Dr. Jason Blake Cohen is currently an Assistant Professor in Civil and Environmental Engineering at the National University of Singapore. His Sc.D. is from the Massachusetts Institute of Technology (MIT) in the field of Earth, Atmospheric, and Planetary Sciences with a Major in Climate Chemistry and Physics. He also has an MS from the California Institute of Technology (Caltech) in Environmental Engineering Science, and an AB from UC Berkeley in Applied Mathematics.

His current work develops and improves models of aerosols, which are tiny substances that greatly influence haze and climate change. The recent work has successfully built a new world-class emissions database; derived new ways to analyze the spatial and temporal patterns of fire emissions; and created new approaches to distinguish aerosols from urban and fire-burning regions.This advanced research has led to a breakthrough in our understanding of aerosols and climate change. The breadth of these results concludes that to ultimately mitigate haze in Asia, we must first properly consider the simultaneous contributions from and impacts of both urban and fire burning sources.

In addition to publishing research articles in leading scientific journals, Dr. Cohen teaches classes in environmental modeling and climate change.  Also he has worked with a few interested government agencies and non-governmental organizations that want to increase their analytical capability to deal with haze. Finally, he is a regular commentator on Environmental Science topics for the Singapore and International Media.

Speaker Abstract

Quantifying the Sources of Haze and Associated Impacts on Tropical Urban Singapore: Lessons Learned

The issue of haze has become more important in Singapore in the recent couple of decades. A combination of a rise in local sources, an increase in the local economy as well as that of the surrounding nations, and an increase in large-scale forest fires have all occurred. These changes all lead to increased emissions of haze and ultimately to greater burdens in Singapore and the region at large.

A new aerosol emissions dataset will be shown to produces a much better fit when compared with measurements, both locally, and from around the world. This new dataset offers a means to quantify both the fire fraction as well as the amount from urban sources. When specifically quantified for the Southeast and East Asian regions, it is shown to compare favorably against multi-year measurements, during both the local wet and dry seasons. It is shown that while urban emissions are an important source, that the fires in Southeast Asia have a significant impact not only regions local to Southeast Asia, but also locations far away, including Hong Kong, Guangzhou, and Taipei.

Using this information, an improved understanding is gained from the strict local haze source mitigations steps taken in Singapore. It is clear that such actions are useful for reducing the levels of haze, but that the impacts of fire sources, even from thousands of kilometers upwind, can easily outweigh or completely cancel out any such steps at controlling the air quality. Steps will then be mentioned on how to address this problem into the future.