Two sets of Chemical Speciation Network (CSN) carbon samples collected on 25mm diameter quartz filters were respectively analyzed by thermal-optical reflective analysis with the IMPROVE_A protocol. Set 1 consists of 303 CSN filters sampled in September and October 2007 that were previously analyzed by DRI with the DRI-2001 models in the year 2008. Set 2 consists of 4073 CSN samples and 622 CSN field blanks collected between May and September 2017, which were sequentially analyzed by the Sunset analyzers at UC Davis and by the DRI-2015 analyzers at DRI within a year after sample collection. Sunset and DRI-2015 data are reported in mass loadings (μg/cm2). Sunset raw data were processed using a custom R computing package developed by UC Davis. DRI-2015 data were calculated by the program supplied by the manufacturer. DRI-2001 data from the archived 2007 CSN samples were downloaded from the EPA Air Quality System (AQS) database (https://aqs.epa.gov/aqsweb/documents/data_api.html, last access: 28 April 2021). The concentration data (μgm-3) were converted to mass loadings (μg/cm2) using a nominal sample volume (33m3) and filter area (3.53 cm2) for direct comparison against the Sunset data.

This data file contains 5 columns with header. Specifically, SampleID = original CSN filter identifier Parameter = carbon fractions speciated by thermal-optical analysis UCD_massloading = carbon mass loading in the unit of μg/cm2 measured by Sunset analyzers in UC Davis laboratory DRI_massloading = carbon mass loading in the unit of μg/cm2 measured by DRI analyzers in Desert Research Institute laboratory DRI Analyzer = the model type of the DRI analyzer, used as a flag to distinguish Set 1 and Set2 specified in the Methods section

This dataset contains thermal-optical analysis (TOA) carbon data from an inter-laboratory comparison study described in the paper: Zhang, X., Trzepla, K., White, W., Raffuse, S., and Hyslop, N. P.: Intercomparison of thermal–optical carbon measurements by Sunset and Desert Research Institute (DRI) analyzers using the IMPROVE_A protocol, Atmos. Meas. Tech., 14, 3217–3231, https://doi.org/10.5194/amt-14-3217-2021, 2021.