Diurnal variation of ClO: Implications for the stratospheric chemistries of ClONO₂, HOCl, and HCl

This is the authors' abstract. We don't add key points for this paper.

Numerical results are presented for the diurnal variations of stratospheric species, including the chlorine species. The calculated diurnal variation of the column density of stratospheric chlorine monoxide (ClO) appears to be in good agreement with the recent measurement obtained from ground‐based millimeter‐wave spectroscopy. The observed large diurnal variation of the column density of ClO above 30 km can be understood in terms of various exchange processes between ClO x (Cl+ClO) and the temporary chlorine reservoirs (ClONO 2 and HOCl). The rapid early morning rise in the column density of ClO above 30 km is mainly attributed to photolysis of ClONO 2 , whereas its continual decrease during the nighttime may be attributed to the recombination of ClO with NO 2 , forming ClONO 2 as the major product. The predicted diurnal behavior of the upper stratospheric ClO, however, is mainly due to the exchange between ClO x and HOCl. Observation of the diurnal behavior of ClO in the upper stratosphere can place important constraints on the chemistry of HOCl.