Kristine Larson was awarded the 2020 Charles A. Whitten Medal at the AGU Fall Meeting Honors Ceremony. The medal is for “her innovative applications of GPS geodesy to problems in environmental sensing, water cycle, geodetic seismology, and crustal dynamics.”

Kristine Larson is among the great innovators in geodesy. Whitten would be impressed and pleased to see the revolutionary applications she has invented or advanced, many of which were unimaginable at the time of Whitten’s 1994 death. Her innovative use of kinematic GPS and ground multipath reflectometry has led to the establishment of two new, distinctive areas of study: Global Positioning System (GPS) seismology and the use of GPS for environmental sensing.

Dr. Larson began her career using GPS geodesy for the measurement of crustal motions from local to global scales. In the late 1990s, she applied high-rate GPS positioning to study more dynamic ground motion, starting with deformation associated with Kīlauea Volcano. Subsequently, she advanced GPS techniques for investigation of earthquake ground motion, including a groundbreaking 2003 Science paper demonstrating that surface waves from the 2002 Denali Fault earthquake could be measured faithfully across all of North America. In this and later papers, she and her coauthors demonstrated that these GPS ground motion records contain unique seismological information, thereby establishing GPS as a tool that complements classical seismic observations.

Dr. Larson’s work in kinematic GPS led her to an intensive study of signal multipath and to her revolutionary application of GPS to many kinds of environmental sensing. She recognized that multipath was not just an annoying source of error to be removed but also a signal that contained information about the environment around the GPS antenna. She and her coworkers then devised simple but clever ways to extract quantitative information from the multipath signal. As a result, she has turned GPS sites into tide gauges, snow depth meters, permafrost sensors, glacier ablation meters, soil moisture meters, and vegetation water content meters, all validated against ground truth or independent data. Her team’s soil moisture products have further been used as validation for space-based remote sensing. Dr. Larson’s work in environmental sensing created a new range of applications of GPS geodesy. These advances and others are detailed in her recent review paper, “Unanticipated Uses of the Global Positioning System,” which I recommend all geodesists read. Her dual quest to understand both the behavior of the dynamic Earth system and also the intricacies of modern geodetic observing systems will inspire our field for many years.

—Jeff Freymueller, Michigan State University, East Lansing

16.00 Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:8.0pt; mso-para-margin-left:0in; line-height:107%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri",sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} First and foremost, I want to thank AGU, the Whitten Medal selection committee, the nominators, and my colleagues for this honor. I had gone to college expecting to become an engineer—and soon frightened my family by initially choosing to major in history of science. How then did I end up measuring plate motions with GPS? I was first introduced to geophysics by my thermodynamics professor, James Rice; I was also inspired to become a geophysicist by the Harvard Seismology Group. I came home to San Diego for graduate school in 1985 and, thanks to Duncan Agnew, became involved with one of the first GPS experiments to measure crustal deformation. At some point I was asked to drive a TI-4100 to Los Angeles, which serendipitously led to both a NASA fellowship and a long-term research affiliation with the Jet Propulsion Laboratory. When I graduated from Scripps in 1990, Earth science departments still hadn’t decided what to think of so-called GPS people, so I took a position in an aerospace engineering department. Colorado has been my home these last 30 years. My colleagues in Boulder have inspired the interdisciplinary GPS applications cited by Jeff Freymueller. Perhaps in some way working in geophysics while being surrounded by engineers has allowed me to successfully blur the line between those fields. I also had the good fortune to learn from colleagues at the U.S. Geological Survey (USGS) Hawaiian Volcano Observatory, Stanford University, the USGS Earthquake Program, the Earthquake Research Institute in Tokyo, the Onsala Space Observatory, and GeoForschungsZentrum in Potsdam while on sabbatical. Growing up in the 1970s, I don’t remember anyone encouraging girls to pursue research careers in science or engineering. At the same time, my parents and grandparents never told me I couldn’t do something because I was a girl. Not ever. After I moved to Boulder I met my husband, George Rosborough, who has also supported my career throughout. I will always be grateful to him and our son, Radon. Sometimes I am asked by people how I chose to work on all these nontraditional applications of GPS. I recently found this quote by David Blackwell, and I think he has summarized my views perfectly: “Don't worry about the overall importance of the problem; work on it if it looks interesting. I think there's a sufficient correlation between interest and importance.”  —Kristine M. Larson, University of Colorado Boulder       

For developing new and creative applications for the Global Positioning System and Earth sciences.

