Long-term characteristics of dust aerosols over central China from 2010 to 2020 observed with polarization lidar

Abstract

Plenty of dust aerosols are emitted into the atmosphere in East Asian regions and significantly impact the regional environment and climate. In the past decade, the frequency of dust storm outbreaks has largely declined in the sources of Asian dust. However, it is still rarely reported how the dust properties after long-range transport in the downstream regions respond to this downtrend. Here we report on the long-term characteristics of dust aerosols over central China with the observations of a polarization lidar at Wuhan (30.5°N, 114.4°E) during 2010–2020. The dust optical depths (DOD) exhibit a decrease trend with a rate of −0.011 yr−1, accounting for 22% of the decrease rate for total aerosol optical depths (AOD) in Wuhan. The mass concentration and columnar mass density of dust also decline with a rate of −2.03 μg·m−3·yr−1 and -1.97 mg·m−2·yr−1, respectively. Spring and winter are the most active seasons for dust intrusion, with seasonal mean DOD of 0.21 and 0.15, respectively. Compared with spring, dust aerosols in winter generally concentrate at lower levels below 1.0 km with a slightly smaller particle depolarization ratio of 0.11 (0.14 in spring), attributing to the weakened nonspherical shape of dust particles under wintertime high-level moisture/polluted conditions. Both the surface PM10 concentration and lidar-derived dust mass concentration at 0.3 km present a downtrend with a rate of −8.0 μg·m−3·yr−1 and -20.1 μg·m−3·yr−1, respectively. This study provides a comprehensive long-term and seasonal analysis of dust properties in central China, which can supplement our understanding of the feedback in the downstream regions to the reduction of dust emissions in the deserts of East Asia.