Air quality forecasting for winter-time PM2.5 episodes occurring in multiple cities in central and southern Chile

An air quality prediction system is developed to predict such events in near real time up to 3 days in advance for nine cities with regular air quality monitoring: Santiago, Rancagua, Curicó, Talca, Chillan, Los Ángeles, Temuco, Valdivia, and Osorno.

The system uses the Weather Research and Forecasting with Chemistry model configured with a nested 2 km grid-spacing domain to predict weather and inert tracers. The tracers are converted to hourly PM2.5 concentrations using an observationally based calibration which is substantially less computationally intensive than a full chemistry model. The conversion takes into account processes occurring in these cities, including higher likelihood of episode occurrence during weekends and during colder days, the latter related to increased wood-burning-stove activity for heating.