A new data product from the Atmospheric Radiation Measurement (ARM) user facility corrects time-of-flight aerosol chemical speciation monitor (ToF-ACSM) data for non-unity particle detection.
The ToF-ACSM provides a quantitative measurement of aerosol particle chemical composition for nonrefractory aerosol components. One well-known limitation to the accuracy of the ToF-ACSM data is in evaluating the fraction of sampled aerosol particles that the instrument detects. This quantity is referred to as the collection efficiency.
Often, scientists will assume collection efficiency equals 0.5 for ambient particles collected during field campaigns. However, parameterizations have been developed that express collection efficiency as a function of the measured chemical composition, referred to as the composition-dependent collection efficiency (CDCE).
The new ACSMTOFCDCE product applies one such parameterization, developed by Middlebrook et al. (2012), to the ToF-ACSM data. Applying this parameterization improves the accuracy of the data and brings it into better agreement with other co-located aerosol measurements.
The new product is available from June 1 to September 16, 2022, for the TRacking Aerosol Convection interactions ExpeRiment (TRACER) near Houston, Texas. Also, data are available from May 13 to September 16, 2022, for the Surface Atmosphere Integrated Field Laboratory (SAIL) campaign currently being conducted near Crested Butte, Colorado.
Scientists can begin using ToF-ACSM aerosol particle concentration data corrected for CDCE. In the future, data will be available in near-real time for sites where ToF-ACSM data are available.
To learn more about the new data product, go to the ACSMCDCE web page.
Data can be referenced as doi:10.5439/1878136.
Reference: Middlebrook AM, R Bahreini, JL Jimenez, and MR Canagaratna. 2012. “Evaluation of Composition-Dependent Collection Efficiencies for the Aerodyne Aerosol Mass Spectrometer using Field Data.” Aerosol Science and Technology, 46(3):258-271, https://doi.org/10.1080/02786826.2011.620041.# # #
ARM is a DOE Office of Science user facility operated by nine DOE national laboratories.