Tropospheric NO₂ Pollution Monitoring with the GF-5 Satellite Environmental Trace Gases Monitoring Instrument over the North China Plain during Winter 2018–2019

• Main Authors: Dongshang Yang, Yuhan Luo, Yi Zeng, Fuqi Si, Liang Xi, Haijin Zhou, Wenqing Liu
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Atmosphere
• Subjects: Environmental Trace Gases Monitoring Instrument; multi-axis differential optical absorption spectroscopy; tropospheric NO₂; spatial distribution; North China Plain; meteorological conditions
• Online Access: https://www.mdpi.com/2073-4433/12/3/398

The Environmental Trace Gases Monitoring Instrument (EMI) is a high-spectral-resolution payload onboard the latest pathfinder mission GaoFen-5, designed specifically for the monitoring of global atmospheric trace gas compositions and trends. This study describes a comparative analysis of the tropospheric nitrogen dioxide (NO₂) columns over the North China Plain (NCP) from November 2018 to April 2019 based on EMI products. Validation of satellite products based on a cross-correlation analysis with data from four ground-based multi-axis differential optical absorption spectroscopy sites provided good correlation coefficients (r) ranging from 0.78 to 0.88. The distribution and monthly averaged tropospheric NO₂ columns revealed high pollution exposure levels during winter (November–January) and a decrease from February onward in the NCP. Moreover, a typical pollution event was analyzed in detail in combination with wind field statistics. The results indicated that variations of NO₂ concentrations in Beijing and Tianjin were highly correlated with the wind direction from 22.5–45.0 degrees west of south, especially during times of high NO₂ amounts. These findings highlight that the EMI payload on the GaoFen-5 (GF-5) satellite is useful for remote sensing of regional and global NO₂ detection.