Abstract. Spatial and temporal variations in the level of dust activity can provide valuable information for policymaking and climate research. Recently, Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol products have been successfully used for retrieving dust aerosol optical depth (DAOD), especially over bright dust source areas, and Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) aerosol reanalysis provides DAOD and additionally other dust-aerosol-related parameters. In this study, spatial and temporal variations in dust activity in Australia were analyzed using MODIS and MERRA-2 combined (M&M) DAOD and MERRA-2 near-surface dust concentrations and estimated PM10 for the period 1980–2020. Validation results show that M&M DAOD has an expected error of ±(0.016+0.15τ) compared to the ground observations at the AErosol RObotic NETwork (AERONET) dust storms on populated areas sites. MERRA-2 near-surface dust concentrations show a power-law relationship with visibility data collected at meteorological stations with an r2 value from 0.18 to 0.44, and the estimated MERRA-2 PM10 shows similar temporal variations and correlates with ground-based PM10 data with an r2 value from 0.14 to 0.44 at six selected stations in Australia. Moreover, MERRA-2 horizontal dust flux shows the same major dust pathways as those in previous studies and similar dust emissions and deposition areas identified using ground-based observations. Dust events based on DAOD over eastern Australia are concentrated in the north in December, are concentrated in the south in February, and can occur anywhere in January. Near-surface dust concentration was found to be the highest (over 200 µg m−3) over the center of Lake Eyre basin in central Australia and radially decreased toward the coast to below 20 µg m−3 via the two main pathways in the southwest and northeast. The ratio of near-surface dust concentration to PM10 shows a similar spatial pattern. Total dust emission was estimated to be 40 Mt (megatonnes) per year over the period 1980–2020, of which nearly 50 % was deposited on land and the rest exported away from the Australian continent.

中文翻译：

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基于遥感和再分析数据集的澳大利亚沙尘活动的时空变化

摘要。沙尘活动水平的空间和时间变化可以为政策制定和气候研究提供有价值的信息。最近，中分辨率成像光谱仪 (MODIS) 气溶胶产品已成功用于反演灰尘气溶胶光学深度 (DAOD)，特别是在明亮的灰尘源区域，以及现代时代研究和应用回顾分析，版本 2 (MERRA-2)气溶胶再分析可提供 DAOD 以及其他与粉尘气溶胶相关的参数。在本研究中，使用 MODIS 和 MERRA-2 组合 (M&M) DAOD 和 MERRA-2 近地表粉尘浓度以及 1980-2020 年期间的 PM10 估算值分析了澳大利亚粉尘活动的时空变化。验证结果表明，与人口稠密地区 AErosol RObotic NETwork (AERONET) 沙尘暴的地面观测结果相比，M&M DAOD 的预期误差为 ±(0.016+0.15τ)。 MERRA-2 近地表尘埃浓度与气象站收集的能见度数据呈现幂律关系，r2 值为 0.18 至 0.44，估计的 MERRA-2 PM10 显示出类似的时间变化，并与地面 PM10 数据相关澳大利亚六个选定站点的 r2 值从 0.14 到 0.44。此外，MERRA-2水平灰尘通量显示出与之前研究相同的主要灰尘路径，以及使用地面观测确定的类似灰尘排放和沉积区域。基于 DAOD 的澳大利亚东部沙尘事件 12 月集中在北部，2 月集中在南部，1 月任何地方都可能发生。澳大利亚中部艾尔湖盆地中心附近的近地表灰尘浓度最高（超过 200 µg m−3），并通过西南部的两条主要路径向海岸呈放射状下降至 20 µg m−3 以下和东北。近地表灰尘浓度与 PM10 的比率显示出类似的空间模式。 1980 年至 2020 年间，粉尘排放总量估计为每年 40 公吨（百万吨），其中近 50% 沉积在陆地上，其余则从澳大利亚大陆出口。