Aerosol hygroscopicity measurements at Gosan, Jeju Islands, and Seoul, Korea

A Hygroscopicity Tandem Differential Mobility analyzer (H-TDMA) system was setup to measure hygroscopic growth properties of atmospheric aerosols at Gosan, Jeju Island, and Seoul, Korea. This study is the first such measurements in Korea. First, deliquescence relative humidity (DRH) of NaCl was measured to confirm the validity of the H-TDMA system setup. Monodisperse particles of dry diameter (D0), 50 nm, 100 nm, 150 nm and 200 nm, are classified and then exposed to humidified environment of RH 85 ± 3% before the grown diameter (D) is measured to calculate hygroscopic growth factor (D/D0). Measured hygroscopic growth factors were on average 1.37, 1.56, 1.61 and 1.64 for the four diameters listed above, which are in the similar range to most of precious measurements. Preliminary measurements at the coastal site at Anmyeon and in Seoul were on average 1.93 and 1.75, respectively, for the single diameter of 98 nm and RH of about 85%, which were somewhat higher than those reported in many other studies. This may indicate improvement of our current setup. It is also scheduled to measure hygroscopic growth factors of aerosols in Seoul for the same four diameters in October, 2006, with our current setup. Measured hygroscopic growth factors at Gosan and Seoul will be presented at the conference. Variation of growth factors due to airmass changes and weather conditions will also be closely examined.