ARM Expands Collection of Aerosol Mass Concentration Data Sets

Published: 17 November 2025

The Atmospheric Radiation Measurement (ARM) User Facility recently released new data from the Aerosol Chemical Speciation Monitor (ACSM) Composition-Dependent Collection Efficiency (CDCE) value-added product (ACSMCDCE VAP).

The ACSMCDCE VAP implements a procedure described by Middlebrook et al. (2012) to correct ACSM aerosol mass concentration data for CDCE, or non-unity detection of particle mass by the instrument. This improves the accuracy of the ACSM data and brings them into better agreement with other colocated aerosol measurements.

ARM produces ACSMCDCE for its quadrupole and time-of-flight (ToF) ACSMs, which use different mass spectrometers to separate ions by their mass-to-charge ratio. The ToF instrument is newer technology and has better (lower) detection limits than the quadrupole ACSM.

The ACSMCDCE VAP is now in production for three new ARM sites:

• the main site of the Bankhead National Forest (BNF) atmospheric observatory in Alabama from November 2024 onward
• North Slope of Alaska (NSA) extended facility E30 at Utqiaġvik (formerly Barrow) from November 2024 onward
• the rural supplemental site (S2) near Mount Airy, Maryland, for the Coast-Urban-Rural Atmospheric Gradient Experiment (CoURAGE) from December 2024 onward.

In addition, historical ACSMCDCE data are now available for:

• the Cloud, Aerosol, and Complex Terrain Interactions (CACTI) field deployment in Argentina’s Sierras de Córdoba from September 2018 to May 2019
• the Two-Column Aerosol Project (TCAP) at Cape Cod, Massachusetts, from June 2012 to March 2013
• ARM’s Eastern North Atlantic observatory in the Azores when an ACSM ran there from July 2014 to September 2023
• ARM’s Southern Great Plains Central Facility near Lamont, Oklahoma, when an ACSM ran there from November 2010 to December 2016.

The BNF main site and NSA E30 have ToF-ACSMs, so an ACSMTOFCDCE c1-level data product is available for those sites. Quadrupole ACSMCDCE c1-level VAP data are available for the other sites.

More information about the data, including the technical report, is available on the ACSMCDCE web page.

Scientists can access the new data now in the ARM Data Center. (To download the data, first create an ARM account.)

Please contact ARM translator John Shilling or VAP developer Maxwell Levin to ask questions, report data issues, or provide feedback to help improve these data.

Data can be referenced as doi:10.5439/1641833 for the quadrupole ACSMCDCE data and doi:10.5439/1878136 for ACSMTOFCDCE.

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