Citation for Andy Hooper
Andy Hooper is a specialist and innovator in geodetic imaging methods using interferometric analysis of satellite radar images (InSAR). At the same time, he has improved our understanding of magmatism and tectonics with geophysical models interpreting ground deformation. He is unusual in being at the top of his field in the technical aspects of geodetic data acquisition and processing, as well as being one of the leading modelers of geodetic data.
With InSAR analysis, the phases of radar echoes on multiple passes of a satellite over the same terrain are compared to reveal changes in the line-of-sight distance between the satellite and the ground. One approach to the problem is to identify those image pixels for which the radar echo is dominated by a single dominant scatterer. One of Andy’s contributions was to develop an approach to identify such persistent scatterers using phase stability, the parameter of interest, rather than radar brightness as in earlier methods. He also made no assumptions about the temporal nature of the deformation, rather relying on the spatial coherence of the deformation signal. His algorithms offered several significant advances and are well suited for nonurban settings such as volcanoes. This work has had major impact, with his four papers on the subject attracting over 1500 citations to date.
Andy has unselfishly shared his advanced approaches to the analysis of InSAR time series by releasing his software (Stamps) to the community as open-source code, significantly impacting the community of scientists using satellite geodesy. The software has been used in a wide range of applications spanning volcanic and tectonic deformation through to urban subsidence caused by water extraction. In 2015 alone, over 150 papers were published that used the Stamps software.
Andy’s work on volcanic and tectonic processes has also had a major impact. In particular, he has led modeling efforts to understand magmatic processes in Iceland associated with recent eruptions, as well as demonstrating how ice cap retreat in Iceland can perturb the crustal stress state sufficiently to alter the tendency for magma to be trapped within the crust as opposed to erupting. His results have been published in several high-level journal articles. Since moving to the United Kingdom in 2013, Andy has helped establish Leeds as a world-leading research center for applied satellite geodesy.
—Freysteinn Sigmundsson, University of Iceland, Reykjavík
Thank you to the medal committee for this award, which I am honored to receive, and thank you, Freysteinn, for those generous words. I do feel fortunate to be in a position where I can straddle two realms, working as both engineer and scientist.
Scientific endeavor is all about people, of course, and there are many exceptional individuals responsible for my being in this position today, although I can mention only a few here. My Ph.D. advisors at Stanford, Paul Segall, himself a former Macelwane Medal recipient, and Howard Zebker, mentored me through graduate school and taught me intellectual rigor and critical thinking. Their influence continues to very much shape my own approach to scientific problems.
My time spent during a postdoc in Iceland gave me the chance to live close to volcanoes. There, from Freysteinn Sigmundsson, I learned the importance of collaboration and working across disciplines, and I continue to work closely with colleagues there today.
Ramon Hanssen was instrumental then in getting me hired at Delft, where I spent several years in an engineering faculty, learning how to deal robustly with observations and errors. Ramon also taught me much about strategic thinking.
Now I am back in a geoscience-focused environment at Leeds, where I work with many talented individuals. Tim Wright, with whom I collaborate particularly closely, deserves special mention, and I have learned a great deal about leadership from him.
One of the most enjoyable aspects of my job has been working with graduate students. I have gained much from two former students, in particular, David Bekaert and Karsten Spaans, whom I had the pleasure of advising both during their master’s degrees at Delft and then during their Ph.D. studies at Leeds.
There have been many others who have shaped the way I think about science and have contributed to this award. My wife, Julia, deserves special thanks for her advice on all aspects of scientific life, from dealing with colleagues to wrestling with gritty scientific problems. Last, I thank my children for keeping me grounded. When I told my 8-year-old son Tom, a keen runner, I had been awarded a medal, he was pretty impressed—until he found out that I had not actually won a race.
—Andy Hooper, University of Leeds, Leeds, U.K.
