News & Updates

New Book on Volatile Organic Compound Emissions

Ulo Niinemets and I just published an edited book with Springer Publishers on the topic of volatile organic compound emissions from forest trees. Ignoring methane, volatile organic compounds are emitted from all forests around the globe and these emissions add approximately 2 billion metric tons of organic molecules to the atmosphere each year. The emitted compounds include methanol, acetone, terpenes, and acetaldehyde. You are familiar with many of these compounds through the scents you smell when you walk through a pine forest, or smell the sweet aroma of a recently mowed lawn. These compounds react with various other chemicals in the atmosphere and support an active form of chemistry that, in some cases, produces ozone (a common pollutant in the lower atmosphere) and in other cases produces small, suspended aerosol particles that can cause the formation of clouds and induce precipitation. This edited book contains 18 chapters from scientists located around the world. The chapter I wrote is entitled "Metabolic and Gene Expression Controls on the Biogenic Volatile Organic Compound Emissions".

IPCC Roll-Out Event at the University of Arizona

A week ago last Friday, I participated in a panel discussion to present a summary of the latest report from the Intergovernmental Panel on Climate Change (IPCC) (Assessment Report 5) and its findings on the state of the planet with regard to this important issue. An audience of approximately 200 people attended and the event was covered by local media. We focused on the fact that we are in 'uncharted territory' with regard to greenhouse gas concentrations in the atmosphere (highest concentrations of CO2 probably since the origins of humanity) and the fact that the recently observed slowing of global warming appears to be due to greater heat storage in the deep oceans (which will eventually work its way back into the atmosphere). You can find coverage of the event at: http://uanews.org/story/in-the-bull-s-eye-of-climate-change.

North American Monsoon Macrosystems Modeling Update

For the past two years members of the North American Monsoon modeling team, associated with the NSF-funded Macrosystems project has been attempting to couple the Weather Research and Forecast (WRF) model with a new land surface model capable of simulating biophysical processes associated with a green and transpiring surface. This was recently accomplished at the 5 km scale using the land surface model NOAH Microphysics (NOAH-MP). In the figure below you can see that modeling the southwestern US monsoon precipitation with the NOAH-MP surface model results in slightly reduced precipitation during June, July and August (especially over western and central Mexico where the monsoon originates) (lower row of panels), compared to the old version of the model with a less sophisticated land surface model (NOAH) (middle row of panels). The results from the new NOAH-MP runs more closely match the observed precipitation which was derived from the NOAA precipitation database, and are shown in the top row of panels. These results are exciting because we are reaching a point in our modeling where we can actually see the effect of a land-surface feedback on monsoon activity in a model that resolves monsoon rain events at the scale of local watersheds (5 km). We are finally gaining access to dynamically-coupled models at the spatial scale we need to simulate monsoon rain events. This work was conducted by post-doctoral associate Hsin-I Change and Professor Chris Castro, who are both co-investigators on the Macrosystems project.

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