Terrestrial Reference Frame Requirements for Studies of Geodynamics and Climate Change

Scientific applications critically depend on the ITRF and impose the most stringent requirements on terrestrial reference frame accuracy and long-term stability. A recent US National Research Council report (Minster et al., Precise geodetic infrastructure: national requirements for a shared resource. The National Academies Press, Washington, DC, 2010) found that the applications demanding the highest accuracy and long-term stability were sea level, geodynamics from vertical land motion and large-scale horizontal deformation, and decadal satellite survey missions. A key recommendation was to make a long-term commitment to maintain the ITRF to ensure its continuity and stability, so as to provide a foundation for Earth system science and studies of global change. In this paper, we focus on characteristics of the ITRF that have demands placed upon them by these most stringent scientific users. We consider in detail each characteristic in terms of what the user needs, and provide examples of how such needs can be met, and identify factors that strengthen or weaken terrestrial reference frames from a user’s perspective. We find the most important feature of a terrestrial reference frame is “predictability”, the ability of the frame to predict future positions of stations in a multi-technique network to support science. Specifically, the key requirement of the ITRF, in order to support the most demanding scientific applications with large societal impacts, is to provide access to station coordinates that have secular predictability at the level of 1 mm per decade (0.1 mm/year).