Analysis of the Characteristics of Tropospheric NO₂ in Xianghe Based on MAX-DOAS Measurement

Based on the measurements by Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) and the 32-m meteorological tower at Xianghe station of Atmospheric Comprehensive Observation, Institute of Atmospheric Physics, Chinese Academy of Sciences (Xianghe: 39.77°N, 117.0°E), from March 2010 to February 2012, the tropospheric vertical column density (VCD) of NO₂ in Xianghe was retrieved and its seasonal characteristics were analyzed. The results show that MAX-DOAS is an effective method for measuring NO₂ VCD, which can be well retrieved from wavelength intervals of 455-485 nm in the visible and 330-370 nm in the UV range. NO₂ VCD in Xianghe has an obvious seasonal variation, with its monthly mean being maximum in winter (November) and minimum in summer (July). The variation of NO₂ VCD is closely related to solar radiation intensity, source emission, atmospheric stability, and wind. Higher values of NO₂ VCD are observed in the eastern part of the region; the diurnal variation of NO₂ VCD is obvious in autumn and winter.