Dynamic Dust Source Regions and the Associated Natural and Anthropogenic Dust Emissions at the Global Scale

Siyu Chen,Yu Chen,Shanlin Cheng,Zhen Wang,Yongqi Gong,Chenxi Liu

doi:10.3389/feart.2022.802658

Abstract

Dust emission is a key factor for reproducing dust’s physical process and its climate impact in dust modeling. However, previous studies always employed static land cover types to classify potential dust sources, ignoring dynamic variations in the surface bareness, which may lead to large uncertainties in the simulated dust emission fluxes, especially in regard to anthropogenic dust (AD) emission induced by wind erosion of human-disturbed land surfaces. Combined with anthropogenic land use and land cover change, dynamic dust source regions and the associated natural dust (ND) and AD emissions at the global scale from 2001 to 2018 are estimated in this study. The results show that the AD emissions exhibit a significant seasonal variability and dispersion at the global scale in contrast to the generally concentrated spatial distributions of ND emissions. The high-value ND areas are primarily located in the Sahara Desert, Arabian Peninsula, Karakum Desert, East Asia, Australian Desert, and other large desert areas, and the ND emission flux reaches a maximum of 50 μg m−2 s−1 or higher. High values of the annual average AD emission fluxes are located in southern Russia (124.6 ± 26.6 μg m−2 s−1), northern China (103.2 ± 21.9 μg m−2 s-1), the central and northern United States (56.0 ± 17.4 μg m−2 s−1), and the southern side of the Sahara Desert (74.1 ± 14.2 μg m−2 s−1). Especially in southern Russia and northern Kazakhstan, the AD emission flux accounts for the largest contribution to the total dust emission flux, at 98.2%. The ND emission flux demonstrates an upward trend in the central Sahara Desert, southern Arabian Desert, and Iranian regions and a significant downward trend in northwestern China. The AD emissions exhibit a decreasing trend in northern China, western India, the southern side of the Sahara Desert, and the central United States from 2001 to 2018 due to the implementation of environmental protection policies and a decrease in the wind speed, with the highest rate of decline reaching −74.9 μg m−2 s−1/decade. This study provided confidence for the further investigation of dust mass balance and the climatic impacts of natural and anthropogenic dust.

Highlights

Dust aerosols, as one of major aerosols in the tropospheric atmosphere, play a critical role in the energy balance and hydrological cycle of the Earth system (Mao et al, 2011; Chen et al, 2021)
A major and critical problem faced by the empirical dust emission and the detailed microphysical dust emission scheme is the lack of direct dust flux data for model verification
The static dust source function ignores the seasonal and interannual variations in the surface bareness during dust modeling, which leads to large uncertainties in the simulated dust emission fluxes

Summary

Introduction

As one of major aerosols in the tropospheric atmosphere, play a critical role in the energy balance and hydrological cycle of the Earth system (Mao et al, 2011; Chen et al, 2021). It directly affects radiative forcing by solar radiation scattering and absorption (Liu et al, 2011; Chen et al, 2018) and indirectly affects cloud properties and lifetime as cloud condensation nuclei and ice nuclei, further influencing precipitation efficiency (Liu et al, 2019a; Liu et al, 2019b). Du et al (2019) found that grassland reduction exacerbated wind erosion and observed that this greatly increased dust emission fluxes from 38.6 to 2,182.6 g m−2 d−1

Methods

Results

Conclusion