Mineral Dust Aerosols: Ecological and radiative impacts

矿物粉尘气溶胶通过对短波和热辐射的散射和吸收直接影响气候，目前在当前全球气候模式的辐射强迫中占最大的不确定性。干旱地区的陆地和海洋生态系统依靠风蚀造成的矿物气溶胶在大气中的沉积来提供必需的可溶性营养物质。目前，全球气候模式中使用的矿物粉尘排放方案是基于参数化的理论模式，并用高度理想化的实验室结果进行校正。这种简化导致模拟排放不能很好地代表实际运输尺寸分布，因此矿物粉尘的产生和沉积速率。虽然模型中保持了质量守恒，但来自源材料的矿物质和营养物质的通量率存在偏差，导致对风蚀的生物影响的估计不准确。拟议的研究计划旨在为测量和量化矿物粉尘排放的动态风蚀过程提供一种新的方法。该方案由两种互补的方法方法组成，以确定矿物粉尘大小和化学分布在整个运输过程中的作用和影响。首先，它将通过一系列实验室风洞研究，通过天然和人造土壤来评估颗粒大小分布和颗粒相关矿物学的变化，这是运输过程的结果。这些拟议的调查将寻求量化运输过程中营养物质的富集，以估计矿物气溶胶与其母质土壤的辐射和生物特性的差异。其次，提出了一种利用涡旋相关方差测量粉尘排放通量的新方法，以提供比传统时间平均方法更可靠的估计。在纳米比亚进行的一系列比较实地研究将利用这些不同的方法在一系列表面上提供第一套这样的数据。所选的场址位于直接受到矿物粉尘施肥成分影响的地区。这些结果将根据目前的粉尘排放通量模型进行测试，以改进现有模型的性能，并重新定义测量矿物粉尘排放的标准程序。这一研究计划将提高沙尘暴及其对社会和自然环境影响的预测能力。这项新研究还将提高预测加拿大草原和其他干旱地区能见度和相关运输危险系统的时间和严重程度的能力。

Mineral dust aerosols affect climate directly through the scattering and absorbing of shortwave and thermal radiation and currently account for the largest uncertainty in the radiative forcing within current global climate models. Terrestrial and marine ecosystems in arid regions rely on the atmospheric deposition of mineral aerosols as a result of wind erosion to provide essential soluble nutrients. Currently, mineral dust emission schemes used within global climate models are based on theoretical models parameterized and corrected with highly idealized laboratory results. This simplification leads to simulated emissions that poorly represent actual transported size distributions and therefore mineral dust production and deposition rates. Although mass conservation is maintained in the models, biased rates of flux occur for minerals and nutrients from the source material, resulting in poor estimates of the biological impact of wind erosion. The proposed research program seeks to provide a new approach to the dynamic wind erosion process for measuring and quantifying mineral dust emissions. The program consists of two complementary methodological approaches to establish the role and impact of mineral dust size and chemical distributions throughout the transport process. First, it will evaluate the change in particle size distribution and associated mineralogy of particles as a result from the transport process through a series of laboratory wind tunnel investigations with natural and fabricated soils. These proposed investigations will seek to quantify the enrichment of nutrients in the transportation process to estimate the differences in the radiative and biological properties of mineral aerosols from their parent soils. Secondly, a novel methodology to measure dust emission fluxes is proposed using eddy covariance to provide more reliable estimates over traditional time-averaged methods. A series of comparative field studies in Namibia will utilize these different approaches over a range of surfaces to provide the first such set of this data. The chosen field sites are situated in regions that are directly impacted by the fertilizing component of mineral dust they receive. These results will be tested against current dust emission flux models to improve the performance of existing models and redefine standard procedures for measuring mineral dust emissions. This proposed research program will increase the ability for forecasting dust storms and their impacts on society and the natural environment. This new research will also improve the ability to predict the timing and severity of visibility and associated transport hazard systems within Canadian prairies and other arid zones.