction. This coordinate system is a natural coordinate system. (2) Ground horizontal displacement vector (EN). The first component points to the east direction, and the second component points to the north direction, which forms a right-handed rectangular coordinate system with the ground radial displacement direction. (3) Tangential gravity gradient variation vector (NW). The first component points to the north direction, and the second component points to the west direction, which forms a right-handed rectangular coordinate system with the radial gravity gradient variation direction. (4) The harmonic constants of the tidal constituent. The first component is the in-phase amplitude for cos(argument), and the second component is the out-of-phase amplitude for sin(argument). The geodetic variation time series files adopt the ETideLoad own format, which include the ground variation time series file, geodetic network site record time series file, geodetic network observation record time series file, variation (vector) grid time series files and spherical harmonic coefficient (Stokes coefficient) model time series files. (1) The ground variation time series file A ground variation time series file can store the time series data of several kinds of variations at a certain site, a certain baseline or route, and the sampling epochs (here, the epoch is an instantaneous time) of these variations are the same. Such as CORS station coordinate solution time series, solid tide station observation or analysis result time series, GNSS baseline solution time series, etc. (2) The geodetic site variation record time series file A geodetic site variation record time series file can store the time series data of one kind of variations for a group of geodetic sites. Such as the station coordinate time series for the CORS network, benchmark height time series for the levelling network, observation time series for the tide station network, and InSAR monitoring time series, etc. (3) The geodetic network observation record time series file A geodetic network observation record time series file can store the variation record time series of the baseline component for the CORS network, the variation record time series of the height difference for the levelling network, or the variation record time series of the gravity difference for the gravity network. (4) The variation grid time series files for geodetic field A group of variation grid time series files are composed of a series of numerical grid model files of a certain kind of variation (vector), and the seventh attribute of the header in each grid file is agreed to be the sampling epoch time. Such as the grid time series of land water equivalent height, sea level variation, and grid time series of various regional load deformation field or temporal gravity field, etc. (5) The spherical harmonic coefficient model time series files A group of spherical harmonic coefficient model time series files can store the time series of the spherical harmonic coefficient (Stokes’ coefficient) models of the global surface load variation, global load deformation field, or temporal global gravity field. The file header occupies one row and consists of three attributes, namely the geocentric gravitational constant GM(×10¹⁴m³/s²), equatorial radius of the Earth a(m), and sampling epoch time (in ETideLoad format). GM,a are the scale parameters of the model. Here, the surface harmonic functions in the spherical harmonic coefficient model are defined on the spherical surface whose radius is equal to the equatorial radius of the Earth. |