Atacama Desert Dust Emission Research (ADDER): Resolving aeolian dust source dynamics

了解风沙在何时、何地以及如何从沙漠中排放出来是很重要的，因为沙尘可能对人类健康有害，可能污染顺风处的环境系统，并且当空气传播时，可能影响气候。沙漠沙尘也可能富含铁和其他营养物质，因此当它落在沙漠源头的顺风处时，它可以刺激地表水中海洋生物群的生产力。这种影响在某些敏感的沿海地区尤其重要，因为在这些地区，冷水的混合发生在靠近海岸的地方，例如在阿塔卡马和纳米布沙漠海岸线。这些沿海水域可能特别容易接受沉积的尘埃可能提供的营养物质。英国研究小组多年来一直在研究南部非洲沙漠中的风沙。我们的方法是使用卫星观测来确定沙漠景观不同区域的沙尘来源，然后在这些沙尘排放的“热点”安装最先进的监测和调查设备，以测量风和控制沙尘如何以及何时被风侵蚀的地表特征。我们的数据可以改进风吹尘埃排放到大气中的模型，也显示了沉积的尘埃在南大西洋施肥中的重要性。阿塔卡马沙漠在许多有趣的方面与非洲南部的纳米布沙漠相似。这两个沙漠都位于大陆西海岸，西边是寒冷的洋流，东边是陡峭的地形。它们有着相似的地貌类型，包括干河谷、石质平原和咸干湖。在纳米比亚，这样的表面已经被证明容易受到风蚀和产生沙尘暴。然而，虽然我们知道风会在阿塔卡马沙漠中产生灰尘，但我们对这种风暴发生的时间和地点知之甚少，也不知道灰尘中是否含有可能影响邻近海水营养水平的铁。我们的目标是与来自智利、英国和纳米比亚的科学家开展新的合作，开始回答这些问题，并确定阿塔卡马沙漠风沙的影响和控制。我们希望对阿塔卡马的有关进程取得一种同我们在纳米比亚取得的一样好的理解。这项研究将汇集来自英国和纳米比亚的科学家，他们在确定纳米比亚的沙尘侵蚀地点（称为排放“热点”）方面具有专业知识，以及一位在阿塔卡马风蚀系统方面具有专业知识的智利科学家。这个新团队将首次以高分辨率确定该地区的尘埃来自哪里（使用卫星图像识别“热点”），以及沙尘暴发生的频率。然后，该小组将进行实地考察，探索这些“热点”的地表地面状况，并在特定地点安装仪器，直接测量被侵蚀的尘埃量。根据该项目的成果，该团队将建立长期合作关系，通过额外的拨款提案更详细地探索尘埃对阿塔卡马地区的影响。这将包括调查气候周期对风蚀效率的影响，该地区的沙尘对海洋生产力的重要性，以及采矿等人类影响对产生风吹沙尘的重要性。

Understanding when, where, and how windblown dust is emitted from deserts is important because dust can be detrimental to human health, can pollute downwind environmental systems, and, when airborne, can influence climate. Desert dust can also be rich in iron and other nutrients so when it falls into oceans downwind of its desert source, it can stimulate the productivity of marine biota in the surface waters. The impact of this is especially important in certain sensitive coastal areas where the mixing of cold water occurs close to the shore, such as at the Atacama and Namib Desert coastlines. These coastal waters can be particularly receptive to the nutrients that deposited dust might be providing.The UK Team have undertaken research on windblown dust in southern African deserts for many years. Our approach has been to use satellite observations to identify the sources of dust in different areas of the desert landscape, and then install state-of-the-art monitoring and survey equipment in these 'hot-spots' of dust emission to measure the wind and surface characteristics that control how and when dust is eroded by the wind. Our data have allowed improvements to be made in models of windblown dust emission into the atmosphere, and have also shown the significance of deposited dust in the fertilisation of the South Atlantic Ocean.The Atacama Desert is similar in many interesting respects to the Namib Desert in southern Africa. Both deserts are located on continental west coasts, fringed by cold ocean currents to the west and steep topography to the east. They have similar types of landscapes with a mix of dry river valleys, stony plains, and salty dry lakes. In the Namib, such surfaces have been shown to be prone to wind erosion and the generation of dust storms. However, whilst we know that winds generate dust in the Atacama Desert, we know very little about when and where such storms occur, or whether the dust contains iron which might affect the nutrient levels in the adjacent ocean waters. Our aim is to start a new collaboration of scientists from Chile, the UK, and Namibia to begin to answer these questions and determine the impacts of and controls on windblown dust in the Atacama Desert. We wish to achieve an understanding of the relevant processes in the Atacama which is as good as that which we have gained in the Namib.This research will bring together researchers from the UK and Namibia who have expertise in identifying sites of dust erosion (termed emission 'hot-spots') in Namibia, and a Chilean researcher who has expertise on the Atacama wind erosion system. Together this new team will establish, for the first time and at high resolution, where dust in the region comes from (using satellite images to identify 'hot-spots'), and how frequently dust storms occur. The team will then undertake fieldwork to explore the surface ground conditions at these 'hot-spots' and, at specific sites, install instruments to directly measure the amount of dust that is being eroded. Based on the outputs from this project, the team will develop a long-term collaborative relationship that will explore the effects of dust in the Atacama region in more detail through additional grant proposals. This will include investigating the influence of climate cycles on the efficiency of wind erosion, how important dust in this region is for ocean productivity, and the significance of human impact, such as mining, on generating windblown dust.