AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Low Cost Sensor Approach to Intra-Urban UFP Characterization in Austin, TX
MARK CAMPMIER, Rijul Gosar, Jing Wu, Betty Molinier, Joshua Apte, University of Texas at Austin
Abstract Number: 706 Working Group: Air Quality Sensors: Low-cost != Low Complexity
Abstract Ultrafine Particles (UFP) or particles with a diameter smaller than 100 nm have been difficult to continuously measure, characterize, and attribute to emissions sources. In addition, the influence of photonucleation in high insolation regions has required the usage of relatively expensive and challenging to maintain particle size analyzers to fully capture the nuance of UFP number concentration (PN) measured by Condensation Particle Counters (CPC). Over the course of Summer, and Fall 2018 the University of Texas at Austin conducted a citywide measurement campaign in Austin with an ensemble of sensors as part of the Center for Air, Climate, and Energy Solutions (CACES). The goal of the campaign was to evaluate the performance of the low-cost sensors, characterize intra-urban PN variation, and increase understanding of the role of local and regional emissions sources. In this study, we show that a regionally dense sensor network including packages of water-based CPCs co-located with low-cost optical PM2.5, CO2, and NO2 sensors can effectively characterize some urban scale and neighborhood scale phenomena. Throughout the three operational phases (July 16-Aug 8, Aug 8-Aug 31, Oct 5-Nov 25) of the campaign, despite varying sensor package locations, midday peaks in PN were observed throughout the high insolation summertime. Fewer of these midday peaks were observed during phase 3, which occurred in the cooler and more nebulous autumn. During the pre-calibration phase (June 4- July 16), these peaks were observed to correlate with nucleation events measured by a co-located SMPS. Other PN peaks seemed to match expected traffic trends, with some sites experiencing only single traffic peaks (morning or evening), likely caused by wind conditions favoring a given direction of traffic. PM2.5 trends were relatively homogenous across the region and measurement phase, following a distinctive weekday vs weekend pattern.