Citation for Maureen D. Long
Maureen Long has made seminal contributions to our understanding of circulation in the Earth’s mantle by combining seismology, mineral physics, and geodynamics. Much of Maureen’s work concerns subduction zones, which are delineated by deep ocean trenches, where tectonic plates sink, or subduct into the Earth’s mantle. The direction of mantle flow driven by convection, plate motion, and sinking slabs is best detected with seismic anisotropy that is caused by deformation-induced fabric in minerals. Maureen Long is a pioneer and leader in using seismic anisotropy to reveal how slabs subduct and the mantle circulates.
For her graduate work at the Massachusetts Institute of Technology, Maureen combined seismic observations with numerical models and mineralogical experiments to study anisotropy beneath Japan. With her multidisciplinary tool kit, she then began her major research thrust on subduction zones, first as a postdoctoral fellow at the Carnegie Institution of Washington’s Department of Terrestrial Magnetism and later as a faculty member at Yale. Maureen led or co-led seismological field deployments in Oregon, the Appalachians, and Peru and an oceanographic survey over the U.S. Atlantic continental shelf. Her work resulted in key insights on subduction anisotropy and mantle flow near, for example, Japan, Tonga, Alaska, Oregon, Peru, and the Caribbean and Scotia Arcs.
Maureen’s early studies showed that anisotropic fabric in the mantle beneath subduction zones is pervasively trench parallel, which suggests a component of flow perpendicular to plate motion. This discovery implied that slabs do not merely sink vertically but roll backward, squeezing the mantle out of the way and parallel to the trench. However, with new data, Maureen showed that while subduction zones attached to old plates have trench-parallel fabric, younger ones have trench-perpendicular fabric; this suggests that subducting plates transition from steadily subducting to foundering backward, depending on their age.
Maureen’s contributions extend beyond studying subduction zone flow. She and colleagues used their Peru data to show that shallow slabs are weak and undergo extensive internal deformation. Her analysis of anisotropy in the lower mantle indicates flow deflected by chemically stable “piles” (large low shear velocity provinces) at the core-mantle boundary. Her recent work on anisotropy in the mantle transition zone and the lithosphere beneath continents has yielded new insights into deformation in these regions of the mantle.
Maureen Long is a rising star of mantle seismology and dynamics. With her field programs and interdisciplinary approach, she has made, and will continue to make, lasting discoveries about subduction zones and how the Earth’s mantle convection engine works.
—David Bercovici, Yale University, New Haven, Conn.
Thank you to the American Geophysical Union (AGU) for this tremendous honor and to Dave Bercovici for the generous citation, for spearheading my nomination, and for years of mentorship and support. I am delighted to be named as a recipient of the Macelwane Medal, not least because I am grateful for the rare privilege of being able to thank my mentors, students, and collaborators in a public forum.
I decided that I wanted to become a geophysicist in middle school, after learning about plate tectonics in science class and realizing that it was the coolest thing I had ever heard of. Not many people see their career dreams at the age of 12 realized, and the fact that I have is due to my good fortune in having a string of extraordinary teachers and mentors. My professors at Rensselaer Polytechnic Institute treated me like a scientist from the day I walked in the door as a freshman, and two summers as a summer intern in Shun Karato’s lab introduced me to seismic anisotropy—I’ve been hooked ever since. I pursued my Ph.D. in the fantastically rich environment of the Department of Earth, Atmospheric and Planetary Sciences at Massachusetts Institute of Technology; Rob van der Hilst was a consummate thesis advisor, and I’m grateful for his mentorship. My time in postdoc paradise at Carnegie was a joy, and working with David James and the late Paul Silver—whom I miss dearly—was a privilege. Since moving to Yale, I’ve been fortunate to be part of an outstanding department and an exceptional cohort of fellow junior faculty.
I share this recognition with a large group of collaborators with whom I’ve worked and adventured—thanks to all of you for your brilliance, your friendship, and for making my science better. It has been an honor to work with my extraordinary students and postdocs, especially Juan Aragon, Neala Creasy, Caroline Eakin, Heather Ford, Xiaobo He, Colton Lynner, Karen Paczkowski, and Erin Wirth. As a seismologist, I feel fortunate to be part of a scientific community that encourage early-career scientists, fosters collaboration and cooperation, and increasingly values diversity.
