South Africa's agricultural dust sources and events from MSG SEVIRI
South Africa's agricultural dust sources and events from MSG SEVIRI
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DOI：
10.1016/j.aeolia.2020.100637
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发表时间：
2020-12-01
期刊：
影响因子：
3.3
通讯作者：
Palmer, A. R.
中科院分区：
文献类型：
--
作者：
Eckardt, F. D.;Bekiswa, S.;Palmer, A. R.
非洲南部的地貌尘埃研究主要集中在纳米比亚和博茨瓦纳的自然来源。在这里，我们的目标是确定南非的灰尘来源，使用旋转增强可见光和红外成像仪数据（SEVIRI）在2006年至2016年。在6月至1月期间，共有334，497张图像在75个沙尘日识别出178个沙尘羽流，这些沙尘羽流主要来自自由州。源区包括商业农业、草地和灌木丛。根据标准化降水蒸散指数，有记录的所有事件天中有一半发生在2015年至2016年之间，这是一场严重的干旱。作物统计数据显示，玉米覆盖面积从120万公顷减少到60万公顷，休闲地覆盖面积明显增加，低于平均水平的归一化植被指数证实了这一点。运输能力似乎在干旱年份和增加风记录。无论天气条件如何，所有沙尘天气日都遵循昼夜风模式，大多数轨迹都朝向印度洋。就频率和范围而言，SEVIRI事件与北方相比是次要的。然而，南非的主要粉尘来源不同，因为它们似乎主要与人类活动有关，特别是农业。自然表面的排放潜力仍有待研究。然而，火灾在尘土飞扬的年份并不是一种常见的前兆。广泛分布的淋溶土和砂质土富含淤泥和沙子，延伸到更广阔的内陆地区，包括卡拉哈里沙漠，其他人预测未来的气候情景会增加粉尘排放。
Geomorphological dust research in Southern African has focused on natural sources in Namibia and Botswana. Here we aim to identify South Africa's dust sources using the Spinning Enhanced Visible and Infra-red Imager data (SEVIRI) between 2006 to 2016. A total of 334,497 images identified 178 dust plumes on 75 dust days, which originate mostly from the Free State, between June to January. Source areas consist of commercial agriculture, grass and shrublands. Half of all event days in the record occurred between 2015 and 2016, a severe drought, according to the Standardised Precipitation Evapotranspiration Index. Crop statistics report a decline in maize cover from 1.2 to 0.6 million hectares and a pronounced increase in fallow cover, confirmed by a below average Normalized Difference Vegetation Index. Transport-capacity appears to be enhanced during drought years and on the increase in wind records. All dust event days adhere to a diurnal wind pattern, irrespective of synoptic conditions and most trajectories head towards the Indian Ocean. In terms of both frequency and extend, SEVIRI events are minor when compared to the northern hemisphere. However South Africa's major dust sources differ in that they appear to be mostly associated with anthropogenic activities especially rainfed agriculture. The emission potential from natural surfaces remains to be examined. Fire however is not a common precursor in dusty years. The widespread Luvisols and Arenosols, are rich in silt and sand, extend into the wider interior, including the Kalahari, where future climate scenarios by others have predicted increases in dust emissions.