ACROSS_LCE_PRG_SMPS_5 min_L2

The particle number and size distribution in different size classes between 23 and 982 nm electrical mobility diameter was measured at the ground–based PRG urban site during ACROSS by a scanning mobility particle sizer (SMPS, TSI). The instrument was installed in a dedicated measuring room at the 7th floor of the Lamark B building of Université Paris Cité. Air was taken from a common certified PM1 sampling head located on the roof of the building at about 30 m height above the ground level. A copper tube of 7 mm inner diameter and 10 m length (flow = 15.6 L/min) connected the PM1 head to a 4 way–stainless-steel flow slitter (TSI) located in the measuring room that dispatched the air flow to different instruments. The sampled air from this common line was directed to the SMPS through a 2.7 m long conductive silicon tubing (4.5 mm inner diameter) using an extra pump and mass flow controller to regulate the flow at 1 L/min. Then the SMPS sampled air from this last line using a short tube of conductive silicon tubing (ca 0.2 m) at 0.3 L/min. Data were acquired continuously at 5 min time resolution corresponding to the average of 2 scans. Sheath flow was kept at 1.5 L/min to cover a larger range of particle size distribution. Blank were performed art least twice a week during the campaign to evaluate leak or instrument contamination, by placing a HEPA filter either at the inlet of the SMPS or instead of the PM1 common inlet. Data acquired at ambient conditions (meteorological data measured at the site were used as reference for ambient T and P). Raw data were controlled manually to check periods when specific conditions prevented to do measurements or affected the quality of the measurements (power cut, zero check, disconnection from the sampling line, misfunctioning). Data in correspondence of these periods were removed from this file and intentionally left empty.