Contact Dr. Ray Nassar:

Phone & Address



York University, Graduate Program in Earth & Space Science, Adjunct Professor, 2013-2018

University of Toronto, Department of Physics, NSERC Postdoctoral Fellow, 2008-2010

Harvard University, Atmospheric Chemistry Modelling Group, Postdoctoral Fellow, 2006-2008


Ph.D. University of Waterloo, 2006

B.Ed. Queen's University, 1998

B.Sc. University of Waterloo, 1998


Dr. Ray Nassar

Research Scientist - Greenhouse Gas Measurements and Modelling

CURRENT S&T / RESEARCH - Improving our understanding of natural and anthropogenic greenhouse gas (GHG) sources and sinks using surface and satellite observations and models

  • Development of 3-D global atmospheric CO2 models for investigating the natural carbon cycle and impacts of anthropogenic CO2 emissions
  • Retrieval and application of CO2 concentrations from satellite observations
  • Quantification of CO2 sources and sinks by data assimilation using surface-based and satellite-based atmospheric CO2 observations
  • Observing System Simulation Experiments (OSSEs) to determine the benefit of planned or hypothetical satellite and surface CO2 data sets


  • Science team member for the Atmospheric Chemistry Experiment (ACE, since 2000), Orbiting Carbon Observatory (OCO/OCO-2, participant/member since 2007), Greenhouse Gases Observing Satellite (GOSAT, since 2009), the Weather, Climate and Air quality (WCA) concept proposed for the Polar Communications and Weather (PCW) mission (since 2010)
  • Reviewer for the Intergovernmental Panel on Climate Change (IPCC) 5th Assessment Report
  • Committee on Earth Observation Satellites (CEOS) Carbon Task Force report writing team member since 2011
  • GEOS-Chem steering committee member and co-chair of the Carbon Gases and Organics working group, 2011-2015


Nassar, R., C.E. Sioris, D.B.A. Jones, J.C. McConnell. 2014. Satellite observations of CO2 from a highly elliptical orbit for studies of the Arctic and boreal carbon cycle. Journal of Geophysical Research: Atmospheres, 119, 2654-2673.

Garand, L., A.P. Trishchenko, L. Trichtchenko, R. Nassar. 2014. The Polar Communications and Weather Mission: Addressing remaining gaps in the Earth Observing System, Physics in Canada, 70 (4), 247-254.

Deng, F., D.B.A. Jones, D.K. Henze, N. Bousserez, K.W. Bowman, J.B. Fisher, R. Nassar, C. O'Dell, D. Wunch, P.O. Wennberg, E.A. Kort, S.C. Wofsy, T. Blumenstock, N.M. Deutscher, D. Griffith, F. Hase, P. Heikkinen, V. Sherlock, K. Strong, R. Sussmann, T. Warneke. 2014. Inferring regional sources and sinks of atmospheric CO2 from GOSAT XCO2 data. Atmospheric Chemistry and Physics, 14, 3703-3727.

Nassar, R., L. Napier-Linton, K.R. Gurney, R.J. Andres, T. Oda, F.R. Vogel, F. Deng. 2013. Improving the temporal and spatial distribution of CO2 emissions from global fossil fuel emission datasets. Journal of Geophysical Research: Atmospheres, 118, 917-933.

Nassar, R., D.B.A. Jones, S.S. Kulawik, J.R. Worden, K.W. Bowman, R.J. Andres, P. Suntharalingam, J.M. Chen, C.A.M. Brenninkmeijer, T.J. Schuck, T.J. Conway, D.E. Worthy. 2011. Inverse modeling of CO2 sources and sinks using satellite observations of CO2 from TES and surface flask measurements. Atmospheric Chemistry and Physics, 11:6029-6047.

Nassar, R., D.B.A. Jones, P. Suntharalingam, J.M. Chen, R.J. Andres, K.J. Wecht, R.M. Yantosca, S.S. Kulawik, K.W. Bowman, J.R. Worden, T. Machida and H. Matsueda. 2010. Modeling global atmospheric CO2 with improved emission inventories and CO2 production from the oxidation of other carbon species. Geoscientific Model Development, 3:689-716.

Kulawik, S.S., D.B.A. Jones, R. Nassar, F.W. Irion, J.R. Worden, K.W. Bowman, T. Machida, H. Matsueda, Y. Sawa, S.C. Biraud, M. Fisher and A.R. Jacobson. 2010. Characterization of Tropospheric Emission Spectrometer (TES) CO2 for carbon cycle science. Atmospheric Chemistry and Physics, 10:5601-5623.

Payne, V.H., S.A. Clough, M.W. Shephard, R. Nassar and J.A. Logan. 2009. Information-centered representation of retrievals with limited degrees of freedom for signal: Application to methane from the Tropospheric Emission Spectrometer. Journal of Geophysical Research, 114:D10307, doi:10.1029/2008JD010155.

Expertise Categories associated with this S&T Expert:

     Air Pollution & Quality
          Greenhouse gases
     Climate Change and Processes
          Greenhouse gases
          Land Surface/Atmosphere Interactions
          Satellite remote sensing
          Carbon budget
Date modified: