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News & Events

Dec
7
Wed
Ralf Koppmann – 2005 @ Senate Chamber, N940, Ross Building, York University
Dec 7 @ 2:30 pm – 4:30 pm

Title: The Forest as the chemical reactor – Results of the Echo Project.

Abstract: In this lecture, Dr. Ralf Koppmann will provide an overview of a unique research project known as Emission and Chemical Transformation of Biogenic Volatile Organic Compounds, or ECHO. Koppmann will highlight the results of the field and simulation experiments conducted during the ECHO project. The goal of the ECHO project was to provide a better understanding of forest stands as a complex source of reactive trace gases into the troposphere. Forests are complex sources of biogenic volatile organic compounds (VOC) in the planetary boundary layer of the atmosphere. Previous studies estimate that global emissions of these compounds are five to 10 times higher than man-made emissions. These biogenic compounds have a significant impact on the formation of photo-oxidants in the troposphere. Since these compounds can travel quickly up through the atmosphere, they may have an impact on the chemistry of the upper troposphere. Altogether, the impact of biogenic VOC on tropospheric photochemistry, air quality, and the formation of secondary products affecting the earth’s climate on a regional and global scale, is not well understood. Brochure - Y-File Article

Dec
8
Fri
Daniel J. Jacob – 2006 @ Senate Chamber, N940, Ross Building, York University
Dec 8 @ 2:30 pm – 3:30 pm

Title: The Hemispheric Transport of Pollution: Ozone, Particles, and Mercury.

Abstract: Surface ozone, particulate matter (PM), and mercury are well-recognized anthropogenic pollutants targeted by regulations throughout the developed world. Regulations are enacted by individual nations on their domestic emissions, but there is increasing evidence that a hemispheric approach is necessary because of pollutant transport on international and intercontinental scales. The associated environmental issues, transport pathways, and process uncertainties including chemistry are very different for ozone, PM, and mercury, and I will discuss each of these in turn. However, I will also show how an integrated approach to hemispheric pollution research is useful because of commonality in modeling tools, observational approaches, and policy challenges. I will discuss prospects for improving our understanding of long-range transport of pollution to the Arctic during the International Polar Year (IPY) by describing plans for the NASA ARCTAS aircraft/satellite mission to be conducted in spring/summer 2008 as part of POLARCAT. Brochure - Y-File Article

Nov
27
Tue
Paul B. Shepson – 2007 @ Senate Chamber, N940, Ross Building, York University
Nov 27 @ 2:30 pm – 4:00 pm

Title: Climate Change, and Atmosphere-Surface Interactions in the Arctic.

Abstract: Climate change in the Arctic is proceeding at a pace considerably greater than the global average, with evident consequences for sea ice, snow packs, permafrost, the associated biota, and with important yet poorly understood climate and chemical exchange feedbacks between the surface and the atmosphere.  Numerous questions now arise about interactions between a changing Arctic surface, and impacts on the frequency and nature of ozone and mercury depletion events, and the way toxic pollutants are processed in the Arctic.  In this talk I will review the many contributions of Canadian science to a better nderstanding of the role of the cryosphere in mediating atmospheric composition, chemistry and climate in the Arctic.  I will discuss current activities of the international project Ocean-Atmosphere-Sea Ice-Snowpack (OASIS), which focuses on chemical exchange between the surface and the atmosphere in the Arctic, and I will comment on the future of atmospheric chemistry research in the Arctic, and how it connects to Arctic and global climate change, and international politics. Brochure - Y-File Article

Dec
3
Wed
Douglas R. Worsnop – 2008
Dec 3 @ 4:00 pm – 5:00 pm

Title: Aerosols in the Atmosphere: From the Ozone Hole to Climate Change.

Abstract: Much of the uncertainty in predicting future climate change is associated with the properties of atmospheric aerosols and clouds.  Though low in absolute concentration (ppb loadings for background aerosol), the impact on the earth’s radiative balance of sub-micron particles is roughly equivalent to that of greenhouse gases (> ppm concentrations).  Mechanisms for the role for aerosols will be discussed in the context of work in the last 25 years that elucidated the kinetics of heterogeneous aerosol chemistry underlying acid rain production in the troposphere and ozone loss in the stratosphere.  Experimental observations of aerosol chemistry will be related to uncertainties in global aerosol loadings and processes, comparing effects of inorganic and organic constituents.  Brochure - Y-File Article

Dec
4
Fri
David D. Parrish – 2009 @ Senate Chamber, N940, Ross Building, York University
Dec 4 @ 2:30 pm – 3:30 pm

Title: Air Quality Across Large Temporal and Spatial Scales.

Abstract: When considering air quality we often limit our thoughts to a particular place at a particular time, usually the present. The goal of this talk is to provide a wider temporal and spatial context for our considerations.  Temporally, photochemical smog (i.e. ozone pollution) in Los Angeles has been the subject of research and control efforts for five decades.   The progress that Los Angeles has made will be reviewed, and the temporal trends of ozone and other pollutant concentrations there will be compared with those from other metropolitan areas of the world.  This review may usefully inform air quality policy decisions in developing cities throughout the globe.  On the broadest spatial scale, the limited available data sets indicate that “background” ozone at northern midlatitudes increased substantially over the past century, and this increase continues today.  Current global chemical transport models cannot accurately reproduce the observed trend, indicating that our understanding of the tropospheric ozone budget is incomplete.  A significant component of particulate matter observed locally also has been transported on intercontinental scales.  On regional spatial scales, transport between adjacent urban areas or air basins can be quite important.  Consequently, as local air quality standards are tightened, long-range and regional transport of “background” concentrations contribute an increasing fraction of allowable pollutant concentrations for both ozone and particulate matter, and the “background” concentration may be increasing, particularly for ozone. In summary, effective control strategies for local air quality must encompass local, regional and hemisphere-wide scales and consider changing “background” concentrations as well as changing local emissions.  Brochure - Y-File Article

Nov
18
Thu
Barbara Finlayson-Pitts – 2010 @ Senate Chamber, N940, Ross Building, York University
Nov 18 @ 2:45 pm – 3:45 pm

Title: Reactions at interfaces in the atmosphere:  Challenges and Opportunities. November 18, 2010.

