A new value-added product (VAP) from the Atmospheric Radiation Measurement (ARM) user facility corrects aerosol chemical speciation monitor (ACSM) data for non-unity particle detection. Users can now evaluate this VAP, referred to as ACSM, corrected for composition-dependent collection efficiency (ACSMCDCE).
The ACSM, installed in most ARM Aerosol Observing Systems, provides a quantitative measurement of aerosol particle chemical composition for nonrefractory aerosol components. One well-known limitation to the accuracy of the 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.
The ACSMCDCE VAP applies one such parameterization, developed by Middlebrook et al. (2012), to the ACSM data. Applying this parameterization improves the accuracy of the data and brings them into better agreement with other co-located aerosol measurements.
The first available ACSMCDCE data are from September 30, 2019, to July 6, 2020, for ARM’s Southern Great Plains E13 site near Lamont, Oklahoma.
Scientists can begin using the ACSMCDCE data now. Future work will involve expanding the availability of ACSMCDCE data at more ARM sites where ACSM data are available.
To learn more about ACSMCDCE, go to the VAP web page.
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.