Each year, considerable levels of dust particles coming from arid regions of the earth contribute to the atmosphere. Because dust has serious environmental and human health effects, predictions of dust concentrations and their contribution to PM surface concentrations are essential for atmospheric research and the implementation of air quality programs and rules. This study aims to assess dust contributions to PM_2.5 in Tehran in order to provide guidance for air quality management systems as well as validate the updated Dust Regional Atmospheric Model version 2 (BSC-DREAM8b) and the NMMB/BSC-Dust model using chemical speciation of ground-based measurements of PM_2.5. Accurate and reliable measurements are necessary to determine the sources of pollutants as well as to confirm, validate, and improve models. For this purpose, dust concentration and contribution were calculated from chemical speciation of PM_2.5 samples that were obtained on a 6 day basis for a whole year from February 2014 to February 2015. The comparison of the dust observations to the model products revealed that model outputs were in good agreement for the monthly averaged values. However, for the daily averaged values, models and ground observation showed a considerable difference. In order to understand possible reasons for the discrepancy, differences between neighboring grid cells were investigated, as well as the effect of sampling frequency. It is found that agreement between models and observations was sensitive to sampling duration and frequency but not to spatial variability between grid cells. This study is the first validation of model outputs with the calculated dust concentration from ground-based chemical speciation of PM_2.5 rather than using total PM or aerosol optical depth measurements as a proxy for dust concentrations.

每年，来自地球干旱地区的大量尘埃颗粒都会对大气产生影响。由于粉尘会对环境和人类健康造成严重影响，因此对粉尘浓度及其对PM表面浓度的影响进行预测对于大气研究以及实施空气质量计划和规则至关重要。这项研究旨在评估德黑兰粉尘对PM _2.5的贡献，以便为空气质量管理系统提供指导，并使用化学形态验证更新的粉尘区域大气模型版本2（BSC-DREAM8b）和NMMB / BSC-Dust模型PM _2.5的地面测量。准确可靠的测量对于确定污染物的来源以及确认，验证和改进模型是必要的。为此，根据PM _2.5的化学形态计算了粉尘浓度和贡献从2014年2月到2015年2月，以全年为期6天的时间获取样本。对粉尘观测结果与模型产品的比较表明，模型输出与每月平均值非常吻合。但是，对于每日平均值，模型和地面观测显示出相当大的差异。为了理解差异的可能原因，研究了相邻网格单元之间的差异以及采样频率的影响。发现模型与观测值之间的一致性对采样持续时间和频率敏感，但对网格单元之间的空间变异性不敏感。这项研究是对模型输出的首次验证，该模型具有根据PM _2.5的地面化学形态计算得出的粉尘浓度 而不是使用总PM或气溶胶光学深度测量值作为粉尘浓度的代表。