Abstract
Based on observations from the Unmanned Aerial Vehicle (UAV) together with an environmental particulate matter analyzer (Grimm-180) and Global Positioning System (GPS) sounding balloons, the vertical structure of dust with different particle sizes was explored over the Taklimakan Desert (TD) during an intensive observation from 1 July 2021 to 31 July 2021. The power functions were fitted between the particle counts and particle sizes, indicating negative correlations with an R2 higher than 0.99 under different dust pollution conditions in Tazhong (TZ). The dust concentrations show a sharp vertical increase over the TD during dust pollution; however, more particles with larger sizes are entrained into the air in TZ compared with Minfeng (MF). The total solar radiation during dust pollution days is significantly weakened, accompanied by major modifications in the temperature stratification, which were characterized by low-level cooling (with −2.71 K mean intensity) and high-level heating (with +0.70 K mean intensity). On clear days, the average convective boundary layer (CBL) heights at the TZ and MF are approximately 3.94 and 2.84 km, respectively, and the average stable boundary layer (SBL) height at the TZ and MF are approximately 0.19 and 0.14 km, respectively. With the increasing dust pollution level, the CBL height decreases rapidly while the SBL height shows the opposite trend. The unique ultra-high atmospheric boundary layer structure in daytime provides beneficial conditions for the suspension and vertical transportation of dust over TD. Moreover, a negative correlation between the CBL height and near-surface PM10/PM2.5/PM1.0 concentration in TD is revealed by power function fittings.
Highlights
Dust is one of the strongly light-absorbing aerosols, which directly absorbs and scatters solar radiation and indirectly alters cloud microphysical properties, resulting in the changing radiation budget of the land–atmosphere system and global/regional climate change [1,2,3,4]
We evaluated the atmospheric boundary layer (ABL) height according to the thermodynamic method as follows [23,24]: the potential temperature was calculated based on the temperature profiles and the height, where there was a discontinuous gradient and strong inversion, was defined as the ABL height
The lower surface pressure (P) is observed during dusty days (865.6 hPa), while the average P during clear days is 867.2 hPa. This indicates that dust events occurred under favorable weather conditions, including high wind speed and temperature and low surface pressure, which are consistent with the previous study [25]
Summary
Dust is one of the strongly light-absorbing aerosols, which directly absorbs and scatters solar radiation and indirectly alters cloud microphysical properties, resulting in the changing radiation budget of the land–atmosphere system and global/regional climate change [1,2,3,4]. The Taklimakan Desert (TD) is one of the largest shifting deserts in the world and is an important source of dust aerosols in Asia [5,6]. The study of TD dust plays an important role in global dust weather and the atmospheric environment. The vertical distribution of dust aerosols is one of the important parameters in the estimation of the dust radiative effect [8,9].
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