Most important, I am grateful to my parents, siblings, and family for their love and support over the years. Above all, a huge thank you to my husband, Tony, and our children, Patrick and Caroline; you are the light of my life and I would never be able to do the work I do without you.
—Maureen D. Long, Yale University, New Haven, Conn.
Citation for Yukitoshi Nishimura
Yukitoshi “Toshi” Nishimura has transformed our understanding of plasma processes in near-Earth space. His research into substorms led the geospace research community to see this dynamic process as system-wide, wherein plasma is transported hundreds of thousands of kilometers from the dayside magnetopause to the magnetotail and then the inner magnetosphere, leading to an instability that creates beautiful auroras and changes Earth’s plasma environment. Using NASA Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellite plasma observations, together with images from ground-based auroral cameras, Toshi made the first unequivocal causal connection between a space plasma process and a specific type of aurora. With that same research, Toshi also made the first testable magnetic mapping between deep in the magnetosphere and the auroral ionosphere. I will limit my citation to the substorm work, but suffice it to say that I consider his auroral and mapping results to be equally important.
At the heart of Toshi’s research is innovative use of data from multiple observational platforms. He has combined plasma and wave observations from an international fleet of satellites with ground-based observations from auroral imagers, radars, and magnetometers to “see” geospace in fundamentally new ways. Where the rest of our field looked at the data from the perspective of the leading paradigms, Toshi found something new that did not fit existing ideas. What Toshi had found were north–south auroral forms stretching from the poleward to the equatorward edge of the auroral oval during, he argued, every substorm. This was perplexing, as neither dominant paradigm required anything that might correspond to these streamers.
Toshi faced a tough crowd not at all receptive to his ideas. He had to explain what the streamer signified in terms of magnetospheric dynamics, and so he did. He had to discover what the arrival of the streamer at the equatorward edge of the oval signified in terms of stability of the system, and so he did. Throughout, Toshi did the necessary work and injected his judicious creativity.
The influence of Toshi’s substorm research has been profound. Now substorm onset is seen as part of a larger process, where flux tubes move from the dayside, across the polar cap and the inner edge of the plasma sheet, carrying plasma with different physical properties that pushes a stable magnetotail into instability. Toshi brought open-mindedness and creativity to the problem and opened our eyes to a more comprehensive and self-consistent picture. In a very real sense, his work on the substorm has been paradigm shifting.
—Eric Donovan, University of Calgary, Calgary, Alb., Canada
Thank you, Eric, for your generous citation and nomination. I am truly grateful to the members of AGU for this honor, and I am humbled to join the company of the many prestigious scientists who have received the Macelwane Medal. This could not have happened without strong support and encouragement from my close colleagues, and I would like to take this opportunity to express my deep gratitude to them.
Unlike many of the past recipients in space physics and possibly in other fields, I did not build any instruments or large simulation codes by myself. My research almost always relies on hard work from my kind collaborators who invest a countless amount of time and effort making data available. My postdoctoral research at University of California, Los Angeles started when new science from NASA’s THEMIS mission led by Vassilis Angelopoulos was blooming. Eric Donovan and colleagues at University of Calgary and University of California, Berkeley built world-class imaging networks, and my postdoctoral advisor, Larry Lyons, shared with me his enthusiasm and ambition to solve the substorm problem. My part of the work was just to make things happen by cooking data. It was, of course, not easy, but I have been extremely fortunate to interact with the experts in the field who have paved the way for my research. I am also thankful to strong supporters in the community, particularly Bob Lysak.
Back when I worked in Japan, my advisors, Takayuki Ono and Takashi Kikuchi, as well as their lab members, opened the door for me to the exciting science of space physics. Their enthusiasm for science, deep knowledge, and dedication to education made me think that I wanted to be such a professional scientist. Sometimes they were a bit intense; we spent hours just to discuss a figure, and group meetings lasted until midnight. But all those became precious memories and still influence me.
I have also been privileged to work with talented students, most recently with Ying Zou, Bea-Gallardo-Lacourt, Boyi Wang, and Cheng Zhen. I am grateful for their hard work, and it has been a great pleasure to witness their tremendous growth both academically and personally; I believe more is yet to come.
