ENSO Contribution to Aerosol Variations over the Maritime Continent and the Western North Pacific during 2000–10

Abstract

Abstract This study investigates interannual aerosol variations over the Maritime Continent and the western North Pacific Ocean and aerosol–cloud–precipitation relationship during the period 2000–10 based on monthly-mean anomalies. The local aerosol–cloud–precipitation relationship displays strong regional characteristics. The aerosol variation is negatively correlated with cloud and precipitation variation over the Maritime Continent, but is positively correlated with cloud and precipitation variation over the region southeast of Japan. Over broad subtropical oceanic regions, the aerosol variation is positively correlated with cloud variation, but has a weak correlation with precipitation variation. Aerosol variations over the Maritime Continent and over the region southeast of Japan display a biennial feature with an obvious phase lag of about 8 months in the latter region during 2001–07. This biennial feature is attributed to the impacts of El Niño events on aerosol variations in these regions through large-scale circulation and precipitation changes. Around October of El Niño–developing years, the suppressed precipitation over the Maritime Continent favors an aerosol increase by reducing the wet deposition and setting up dry conditions favorable for fire burning. During early summer of El Niño–decaying years, suppressed heating around the Philippines as a delayed response to El Niño warming induces an anomalous lower-level cyclone over the region to the southeast of Japan through an atmospheric teleconnection, leading to an accumulation of aerosol and increase of precipitation. The aerosol–precipitation relationship shows an obvious change with time over eastern China, leading to an overall weak correlation.