Size-resolved absorption coefficient of ambient aerosol at Stockholm University, January to February 2019

Roxana Cremer, Paul Zieger, Johan Ström

The data describe the absorption coefficient of ambient aerosol at Stockholm University over a size range. Therefore a Multi-Angle Absorption Photometer (MAAP) and two Particle Soot/Absorption Photometers (PSAP) were set up in combination with a Differential Mobility Particle Sizer (DMPS) to measure light absorption on a size resolved grid.

The goal was to see in which particle sizes the most absorbing particles are present and to get a particle size distribution for ambient air and absorbing aerosols. Therefore PSAP #2 was built up behind the DMPS to get the light absorption coefficient in the according size bin. The DMPS selects a particle size range and counts the particles, after that the PSAP #2 measures the absorption of the outgoing flow. The MAAP and PSAP #1 was used as a control background measurement to know how much light the ambient air absorbs over all sizes and to compare with each other for data quality purposes.

The data were collected at Stockholm University, Stockholm, Sweden, from 2019-01-11 15:09 until 2019-02-25 07:50. All absorption coefficients were corrected according to established procedures.

Citation

Roxana Cremer, Paul Zieger, Johan Ström (2020) Size-resolved absorption coefficient of ambient aerosol at Stockholm University, January to February 2019. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/cremer-2020-size-resolved-1

References

Tunved P, Cremer RS, Zieger P, Ström J (2021) Using correlations between observed equivalent black carbon and aerosol size distribution to derive size resolved BC mass concentration: a method applied on long-term observations performed at Zeppelin station, Ny-Ålesund, Svalbard, Tellus B: Chemical and Physical Meteorology 73:1, 1-17. https://doi.org/10.1080/16000889.2021.1933775

Bond TC, Anderson TL, Campbell D (1999) Calibration and intercomparison of filter-based measurements of visible light absorption by aerosols. Aerosol Science and Technology, 30, 582⁠ – ⁠600. https://doi.org/10.1080/027868299304435

Data description

There is one datafile, in semicolon-separated (.csv) format, with data columns structured in the following way:

• Date and Time in the format yyyy-mm-dd HH:MM:SS
• Size bins according to the DMPS system: 13 bin in total and in the unit [nm]: 13; 17; 23; 31; 41; 55; 73; 97; 129; 172; 229; 305; 406
• Integrated sum of the size bins, called PSAP2_sum
• Parallel measured PSAP1.

All data are in the unit m⁻¹. The time stamp is related to the measuring cycle of the DMPS, which was set for an hour. Each of the size bins was measured for 4 minutes. The smallest (10 nm) and the largest (504 nm) channels were excluded. The dataset was corrected according to Bond et al. (1999).

Instrumentation: From Centre for Atmospheric Science, University of Manchester — MAAP and PSAP and DMPS.

The method and structure of the experiment is explained in more detail by Tunved et al. (2020).

Comments

During the measurement period a fire event happened in Täby, approx. 5 km north of Stockholm University. The wind transported the plume directly to our measurements: 2019-01-24 23:54 (start of the fire) until the following early morning hours 2019-01-25 08:50.