Christopher Jekeli

The 2021 Vening Meinesz Medal is awarded to Christopher Jekeli for his pioneering work on theory, methodology, and application of geodetic measurement techniques, in particular to determine the Earth’s gravity field using spaceborne, airborne, and terrestrial sensors.

When we think about quality, relevance, and innovation in geodetic science of the recent decades, the work of Christopher Jekeli is certainly among the first that comes to mind. The complete work of Jekeli on geodetic measurement techniques and applications, spanning more than 40 years, has contributed enormously to geodesy. It has played a central role in the very successful development of the discipline, and it serves as a lasting reference.

Early in his career, Jekeli developed methods for the use of high-degree spherical and ellipsoidal harmonics that are standard today for all Earth and planetary gravity field models. Later, when the Gravity Recovery and Climate Experiment (GRACE) mission became reality, he made essential contributions to the understanding of gravity recovery from satellite-to-satellite tracking observations, developing analysis methods that are now used to monitor the global mass redistribution in the Earth’s water cycle. In a different but complementary direction, Jekeli’s textbook on inertial navigation is considered seminal in the field, setting a very high standard and finding very wide appreciation. It provides a comprehensive theoretical framework and clarifies the role of the Earth gravity field in inertial navigation. His research on airborne gravimetry has enabled the tremendous success of the measurement technique in many regions of our Earth, including the polar areas. Beyond, Jekeli has addressed an impressive range of very relevant topics: his studies on the vertical datum in geodesy, on least squares collocation, on geophysical applications of gravity field modelling, on non-Newtonian gravity, and on quantum sensors for geodesy all have opened important windows into the future.

But the huge value is not just in the content of Jekeli’s publications. It is equally in the quality and scientific soundness of his writing that has inspired generations of young geodesists and continues to do so. That is even truer for those who had the privilege to witness him as a teacher in person, whether at Ohio State University or at the international summer schools he attended. Therefore, it is with gratitude and highest respect that we honour the contribution of Christopher Jekeli to geodetic science with the 2021 Vening Meinesz Medal.