RESEARCH

Our work focuses on using observations of the atmosphere from all scales (in situ to satellite) with global models to understand the composition and chemistry of the troposphere. Research in our group is supported by NASA, NSF, Ball Aerospace and the EPA. Primary research areas include (click on the pictures for more information):

AEROSOL SOURCES, COMPOSITION AND CHEMISTRY	BIOGENIC AND ANTHROPOGENIC INFLUENCES ON CHEMISTRY AND CLIMATE	THE ORGANIC COMPOSITION OF THE TROPOSPHERE	INTERCONTINENTAL TRANSPORT OF POLLUITION	MAPPING EMISSION SOURCES

Aerosol sources, composition and chemistry

"View" of Hong Kong Island from Star Ferry on a polluted day (C.L.Heald)
OVERVIEW:
Aerosols are particles suspended in the atmosphere. They have both natural (e.g. dust and volcanic) and anthropogenic (e.g. vehicle emissions, industrial) sources and through their interaction with radiation can affect climate. Aerosols can also be a component of urban smog and contribute to visibility degradation. Understanding the sources, formation and transformation of aerosols in the troposphere is key to characterizing their role in climate and air pollution.

CURRENT/FUTURE PROJECTS

1. "Improved treatment of atmospheric organic particulate matter concentrations from biomass burning emissions: A global modeling approach"
2. "Investigating the global budget of primary biological aerosol particles" (Heald)
3. "Investigating tropospheric sulfate formation and potential biases associated with cloud processing" (Patterson)
4. "Investigating aerosol concentrations over the Amazon during the wet season" (Heald)
5. "Examining sources and transport of aerosols in the tropics" (Ridley)

RELEVANT PUBLICATIONS:

• Heald, C.L., D.V. Spracklen (2009), Atmospheric budget of primary biological aerosol particles from fungal sources, Geophysical Research Letters, submitted. [Full Text(pdf)]
• Heald, C.L., D.J. Jacob, S. Turquety, R.C. Hudman, R.J. Weber, A.P. Sullivan , R.E. Peltier, E.L. Atlas, J.A. de Gouw, C. Warneke, J.S. Holloway, J.A. Neuman , F.M. Flocke, and J.H. Seinfeld (2006), Concentrations and sources of organic carbon aerosol in the free troposphere over North America, J. Geophys. Res., 111, D23S47, doi:10.1029/2006JD007705. [Full Text(pdf)]
• Heald, C.L., D.J. Jacob, R.J. Park, L.M. Russell, B.J. Huebert, J.H. Seinfel d, H. Liao and R.J. Weber (2005), A large organic aerosol source in the free troposphere missing from current models, Geophys. Res. Lett., 32, L18809, doi:10.1029/2005GL023831, 2005. [Full Text (pdf)]

Biogenic and anthropogenic influences on chemistry and climate

Muir Woods (left), Hong Kong (right) (C.L. Heald)

OVERVIEW:
Our climate is influenced by the combination of natural and human-induced changes, including feedbacks within the climate system. For example, volatile organic compounds (VOCs) emitted from vegetation (example: isoprene) participate in the formation of ozone and also of organic aerosol, both of which are sensitive to anthropogenic emissions of nitrogen oxides and VOCs as well. The latest generation of models can be used to investigate these chemistry-climate interactions and project how the composition of the atmosphere may change.

CURRENT/FUTURE PROJECTS:

1. "CO2 inhibition of isoprene emissions: Present-day and future response"(Heald)

RELEVANT PUBLICATIONS:

• Heald, C.L., M.J. Wilkinson, R. Monson, C.A. Alo, G. Wang and A. Guenther (2008), Response of isoprene emission to ambient CO₂ changes and implications for global budgets, Global Change Biology, in press. [Full Text (pdf)]
• Heald, C.L., D.K. Henze, L.W. Horowitz, J. Feddema, J.-F. Lamarque, A. Guenther, P.G. Hess, F. Vitt, J.H. Seinfeld, A.H. Goldstein, and I. Fung (2008), Predicted change in global secondary organic aerosol concentrations in response to future climate, emissions, and land-use change, J. Geophys. Res., 113, D05211, doi:10.1029/2007JD009092. [Full Text (pdf)].

