91ÑÇÉ« alumnus and Professor Tom McElroy, widely recognized as one of the world’s leading atmospheric scientists, recently passed and the University community will gather for a on May 26.
The life and work of McElroy, who spent 15 years at 91ÑÇÉ«'s , was built on a lifetime of scientific contributions and knowledge sharing through mentorship and field research.
After earning his PhD at 91ÑÇÉ« in the late 1970s, McElroy returned to 91ÑÇÉ« in 2011 as a CSA/ABB/NSERC Industrial Research Chair in Atmospheric Remote Sounding. He brought with him a breadth of experience and accomplishments, which he translated to meaningful research and teaching.
Among his most notable accomplishments, McElroy was the co-inventor of the Brewer ozone spectrophotometer in the early 1970s. The instrument measures how much ozone is in the atmosphere by analyzing sunlight as it passes through it. At the time, it marked a major advance in how scientists could track changes in the ozone layer. It went on to underpin global monitoring efforts and informed public and scientific understanding of ozone depletion, including the heightened awareness of the issue in the late 20th century.
He also co-developed the UV Index, a public-facing tool used around the world to show how strong the sun's ultraviolet radiation is. It provides simple guidance that helps people make decisions about sun exposure, such as when to seek shade or apply sunscreen. Widely adopted in weather reporting, it has become a familiar part of how people assess their risk when spending time outdoors.
McElroy continued to build on his contributions over a 36-year period with Environment Canada, where he served as a senior research scientist. It became a defining focus of his career, as he advanced work in ozone science, atmospheric physics and remote sensing. He developed new techniques to track atmospheric gases from the ground, from aircraft and from space, helping scientists better understand how the Earth’s atmosphere is changing across different environments.
His research extended into space-based observation as well, including contributions to Canada’s SCISAT mission – a satellite designed to study the chemistry of the Earth’s atmosphere – through the MAESTRO spectrophotometer, an instrument used to measure ozone and other gases from orbit.
Much of his research is reflected in hundreds of scientific publications, many of which have been widely cited. His work was also recognized with numerous national and international honours. He was elected a Fellow of the Royal Society of Canada in 2009 and received the Patterson Medal from Environment Canada and the United Nations Environment Programme Innovators Award.
During his time at 91ÑÇÉ«, he helped train students and early-career researchers, often introducing them to the rewards of working in remote environments, from the High Arctic to international monitoring stations.
His legacy lives on in the careers of the many students and colleagues he helped to shape at 91ÑÇÉ«, in the instruments still operating around the world and in the data that continues to inform environmental research and policy.
The memorial and celebration of life will take place at 91ÑÇÉ«'s Keele Campus, Bethune College, Room 203, from 11:30 a.m. to 2:30 p.m. Colleagues, former students, collaborators and family will gather both in person and online to reflect on his impact.