Deducing dust emission mechanisms from field measurements
1, Nicholas Webb1, Justin Van Zee1, Brad Cooper1, Scott Van Pelt2, Gregory Okin3, Jason Karl1
1USDA-ARS Jornada Experimental Range, Las Cruces, NM, USA, 2USDA-ARS Wind Erosion and Water Conservation Research Unit, Big Spring, TX, USA, 3Department of Geography, University of California, Los Angeles, CA, USA
Field observations are needed to both develop and test theories on dust emission for use in global modeling systems. The mechanism of dust emission (aerodynamic entrainment, saltation bombardment, aggregate disintegration) and the amount and particle-size distribution of emitted dust may vary under sediment supply- and transport-limited conditions. This complexity, which is caused by heterogeneity of the surface and the atmosphere, cannot be fully captured in either field measurements or models. However, uncertainty in dust emission modeling can be reduced through more detailed observational data on the dust emission mechanism itself. To date, most measurements do not provide enough information to allow for a determination of the mechanisms leading to dust emission and often focus on a small variety of soil and atmospheric settings. Additionally, data sets are often not directly comparable due to different measurement setups. As a consequence, the calibration of dust emission schemes has to rely on a selective set of observations, which leads to an idealization of the emission process in models and thus affects dust budget estimates. Here, we will present preliminary results of a study which aims to decipher the dust emission mechanism from field measurements as an input for future model development. Detailed and standardized field measurements will be conducted, which allow for a differentiation between dust emission mechanisms and for a comparison of dust emission for different surface and atmospheric conditions. Measurements include monitoring of the surface, loose erodible material, transported sediment, and meteorological data, and are conducted in different environmental settings in the southwestern United States.