A Functional Model for Quantifying Deformation in Reference Frame Transformations

Abstract

IAG Commission 1 Working Group 1.3.1 in association with the Open Geospatial Consortium (OGC) have developed a functional model for crustal deformation (FMCD) and an associated Geodetic Grid Exchange Format (GGXF) for quantifying and disseminating deformation information for use in time-dependent reference frame transformations.The FMCD provides a framework within which producers and users of deformation models can describe crustal displacement and velocity data using robust grid formats such as GGXF. Using the FMCD and GGXF combined, positional displacements can be readily applied in point motion coordinate operations and non-conformal time-dependent transformations. This approach is essential in deforming zones where conformal time-dependent transformation approaches do not adequately handle crustal deformation.This paper describes application of the FMCD in typical cases including: (1) transformation of GNSS PPP positions (e.g. in an IGS20 frame) to a national geodetic datum in a deforming zone and (2) transformation between reference frames across earthquake events that resulted in significant coseismic and postseismic crustal displacement. The FMCD and associated GGXF provide a framework for developers of geodetic software such as those used in GIS, GNSS processing and positioning to better handle complex deformation.