Finally, I wish to thank my family, in particular, my wife and fellow space physicist, Wen Li, for her kind support and sharing joy in life and science.
—Toshi Nishimura, University of California, Los Angeles
Citation for Appy Sluijs
It is my honor to introduce Appy Sluijs, a recipient of the 2016 James B. Macelwane Medal. Appy, a geobiologist, is being recognized for his prolific and leading-edge contributions to resolving the nature of extreme climate change and impacts on marine biota in Earth’s past.
Appy’s scientific achievements come as no surprise. His deep passion and aptitude for his craft were evident early on when, as an undergraduate at Utrecht, he participated in Ocean Drilling Program (ODP) Leg 208 to the South Atlantic. Despite his inexperience, he made the most of the opportunity, becoming a valued member of the scientific party and eventually contributing to several seminal publications that defined the scale and timing of Eocene hyperthermals and ocean acidification, including the Paleocene-Eocene Thermal Maximum (PETM). Building on this foundation, as a graduate student under the tutelage of Henk Brinkhuis and later as a postdoc, he produced a series of landmark papers involving dinoflagellate taxonomy and geochemical proxies to constrain changes in ocean temperatures, salinity, and ecology of the Arctic and lower-latitude coastal oceans. Key to this effort was his creative use of organic biomarker proxies which he and colleagues at the Royal Netherlands Institute for Sea Research, J. Sinninghe Damsté and S. Schouten, began to apply to Paleogene archives across the globe. This work not only established the extreme warmth and stratification of the Arctic during the PETM but also served as a cornerstone for subsequent reconstructions of global meridional temperature gradients for the Paleogene. In addition to the landmark work on Eocene hyperthermals, Appy contributed to high-impact studies of several other key climate events of the Paleogene, including the middle Eocene Climatic Optimum and the Eocene-Oligocene transition.
Not long after these very early career accomplishments, Appy was appointed full professor, one of the youngest to achieve the rank at Utrecht University. He has since established a major research program and continues to address fundamental issues on the character and impacts of major changes in climate during the Cenozoic. He is also recognized for his extensive service to the scientific community and for exceptional public outreach and education, particularly his work with students in the Young Academy of the Royal Society of the Netherlands.
—James C. Zachos, University of California, Santa Cruz
Thank you, Jim, for this generous citation. I also thank you and my colleagues who wrote letters for the nomination. I thank the members of the Macelwane Medal Committee and AGU for this great honor.
Similar to many of us, my story is one of remarkable serendipity. Coming from a nature-loving family and focusing on biology during my undergraduate studies, I miraculously ran into Henk Brinkhuis at Utrecht University, who introduced me to the wonderful world of dinoflagellates, micropaleontology, and paleoceanography. I would not be where I am without his generosity and inspiration. After my first micropaleontological work, Henk sent me to University of California, Santa Cruz to work with Jim and Stephen Schellenberg, who introduced me to geochemistry. During my graduate work I had the pleasure to collaborate with a set of truly unique, diverse, and creative scientific innovators. Along with Henk and Jim, these were Jerry Dickens, Jaap Sinninghe Damsté, Stefan Schouten, Lucas Lourens, Matt Huber, Ellen Thomas, and many others, discovering, describing, and understanding Paleocene-Eocene transient global warming events. Later on, Gert-Jan Reichart helped me design biogeochemical culturing experiments for dinoflagellate proxy development. I consider all of these people to be incredible scientists and great friends. I also thank my parents and the rest of my family and friends for their unconditional support and Margriet for being who she is.
I cannot name all colleagues who inspired me and with whom I have had the pleasure to work (even Scopus stops counting at 150 collaborators). I would, however, like to mention that much of my work was driven by two institutes: the International Ocean Discovery Program and the Urbino Summer School on Paleoclimatology, dominantly initiated by Henk and Simone Galeotti, which by now has taught over 800 international graduate students.
