MAX-DOAS Measurements of Nitrogen Dioxide and Aerosol

• Main Author: Mendolia, Deanna
• Other Authors: Evans, Greg J.
• Language: en_ca
• Published: 2012
• Subjects: Differential Optical Absorption Spectroscopy; MAX-DOAS; tropospheric nitrogen dioxide and aerosol; vertical pollutant profiles; aerosol optical properties; 0799; 0608; 0775
• Online Access: http://hdl.handle.net/1807/32607

Multi-axis differential optical absorption spectroscopy (MAX-DOAS) was applied to retrieve tropospheric NO2 and aerosol vertical profiles from downtown Toronto, and King City, Ontario during select periods in 2006 – 2010. Linear regression of MAX-DOAS NO2 vertical column density (VCD) versus OMI (satellite) VCD yielded a good correlation (R = 0.88) and MAX-DOAS negative bias of 20%, which was within the reported uncertainty of the MAX-DOAS and OMI VCD. The average regional Toronto VCD (remotely-sensed via MAX-DOAS and OMI) was half of the near-road VCD obtained in-situ (2.4 x 1016 ± 1.2 x 1016 molec/cm2). MAX-DOAS measurements of O4 were coupled with radiative transfer modeling to obtain vertical aerosol extinction profiles and aerosol optical depth (AOD). A strong linear agreement was observed between PM2.5 concentration and aerosol extinction coefficient (R = 0.92), and MAX-DOAS versus sun photometer AOD (slope = 0.94; R= 0.90).