Articles | Volume 8, issue 1
Atmos. Meas. Tech., 8, 505–521, 2015
Atmos. Meas. Tech., 8, 505–521, 2015

Research article 30 Jan 2015

Research article | 30 Jan 2015

SPARTAN: a global network to evaluate and enhance satellite-based estimates of ground-level particulate matter for global health applications

G. Snider1, C. L. Weagle2, R. V. Martin1,2,3, A. van Donkelaar1, K. Conrad1, D. Cunningham1, C. Gordon1, M. Zwicker1, C. Akoshile4, P. Artaxo5, N. X. Anh6, J. Brook7, J. Dong8, R. M. Garland9, R. Greenwald10, D. Griffith11, K. He8, B. N. Holben12, R. Kahn12, I. Koren13, N. Lagrosas14, P. Lestari15, Z. Ma10, J. Vanderlei Martins16, E. J. Quel17, Y. Rudich13, A. Salam18, S. N. Tripathi19, C. Yu10, Q. Zhang8, Y. Zhang8, M. Brauer20, A. Cohen21, M. D. Gibson22, and Y. Liu10 G. Snider et al.
  • 1Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada
  • 2Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada
  • 3Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts, USA
  • 4Department of Physics, University of Ilorin, Ilorin, Nigeria
  • 5Instituto de F\'isica, Universidade de São Paulo, Rua do Matão, Travessa R, 187, São Paulo, Brazil
  • 6Institute of Geophysics, Vietnam Academy of Science and Technology, Hanoi, Vietnam
  • 7Department of Public Health Sciences, University of Toronto, Toronto, Ontario, Canada
  • 8Center for Earth System Science, Tsinghua University, Beijing, China
  • 9Unit for Environmental Science and Management, North-West University, Potchefstroom, South Africa
  • 10Rollins School of Public Health, Emory University, 1518 Clifton Road NE, Atlanta, Georgia, USA
  • 11Council for Scientific and Industrial Research (CSIR), Pretoria, South Africa
  • 12Earth Science Division, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
  • 13Department of Earth and Planetary Sciences, Weizmann Institute, Rehovot 76100, Israel
  • 14Manila Observatory, Ateneo de Manila University campus, Quezon City, Philippines
  • 15Faculty of Civil and Environmental Engineering, Institute of Technology Bandung (ITB), JL. Ganesha No.10, Bandung 40132, Indonesia
  • 16Department of Physics and Joint Center for Earth Systems Technology, University of Maryland, Baltimore County, Baltimore, Maryland, USA
  • 17UNIDEF (CITEDEF-CONICET) Juan B. de la Salle 4397 – B1603ALO Villa Martelli, Buenos Aires, Argentina
  • 18Department of Chemistry, University of Dhaka, Dhaka – 1000, Bangladesh
  • 19Center for Environmental Science and Engineering, Indian Institute of Technology, Kanpur, India
  • 20School of Population and Public Health, University of British Columbia, Vancouver, British Columbia, Canada
  • 21Health Effects Institute, 101 Federal Street Suite 500, Boston, Massachusetts, USA
  • 22Department of Process Engineering and Applied Science, Dalhousie University, Halifax, Nova Scotia, Canada

Abstract. Ground-based observations have insufficient spatial coverage to assess long-term human exposure to fine particulate matter (PM2.5) at the global scale. Satellite remote sensing offers a promising approach to provide information on both short- and long-term exposure to PM2.5 at local-to-global scales, but there are limitations and outstanding questions about the accuracy and precision with which ground-level aerosol mass concentrations can be inferred from satellite remote sensing alone. A key source of uncertainty is the global distribution of the relationship between annual average PM2.5 and discontinuous satellite observations of columnar aerosol optical depth (AOD). We have initiated a global network of ground-level monitoring stations designed to evaluate and enhance satellite remote sensing estimates for application in health-effects research and risk assessment. This Surface PARTiculate mAtter Network (SPARTAN) includes a global federation of ground-level monitors of hourly PM2.5 situated primarily in highly populated regions and collocated with existing ground-based sun photometers that measure AOD. The instruments, a three-wavelength nephelometer and impaction filter sampler for both PM2.5 and PM10, are highly autonomous. Hourly PM2.5 concentrations are inferred from the combination of weighed filters and nephelometer data. Data from existing networks were used to develop and evaluate network sampling characteristics. SPARTAN filters are analyzed for mass, black carbon, water-soluble ions, and metals. These measurements provide, in a variety of regions around the world, the key data required to evaluate and enhance satellite-based PM2.5 estimates used for assessing the health effects of aerosols. Mean PM2.5 concentrations across sites vary by more than 1 order of magnitude. Our initial measurements indicate that the ratio of AOD to ground-level PM2.5 is driven temporally and spatially by the vertical profile in aerosol scattering. Spatially this ratio is also strongly influenced by the mass scattering efficiency.

Short summary
We have initiated a global network of ground-level monitoring stations to measure concentrations of fine aerosols in urban environments. Our findings include major ions species, total mass, and total scatter at three wavelengths. Results will be used to further evaluate and enhance satellite remote sensing estimates.