Comparisons of Aerosol Absorption Coefficients from multiple techniques at ARM Houston site: A case study

The Atmospheric Radiation Measurement (ARM) program has been collecting data to advance atmospheric and climate research since the early 1990s. Measurements from permanent ARM sites (e. g. Southern Great Plains [SGP], North Slope of Alaska [NSA], Eastern North Atlantic [ENA] ) extend for 5-30 years. In addition, deployments of ARM mobile facilities have data periods of 6 months to 2 years (https://www.arm.gov/about). Each ARM Mobile Facility (AMF) has at least one Aerosol Observation System (AOS) with instruments to measure aerosols, gases, and other related properties. Here we present an intercomparison of aerosol light absorption coefficients from the AMF1 aethalometer with Particle Soot Absorption Photometer (PSAP) and two guest instruments (Integrated Photoacoustic Nephelometers [IPN] and Tricolor Absorption Photometers [TAP]) from the TRACER field campaign in Houston (HOU) https://www.arm.gov/publications/programdocs/doe-sc-arm-19-017.pdf). The light absorption coefficients from the nearest aethalometer wavelengths are compared with those from the PSAP, TAP, and IPN. It is worth noting that the first three instruments (aethalometer, PSAP, TAP) measure light absorption of particles deposited on a filter while the IPN measures in-situ absorption of particles suspended in air. As ARM is in planning stage to replace PSAPs with two spot aethalometers at all sites, the intercomparison of absorption coefficients between these two instruments will help to better understand the performance, improve the data quality, and understand the uncertainties of light absorption at the ARM-HOU site.