The Lagged Effect of Anthropogenic Aerosol on East Asian Precipitation during the Summer Monsoon Season

Su-Jung Lee,Yong-Cheol Jeong,Sang-Wook Yeh

doi:10.3390/atmos11121356

Abstract

The authors investigated the lagged effect of anthropogenic aerosols (AAs) during the premonsoon season (April–May–June) on the East Asian precipitation during the postmonsoon season (July–August) using the aerosol optical depth (AOD) from a satellite dataset and reanalysis datasets. When the AOD is high in Eastern China during the premonsoon season, the amount of precipitation increases in the western North Pacific, including the Korean Peninsula and Japan, during the postmonsoon season. The amount of cloud in the western-to-central North Pacific in the premonsoon season increases during the high-AOD period. Subsequently, it cools the sea surface temperature until the postmonsoon season, which strengthens the North Pacific High. The strengthened North Pacific High in the postmonsoon season expands to the western North Pacific, which leads to the enhancement of the moisture flows from the ocean. This results in the increase in precipitation in the western North Pacific, including the Korean Peninsula and Japan, during the postmonsoon season.

Highlights

Anthropogenic aerosols, which include sulfate, nitrate, black carbon, and organic carbon, can change atmospheric conditions in many complex ways [1]
To explore the variability of anthropogenic aerosols (AAs) concentration in East Asia during the premonsoon season (April–May–June, hereafter, AMJ), we introduced the aerosol optical depth (AOD) index defined as an area-averaged AOD in
(2000–2017) AOD in the Northwestern Pacific is high, which may be due to the advection of AAs from Eastern China by the climatological westerlies in the midlatitudes

Summary

Introduction

Anthropogenic aerosols (hereafter, AAs), which include sulfate, nitrate, black carbon, and organic carbon, can change atmospheric conditions in many complex ways [1]. Mu and Wang [37] argued that aerosol forcing leads to the weakening of the EASM circulation and decreases in precipitation via upper-tropospheric cooling in the midlatitudes of East Asia by AA forcing. Some studies argued that the precipitation in northern China increases due to the enhancement of the western North Pacific subtropical high through the semidirect effect and indirect effect of AAs [38,39]. These results indicate that the issue of how AA interacts with the precipitation variability in East Asia during summer is still under debate, which requires further understanding of the effect of AA forcing.

Data and Methodology

Results

Summary and Discussion