Quantitative classification of northeast Asian dust events

In this paper, we introduce a quantitative classification of dust events on the basis of dust, PM10 concentration, and wind speed for northeast Asia. The empirical relationship between visibility and PM10 concentration is established by regression of visibility and PM10 concentration that were taken every 5 min at 11 sites in the spring of 2004 and 2005. The empirical relationship is then applied to establish the spatial and temporal patterns of dust and PM10 concentrations by using the visibility data obtained from 1680 meteorological stations in the spring seasons of 2000-2005. The results showed that the PM10 concentration estimated from visibility is consistent with the observed PM10 concentration. The classification standard of dust events used by different countries did not show consistent results in northeast Asia. It is recommended that dust events in northeast Asia be classified as follows: (1) severe dust storm, rho(TSP) >= 6000 mu g m(-3), rho(PM10) >= 5000 mu g m(-3), and v >= 10 m s(-1); (2) dust storm, 3000 mu g m(-3) <= rho(TSP) < 6000 mu g m(-3), 3000 mu g m(-3) <= rho(PM10) < 5000 mu g m(-3), and 10 m s(-1) <= v < 15 m s(-1); (3) blowing dust, 900 mu g m(-3) <= rho(TSP) < 1500 mu g m(-3), 200 mu g m(-3) <= rho(PM10) < 600 mu g m(-3), and 5 m s(-1) <= v < 10 m s(-1); and (4) floating dust, 750 mu g m(-3) <= rho(TSP) < 1200 mu g m(-3), 200 mu g m(-3) <= rho(PM10) < 400 mu g m(-3), and 2 m s(-1) <= v < 5 m s(-1).