Mechanics and dynamics of mineral dust production within cold climates

寒冷气候下矿物粉尘产生的力学和动力学

• 批准号: RGPIN-2022-03785
• 负责人: King, James
• 金额: $ 1.82万
• 依托单位: Université de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=743918
• 关键词: Mechanics; dynamics; mineral; dust; production

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.

大气气溶胶是无机和有机成分的复杂混合物，尺寸范围从几纳米到几十微米。全球气溶胶总预算的一个重要部分是矿物尘埃气溶胶（MDA），它通过直接反射或吸收太阳辐射以及间接地通过充当云凝结或冰核来增加大气辐射预算，改变云的特性，例如反照率、寿命，以及降水量。一旦沉积，MDA 就会像黑体一样，不成比例地促进雪面融化，并为生态系统提供必需的营养。尽管估计每年有 80-100 Tg 或全球 MDA 负担的 5-8% 来自高纬度逃逸源，但目前尚无加拿大年度 MDA 排放总量的估计。这些北纬地区和加拿大境内当前和历史来源识别的困难具体是由于高度季节性排放、低水平和一致的云量、可及性、现有监测或基础设施的低密度以及使当地社区参与研究计划的尝试最少。许多极地景观表现出零星或大面积不连续的永久冻土，并且年降水量有限，限制了区域之间的运输连通性，从而限制了通过景观的功能性养分转移，从而增强了极地景观中可溶性养分的大气沉积的重要性。此外，山区容易出现每天产生热排水（例如下降）风的气象条件，当土壤表面无雪、解冻且地表水有限时，这些风会定期侵蚀和运输 MDA。由于北方平均气温不成比例地上升，导致降雪覆盖时间缩短、解冻提前以及河流流量变化增加，更多地区将容易因裸露未冻土壤面积增加而长期遭受风蚀。在风蚀严重危害的许多地区，植被在降低地表风速、从而降低 MDA 频率方面发挥着至关重要的作用。在北方地区，灌木物种相对于原生草类的持续增加，暴露了更多的土壤表面，从而促进了风蚀，正如在许多地区所看到的那样，野火干扰促进了原生草类的替代。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，并探讨这些排放在加拿大和全球背景下历史、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法探索其中一些方面。