Colette L. Heald

Massachusetts Institute of Technology

2015 James B. Macelwane Medal Winner

Paul Cassak, Bethany List Ehlmann, Colette L. Heald, Matt Jackson, and Kate Maher were awarded the 2015 James B. Macelwane Medal at the AGU Fall Meeting Honors Ceremony, held on 16 December 2015 in San Francisco, Calif. The medal is for “significant contributions to the geophysical sciences by an outstanding early career scientist.”


Colette Heald is a greatly respected and influential young leader in atmospheric chemistry. Her work has broken new ground in a number of areas, including the use of satellite data to quantify emissions and track intercontinental transport of pollution; methods for investigating aerosol aging processes; and insights into the factors controlling the abundances of organic aerosols, dust, and primary biological particles.

One of Colette’s great strengths is her ability to effectively interact with experimentalists, synthesizing observations and modeling into new provocative concepts. In one of her most cited papers, she used aircraft data and modeling to demonstrate the woeful inadequacy of current understanding of organic aerosol sources in the remote atmosphere. This paper triggered a decade of research to improve models and observations. Colette’s own subsequent excellent work on the topic established her as an authority on secondary organic aerosols. She documented in particular the unique interactions between natural and anthropogenic emissions in the formation of organic aerosol, and she applied her knowledge of satellite remote sensing to place new constraints on the global budget of organic aerosol, dramatically reducing the previous range of uncertainty.

Colette has a talent for innovative thinking that leads to new ways of approaching problems. An outstanding example is her proposal of the van Krevelen diagram to quantitatively track the evolution of the composition of organic aerosol during its aging in the atmosphere. The van Krevelen diagram has its origin in the petrochemical processing field. Colette’s idea to apply it to field data to track the progress of atmospheric oxidation was simply brilliant!

Colette distinguishes herself also by her service to the research community. She has chaired the Aerosols Working Group of the GEOS-Chem atmospheric model for many years, leading a group of over 50 aerosol scientists worldwide in identifying and implementing priorities in model development. She has convened five AGU Fall Meeting sessions.

Colette’s vision for the importance of aerosols in the Earth system, combined with her strong grounding in aerosol chemistry and physics, puts her in a powerful position to lead the development of new understanding on the connected roles of aerosols in affecting climate, air quality, and biogeochemical cycles.

—Sonia Kreidenweis, Colorado State University, Fort Collins


My deepest thanks to my colleagues for supporting this nomination and AGU for the tremendous honor. In particular, I’d like to thank Sonia Kreidenweis for her kind nomination and her support as a colleague and mentor.

The Macelwane Medal represents the highest honor of my career. It is especially humbling to receive this as a recognition of contributions to geosciences. Atmospheric chemistry is a fairly young discipline in the geosciences; it brings together scientists with a range of backgrounds to study what I consider to be the science behind the Earth’s most pressing environmental issues. This makes for a magical combination of multidisciplinary problem solving within a friendly and collaborative community. I count myself lucky to be a part of it. And I am grateful for AGU’s recognition of our field.

It has been my privilege to work with inspiring people within outstanding institutions. My Ph.D. adviser Daniel Jacob taught me how to put together a compelling scientific argument; he also taught me that boring talks and papers are the scourge of academia! Harvard showed me how motivating it is to be surrounded by smart people. As a postdoc at Berkeley, I learned to appreciate the diversity of scientific perspectives and approaches. Allen Goldstein taught me how to believe in my own scientific vision, and I’ve benefited tremendously from his generosity ever since. I can’t say enough about the support and encouragement I received from my colleagues at the Department of Atmospheric Science at Colorado State University; they truly helped launch my faculty career. Finally, it’s a privilege and inspiration to be at the Massachusetts Institute of Technology (MIT). I’d like to thank my colleagues in the Department of Civil and Environmental Engineering and the Department of Earth, Atmospheric and Planetary Sciences for their support. Living up to this institution is a daily challenge!

I would also like to thank all of the women in science who have made it possible for me to receive this award and whose own accomplishments are far too rarely recognized. I hope that AGU continues to support and honor the work of women in the geosciences. For myself, I cannot overstate the importance of having a support network of women colleagues whose advice, commiseration, and “gold stars” are invaluable to me: Arlene Fiore, Allison Steiner, Julie Fry, Delphine Farmer, Annmarie Carlton, and Jen Murphy.

Finally, I’d like to thank my research group, past and present, for making it such a wonderful experience to come to the office and work with you every day.

—Colette L. Heald, Massachusetts Institute of Technology, Cambridge