Supplementary material to "Evaluating the PurpleAir monitor as an aerosol light scattering instrument"
Supplementary material to "Evaluating the PurpleAir monitor as an aerosol light scattering instrument"
复制标题
“评估 PurpleAir 监测仪作为气溶胶光散射仪器”的补充材料
DOI：
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发表时间：
2021
影响因子：
3.8
通讯作者：
W. Arnott
中科院分区：
文献类型：
--
作者：
J. Ouimette;W. Malm;B. Schichtel;P. Sheridan;E. Andrews;J. Ogren;W. Arnott
抽象的。PurpleAir（PA）监测器PA-II-SD配置中使用的Plantower PMS 5003传感器（PA-PMS）等同于使用657 nm垂直偏振光源的细胞互易浊度计，该光源集成了18至166度的光散射。美国国家海洋和大气管理局（NOAA）莫纳罗亚天文台（MLO）和博尔德桌山（BOS）站点长达一年的现场数据显示，PA-PMS第一尺寸通道的1小时平均值，标记为“> 0.3 μm”（“CH 1”）在550 nm和700 nm波长下，与TSI 3563积分测量的亚微米气溶胶散射系数高度相关浊度计，从0.4 Mm−1到500 Mm−1。这相当于每小时平均亚微米气溶胶质量浓度约为0.2至200 ug m−3。的PA-PMS的物理光学模型的开发，以估计光电二极管上的光强度，占角截断作为颗粒尺寸的函数。然后将预测结果与BOS站点全年的细气溶胶粒径分布和散射系数场数据进行比较。结果表明，CH 1与模型预测的PA-PMS激光器中粒子散射到其光电二极管的光强度成线性比例，超过4个数量级。这与CH 1是散射系数的测量值而不是颗粒数浓度或颗粒物浓度是一致的。BOS的现场数据证实了模型预测，即对于中值散射直径< 0.3 μm的气溶胶，CH 1与散射系数的比值最高。PA-PMS可检测直径小于0.3 μm的气溶胶，并与其对散射系数的贡献成比例。该模型预测，对于粒径≥ 1.0 μm的颗粒，PA-PMS对> 0.3 μm颗粒的响应相对于理想浊度计降低约75%。这是使用偏振激光器、散射光的角度截断以及到达激光器之前仪器中的颗粒损失的结果。本研究的结果表明，PA-PMS不是一个光学颗粒计数器，其六个尺寸分数是不是一个准确的粒度分布的代表。PA-PMS 1 h平均CH 1和bsp 1（空气动力学直径小于1 μm的颗粒在波长550 nm处的散射系数，单位为Mm−1）之间的关系为bsp 1 = 0.015 ± 2.07 × 10−5 × CH 1（相对湿度低于40%）。决定系数R2为0.97。这表明，低成本和广泛使用的PA监测器可以用来测量和预测气溶胶的光散射系数在中可见光几乎一样，积分浊度计。
Abstract. The Plantower PMS5003 sensors (PA-PMS) used in the PurpleAir (PA) monitor PA-II-SD configuration are equivalent to cell-reciprocal nephelometers using a 657 nm perpendicularly polarized light source that integrates light scattering from 18 to 166 degrees. Yearlong field data at the National Oceanic and Atmospheric Administration’s (NOAA) Mauna Loa Observatory (MLO) and Boulder Table Mountain (BOS) sites show that the 1 h average of the PA-PMS first size channel, labeled “> 0.3 μm” (“CH1”) is highly correlated with submicrometer aerosol scattering coefficients at the 550 nm and 700 nm wavelengths measured by the TSI 3563 integrating nephelometer, from 0.4 Mm−1 to 500 Mm−1. This corresponds to an hourly average submicrometer aerosol mass concentration of approximately 0.2 to 200 ug m−3. A physical-optical model of the PA-PMS is developed to estimate light intensity on the photodiode, accounting for angular truncation as a function of particle size. Predictions are then compared with yearlong fine aerosol size distribution and scattering coefficient field data at the BOS site. It is shown that CH1 is linearly proportional to the model-predicted intensity of the light scattered by particles in the PA-PMS laser to its photodiode over 4 orders of magnitude. This is consistent with CH1 being a measure of the scattering coefficient and not the particle number concentration or particulate matter concentration. Field data at BOS confirm the model prediction that the ratio of CH1 to the scattering coefficient would be highest for aerosols with median scattering diameters < 0.3 μm. The PA-PMS detects aerosols smaller than 0.3 μm diameter in proportion to their contribution to the scattering coefficient. The model predicts that the PA-PMS response to particles > 0.3 μm decreases relative to an ideal nephelometer by about 75 % for particle diameters ≥ 1.0 μm. This is a result of using a laser that is polarized, the angular truncation of the scattered light, and particle loss in the instrument before reaching the laser. The results of this study indicate that the PA-PMS is not an optical particle counter and that its six size fractions are not an accurate representation of particle size distribution. The relationship between the PA-PMS 1 h average CH1 and bsp1, the scattering coefficient in Mm−1 due to particles below 1 μm aerodynamic diameter, at wavelength 550 nanometers, is found to be bsp1 = 0.015 ± 2.07 × 10−5 × CH1, for relative humidity below 40 %. The coefficient of determination R2 is 0.97. This suggests that the low-cost and widely used PA monitors can be used to measure and predict the aerosol light scattering coefficient in the mid-visible nearly as well as integrating nephelometers.
影响因子：
8.9
作者：
Kelly, K. E.;Whitaker, J.;Petty, A.;Widmer, C.;Dybwad, A.;Sleeth, D.;Martin, R.;Butterfield, A.
通讯作者：
Butterfield, A.