[A-CG39] Biogeochemical cycles in Land Ecosystem

[ACG39-07] Estimating the sand saltation thresholds from Sentinel-1 SAR data in the Gobi Desert, Mongolia

*Batjargal Buyantogtokh¹, Yasunori Kurosaki¹, Atsushi Tsunekawa¹, Mitsuru Tsubo¹, Masahide Ishizuka², Batdelger Gantsetseg³, Ganhuyag Batjargal³ (1.Arid Land Research Center, Tottori University, 2.Faculty of Engineering and Design, Kagawa University, 3.Information and Research Institute of Meteorology, Hydrology and Environment)

Keywords:arid region, surface roughness, Synthetic Aperture Radar (SAR), threshold friction velocity

The spatial information about the sand saltation threshold is essential for quantifying the sand saltation transport and dust emission as sand saltation is the most important process of dust emission. It is a challenge to estimate/simulate the threshold over a wide area as the main influence factor of sand saltation, the surface roughness elements (e.g., vegetation, stone, soil crust, etc.), are unknown. Here, we explored the potential of the Sentinel-1 Synthetic Aperture Radar (SAR) data to quantify the surface roughness conditions and its temporal changes and to map the sand saltation threshold. The sand saltation thresholds were observed from sand saltation count, wind speed in dry periods of spring 2018-2020 at 3 year-round, and 8 temporary sites during natural sand and dust storm. We found a linear relationship between the observed threshold and the SAR gamma naught VV intensity where the site surface was stony or vegetated except the crusted surface. This indicates that the SAR data has the potential to estimate the distribution of the threshold spatially and temporary during dry periods. The estimated thresholds from SAR in spring 2017-2021 indicate high thresholds on the slopes and mountains due to the mainly stone and vegetation effects and it varied in the topographic depression due to changes of land surface roughness conditions. From these results, we can expect that the high spatial resolution thresholds can greatly contribute to simulating sand horizontal transport and dust emission by theoretical models over a wide area.