资源环境科技发展态势分析平台

The seasonal evolution of O-3 and its photochemical production regime in a polluted region of eastern China between 2014 and 2017 has been investigated using observations. We used tropospheric ozone (O-3), carbon monoxide (CO), and formaldehyde (HCHO, a marker of VOCs (volatile organic compounds)) partial columns derived from high-resolution Fourier transform spectrometry (FTS); tropospheric nitrogen dioxide (NO2, a marker of NOx (nitrogen oxides)) partial column deduced from the Ozone Monitoring Instrument (OMI); surface meteorological data; and a back trajectory cluster analysis technique. A broad O-3 maximum during both spring and summer (MAM/JJA) is observed; the day-to-day variations in MAM/JJA are generally larger than those in autumn and winter (SON/DJF). Tropospheric O-3 columns in June are 1.55 x 10(18) molecules cm(-2) (56 DU (Dobson units)), and in December they are 1.05 x 10(18) molecules cm(-2) (39 DU). Tropospheric O-3 columns in June were similar to 50 % higher than those in December. Compared with the SON/DJF season, the observed tropospheric O-3 levels in MAMMA are more influenced by the transport of air masses from densely populated and industrialized areas, and the high O-3 level and variability in MAMMA is determined by the photochemical O-3 production. The tropospheric-column HCHO/NO2 ratio is used as a proxy to investigate the photochemical O-3 production rate (PO3). The results show that the PO3 is mainly nitrogen oxide (MX) limited in MAM/JJA, while it is mainly VOC or mixed VOC-NOx-limited in SON/DJF. Statistics show that NOx-limited, mixed VOC-NOx-limited, and VOC-limited PO3 accounts for 60.1 %, 28.7 %, and 11 % of days, respectively. Considering most of PO3 is NOx limited or mixed VOC-NOx-limited, reductions in NOx would reduce O-3 pollution in eastern China.