Articles | Volume 9, issue 15
Atmos. Chem. Phys., 9, 5813–5827, 2009
https://doi.org/10.5194/acp-9-5813-2009

Special issue: MILAGRO/INTEX-B 2006

Atmos. Chem. Phys., 9, 5813–5827, 2009
https://doi.org/10.5194/acp-9-5813-2009

  12 Aug 2009

12 Aug 2009

Retrieval of aerosol single scattering albedo at ultraviolet wavelengths at the T1 site during MILAGRO

C. A. Corr1,*, N. Krotkov2, S. Madronich3, J. R. Slusser4, B. Holben5, W. Gao4, J. Flynn6, B. Lefer5, and S. M. Kreidenweis1 C. A. Corr et al.
  • 1Department of Atmospheric Sciences, Colorado State University, Fort Collins, CO 80521, USA
  • 2Goddard Earth Sciences and Technology Center, University of Maryland, Baltimore County, MD 20771, USA
  • 3Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, CO 80407, USA
  • 4The USDA UV-B Monitoring and Research Program, Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80521, USA
  • 5Biospheric Sciences Branch, NASA's Goddard Space Flight Center, Greenbelt, MD 20771, USA
  • 6Department of Earth and Atmospheric Sciences, University of Houston, 4800 Calhoun Rd, Houston, TX 77204-5007, USA
  • *now at: Complex Systems Research Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824, USA

Abstract. Surface measurements of direct and diffuse voltages at UV wavelengths were made at the T1 site during the MILAGRO (Megacity Initiative: Local and Global Research Observations) field campaign in March 2006, using a multifilter rotating shadowband radiometer (UV-MFRSR). We used the MFRSR data, together with measurements from a co-located CIMEL Sun photometer at the site operating as part of the AERONET network, to deduce aerosol single scattering albedo (ω) at 368 and 332 nm for four cloud-free days during the study. Our retrievals suggest that T1 aerosols with aerosol extinction optical depth τ368>0.1 that are influenced by Mexico City emissions, blowing dust, and biomass burning, are characterized by low ω368=0.73–0.85 and ω332=0.70–0.86, with small or no spectral variation of ω between 368 and 332 nm. Our findings are consistent with other published estimates of ω for Mexico City aerosols, including those that suggest that the absorption attributable to these aerosols is enhanced at UV wavelengths relative to visible wavelengths. We also demonstrate, via sensitivity tests, the importance of accurate τ and surface albedo measurements in ω retrievals at UV wavelengths.

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