Threshold wind speed for dust emission in east Asia and its seasonal variations

[1] We present maps of threshold wind speed for dust emission in east Asia, which are statistically evaluated from synoptic surface meteorological data. We define threshold wind speeds as u(t)5% and u(t)50%, which can be identified as threshold wind speeds at close to the most favorable land surface condition for dust emission and under normal land surface conditions, respectively. Spatial distributions of u(t)5% and u(t)50% are similar and roughly correspond to the land cover type. The threshold wind speed is low in desert regions such as the Taklimakan Desert (u(t)5% = 4.4 +/- 0.6 m s(-1) and u(t)50% = 6.7 +/- 1.5 m s(-1)) and the Loess Plateau (u(t)5% = 6.9 +/- 1.2 m s(-1) and u(t)50% = 9.4 +/- 1.6 m s(-1)). On the other hand, the highest is seen in northern Mongolia (u(t)5% = 9.8 +/- 2.2 m s(-1) and u(t)50% = 16.2 +/- 2.5 m s(-1)), whose land cover type is grassland. One exception is the high threshold wind speed recorded in the Gobi Desert (u(t)5% = 8.9 +/- 2.2 m s(-1) and u(t)50% = 13.8 +/- 2.0 m s(-1)). Seasonal variations in the threshold wind speed are narrow in desert regions such as the Taklimakan Desert, the Gobi Desert and Loess Plateau, but wide in grassland regions such as northern Mongolia. This suggests that land surface conditions are the similar throughout the year in desert regions, but seasonally variable in grassland regions.