Department of Environmental & Occupational Health Sciences, University of Washington, Seattle, Washington 98195, United States.
Department of Civil & Environmental Engineering, University of Washington, Seattle, Washington 98195, United States.
Environ Sci Technol. 2020 Apr 7;54(7):4286-4294. doi: 10.1021/acs.est.0c00612. Epub 2020 Mar 17.
This study examines the feasibility of the in situ calibration of instruments for fleet vehicle-based mobile monitoring of ultrafine particles (UFPs) and black carbon (BC) by comparing rendezvous vehicle measurements. Two vehicles with identical makes and models of UFP and BC monitors as well as GPS receivers were sampled within 140 m of each other for 2 h in total during winter in Seattle, Washington. To identify an optimal intervehicle distance for rendezvous calibration, 6 different buffers within 0-140 m for UFP monitors and 5 different buffers within 0-90 m for BC monitors were chosen, and the results of calibration were compared against a reference scenario, which consisted of mobile colocation measurements with both sets of the UFP and BC monitors deployed in one of the vehicles. Results indicate that the optimal distances for rendezvous calibration are 10-80 m for UFP monitors and 0-30 m for BC monitors. In comparison with the mobile colocation calibration, the rendezvous calibration shows a normalized root mean squared deviation of 6-14% and a normalized mean absolute deviation of 4-8% for these monitors. Criteria for applying a rendezvous calibration approach are presented, and an extension of this approach to an instrumented fleet of mobile monitoring vehicles is discussed.
本研究通过比较中途相遇车辆测量值，检验了对车队车辆进行现场校准超细微粒 (UFPs) 和黑碳 (BC) 移动监测仪器的可行性。两辆具有相同 UFPs 和 BC 监测器以及 GPS 接收器的车辆在华盛顿州西雅图的冬季，以 140 米以内的距离彼此相距 2 小时，总共进行了 2 小时的采样。为了确定中途相遇校准的最佳车辆间距，在 0-140 米范围内选择了 6 个不同的 UFPs 监测器缓冲区，在 0-90 米范围内选择了 5 个不同的 BC 监测器缓冲区，并将校准结果与参考方案进行了比较，该参考方案由将两套 UFPs 和 BC 监测器部署在一辆车辆中的移动共置测量组成。结果表明，对于 UFPs 监测器，中途相遇校准的最佳距离为 10-80 米，对于 BC 监测器，最佳距离为 0-30 米。与移动共置校准相比，中途相遇校准对这些监测器的归一化均方根偏差为 6-14%，归一化平均绝对偏差为 4-8%。提出了应用中途相遇校准方法的标准，并讨论了将该方法扩展到装有仪器的移动监测车队的问题。
