(1) Using the consistent geophysical models and uniform numerical standards, accurately compute the various tidal and non-tidal effects onvarious geometric and physical geodetic quantities on the ground and outsidethe solid Earth by constructing compatible geodetic and geodynamic algorithms. (2) Unifying various geodetic spatiotemporal monitoring datum frames and reference epoch time, by constructing geometric and physical geodetic constraints between various monitoring quantities, highlight the spatiotemporal geodynamic relationships between these monitoring quantities to promote the collaborative monitoring of multi-technologies. (3) Provide a set of scientific and practical geodetic geodynamic computation tools for construction and maintenance of geodetic spatiotemporal monitoring frames, and deep fusion of multi-source heterogeneous Earth monitoring quantities, computation of solid Earth deformation, monitoringof surface hydrology environment, and surveying of geological disasters.. (1) Adopt the scientific uniform numerical standards and analytic compatible geophysical algorithms accurately to compute the Earth tidal, ocean tidal, and surface air pressure tidal, permanent tidal, polar motions, and geocentric motions effects on various geodetic quantities on the ground and outside the solid Earth. Realize global forecasts of various tidal effects on surface various geodetic quantities. (2) Compute global or regional load-deformation field and temporal gravity field caused by surface non-tidal load variations such as air pressure, sea level, soil water, lakes, rivers, glaciers, and snow. From various geodetic observations time series, assimilate the surface load observations by some constraints of the solid Earth deformation, to monitor the spatiotemporal variations of regional land water, and then to improve the load-deformation field and temporal gravity field. (3) Construct regional uniform geometric and physical spatiotemporal monitoring datum frames with high robustness to make scientific computations and deep fusion of the CORS, InSAR, and other geodetic variations to promote multi-geodetic collaborative monitoring. Propose the quantitative deterministic criteria of the ground stability reduction based on temporal geodetic field, to realize quantitative monitoring of the ground stability spatiotemporal variations. ETideLoade4.0 is mainly based on the geophysical models and numerical standards recommended by IERS Conventions (2010). You can update them from the program [geophysical models and numerical standards settings]. These geophysical models and numerical standards are stored in file form in the folder of C:\ETideLoad4.0_win64cn. Geophysical models and numerical standards in ETideLoad4.0 mainly include the surface air pressure tidal load spherical harmonic coefficients model, ocean tidal load spherical harmonic coefficients model, Earth’s Load Love numbers, IERS Earth orientation parameters time series, geocentric motion parameters time series, ocean tidal constituent harmonic parameters grid model, JPL Moon and Planetary Ephemeris DE405, corrections coefficients of frequency dependence on Love numbers, Desai ocean pole tide coefficients, and center of mass correction coefficients for the ocean tide. Geodetic variation in ETideLoad is defined as the difference between the geodetic quantity at the current epoch time and the mean of the quantities over a period or the difference between the geodetic quantity at the current epoch time and the geodetic quantity at a certain reference epoch time. The geodetic quantity may be a geodetic observation or a geodetic parameter, and the geodetic variation refers to the difference in the geodetic quantity 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, and tangential gravity gradient vector variation in the unit of 10μE. (4) External (outside the Earth) 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 in the unit of cm, sea level variation in unit of cm, ocean tidal height in unit of cm, and air pressure variation in unit of hPa.
(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 (NE). The first component points to the north direction, and the second component points to the east direction, which forms a right-handed rectangular coordinate system with the gravity gradient variation direction. (4) The harmonic parameters of the tidal constituent. The first component is the prograde amplitude for cos(argument), and the second component is the retrograde amplitude for sin(argument). The geodetic variation time series files adopt the ETideLoad own format, which include the ground geodetic variations time series file, geodetic site variation records time series file, geodetic network observation records time series file, variation (vector) grids time series files, and spherical harmonic coefficient (Stokes coefficient) models time series files. (1) The ground geodetic variations time series A ground geodetic variations time series file can store the time series data of several kinds of variations on 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 the 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 records time series A geodetic site variation records time series file can store the time series data of one kind of variation for a group of geodetic sites. Such as the station coordinates time series for the CORS network, benchmark heights time series for the leveling network, observations time series for the tide station network, and InSAR monitoring time series, etc. (3) The geodetic network observation records time series A geodetic network observation records time series file can store the variation records time series of the baseline component for the CORS network, the variation records time series of the height difference for the leveling network, or the variation records time series of the gravity difference for the gravity control network. (4) The variation grids time series for geodetic field A group of variation grids time series files is composed of a series of numerical grid model files of one 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 grids time series of the land equivalent water height, sea level variation, and the grids time series of various regional load-deformation fields or temporal gravity fields, etc. (5) The spherical harmonic coefficient models time series A group of spherical harmonic coefficient models time series files can store the time series of the spherical harmonic coefficients (Stokes’ coefficients) models of the global surface load variations, global load-deformation field, or temporal global gravity field. The header file 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. |