Tonie van Dam
The 2019 Vening Meinesz Medal is awarded to Tonie van Dam for pioneering work on the deformations of the solid Earth under a variety of surface loads and on their measurements using space geodetic observation techniques.
Tonie van Dam is a world leader in modelling geodetic observations. She is a pioneer in quantifying hydrologic and atmospheric loading effects and has demonstrated their importance in multiple geodetic observing systems, namely from GPS and VLBI (very-long-baseline interferometry) to GRACE (Gravity Recovery and Climate Experiment) and ground-based gravimetric systems.
Van Dam’s long and distinguished career as a research geophysicist began with the distinguished professor John Wahr during her PhD in the late 1980’s on the inverted barometric effect. At that time the magnitude of predicted displacements due to surface pressure loads was just at the margins of reliable detection by existing space geodetic techniques. Nowadays load signals are readily and routinely observed, even at the level of 0.1 mm or better for annual amplitudes, especially using GNSS methods. Van Dam’s paper from 2001, titled ‘Crustal displacements due to continental water loading’, initiated a pioneering interdisciplinary research topic involving GPS and continental hydrology; it became a classic in geodesy. In recent years, she published a large number of articles on the effect of ice mass loss from the Greenland ice sheet on horizontal and vertical deformations of the crust. This research is very important and offers complementary information on the present-day mass balance of the Greenland ice sheet from GRACE-based space gravimetry and the separation of current and post-glacial isostatic adjustments to unloading processes. Van Dam also contributed to measure motions of the geocentre and estimated the impact of loading effects on the determination of the International Terrestrial Reference Frame.
Van Dam has been extremely active in the international space geodesy community. She has been a member of the directing board of the International Earth Rotation and Reference Systems Service (IERS) and the chair of the IERS Global Geophysical Fluids Center. She served as secretary of the geodesy section of the American Geophysical Union and was president of the EGU Geodesy Division. Van Dam is not only a widely recognised scientist, but she has also advised many PhD students and post-docs. At present she is the Vice-Rector for Doctoral Education and Training, Gender, and International Relations at University of Luxembourg. In this role, her contributions are amplified beyond her research, through service to improvement of the quality of education and increased diversity in research. Van Dam’s pioneering and continuing research activities on the theory, refined modelling, analysis of geodetic observations, and applications of loading corrections, have played a major role in advancing our understanding of interactions between Earth’s fluid envelope and the solid Earth. This all led to Tonie van Dam emerging as the world’s leading expert in this domain and explains the great impact and the high relevance of her work in modern geodesy.