Abstract
Haze pollution in recent decades varies largely with both pollutant emissions and meteorological conditions. Using the discrete wavelet transform (DWT) method, we separate these two influences on haze variations in southern China in the time series of haze observations from 1981 to 2011. This helps us to identify the meteorological influence on interannual variation in haze occurrences in southern China and thus observe a teleconnection between the thermal forcing of sea surface temperature (SST) in the central and eastern Pacific and wintertime haze occurrences in southern China (R = − 0.51, p < 0.05). The total haze days in winter is highest among all seasons over southern China and the climotological mean of number of winter haze days is 7.5 days for the region. Compared with the normal winters, the regional mean of the number of haze days in southern China is reduced by ~ 5 days in the winters with above-normal Niño3.4 SST (during El Niño phases), but increased by ~ 4 days in the winters with below-normal Niño3.4 SST (during La Niña phases). In the warm SST winters, the cumulative consequences of strong winds, more precipitation, and a more unstable atmosphere with an “upper colder and lower warmer” vertical pattern leading to more ascendance can all hinder haze formation, whereas in the cold SST winters, opposite meteorological conditions are favorable to haze formation. These meteorological conditions induced by anomalous SST make wintertime haze pollution in southern China vary from year to year to a large extent. This study suggests a strong sensitivity of winter haze occurrences in southern China to the viability of the SST in the central and eastern Pacific.
Highlights
Haze with high concentrations of aerosols is one of societal and scientific concerns because of its negative effect on human health and ecosystem and its impact on climate change
Based on analysis of wintertime observations from 1981 to 2011, we show that a teleconnection between the Niño3.4 sea surface temperature (SST) and haze occurrences in Southern China (SC)
Through the discrete wavelet transform (DWT) analysis, the time series of wintertime haze days over SC is decomposed into a LF component and three HF components, which represent the long-term trend and the short-term variability in the observational time series, respectively
Summary
Haze with high concentrations of aerosols is one of societal and scientific concerns because of its negative effect on human health and ecosystem and its impact on climate change. The climate forcing factors, such as Atlantic Ocean sea surface temperature (SST) and Eurasian snow cover and Arctic Oscillation (AO), were found to play an important role in the variations of haze occurrences during winter in different regions over China on the interannual time scales (Xiao et al 2015; Yin and Wang 2018; Lu et al 2020). Of meteorological conditions and pollutant emissions and examined the underlying mechanisms for the teleconnection from multiple meteorological factors that are conducive to haze formation and depletion, including wind field, vertical thermal structure, stability, and precipitation.
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