Mechanics and dynamics of mineral dust production within cold climates

大气气溶胶是无机和有机成分的复杂混合物，其大小从几纳米到几十微米不等。矿物尘埃气溶胶（MDA）是全球气溶胶收支的重要组成部分，它通过直接反射或吸收太阳辐射，间接地作为云凝结或冰核，改变云的性质，如云的寿命和降水量，从而增加大气辐射收支。一旦沉积，MDA就像一个黑体，不成比例地增加雪表面的融化，并为生态系统提供必要的营养。尽管估计每年有80-100 Tg或5-8%的全球MDA负担来自高纬度散逸性来源，但目前还没有加拿大MDA年度总排放量的现有估计。在这些北方纬度地区，特别是在加拿大，目前和历史上的来源识别困难是由于高度季节性排放，低水平和一致的云层覆盖，可访问性，现有监测或基础设施的低密度，以及最小的尝试，使当地社区参与研究计划。许多极地景观表现出零星或广泛的不连续的永久冻土，并受到有限的年降水量，限制了区域之间的运输连接，因此，通过景观的功能养分转移，提高大气沉积的可溶性养分在极地景观的重要性。此外，山区容易受到气象条件的影响，每天都会产生热量排放（例如，当土壤表面无雪、解冻和地表水有限时，可以定期侵蚀和运输MDA的下降风。随着北方平均气温的持续上升，导致降雪覆盖时间减少，融化提前，河流流量变化增加，更多的地区将容易受到风蚀，因为裸露的未冻土壤面积增加，时间更长。在许多地区，风蚀是一个重大的危险，植被可以发挥至关重要的作用，降低风速在表面，从而减少MDA的频率。在北方范围内，灌木物种的持续增加超过了原生草，通过暴露更多的土壤表面来促进风蚀，正如在野火干扰促进原生草替代的许多地区所看到的那样。该研究计划旨在确定加拿大北部MDA排放的机制，程度和频率，并探索这些排放在加拿大和全球范围内的历史，当前和未来气候情景下的累积影响。拟议的研究方案将继续开展由其他机构资助的几个研究项目，以包容性、土著社区支持和伙伴关系协助的方式探索其中的一些方面。

Atmospheric aerosols are a complex mixture of inorganic and organic components and can range in size from a few nanometers to several 10s of micrometers. An important fraction of the total global aerosol budget is mineral dust aerosols (MDA), which augment the atmospheric radiation budget by directly reflecting or absorbing solar radiation and indirectly, by acting as cloud condensation or ice nuclei, altering cloud properties such as albedo, lifetime, and the quantity of precipitation. Once deposited, MDA can behave like a black body, disproportionately enhancing the melting of snow surfaces, as well as providing essential nutrients to ecosystems. No existing estimates of the Canadian total annual MDA emissions are currently available despite an estimate of 80-100 Tg or 5-8% per year of the global MDA burden from high latitude fugitive sources. The current and historical source identification difficulties in these northern latitudes and within Canada specifically are due to highly seasonal emissions, low level and consistent cloud cover, accessibility, low density of existing monitoring or infrastructure, and minimal attempts to involve local communities within research programs. Many polar landscapes exhibit sporadic or extensive discontinuous permafrost and are subject to limited annual precipitation, limiting the transport connectivity between regions and therefore the functional nutrient transfer through the landscape, enhancing the importance of atmospheric deposition of soluble nutrients in polar landscapes. In addition, mountainous regions are prone to meteorological conditions that produce daily thermal drainage (e.g., katabatic) winds that can erode and transport MDA regularly when the soil surface is free of snow, thawed, and has limited surface water. As average temperatures rise disproportionally in the North resulting in decreasing snowfall cover duration, earlier thawing, and increased river flow variability, more areas will be prone to wind erosion from increased areas of bare unfrozen soil for longer periods. In many regions where wind erosion is a significant hazard, vegetation can play a vital role in reducing the wind speeds at the surface and therefore reducing the frequency of MDA. Within the northern context, the ongoing increase in shrub species over native grasses promotes wind erosion by exposing more of the soil surface, as seen in many regions where wildfire disturbances promote the replacement of native grasses. This research program will aim to identify the mechanisms, extent, and frequency of MDA emissions within the Canadian North and explore the cumulative impacts of these emissions within the Canadian and global context historically, currently, and under future climate scenarios. The proposed research program will continue several research projects funded by other agencies on exploring some of these aspects with an approach that is inclusive, indigenous community-supported, and partnership-assisted.