Estimation of Dry Deposition during Asian Dust Events in Spring of 2002

Abstract

Dry deposition of Asian dust has been estimated during the intensive dust events in spring 2002 (Period I: 15-24 March 2002, Period II: 4-13 Apri1 2002) using the Asian dust aerosol model (ADAM). The emission module including log-normal distributions of particle size of different soil types of Gobi, Sand, Loess, and Mixed soil in the Asian dust source regions, has been used to calculate the amount of dry deposition. The dry deposition estimated by ADAM is compared with that calculated by using the optical particle counter (OPC) observed at Anmyeondo in Korea. The correlation between the modeled and the calculated dry deposition, is found to be 0.78 and 0.54 in Periods I and II, respectively. The dry deposition velocity depends on the particle size with a minimum value of 0.0272 cm s⁻¹ and 0.0269 cm s⁻¹ in the size range of 0.82-1.35 μm in diameter in Periods I and II, respectively. The averaged spectral distribution of dry deposition indicates that the larger particles are more contributed to the total dry deposition amount than the smaller particles due to the large deposition velocity oflarger particles. Consequently, the dry deposition rate is found to be higher in regions closer to the Asian dust source regions.
The estimated total dry deposition amounts over the South Korea, North Korea and Japan are found to be about 558, 955, and 729 k ton, in Period I, respectively and about 240, 364, and 196 k ton, in Period II, respectively.