Synergetic effect of El Niño‐Southern Oscillation and Indian Ocean Dipole on particulate matter in Guangdong, China

Abstract

The synergetic effect of Indian Ocean Dipole (IOD) and El Niño-Southern Oscillation on the particulate matter (PM 2.5 ) concentration in Guangdong for October-November-December 1980-2016 has been investigated. Results indicate that, during a typical polluted episode, Guangdong is usually under the influence of a high-pressure system behind the cold front, which is characterized by weakened southwesterly, subsidence/divergence, and stable atmospheric conditions. Persistent low values of PM 2.5 are found to prevail during the years when concurrent IOD positive phase and El Niño occur. However, separate occurrence of El Niño and the positive phase of IOD had only marginal effect on PM 2.5 . The remarkable synergetic effect of El Niño and the positive phase of IOD is caused by a significantly strengthened ascending motion associated with anomalous southwesterly, which facilitates the transport of abundant moisture, increasing rainfall and thus suppressing PM 2.5 pollution in