High Spatial Resolution Size Resolved Aerosol Observations on both the Neighborhood Scale and from a UAV in the Lowermost Boundary Layer

Abstract:

Airborne particulates play a central role in both the earth’s radiation balance and as a trigger for a wide range of health impacts. Air quality monitors are placed in networks across many cities globally. Typically these provide at best a few recording locations per city. However, large spatial variability occurs on the neighborhood scale. This study sets out to comprehensively characterize a full size distribution from 0.25 - 32 μm of airborne particulates on a fine spatial scale (meters) using two phases. In phase one the data is gathered at ground level on a near daily basis over the month of May, 2014 in a 100 km2 area encompassing parts of Richardson, and Garland, TX. Variograms were used to determine an appropriate spatial scale for future measurements to provide PM characterization on a neighborhood scale. The results showed the spatial scales varied, depending on the synoptic weather pattern, from 0.8 km to 5.2 km, with a typical spatial scale of 1.6 km. Phase two used a remote-controlled aerial vehicle to look at the horizontal, vertical, and temporal variability of airborne particulates within the first 150 m of the atmosphere. Four flights where conducted on December 4, 2014 between 12:00 pm and 5:00 pm local time. The first three flights flew a pattern of increasing altitude up to 140 m. The fourth flight was conducted at a near constant altitude of 60 m. The mean PM2.5 concentration for the three flights with varying altitude was 36.3 μgm^−3, with the highest concentration occurring below 10 m altitude. The overall vertical variation was very small with a standard deviation of only 3.6 μgm^−3. PM2.5 concentration did not change much throughout the day with mean concentrations variation of only 2.1 μgm^−3. The fourth flight, flown at a near constant altitude, corroborated the spatial scales found in phase one.