Tropical modulation of East Asia air pollution

Abstract Given the high population density and serious air pollution problems, understanding and predicting air pollution in East Asia are of great importance. Here, we show that the day-to-day variability of East Asia air pollution in winter is remotely controlled by the convection over the tropical Indian Ocean and western Pacific, the so-called Madden–Julian oscillation (MJO), through its extratropical teleconnections. In particular, the concentration of particulate matter with aerodynamic diameter less than 10 micron (PM10) becomes significantly high when the tropical convection is suppressed over the Indian Ocean (MJO phases 5–6). In contrast, PM10 concentration becomes significantly low when the convection is enhanced there (MJO phase 1–2). The station-averaged PM10 difference between the two MJO phases reaches up to 47% of the daily PM10 variability, indicating that the MJO is a p…