HR: 14:55h
AN: NG43A-06    [Abstracts]
TI: Influence of Temporal Scales and Soil Properties on Dust Emissions: a Measurement and Modeling Effort
AU: * King, J
EM: james.king@dri.edu
AF: Desert Research Institute, Division of Atmospheric Sciences 755 E. Flamingo Rd, Las Vegas, NV 89119, United States
AU: Etyemezian, V
EM: vic@dri.edu
AF: Desert Research Institute, Division of Atmospheric Sciences 755 E. Flamingo Rd, Las Vegas, NV 89119, United States
AU: Gillies, J A
EM: jack.gillies@dri.edu
AF: Desert Research Institute, Division of Atmospheric Sciences 2215 Raggio Parkway, Reno, NV 89512, United States
AU: Buck, B J
EM: buckb@unlv.nevada.edu
AF: University of Nevada Las Vegas, Department of Geoscience 4505 Maryland Pkwy, Las Vegas, NV 89154, United States
AB: Dust emission events in deserts are usually modeled as large magnitude annual or biannual events driven by larger-scale meteorological processes (e.g., frontal passages, thunder cell downdrafts), partly owing to the relatively coarse temporal and spatial scales of observation. However, there is evidence that smaller, more frequent wind events (either through sandblasting or direct aerodynamic entrainment), may play a previously unknown, but important role in dust emissions, suggesting that current models do not account for all of the dust that is emitted into the atmosphere. This has important implications from the perspective of landscape dynamics for the rates of replenishment of surface dust, principally through processes of deposition or production of silt- and clay-sized particles. Three fundamental research questions remain largely unanswered. The first is: Do large-scale dust storms contribute the majority of fugitive dust to the atmosphere? The spatial and temporal complexity of wind erosion leads to dust emissions that are often too small to be detected by remote sensing and we can ask "do smaller and likely more frequent events (in comparison to annual major dust storm events) result in a large proportion of dust emitted from arid environments? The second question to be addressed is: What is the role of direct entrainment of desert dust in contributing to regional dust emissions? Only recently has research suggested that direct entrainment is a process that can emit a significant amount of dust into the atmosphere. We are investigating whether there is a temporal limitation (associated with deposition or more generally, replenishment) that bounds the magnitude of these types of emissions. The last question to be addressed is: How do soil surficial characteristics affect the temporal aspects of dust emissions. Exposed surfaces in arid climates are often covered with a variable thickness of salt crust. These crusts can vary spatially and temporally between loose individual silt to sand-sized crystals to hard crusts composed of interlocking crystals. In this aspect of the research we aim to examine how surficial salt crust morphology and mineralogy affect dust emissions on various spatial and temporal scales. This paper attempts to provide preliminary answers to these questions by presenting data which: (1) characterize the potential of different soil types to emit dust, based on measurements made using new wind tunnel technology, (2) quantify the vertical dust and horizontal sediment fluxes in conjunction with the physical, chemical, and mineralogical (salt) soil characteristics obtained with new analytical techniques (e.g., XRD, SEM) and, (3) define a temporal scale and associated time-lag for soil surfaces to emit fugitive dust using a new model based on soil profile characteristics (i.e., resistance, genesis and seasonality). Results of this work have a direct impact on the understanding of aeolian and soil surface dynamics and will result in improved accuracy and temporal resolution of dust emission models.
DE: 1622 Earth system modeling (1225)
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
DE: 1824 Geomorphology: general (1625)
DE: 4430 Complex systems
DE: 4475 Scaling: spatial and temporal (1872, 3270, 4277)
SC: Nonlinear Geophysics [NG]
MN: 2007 Fall Meeting