Dylan Millet is a leader in combining measurement and modeling techniques to advance our understanding of volatile organic compounds (VOCs) and their impacts on atmospheric composition, air quality, and climate. His team has been at the forefront in applying high-resolution mass spectrometry to investigate sources and sinks of atmospheric VOCs. The approach is groundbreaking in allowing simultaneous measurement of hundreds of VOCs across the mass spectrum to gain insights into VOC chemical mechanisms and budgets at ecosystem to regional scales. His work has combined this advanced measurement technology with forward and inverse modeling in several important studies. These include collecting the first-ever long-term tall-tower (200-meter) VOC measurements and applying these data sets in a series of papers to characterize the sources and chemistry of key VOCs. He has also extended these measurement techniques to the eddy covariance approach to improve mechanistic understanding of how bidirectional forest-atmosphere VOC exchange drives atmospheric composition. He is also a leader in applying space-based observations of VOCs with chemical transport modeling to understand regional- to global-scale budgets. His team was the first to demonstrate the possibility of direct retrievals of isoprene from space. This seminal work set the stage to transform our understanding of atmospheric VOC sources and chemistry, in particular over critical parts of the world (e.g., the tropics) where in situ measurements are sparse. This new capability has helped to constrain hydroxyl radical (OH) abundance from space over isoprene source regions, where it is notoriously difficult to measure. Dylan’s team uses these novel data sets to advance the development of GEOS-Chem, a leading global atmospheric chemistry and transport model, which is used extensively within the atmospheric sciences community. His group has been pivotal in improving our ability to simulate VOCs and to better quantify their sources using observations. Overall, Dylan’s important contributions to improved in situ surface and satellite observations, model development, and the training of the next generation of atmospheric science students have advanced our understanding of atmospheric composition and chemistry. —Tim Griffis, University of Minnesota, Twin Cities

I am grateful to Tim for the nomination, and to the mentors and colleagues who wrote letters for this award and have supported me in many other ways over the years. It is an honor to be recognized alongside the other current and previous Ascent recipients who have contributed so much to our field. The research behind this award was performed by an entire team, and especially by the outstanding students, postdocs, and scientists who I have been lucky to host in my group. I also want to acknowledge many collaborators beyond our group. I find that much of the most exciting science in atmospheric chemistry occurs when we combine measurement and modeling tools to test current understanding—and that kind of work would be impossible without a network of talented and generous colleagues. I am very happy to accept this award and hope to pay forward the mentoring and support that I’ve received along the way! —Dylan B. Millet, University of Minnesota, Twin Cities