Geoffrey Blewitt

The 2015 Vening Meinesz Medal is awarded to Geoffrey Blewitt for his pioneering developments in geodetic theory, for advancing the Global Positioning System (GPS) for scientific research and applications, and for his outstanding contributions in applying geodesy to study geophysical and climate processes.

Since the early days of GPS geodesy, Geoff Blewitt was a pioneer in developing and promoting GPS science. Early in his career, Blewitt was a critical member of the team that created one of the most influential and widely used tools of the trade: the GIPSY–OASIS GPS data analysis and simulation software package. His GPS data processing and ambiguity resolution algorithms still represent the state of the art nearly 25 years after Blewitt created them and implemented them. Blewitt is also internationally recognised for his innovative contributions in developing strategies for large network analysis and in precise positioning. Blewitt’s work in fundamental geodesy forms the basis of how geodesists and geophysicists can today implement GPS processing with millimeter accuracy.

Blewitt was instrumental in the establishment and early evolution of the International GPS Service that today consists of over one thousand continuously operating globally distributed sites, twelve analysis centers, and provides station coordinates, orbits, Earth-rotation, clock, troposphere, and ionospheric products to the greater user community. Blewitt’s work was also important in the systematic densification of the terrestrial reference frame that enables geophysical studies of solid Earth deformation driven by plate tectonic movement, earthquake cycles, environmental and fluid mass loading, volcano deformation, and Earth rotation.

One of Blewitt’s important contributions to geodetic science was the application of GPS to investigate the first large-scale predictions of the relationship between surface mass loading and GPS observations. This result meant that GPS observations of global surface displacements could be used to study climate change related surface mass redistribution on a global scale.

Another of Blewitt’s most important works was an application of GPS for the rapid determination of earthquake magnitude for tsunami warning systems. The revelation that GPS can significantly augment the seismic network to provide more timely and accurate warning of tsunamis ushered in a revolution in the use of GPS for natural-hazard monitoring and has led to a surge of international investment in GPS tracking networks, as well as a number of research and development efforts that aim to derive profound societal benefits from the newly discovered capabilities.

There are very few geodesists who have had such a sustained and significant impact on geodetic science as Geoff Blewitt, as evidenced by his large number of peer-reviewed publications in the field of physics, geodesy, and geophysics. His contributions in developing theory and tools that have fueled the research of an international community, and his professional service to organisations that further the research of a global community of scientists, is worthy of the Vening Meinesz Medal.