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Volume 16, No. 11, November 2016, Pages 2818-2830 PDF(492 KB)  
doi: 10.4209/aaqr.2015.07.0457   

Relationship between Aerosol Optical Depth and Particulate Matter over Singapore: Effects of Aerosol Vertical Distributions

Boon Ning Chew1, James R. Campbell2, Edward J. Hyer2, Santo V. Salinas1, Jeffrey S. Reid2, Ellsworth J. Welton3, Brent N. Holben4, Soo Chin Liew1

1 Centre for Remote Imaging, Sensing and Processing, National University of Singapore, 119076, Singapore
2 Naval Research Laboratory, Marine Meteorology Division, Monterey, CA 93943-5502, USA
3 Micro-Pulse Lidar Network, Code 613.1, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
4 Code 618, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA


  • Aerosol scale height distribution over Singapore is observed to be bimodal.
  • Lidar-derived surface extinctions are well correlated with PM2.5 concentrations.
  • Observational AOD-PM2.5 correlations improve with aerosol scale height corrections.
  • Modeled AOD-PM2.5 correlation improves marginally with similar corrections.



As part of the Seven Southeast Asian Studies (7SEAS) program, an Aerosol Robotic Network (AERONET) sun photometer and a Micro-Pulse Lidar Network (MPLNET) instrument have been deployed at Singapore to study the regional aerosol environment of the Maritime Continent (MC). In addition, the Navy Aerosol Analysis and Prediction System (NAAPS) is used to model aerosol transport over the region. From 24 September 2009 to 31 March 2011, the relationships between ground-, satellite- and model-based aerosol optical depth (AOD) and particulate matter with aerodynamic equivalent diameters less than 2.5 µm (PM2.5) for air quality applications are investigated. When MPLNET-derived aerosol scale heights are applied to normalize AOD for comparison with surface PM2.5 data, the empirical relationships are shown to improve with an increased 11%, 10% and 5% in explained variances, for AERONET, MODIS and NAAPS respectively. The ratios of root mean square errors to standard deviations for the relationships also show corresponding improvements of 8%, 6% and 2%. Aerosol scale heights are observed to be bimodal with a mode below and another above the strongly-capped/deep near-surface layer (SCD; 0–1.35 km). Aerosol extinctions within the SCD layer are well-correlated with surface PM2.5 concentrations, possibly due to strong vertical mixing in the region.



Keywords: Air pollution; Air quality; Aerosol optical depth.



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