@article {JRN55067, title = {Dust emission from crusted surfaces: Insights from field measurements and modelling}, journal = {Aeolian Research}, volume = {40}, year = {2019}, month = {06/2019}, pages = {1-14}, chapter = {1}, abstract = {

Crusted surfaces can be major sources of mineral dust emission. Quantitative understanding of dust emission from crusted surfaces is limited, because (1) theories on dust emission are not well tested for such surfaces; and (2) modelling is hampered by a lack of input data sufficient to describe the surface conditions. Combining detailed field measurements with physics-based numerical modelling, we present new insights into dust emission from crusted surfaces. Our measurements confirm that crust erodibility and dust-emission intensity can increase or decrease after previous erosion events. To support interpretation of the measurements and to test the applicability of a state-of-the-art parameterisation to simulate dust emission from crusted surfaces, we apply the dust emission scheme of Shao (2004). Saltation flux, which is input to the scheme, is approximated using the parameterisation of Kawamura (1964) and a scaling factor obtained from observations. Limitations of this approach are discussed. Our results show that the dust emission scheme is suitable to estimate dust emission from crusted surfaces if accurate input data and parameters describing the soil-surface condition are provided. The parameters were optimized for each dust event to achieve a best estimate. The variation of the resulting parameter values confirms the observed variability of dust-emission efficiency between the events and provides further evidence that it was caused by variations in crust erodibility. Our study demonstrates that available physics-based dust-emission parameterisations are able to simulate dust emissions under complicated conditions, but also that refined information on the soil-surface conditions are needed as input to the schemes.

}, doi = {doi.org/10.1016/j.aeolia.2019.05.001}, url = {files/bibliography/19-008.pdf}, author = {Martina Klose and Thomas E. Gill and Vicken Etyemezian and Nikolich, George and Ghodsi Zadeh, Zahra and Nicholas Webb and Scott Van Pelt} } @proceedings {JRN54782, title = {Can dust emission mechanisms be determined from field measurements?}, volume = {[abstract]}, year = {2017}, month = {04/2017}, publisher = {European Geosciences Union General Assembly}, address = {Vienna, Austria}, abstract = {

Field observations are needed to develop and test theories on dust emission for use in dust modeling systems. The dust emission mechanism (aerodynamic entrainment, saltation bombardment, aggregate disintegration) as well as the amount and particle-size distribution of emitted dust may vary under sediment supply- and transport-limited conditions. This variability, which is caused by heterogeneity of the surface and the atmosphere, is not currently 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 relied 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 field measurements are conducted, which allow for a comparison of dust emission for different surface and atmospheric conditions. Measurements include monitoring of the soil surface, loose erodible material, transported sediment, and meteorological data, and are conducted in different environmental settings in the southwestern United States. Based on the field measurements, a method is developed to differentiate between the different dust emission mechanisms.

}, author = {Martina Klose and Nicholas Webb and Thomas E. Gill and Scott Van Pelt and Gregory S. Okin} } @conference {JRN54638, title = {Deducing dust emission mechanisms from field measurements}, booktitle = {9th International Conference on Aeolian Research}, year = {2016}, month = {07/2016}, publisher = {International Conference on Aeolian Research}, organization = {International Conference on Aeolian Research}, address = {Mildura, Australia}, abstract = {
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.
}, author = {Martina Klose and Nicholas Webb and Justin Van Zee and Brad Cooper and Scott Van Pelt and Gregory S. Okin and Jason W. Karl} } @conference {JRN54613, title = {Disentangling dust emission mechanisms {\textendash} a field study}, booktitle = {American Geophysical Union Fall Meeting}, year = {2016}, month = {12/2016}, publisher = {American Geophysical Union}, organization = {American Geophysical Union}, address = {San Francisco, CA}, abstract = {

Field observations are needed to both develop and test theories on dust emission for use in global modeling systems. The dust emission mechanism (aerodynamic entrainment, saltation bombardment, aggregate disintegration) as well as the amount and particle-size distribution of emitted dust may vary under sediment supply- and transport-limited conditions. This variability, 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 are 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.

}, author = {Martina Klose and Peterson, Sharalyn and Nicholas Webb and Justin Van Zee and Brad Cooper and Scott Van Pelt and Thomas E. Gill and Gregory S. Okin and Jason W. Karl} } @article {JRN54603, title = {A numerical study on dust devils with implications to global dust budget estimates}, journal = {Aeolian Research}, volume = {22}, year = {2016}, month = {09/2016}, type = {Peer Reviewed}, chapter = {47}, abstract = {The estimates of the contribution of dust devils (DDs) to the global dust budget have large uncertainties because the dust emission mechanisms in DDs are not yet well understood. In this study, a large-eddy simulation model coupled with a dust scheme is used to investigate DD dust entrainment. DDs are identified from the simulations using various threshold values for pressure drop and vorticity in the DD center. A vortex-tracking algorithm is presented, which automatically detects and tracks vortices based on different pressure drop and vorticity criteria. The results show that DD dust lifting can be largely explained by convective turbulent dust emission. DD dust entrainment varies strongly between individual DDs even for similar atmospheric conditions, but the maximum emissions are determined by atmospheric stability. By relating DD emission and counts to the Richardson number, we propose a new and simple method to estimate regional and global DD dust transport. }, url = {/files/bibliography/16-019.pdf}, author = {Martina Klose and Shao, Yaping} }