Kristine M. Larson received the Geodesy Section Award on 23 May 2006 at the 2006 Joint Assembly in Baltimore, Md. The award is given in recognition of major advances in geodesy. Citation For the past 15 years, Kristine Larson has been at the forefront of research in the development and application of high-precision Global Positioning System (GPS) techniques to geophysical problems. Kristine received her bachelor’s degree in engineering sciences from Harvard University [Cambridge, Mass.] in 1985. She subsequently entered the Ph.D. program in geophysics at the Scripps Institution of Oceanography [La Jolla, Calif.]. Working with Duncan Agnew, her dissertation was one of the first to evaluate GPS accuracy and use it for geophysical studies. From 1988 to 1990, she was also a member of the technical staff at the Jet Propulsion Laboratory (JPL) [Pasadena, Calif.] where she worked with the team that developed the GIPSY [GPS Inferred Positioning System] software. In 1990, she joined the faculty at the University of Colorado, Boulder, where she is now a professor of Aerospace Engineering Sciences. Kristine’s science research focuses on measuring and interpreting crustal deformation with GPS. She published some of the first plate velocities based solely on GPS. She has also studied plate boundary zone deformation in Alaska, Nepal, Tibet, Ethiopia, California, and Mexico. In the latter collaboration with UNAM [Universidad Nacional Autónoma de México], episodic slip was first reported in Guerrero [Mexico]. Kristine’s research has also emphasized engineering development by pushing the temporal sampling of GPS to subdaily intervals. She has worked on problems as diverse as measuring ice sheet motion in Greenland, comparing atomic frequency standards, and volcanic inflation on Kilauea [Hawaii]. In 2003, she and her colleagues extended GPS into seismic frequencies with the first observations of seismic waves. These data were subsequently used to evaluate triggering of earthquakes outside the Denali rupture zone [Alaska]. Her group has more recently improved high-rate GPS analysis techniques for source studies of the San Simeon [California], Tokachi-Oki [Japan], and Parkfield [California] earthquakes. Larson has clearly established herself as a leader in the field of GPS geodesy. Her research program is extremely vibrant and has brought much benefit to the community. Her unique expertise is an outgrowth of exceptional engineering and scientific skill combined with great intellectual curiosity, creativity, and persistence. I am very grateful to Tim Dixon [University of Miami, Fla.] and Paul Segall [Stanford University, Palo Alto, Calif.], who strongly supported her nomination, and to the AGU Geodesy Section selection committee for making such an excellent choice. —Penina Axelrad, University of Colorado, Boulder

I would like to thank everyone involved in nominating me for this award. As Penny says, my research program includes both science and engineering. Combining the efforts has forced me to continually challenge myself. Understanding the intricacies of GPS has helped me do better science; conversely, understanding the underlying physics of the problem I am trying to solve has motivated me to think of ways to improve the accuracy of GPS. The reward has come from working on so many interesting problems with a diverse cast of colleagues. In the mid-1980s, I went to graduate school convinced that I wanted to become a seismologist. Instead, I became involved with one of the first geophysics experiments designed with GPS. At this juncture there were very few classes on GPS, and there was no ‘how-to’ book. I was fortunate to be able to learn both from the strong GPS group at JPL and the engineers who developed VLBI (Very Long Baseline Interferometry) and SLR (Satellite Laser Ranging) for the Crustal Dynamics Project. I also had the good luck to work with many geodesists outside the United States on collaborative research projects. Today the use of GPS has become commonplace in geophysics, to the extent that a colleague of mine recently complained that his incoming students think plate tectonics was discovered by GPS. My own work on measuring plate tectonics with GPS always reminds me of my father’s stories about working as an engineer for the Deep Sea Drilling Project in the 1970s. In both cases, scientists and engineers worked together to build new tools for geophysics. I am grateful to many colleagues and cannot properly thank everyone in this short note, but I do want to especially acknowledge my family and Jim Rice [Harvard University, Cambridge, Mass.], Charbel Farhat [Stanford University, Calif.], Bob Miller, and George Rosborough. —Kristine M. Larson, University of Colorado, Boulder