Influence of NOX, Cl, and Br on the upper core of the ozone valley over the Tibetan Plateau during summer: Simulations with a box model

The ozone valley (OV) in the upper troposphere-lower stratosphere (UTLS) over the Tibetan Plateau (TP) has been identified since the 1990s during boreal summer. Recent studies have shown that another upper core of the OV appeared in the middle and upper stratosphere (10–2 hPa); however, the formation mechanism of the OV in the upper stratosphere remains unclear. In this paper, Microwave Limb Sounder (MLS) data from the Aura satellite and the stratospheric heterogeneous chemical reaction box model are used to investigate the impact of chemical substances, including NO, NO2, Cl and Br, on the ozone valley in the middle and upper stratosphere over the TP. The results show that the formation mechanism of the diurnal and nighttime variation in the upper core of the OV over the TP in the summer may be related to the different daytime and nighttime distributions of NO2 and the difference in daytime and nighttime average temperatures between the TP and the same latitude regions. [Display omitted] •There is an upper core of ozone valley over the Tibetan Plateau at 10–2 hPa.•The paper investigated the impact of NO, NO2, Cl and Br on the upper core.•Microwave Limb Sounder data and a stratospheric heterogeneous chemical reaction box model are used.•Different distribution of NO2 and temperature of two regions maybe a possible explanation.