t is with great pleasure and honor that I write this citation for Paul Rebischung, winner of the 2022 Ivan I. Mueller Award for Distinguished Service and Leadership. Paul deserves such recognition by the AGU Geodesy section for his constant dedication to serving and leading the international geodetic community in producing terrestrial reference frames, a critical foundation for the application of geodesy to Earth sciences. Indeed, such dedication has affected and facilitated geodetic research all around the globe, in ways that perhaps users of Global Navigation Satellite Systems (GNSS) data may not fully appreciate. As a Ph.D. student, Paul began his career of service as a member of the International GNSS Service (IGS) Reference Frame Working Group. His initial contribution was to evaluate how GNSS might improve the International Terrestrial Reference Frame (ITRF). Implementing Paul’s research has had a huge impact on improving products of IGS and the International Earth Rotation and Reference Systems Service (IERS). Specifically, Paul developed and implemented the methodology that IGS uses to produce terrestrial reference frame solutions that are aligned to the ITRF by rigorously combining solutions from IGS Analysis Centers. He was also responsible for the IGS input to ITRF2014 and now ITRF2020. In 2017, Paul was appointed chair of the IGS Reference Frame Working Group and took a seat on the IGS Governing Board. Every geodesist, including myself, who is in the business of generating highly precise GNSS position time series uses these reference frame realizations. As such, Paul’s service has played a role in every journal article over the past decade that has used high-precision GNSS position time series, for a wide variety of Earth science applications. In addition to chairing the IGS Reference Frame Working Group, he has served on IERS Working Groups that have further developed IAG products, and on several IAG Working Groups including (1) Global Combined GNSS Velocity Field, (2) Toward Reconciling Geocenter Motion Estimates, (3) Constraining Vertical Land Motion of Tide Gauges, and (4) Integration of Dense Velocity Fields into the ITRF. As current chair of the IGS Reference Frame Working Group, Paul takes a leadership role in the IGS reprocessing of GNSS data, which leads to more accurate reference frames and GNSS orbits and clocks used by geodesists. His service is a critical component for future generations of ITRF and for the continued improvement of products upon which the geodetic community depends. —Geoffrey Blewitt, University of Nevada, Reno

I am extremely honored to receive this award and would like to thank everyone involved in this nomination. Receiving an award bearing the name of Ivan I. Mueller, one of the founders of the International GNSS Service (IGS), in which I have been involved for the past 13 years, is especially meaningful to me. I would like to address deep thanks to Zuheir Altamimi, without whom I would not have been introduced into the IGS community, nor might I have ever started a scientific career. Sincere thanks also to Jim Ray, who acted as my mentor during my early years in the IGS. Thanks as well to the numerous colleagues with whom I have worked and learned over the years, both at my home institute, Institut National de l’Information Géographique et Forestière (and now also Institut de Physique du Globe de Paris), and in the framework of the IGS. The IGS community forms a highly stimulating scientific environment, as well as a remarkable example of global cooperation, successful in providing high-quality, open-access GNSS data and products useful for a wide range of applications. It has been a chance and an honor to participate, at my humble level, in the IGS adventure. In the coming years I hope I can continue to serve the geodetic community by supporting further advancements of IGS products, as well as of the International Terrestrial Reference Frame (ITRF), the necessary backbone for global monitoring of Earth and for global precise positioning. Geodesy has reached unprecedented accuracy, but the requirements have meanwhile never been so stringent. There are still many challenges ahead and prospects for motivating research! —Paul Rebischung, Institut National de l’Information Géographique et Forestière, Institut de Physique du Globe de Paris, Paris