Estimation of Dust Emission Amount for a Dust Storm Event Occurred in April 1998 in China

Abstract

The threshold friction velocities for dust rises in inland China are examined using WMO synoptic station data and the soil types in the source region to estimate dust emission amounts for a dust event occurred from 13 to 24 April 1998 in China. The dust-rise reports in the WMO synoptic data are used for the delineation of dust source regions that are found to be composed of the Gobi, Sand and Loess regions according to soil types in inland China. The estimated threshold friction velocities with the use of wind speeds observed in the Gobi, Sand and Loess regions are found to be about 60, 50, and 40 cm s-1, respectively. The estimated dust-rise occurrencegrids by both the grid interpolated observed wind and the MM5 model wind well coincide with the areas of strong wind speeds. However, the dust-rise areas estimated by the model are larger than those estimated by the observed wind, whereas the friction velocities estimated by the model in the dust-rise areas are much smaller than those estimated by the observed wind, which result in less amount of dust emission by the model in all source regions. The 10-day accumulated total dust emission estimated by the observed wind during the dust storm event is found to be 4.64 × 108 ton in the whole source region of 3.29 × 106 km2. Of which 85, 9 and 6% are, respectively, contributed by the Gobi, Sand and Loess regions,suggesting the dominant emission from the Gobi region for this event.The model estimated total dust emission is found to be about 56% of that estimated by the observed wind, indicating some improvement of the model being required.