Impact of the ENSO Cycle on the Stratospheric Aerosol Distribution



In this paper the Oceanic Nino Index and the HALOE dataset were used to study the impact of the ENSO cycle on the stratospheric aerosols by analyzing the lag correlation. The comparison of aerosol surface area after El Nino and the La Nina images the impact clearly and the change can be explained according to the transporting velocity and stream situation. The result displays that ENSO significantly affects the distribution of stratospheric aerosols, especially above the equator and low latitude. Within six months after El Nino, the aerosol surface density in the tropical lower-stratosphere layer is larger than the average while it's smaller in the middle stratosphere; however, the situation was contrary after La Nina. El Nino and La Nina had significantly different effects, which made the differences in aerosol content in 60 hPa as high as 45%. The change of aerosol surface density in the six months lag could be up to 16% as the temperature changed 1 K. The strong influence of ENSO could last for about six months and faded out in 2 years. Changes in the tropics were stronger than in the middle and high latitudes, while the characteristics of northern and southern hemispheres are different. ENSO lead to a change in the aerosol delivery by affecting the residual circulation, and in turn lead to these differences of the aerosol distribution mentioned above.