Research

FIELD MEASUREMENTS

Haliburton UMBS-PROPHET (2012, 2016)
We have made measurements of nitrogen oxide mixing ratios and fluxes in two summer campaigns at the University of Michigan Biological Station’s Program for Research on Oxidants: PHotochemistry, Emissions, and Transport (PROPHET) tower. During the summer of 2016, we were part of a large collaborative effort to study oxidants in a biogenic-rich environment. Sarah Kavassalis is collaborating with Allison Steiner (University of Michigan) to perform 1D modelling of the canopy turbulence and chemistry.
Haliburton NETCARE (ongoing)
The Network on Climate and Aerosols (NETCARE) is large collaborative project (PI Jon Abbatt) aimed at addressing key uncertainties related to aerosols in remote Canadian environments, funded by the Climate Change and Atmospheric Research program at NSERC.
In the summer of 2014, the Murphy group operated the AIM-IC onboard the CCGS Amundsen while the vessel sailed through the Canadian Arctic. We measured high levels of gas phase ammonia that we were able to associate with biomass burning and emissions from migratory seabird colonies. In the summer of 2016, we brought the AIM-IC to Alert, and our QC-TILDAS instrument onboard the Amundsen to learn more about water-soluble particles and gases in the Arctic.
IMG_5800 UBWOS 2014
The Uintah Basin Winter Ozone Study (UBWOS) campaign took place in January-February of 2014. Angela Hong brought our 2-channel NOx/NOy chemiluminescence analyzer to Horse Pool Utah to study vertical profiles of nitrogen oxides and ozone in the snowpack. The data will be analyzed to better understand the roles of the snowpack in the recycling of nitrogen oxides and radicals in the region. Angela wrote a more detailed description of her experience in an Environmental Chemistry blog.
IMG_4383 FOSSILS 2013
The Fort McMurray Oil Sands Strategic Investigation of Local Sources (FOSSILS) campaign took place in August-September of 2013. The Murphy group was involved in measurements from the AMS 13 ground site, located near Fort McKay. We operated the AIM-IC instrument to make measurements of water-soluble PM2.5 and gas phase NH3, HNO3, and SO2. We also assisted Environment Canada with the operation of a PTR-TOF-MS for the measurement of volatile organic compounds. The data will be analyzed to better understand the sources and fates of emissions from Oil Sands industrial activity.
Haliburton Haliburton Forest (2008-2013)
Haliburton Forest and Wildlife Reserve is a privately-owned mixed hardwoord forest located 200 km northeast of Toronto. We have been making flux measurements from a 32 m tower located in Haliburton Forest since 2009. Our primary interests are the greenhouse gas and reactive nitrogen budgets of the forest.
In the summer of 2011, we made intensive measurements of the canopy-scale fluxes of methane, nitrogen oxides and particulate matter. Our analysis of the carbon dioxide fluxes between 2009 and 2013 indicate that the area around the tower is a negligible sink of carbon, and that a short heatwave in the spring of 2010 led to persistent loss of carbon throughout that summer.
CalNex-150x143 CalNex 2010
The California Nexus (CalNex) campaign took place in California in the summer of 2010, with the objective of understanding issues that relate air quality and climate change. The Murphy group was involved in measurements of gas phase NH3 at the Pasadena ground site, and water-soluble PM2.5 and precursor gases at the Bakersfield ground site. Check out our publications page to see how these data have been used to better understand gas-particle partitioning and particle formation in southern and central California.
Raluca roof BAQS-Met 2007
The Border Air Quality and Meteorology Study (BAQS-Met) took place in June-July 2007, with the objective of understanding the impacts of transboundary transport and local emissions on air quality in southwestern Ontario. The Murphy group was involved in measurements of gas phase NH3 and water-soluble PM2.5 at the Harrow ground site. Many of the results from this study have been published in a special issue of Atmospheric Chemistry and Physics.

ANALYTICAL TECHNIQUES

Ambient Ion Monitor/Ion Chromatograph (AIM-IC)
Capable of highly sensitive, continuous and simultaneous measurements of atmospheric acidic and alkaline soluble gases and aerosol constituents.
Quantum Cascade Tunable Infrared Laser Differential Absorption Spectroscopy (QC-TILDAS)
Capable of making sensitive, high time resolution measurements of ammonia in a wide variety of environments.
Chemiluminescent detection system for NO/NO2/NOy
Makes sensitive, high time resolution measurements of atmospheric NOxspecies and total reactive nitrogen oxides (NOy).

DATA ANALYSIS

In addition to analysis of data obtained in our group, we have support from Environment Canada to analyze observations from many federal and provincial monitoring networks (e.g. NAPS, CAPMON)
Ozone in GTA
An examination of the last decade of observations of ozone and its precursors in the Greater Toronto Area has demonstrated why emission controls that have been so successful for primary pollutants have resulted in only minor reductions in photochemical ozone. This figure displays contours of predicted ozone production rates as a function of NO2 concentration and VOC reactivity, while the shaded arrow shows the chemical space over which the atmosphere has changed in the last eight years, resulting in minimal decreases in ozone.
Acid Deposition in Canada
Our analysis of the chemical composition of gases, particulate matter and precipitation from CAPMON sites across Canada between 1990 and 2007 found that decreases in sulphate yielded increases in the pH of precipitation, but also altered the partitioning between HNO3 and particulate nitrate. The lack of routine measurements of gas phase ammonia complicates the interpretation of trends and underlines the need for the type of accurate measurements we are pursuing.
Ground-based evaluation of OMI NO2
Applications of remotely sensed chemical composition include evaluation of air quality models, assimilation into air quality forecast models, identification of previously unrecognized pollution hot spots or emission sources, and assessments of chronic pollutant exposure in epidemiological studies. There is interest in ascertaining to what degree observations of tropospheric columns of pollutants (e.g. NO2) observed from space can replicate/replace data from sparse networks of traditional in situ monitors, particularly in urban areas where there is a high degree of spatial variability. One caveat is the presence of clouds, which obscure the satellite instrument’s field of view. We are assessing this by using the fractional cloud cover observed by the Ozone Monitoring Instrument (OMI) to screen the ground-based measurements, and calculate whether there is a significant selection bias in NO2 and SO2.