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Evaluation and Evolution of MAX-DOAS-observed Vertical NO2 Profiles in Urban Beijing


Multiaxis differential absorption spectroscopy (MAX-DOAS) is a newly developed advanced vertical profile detection method, but the vertical nitrogen dioxide (NO2) profiles measured by MAX-DOAS have not yet been fully verified. In this study, we perform MAX-DOAS and tower gradient observations to simultaneously acquire tropospheric NO2 observations in the Beijing urban area from 1 April to 31 May 2019. The average values of the tropospheric NO2 vertical column densities measured by MAX-DOAS and the tropospheric monitoring instrument are 15.8 × 1015 and 12.4 × 1015 molecules cm−2, respectively, and the correlation coefficient R reaches 0.87. The MAX-DOAS measurements are highly consistent with the tower-based in situ measurements, and the correlation coefficients R from the ground to the upper air are 0.89 (60 m), 0.87 (160 m), and 0.76 (280 m). MAX-DOAS accurately measures the trend of NO2 vertical profile changes, although a large underestimation occurs by a factor of two. By analyzing the NO2 vertical profile, the NO2 concentration reveals an exponential decrease with height. The NO2 vertical profile also coincides with the evolution of the boundary layer height. The study shows that the NO2 over Beijing mainly originates from local sources and occurs in the boundary layer, and its vertical evolution pattern has an important guiding significance to better understand nitrate production and ozone pollution.

摘 要

多轴差分吸收光谱法(MAX-DOAS)是一种先进的大气污染物垂直廓线探测方法,但其测量的二氧化氮(NO2)垂直廓线尚未得到充分验证。2019年4月1日至2019年5月31日期间,我们同步开展了MAX-DOAS和气象塔梯度观测,结合卫星观测的NO2柱浓度对MAX-DOAS探测结果进行了验证。结果表明,MAX-DOAS和卫星测量的对流层NO2垂直柱浓度平均值分别为15.8 × 1015 和 12.4 × 1015 molecules cm-2,相关系数高达0.87。 MAX-DOAS测量值与塔基原位测量值也高度一致,从地面到高空的相关系数分别为0.89(60 m),0.87(160 m)和0.76(280 m)。虽然探测的NO2绝对量值仍存在显著低估(约为塔基原位测量值的二分之一),但是MAX-DOAS可以精确测量NO2垂直变化趋势。 NO2浓度随高度呈指数下降趋势,且其垂直演变规律与边界层高度变化相吻合。以上研究结果表明,北京地区的NO2主要来自局地,控制本地NO2排放是降低硝酸盐生成和臭氧污染的首要手段。

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This work was supported by the National Key R&D Program of China (Grant No. 2017YFC0210000), the National Natural Science Foundation of China (Grant Nos. 41705113, 41877312), the National Research Program for Key Issues in Air Pollution Control (Grant No. DGQQ202004), and the Beijing Major Science and Technology Project (Grant No. Z181100005418014).

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Correspondence to Guiqian Tang or Qihua Li.

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Article Highlights

• MAX-DOAS measurements are highly consistent with TROPOMI and tower-gradient in situ measurements.

• MAX-DOAS accurately measures the trend of NO2 vertical profile changes, although underestimates its concentration by a factor of 2.

• The NO2 vertical profile evolution coincides with the BLH evolution.

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Kang, Y., Tang, G., Li, Q. et al. Evaluation and Evolution of MAX-DOAS-observed Vertical NO2 Profiles in Urban Beijing. Adv. Atmos. Sci. 38, 1188–1196 (2021).

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Key words

  • NO2
  • tower-based in situ observation
  • validation
  • vertical


  • NO2
  • 塔基原位观测
  • 垂直
  • 验证