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，大小从几纳米到几十微米不等。全球气溶胶收支总额的一个重要部分是矿物粉尘气溶胶（MDA），它们通过直接反射或吸收太阳辐射，以及间接地作为云凝结或冰核，改变云的性质，如反照率、寿命和降水量，增加了大气辐射收支。一旦沉积，MDA可以表现得像一个黑体，不成比例地加速雪表面的融化，并为生态系统提供必要的营养。目前没有关于加拿大每年MDA总排放量的现有估计，尽管估计每年来自高纬度逸散源的MDA总量为80-100 Tg或全球MDA负担的5-8%。在这些北纬地区和加拿大境内，当前和历史上的污染源识别困难主要是由于高度季节性的排放、低水平和持续的云层覆盖、可达性、现有监测或基础设施的低密度，以及在研究项目中很少尝试让当地社区参与进来。许多极地景观呈现零星或广泛的不连续永久冻土，年降水量有限，限制了区域间的运输连通性，从而限制了通过景观的功能性营养物质转移，增强了极地景观中可溶性营养物质的大气沉积的重要性。此外，山区容易受到气象条件的影响，每天产生热排水（例如，倾斜）风，当土壤表面无雪、融化和地表水有限时，这些风可以定期侵蚀和运输MDA。由于北方的平均气温不成比例地上升，导致降雪覆盖时间缩短，融化提前，河流流量变异性增加，更多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。在许多风蚀是重大危害的地区，植被可以在降低地面风速从而减少MDA频率方面发挥重要作用。在北部地区，灌木种类的持续增加超过了原生草，暴露了更多的土壤表面，从而促进了风蚀，正如在许多野火干扰促进原生草替代的地区所看到的那样。该研究项目旨在确定加拿大北部地区丙二醛排放的机制、程度和频率，并探索这些排放在加拿大和全球历史、当前和未来气候情景下的累积影响。拟议的研究计划将继续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这些方面的一些问题。

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.