| El Ni(?)o-Southern Oscillation(ENSO)is a phenomenon of periodic changes in sea surface temperature in the equatorial central-eastern Pacific Ocean.El Ni(?)o,as the warm phase of ENSO,has been shown to have important influences on meteorological conditions in China.In this study,the impacts of El Ni(?)o with different durations and spatial locations on PM2.5,dust aerosol concentrations and haze days during December-January-February(DJF)and March-April-May(MAM)in China are quantitatively examined using the state-of-the-science Energy Exascale Earth System Model version 1(E3SMv1)newly released by the U.S.Department of Energy(DOE),through a superposed sea surface temperature perturbation method.This study finds that PM2.5 concentrations are increased by 1-2μg m-3 in northeastern and southern China and decreased by up to 2.4 μg m-3 in central-eastern China during El Ni(?)o events relative to the climatological means.Compared to long duration(LD)El Ni(?)o events,El Ni(?)o with short duration(SD)but strong intensity causes northerly wind anomalies over central-eastern China,which is favorable for aerosol dispersion over this region.Moreover,the anomalous southeasterly winds weaken the wintertime prevailing northwesterly in northeastern China and exacerbate local accumulation of aerosols,enhancing PM2.5 concentrations in northeastern China during SD El Ni(?)o events relative to LD El Ni(?)o events.In addition,the modulation on DJF haze days by SD El Ni(?)o events is 2-3 times more than that by LD El Nivo events in China.In the following spring,anomalous northwesterly winds favoring local aerosol dispersion in northern China significantly reduced PM2.5 concentrations in northern China by about 1 μg m3 relative to the climatological mean during the El Nivo event,and this negative PM2.5 concentration anomaly was more pronounced during the LD El Ni(?)o event.Similarly,the modulation of LD El Ni(?)o events on spring haze days in China is several times greater than that of SD El Ni(?)o event.In both boreal spring and winter,the PM2.5 variations during El Ni(?)o events are mainly controlled by anomalous aerosol accumulation/dispersion and transport due to changes in atmospheric circulation,while El Ni(?)o-induced precipitation change has little effect.The occurrence frequency of SD El Ni(?)o events has been increasing significantly in recent decades,especially after the 1940s,suggesting that El Ni(?)o with short duration has exerted increasingly intense modulation on PM2.5 pollution in China over the past few decades.However,due to its weak persistence,its modulating effect on PM2.5 over China in the following spring is less significant than that of the LD El Ni(?)o event.Dust is an important aerosol affecting air quality in China in winter and spring that is potentially influenced by the interannual climate variability associated with El Ni(?)o.This work finds that the Eastern Pacific(EP),Central Pacific(CP),and short duration(SD)El Ni(?)o events all increase DJF dust concentrations over central-eastern China,while El Ni(?)o event with long duration(LD)decrease DJF dust concentrations over northern China due to the changes in atmospheric circulation,precipitation and relative humidity caused by El Ni(?)o.It should be pointed out that all types of El Ni(?)o events lead to an increase in dust over northern China in the following spring season,but only the increase during the LD El Ni(?)o is statistically significant,suggesting that the LD El Ni(?)o can significantly affect spring dust over China.in other words,LD El Ni(?)o can significantly affect the spring dust over China Our results contribute a better understanding of the influence of different types of El Ni(?)o events on dust pollution in China,which have profound implications for air pollution control and dust storm prediction. |
PDF Full Text Request