Abstract: Multiphase chemistry in the atmosphere has traditionally been viewed as consisting of reactions in the gas phase and in the condensed phase, with mass transfer between the two.  In this case, kinetics and mechanisms determined in laboratory studies of bulk liquid or gas phase systems can be used reliably in atmospheric models.  However, there is increasing evidence that some reactions occur at interfaces between air and condensed phases in the form of airborne particles and surfaces in the boundary layer such as buildings, vegetation, etc.  Such interface reactions often have unique kinetics and mechanisms that are not well represented by bulk phase chemistry.  Furthermore, photochemistry at surfaces may be quite different than that in bulk phases.  Some examples of unique interface chemistry and photochemistry relevant to atmospheric processes and their potential implications for understanding the chemistry of the lower atmosphere will be discussed. Brochure - Y-File Article

Dec
12
Mon
Andreas Wahner – 2011 @ Senate Chamber, N940, Ross Building, York University
Dec 12 @ 2:00 pm – 4:00 pm

Title: Atmospheric Trace Gas Degradation and Secondary Pollutant Formation: New Insights from Process Studies. December 02, 2011.

Abstract: OH radicals play a central role in the chemistry of the troposphere. They are mainly responsible for the chemical degradation of many trace gases and they initiate chemical reactions that may eventually lead to photochemical formation or depletion of tropospheric ozone. Recent field measurements of the key radicals (OH, HO2) and measurements of the turnover rates, which determine the radical recycling, are underestimated significantly by current atmospheric chemistry models. At high load of anthropogenic and biogenic VOCs and low NO a significant OH source is missing. The challenging questions are: Which kind of reactions causes such efficient OH cycling? What does it mean to our understanding of the trace gas degradation and photochemical ozone production which is normally linked with radical cycling through NO reactions? Brochure - Y-File Article

Nov
2
Fri
A.R. Ravishankara – 2012 @ 103 Life Science Building
Nov 2 @ 2:30 pm – 4:30 pm

A.R. RavishankaraTitle: Ozone Layer Depletion and Climate Change: Connections in Science and Policy

Abstract: Ozone layer depletion due to man-made emissions, mostly chlorofluorocarbons (CFCs) and some bromine containing chemicals, have been recognized and addressed via the Montreal Protocol (MP). The successful phase out of ozone depleting substances, listed but not defined by the MP, led to the use of other chemicals that do not deplete the ozone layer. Hydrofluorocarbons (HFCs) were one such class of compounds that have found increasing use over the years.

The Montreal protocol has been credited with helping the climate change issue by phasing out, CFCs, many of which are also powerful greenhouse gases. Many HFCs are also potent greenhouse gases and their increasing use can offset the benefits gained to date. Lastly, all chemicals that can deplete the ozone layer are not necessarily included in the MP and raise the question regarding inclusion of other chemicals in the protocol. A prime example is nitrous oxide, which we argue is the most important ozone depleting gas that is being emitted today. I will discuss the phase in of HFCs, in place of CFCs, and its impact on climate as well as the role of nitrous oxide as an ozone depleting gas. I will discuss the atmospheric science of these chemical as well as their implications to decision making. Brochure - Y-File Article

Oct
31
Thu
23rd Annual Harold I Schiff Lecture Faculty of Science: Prof. Dr. Habil Astrid Kiendler-Scharr @ 103 Life Science Building
Oct 31 @ 2:30 pm – 4:00 pm

Habil Astrid Kiendler-ScharrTitle:  Chemistry Climate Interactions: Biogenic Emissions and their Contribution to Secondary Organic Aerosol

Abstract:   Atmospheric aerosols impact climate directly by scattering and absorbing solar radiation and indirectly by acting as ice and cloud condensation nuclei. Secondary organic aerosols (SOA) comprise an important component of atmospheric aerosols. Biogenic volatile organic compounds (BVOC) emitted by vegetation are a major source of SOA. It is known that BVOC emissions depend on climate, specifically on temperature and light. Therefore it is to be expected that a chemistry-climate interaction exists, in which climate change induces changes in BVOC emissions and thereby SOA formation, which feeds back to climate. The presentation details the state of the art knowledge on biogenic SOA and its climate relevance. The question whether climate induced changes in biogenic SOA formation may attenuate or amplify climate change is addressed based on experiments conducted in the Jülich Plant Atmosphere Chamber. Brochure - Y-File Article

May
28
Thu
Harold I Schiff Lecture in Atmospheric Chemistry: Steven S Brown @ 103 Life Science Building, York University
May 28 @ 2:30 pm – 4:00 pm

Prof. Steven S. Brown, NOAA,  presents the 24th Annual
Harold I Schiff Lecture Faculty of Science.
For more information click here.

 

 

 

Updated on December 6th, 2012.