Evaluating the impact of emissions regulations on the emissions reduction during the 2015 China Victory Day Parade with an ensemble square root filter

In order to guarantee good air quality for the 15th International Association of Athletics Federations World Championships (22-30 August) and the China Victory Day parade (3 September) in Beijing, a series of comprehensive emissions regulations were implemented in Beijing and the surrounding provinces from 20 August to 3 September 2015. During this period, the intensity of the emissions regulation was enhanced step by step in the run-up to the event.

This period therefore allowed us to quantitatively estimate the reduction in emissions as a result of the emissions regulations under different intensity and strategy scenarios. The ensemble square root filter was employed to optimize the initial conditions and the emissions simultaneously. Numerical results showed that the variations of the anthropogenic emissions before, during, and after the emissions regulations were reasonably simulated.