Assessing 3-D Spatial Extent of Near-Road Air Pollution around a Signalized Intersection Using Drone Monitoring and WRF-CFD Modeling

Abstract

In this study, we have assessed the three-dimensional (3-D) spatial extent of near-road air pollution around a signalized intersection in a densely populated area using collaborating methodologies of stationary measurements, drone monitoring, and atmospheric dispersion modeling. Stationary measurement data collected in the roadside apartment building showed a substantial effect of emitted pollutants, such as nitrogen oxides (NOx), black carbon (BC), and ultrafine particles (UFPs), especially during the morning rush hours. Vertical drone monitoring near the road intersection exhibited a steeper decreasing trend with increasing altitude for BC concentration rather than for fine particulate matter (PM2.5) concentration below the apartment building height. Atmospheric NOx dispersion was simulated using the weather research and forecasting (WRF) and computational fluid dynamics (CFD) models for the drone measurement periods. Based on the agreement between the measured BC and simulated NOx concentrations, we concluded that the air pollution around the road intersection has adverse effects on the health of residents living within the 3-D spatial extent within at least 120 m horizontally and a half of building height vertically during the morning rush hours. The comparability between drone monitoring and WRF-CFD modeling can further guarantee the identification of air pollution hotspots using the methods.

Daytime Evolution of Lower Atmospheric Boundary Layer Structure: Comparative Observations between a 307-m Meteorological Tower and a Rotary-Wing UAV

“…The highest BC concentrations were observed at 40 m (07 and 09 LT) and 80 m (06 and 08 LT), whereas the lowest BC concentrations (<0.6 µg m −3 ) were observed above 200 m. In contrast to the BC concentration, the lowest O 3 concentrations appeared at 50 m (07, 08, and 09 LT) and 100 m (06 LT), whereas the highest O 3 concentrations (>48 ppbv) appeared above 250 m. Although the hourly variations in the vertical profiles of BC and O 3 concentrations are not monotonic, it is notable that the vertical differences of BC and O 3 concentrations between altitudes below and above the ABL height are quite substantial in the morning. The typical distribution in the lower ABL has been well known especially in a densely populated urban area at the morning rush hours [39]. This provides solid evidence for ABL height assumed to be between 80 and 200 m above the ground in the morning, which agrees with the ABL height determined from potential temperature and relative humidity profiles.…”

Performance Evaluation of Planetary Boundary Layer Schemes in Simulating Structures of Wintertime Lower Troposphere in Seoul Using One-Hour Interval Radiosonde Observation

“…The MBE and RMSE of the wind speed at 925 hPa were smallest in the simulation with Table 1 shows the mean bias error (MBE) and root mean square error (RMSE) of the simulated air temperature and wind speed near the surface at 925 and 850 hPa. Near the surface, the MBE and RMSE of the air temperature and wind speed were the smallest in the simulation with the MYJ scheme [31]. At 925 hPa, the MBE and RMSE of the air temperature were the smallest in the simulations with the YSU and MYJ schemes, respectively.…”

Ultra-Light Airborne Measurement System for Investigation of Urban Boundary Layer Dynamics

“…Atmospheric measurements by using a UAV can be applied in high-resolution research, verification of modeling results [ 58 ] and as an additional source for data assimilation in the lower troposphere [ 59 ]. Recent study indicates that UAVs that are able to accurately measure three-dimensional wind might be used as a cost-effective and flexible addition to measurement masts and LIDAR scans [ 60 ].…”