Source apportionment of cloud nuclei at 260 m and ground level in urban Beijing

Two scanning mobility particle sizers (SMPSs) were deployed at ground level and 260 m on the Beijing 325 m meteorological tower (Du et al., 2017). At 260 m, the size-resolved particle number concentration (15-685 nm) was measured by the SMPS equipped with a long differential mobility analyzer (TSI, 3081A). At ground level, the particle number concentrations (10–400 nm) was measured by using an SMPS which is as part of an unattended multifunctional hygroscopicity tandem differential mobility analyzer (H-TDMA).