The organic composition of the troposphere

The Blue Mountains, Australia: haze caused by eucalyptus emissions

OVERVIEW:
The atmosphere contains a suite of organic compounds, with varying lifetimes, properties and sources. The global budgets of these compounds are poorly understood and many species have not been measured in the ambient atmosphere. Despite this pressing need for the development of new measurement technologies, much can be learned by developing new frameworks to analyse previous and ongoing measurements from field campaigns. This research topic connects to our work on organic aerosols.

CURRENT/FUTURE PROJECTS:

1. "Investigating the organic oxygen composition of the troposphere"
"Investigating the carboxylic budget of the atmosphere"

RELEVANT PUBLICATIONS:

• Heald, C.L., et al (2008)., Total Observed Organic Carbon (TOOC) in the Atmosphere: A Synthesis of North American Observations, Atmos. Chem. Phys., 8, 2007-2025. [Full Text (pdf)]

Intercontinental transport of pollution

Haze (primarily sulfate and organics from the NE US) transported over the North Atlantic as seen by SeaWiFS (NASA Visible Earth)

OVERVIEW:
Local pollution levels are affected not only by local emissions but also by the long-range transport of pollutants from distant source regions. In this way we are all "breathing the same air". Characterizing the "import" and "export" of pollution from one continental region to another is key to making effective pollution control policy. The last decade has seen a dramatic increase in space observations of pollution in the troposphere and we can now use these observations in concert with global models and in situ sampling to investigate the transport of emissions from sources, across oceans, and ultimately to receptor regions.

CURRENT/FUTURE PROJECTS:

"Export and long range transport of pollution and aerosols: Constraints from the A-Train" (Ford)

"Satellite-based investigation of transpacific transport" (Lapina)

RELEVANT PUBLICATIONS:

• Heald, C.L., D.J. Jacob, R.J. Park, B. Alexander, T.D.Fairlie, D.A. Chu, R.M. Yantosca (2006), Transpacific transport of Asian anthropogenic aerosols and it s impact on surface air quality in the United States, J. Geophys. Res., 111, D14 310, doi:10.1029/2005JD006847. [Full Text (pdf)]
• Heald, C.L., D.J. Jacob, A.M. Fiore, L.K. Emmons, J.C. Gille, M.N. Deeter, J .Warner, D.P. Edwards, J.H. Crawford, A.J. Hamlin, G.W. Sachse, E.V. Browell, M. A. Avery, S.A. Vay, D.J. Westberg, D.R.Blake, H.B.Singh, S.T. Sandholm, R.W. Tal bot, H.E. Fuelberg (2003), Asian outflow and transpacific transport of carbon monoxide and ozone pollution: An integrated satellite, aircraft and model perspective, J. Geophys. Res., 108 (D24), 4804, doi:10.1029/2003JD003507. [Full Text (pdf)]

Improving emission estimates from remote and in situ observations

MOPITT instrument aboard the Terra satellite (www.space.gc.ca)

OVERVIEW:
Space-based observations provide large-scale and continuous insight into the emissions of atmospherically-relevant trace gases. Remotely observed quantities such as fire counts and vegetation cover can be used to make "bottom-up" emission estimates. Observations of trace gas concentrations in the atmosphere can be used as "top-down" constraints on emissions. These observations can be formally used in an inverse modeling context to estimate the relative contributions of different source regions and source types. Combined with in situ observations (from ground sites or aircraft) remote observations are a powerful constraint on surface emissions.

CURRENT/FUTURE PROJECTS:

1. "Bridging models, in situ and satellite observations to improve our understanding of ammonia emissions"

RELEVANT PUBLICATIONS:

• Heald, C.L., D.J. Jacob, D.B.A. Jones, P.I. Palmer, J.A. Logan, D.G. Streets , G.W. Sachse, J.C. Gille, R.N. Hoffman, and T. Nehrkorn (2004), Comparitive inverse analysis of satellite (MOPITT) and aircraft (TRACE-P) observations to estimate Asian sources of carbon monoxide, J. Geophys. Res., 109 (D23), D23306, doi:10.1029/2004JD005185. [Full Text (pdf)]
• Heald, C.L., D.J. Jacob, P.I. Palmer, M.J. Evans, G.W. Sachse, H.B. Singh, a nd D.J. Blake (2003), Biomass burning emission inventory with daily resolution: Application to aircraft observations of Asian outflow, J. Geophys. Res., 108(D21), 8811, doi:10.1029/2002JD003082. [Full Text (pdf)]