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Field observations of saltation and dust emission under crusted ground surface in desert steppe, Mongolia

Masahide Ishizuka 1, Yasunori Kurosaki2, Batdelger Gantsetseg3, Yutaka Yamada4, Dulam Jugder3, Masao Mikami5
1Kagawa University, Takamatsu, Kagawa, Japan, 2Tottori University, Tottori, Tottori, Japan, 3Information and Research Institute of Meteorology Hydrology and Environment, Ulaanbaatar, Mongolia, 4RIKEN, Wako, Saitama, Japan, 5Japan Meteorological Business Support Center, Chiyoda-ku, Tokyo, Japan

Dust monitoring started since the end of March 2012 in Tsogt-Ovoo, which is located in the northern Gobi Desert, Mongolia. Sand particle counter (SPC), SENSIT®, and PM10 /PM2.5 monitor were installed. Sand/Dust and hydro/meteorological measurement instruments were set on a gentle slope in a small valley. The ground was less vegetation in spring but was crusted. In April 2012, a transition in the wind speed threshold ut was observed: ut decreased from 14.0 m/s to 8.8 m/s. This discontinuity might be caused by the difference of the crust status. The 10 m tower was built to observe vertical profile of dust concentration in spring 2014. Strong wind over 14 m/s suddenly blew on 23rd April, 2014. At the same time, PM10 concentration increased to 3 mg/m3 and the visibility decreased. The PM10 concentration at 0.9 and 10 m heights simultaneously increased. These results indicate the dust front passed at the observation site. However, the large increase of saltation particle count was not observed during the passage of the dust front. This reason is also thought to be due to crust. The surface crustiness is important for understanding wind erosion processes.