The Trend Reversal of Dust Aerosol Over East Asia and the North Pacific Ocean Attributed to Large-Scale Meteorology, Deposition, and Soil Moisture

摘要

The long-term trend in dust loading over East Asia remains under debate and is dependent on the study period chosen. In this study, the long-term trends in springtime dust over East Asia and the North Pacific Ocean (NPO) during 1980-2017 were examined based on the Modern-Era Retrospective Analysis for Research and Applications version 2 reanalysis. Results showed that there was a spatial gradient in dust aerosol loadings, with decreases fromwestern China eastward toward the NPO. This pattern was corroborated by Cloud-Aerosol Lidar with Orthogonal Polarization observations. Furthermore, the empirical orthogonal functionmethod was used to reveal the leadingmodes of springtime dust aerosol optical depth (AOD) over East Asia and the NPO. An abrupt shift occurred in the dust AOD trend in 2010 for the empirical orthogonal function 1 mode. The dust AOD increased at a rate of approximately 2 × 10~(-4)/year during 1999-2009 and then decreasedmore sharply (around 5× 10~(-4)/year) afterward. This trend reversal of dustAODwas closely associated with a decrease in 10-m wind velocity, which induces reduced dust emission. Compared with 10-m wind, the soil moisture is less correlated with the trend reversal in dust AOD. Additionally, the trends of dry (wet) deposition were closely associatedwith the trends of the dustAOD, especially for the period 2010-2016.Overall, our findings add new insights to the long-term nonlinear variability of dust.