Our field of science, multidisciplinary paleoclimatology and paleoceanography, had barely started when Father James Macelwane was the AGU president. Now it is a crucial field in improving projections of future change. The rapid progress over the past decades is the accomplishment of a critical but constructive community with excellent leadership in the past and the present. I therefore feel that this medal, although awarded to me, rather marks the success of this research community as a whole, which includes students, postdocs, and faculty, all standing on the shoulders of past giants. And as many grand scientific and societal challenges lie ahead of us, I’m proud to be part of it.
—Appy Sluijs, Utrecht University, Netherlands
Citation for Gabriele Villarini
Gabriele Villarini bridges hydrometeorology, climate dynamics, and disaster science in an innovative way. He has explored the meteorological context of floods as it relates to storm tracks, atmospheric rivers, and tropical cyclones, developing consistent and insightful diagnoses and a fundamental building block for understanding how future climate changes may lead to changed event frequency and spatial structure of floods. His work has also led to a better understanding of storm structure, inferences from radar, and the hydrologic response associated with floods. Collectively, he provides the seminal contribution of his generation to this subject area that is worthy of the Macelwane Medal.
His contributions are diverse and impressive. His graduate work laid the foundation of uncertainty analysis of radar-based rainfall fields and was perhaps the most comprehensive such work. His postdoctoral work on flood hydrology extended his contributions in hydrometeorology by developing and applying tools to identify different forms of nonstationarity in extreme rainfall and flood fields and relating these to specific forms of changes in the driving hydrometeorological mechanisms. This work represents a significant departure from his earlier work and demonstrates considerable dedication to working on an important topic and addressing it in depth. One of his colleagues at the time mentioned that she does not believe that Gabriele ever sleeps. His tenure as a faculty member at the University of Iowa has been equally impressive. He has built a wide array of collaborations with practicing and academic hydrologists, meteorologists, climate modelers, and statisticians. These collaborations have led to a series of interesting papers that connect large-scale atmospheric dynamics and their predictability to local and regional extremes. He has become extremely influential in this area and has been a leading contributor to the U.S. Army Corps of Engineers study on how future flood frequency changes can be diagnosed and risk profiled.
I especially like the humility and dedication with which Gabriele approaches the profession and scholarship. He is an outstanding role model for the future of our interdisciplinary field. I fully expect him to shape the directions of research and practice in the field, as he continues to grow and embrace new topics.
—Upmanu Lall, International Research Institute for Climate and Society, Palisades, N. Y.
Thank you, Manu, for your kind words in the citation, and thanks to AGU and to the colleagues who have supported my nomination. This award arguably represents the highest honor for an early-career scientist in the geophysical sciences, and I am thrilled to have been selected to receive it; it is also very humbling given the caliber of scientists who received it before me. Being selected has given me the opportunity to look back at my career so far and to acknowledge how fortunate I have been.
My career wouldn’t have been the same if I hadn’t had the good fortune to work with my Ph.D. adviser at the University of Iowa, Prof. Witold Krajewski. Witek was the best adviser I could have asked for, and has always been there for me, during my graduate work and afterward. He supported and challenged me at every step, allowing me to develop into the scientist I have become. He taught me never to cut corners or take the easy way out. I take pride in considering Witek a life-long mentor and colleague, but more important a friend.
After completing my Ph.D., I was once again really fortunate to be able to work with Prof. James Smith at Princeton University. Jim was a fantastic mentor, who provided me with great guidance and exposed me to a large number of research topics that I probably wouldn’t have dealt with otherwise. Learning from him was instrumental in shaping my current research interests. Overall, I wish everybody could be as lucky as I have been to work with mentors like Witek and Jim.
During my career, I have met and befriended many great scientists. Enrico Scoccimarro, Gabriel Vecchi, and Rhawn Denniston deserve a special mention for their support and friendship over the years and for making our collaborative research fun, exciting, and enriching.
None of this would have been possible, though, without the continued support from my family. My parents and brother have always given me endless love, and they have taught me never to give up and that hard work always pays off. My wife, Amie, is my rock, and she has always been my number-one supporter. And nothing compares to coming home to my daughters, Eleonora and Camilla, after a long day at work, and being asked “How was work, Papá?” followed by hugs and kisses. Thank you!
—Gabriele Villarini, University of Iowa, Iowa City