The soil particle size dependent emission parameterization for an Asian dust (Yellow Sand) observed in Korea in April 2002

摘要

Intense Asian dust (Yellow Sand) events have been observed in Korea on 21-23 March and 7-9 April 2002. During these periods the observed PM_(10) concentrations were over 1000μgm~(-3) at most monitoring sites in South Korea. The operational meteorological model of the Regional Data Assimilation and Prediction System of the Korea Meteorological Administration and the aerosol transport model with the improved particle size distribution parameterization developed at Seoul National University were used to simulate the intense Yellow Sand event observed on 7-9 April 2002. The comparison with the observational data shows that the present model system could reasonably simulate the evolutionary features of Yellow Sand over South Korea including the starting and ending time of the event, the particle size spectrum and the PM_(10) concentration. It was found that the dominant particle diameter in the mass concentration ranged from 3.67 to 10 um during this dust event. A promising dust emission model depending on the particle size distribution constructed by the sum of several log-normal distributions of particle sizes of different soil types has been developed and found to yield better spectral-mass concentration in the size range of larger than 10 μm. This result suggests that size distributions of Asian dust (Yellow Sand) are consistent with those found in the USA, Central Asia and the Sahara desert. However, the accuracy of the model requires more detailed soil particle distributions in the source region.