Wallum Natasha S, Wiggs Giles F S, Bryant Robert G
School of Geography and the Environment, Oxford University Centre for the Environment, University of Oxford, United Kingdom.
School of Geography and the Environment, Oxford University Centre for the Environment, University of Oxford, United Kingdom.
Sci Total Environ. 2025 Jul 18;995:180088. doi: 10.1016/j.scitotenv.2025.180088.
Ephemeral lake beds are globally significant sources of atmospheric mineral dust aerosols, but emissions from these topographic features are characterised by considerable spatial and temporal variability. Resolving the complex relationships between climatic and surface drivers that control aeolian emissivity has proven extremely challenging, leading to substantial uncertainty in model predictions of atmospheric dust loading and its impacts on other global-scale Earth system processes. This study uses a range of satellite-derived measurements (e.g., MSG-SEVIRI, MODIS) of mineral dust aerosols, lake inundation, catchment precipitation, and climate data (from meteorological stations and model reanalysis data sources) from 2000 to 2022 to assess the influence of regional climate and basin-scale hydrology on the emission of mineral dust from Etosha Pan in Namibia, a major Southern Hemisphere dust source. Significant associations were identified between interannual and seasonal variations in catchment rainfall, ephemeral pan surface inundation, and the frequency and magnitude of dust emissions over the two-decade analysis period. Results indicate that dust production is modulated by seasonal precipitation and ephemeral flooding events, which suppress dust emissions during wet periods and also lead to the delayed production of dust emissions on surface drying. During dry periods, wind speed variability was identified as the primary driver of dust emissions. These regional climate and hydrological factors were found to be closely linked to El Niño-Southern Oscillation (ENSO) phases and shifts in the subtropical Indian Ocean Dipole (SIOD), where seasonal increases (reductions) in dust emissions were associated with positive (negative) ENSO and negative (positive) SIOD events. The identification of robust links between dust emissions and global climate drivers in this study makes a significant contribution to the improved integration of ephemeral lake systems in dust emission models and opens the potential for forecasting future dust trends based on large-scale climate cycles.
短暂性湖床是全球大气矿物粉尘气溶胶的重要来源，但这些地形特征的排放具有显著的时空变异性。事实证明，解析控制风沙尘发射率的气候和地表驱动因素之间的复杂关系极具挑战性，这导致大气尘埃负荷模型预测及其对其他全球尺度地球系统过程的影响存在很大不确定性。本研究利用2000年至2022年一系列卫星衍生的矿物粉尘气溶胶、湖泊淹没、集水区降水测量数据（例如MSG-SEVIRI、MODIS）以及气候数据（来自气象站和模型再分析数据源），评估区域气候和流域尺度水文对纳米比亚埃托沙盐沼（南半球主要沙尘源）矿物粉尘排放的影响。在二十年的分析期内，集水区降雨、短暂性盐沼表面淹没的年际和季节变化与沙尘排放的频率和强度之间存在显著关联。结果表明，沙尘产生受季节性降水和短暂性洪水事件调节，这些事件在湿润期抑制沙尘排放，并且在地表干燥时也导致沙尘排放延迟产生。在干旱期，风速变化被确定为沙尘排放的主要驱动因素。这些区域气候和水文因素被发现与厄尔尼诺-南方涛动（ENSO）阶段以及亚热带印度洋偶极（SIOD）的变化密切相关，沙尘排放的季节性增加（减少）与正（负）ENSO和负（正）SIOD事件相关。本研究中沙尘排放与全球气候驱动因素之间稳健联系的确定，对改进沙尘排放模型中短暂性湖泊系统的整合做出了重大贡献，并为基于大规模气候周期预测未来沙尘趋势开辟了潜力。
