Theses and Dissertations at Montana State University (MSU)
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Item Meteorological controls on wind slab properties(Montana State University - Bozeman, College of Letters & Science, 2023) de Leeuw, Nathalie Marika; Chairperson, Graduate Committee: Jordy HendrikxSnow avalanches are dangerous phenomena, which can be made increasingly consequential through wind transport of snow. Wind-deposited snow has a broad range of possible physical and mechanical properties which can vary greatly over short distances, creating inconsistent and thus difficult avalanche conditions. This variability causes particular challenges for avalanche workers in data-sparse regions where important snowpack information at desired scales may be unavailable. Instead, snowpack properties are commonly inferred from available meteorological data. Though wind slab properties vary in space and time as meteorological conditions change, previous work has not explicitly studied these relationships at the slope-scale. In this research I aim to better understand how changes in meteorological variables relate to changes in wind slab physical properties. During two winters I recorded temperature, humidity, and wind speed at study sites in Montana's Madison Range (45.237, -111.424) and collected snowpack data during or immediately following blowing snow events. I found that average wind speeds at 0.5m and 1.5m above the snow surface were significantly higher during hard wind slab formation than soft wind slab formation, while unobstructed wind speed, maximum gust, and the length of time of wind transport were not associated with wind slab hardness. Temperature was higher during hard than soft wind slab formation, while humidity was not different between the two hardness categories. Although wind speed at 1.5m had a significant positive linear relationship with both wind slab density and blade hardness gauge force, it was a poor predictor of actual values for both of these parameters. Our findings help improve the understanding of the impact of near surface winds on wind slabs, which will aid avalanche forecasting and mitigation planning particularly in windy climates.Item Extracting abstract spatio-temporal features of weather phenomena for autoencoder transfer learning(Montana State University - Bozeman, College of Engineering, 2020) McAllister, Richard Arthur; Chairperson, Graduate Committee: John SheppardIn this dissertation we develop ways to discover encodings within autoencoders that can be used to exchange information among neural network models. We begin by verifying that autoencoders can be used to make predictions in the meteorological domain, specifically for wind vector determination. We use unsupervised pre-training of stacked autoencoders to construct multilayer perceptrons to accomplish this task. We then discuss the role of our approach as an important step in positioning Empirical Weather Prediction as a viable alternative to Numerical Weather Prediction. We continue by exploring the spatial extensibility of the previously developed models, observing that different areas in the atmosphere may be influenced unique forces. We use stacked autoencoders to generalize across an area of the atmosphere, expanding the application of networks trained in one area to the surrounding areas. As a prelude to exploring transfer learning, we demonstrate that a stacked autoencoder is capable of capturing knowledge universal to these dataspaces. Following this we observe that in extremely large dataspaces, a single neural network covering that space may not be effective, and generating large numbers of deep neural networks is not feasible. Using functional data analysis and spatial statistics we analyze deep networks trained from stacked autoencoders in a spatiotemporal application area to determine the extent to which knowledge can be transferred to similar regions. Our results indicate high likelihood that spatial correlation can be exploited if it can be identified prior to training. We then observe that artificial neural networks, being essentially black-box processes, would benefit by having effective methods for preserving knowledge for successive generations of training. We develop an approach to preserving knowledge encoded in the hidden layers of several ANN's and collect this knowledge in networks that more effectively make predictions over subdivisions of the entire dataspace. We show that this method has an accuracy advantage over the single-network approach. We extend the previously developed methodology, adding a non-parametric method for determining transferrable encoded knowledge. We also analyze new datasets, focusing on the ability for models trained in this fashion to be transferred to operating on other storms.Item Connecting microburst precipitation to its scattering mechanism(Montana State University - Bozeman, College of Letters & Science, 2019) Shumko, Mykhaylo Sergeevich; Chairperson, Graduate Committee: John Sample; Drew L. Turner, T. P. O'Brien, Seth G. Claudepierre, John Sample, D. P. Hartley, Joseph Fennell, J. Bernard Blake, Matina Gkioulidou and Donald G. Mitchell were co-authors of the article, 'Evidence of microbursts observed near the equatorial plane in the outer Van Allen Radiation Belt' in the journal 'Geophysical research letters' which is contained within this thesis.; John Sample, Arlo Johnson, Bern Blake, Alex Crew, Harlan Spence, David Klumpar, Oleksiy Agapitov and Matthew Handley were co-authors of the article, 'Microburst scale size derived from multiple bounces of a microburst simultaneously observed with the Firebird-II cubesats' in the journal 'Geophysical research letters' which is contained within this thesis.; A.T. Johnson, J.G. Sample, B.A. Griffith, D.L. Turner, T.P. OBrien, O. Agapitov, J.B. Blake and S. G. Claudepierre were co-authors of the article, 'Microburst size distribution derived with Aerocube-6' submitted to the journal 'Geophysical research letters' which is contained within this thesis.We will review the main structures in the magnetosphere, the motion of charged particles in electric and magnetic fields, how particles are accelerated and lost in the magnetosphere, and asses the current state of our understanding of microbursts. Then the rest of this dissertation expands our knowledge of microbursts. In Chapter 2 we will investigate and model the scattering mechanism responsible for microbursts observed inside the outer radiation belt, near the magnetic equator. Then in Chapters 3 and 4 we will investigate the microburst scattering mechanism indirectly by estimating the microburst footprint size in low Earth orbit and the magnetic equator (near where microburst electrons are believed to be scattered) and compare it to sizes of chorus waves estimated in prior literature.Item Snow drift and avalanche activity in a high arctic maritime snow climate(Montana State University - Bozeman, College of Letters & Science, 2016) Hancock, Holt John; Chairperson, Graduate Committee: Jordy HendrikxSnow drift endangers human life and infrastructure in alpine and arctic environments by contributing to snow avalanche formation in steep terrain and impacting transportation through reduced visibilities and drift deposition on roadways. Understanding the local and synoptic scale meteorological conditions just prior to and during hazardous snow drift conditions is a crucial element in forecasting for -- and mitigating the hazards associated with -- snow drift processes. This is especially true in Svalbard, a High Arctic Norwegian archipelago, where snow drift processes have been linked to avalanche activity and hazardous travel conditions in the region's unique, direct-action maritime snow climate. This study uses a record of road closures due to drifting snow on a mountain road to further investigate Svalbard's snow climate and avalanche regime by characterizing meteorological conditions leading to regional snow drift events and exploring the relationship between these periods of snow drift and regional avalanche activity. A nine-year record of road closures is coupled with local meteorological observations and NCEP/NCAR synoptic composite maps to characterize the local and synoptic weather conditions leading to and occurring during periods of snow drift near Longyearbyen, Svalbard's primary settlement. This record of snow drift events is then compared with regional avalanche observations using a case study approach to illustrate the relationship between snow drift and avalanche activity in Svalbard. Results show snow drift events result from five distinct synoptic circulation types and are characterized by increased wind speeds, higher precipitation totals, and elevated air temperatures relative to average winter conditions. Four case studies qualitatively illustrate the interactions between local and synoptic weather patterns, snow drift processes, and regional avalanche activity. In addition to the suggested mitigation strategies provided, these results will help advance avalanche forecasting efforts throughout the region.Item Radiocesium in Montana soils and applications for soil erosion measurement(Montana State University - Bozeman, College of Agriculture, 1984) Arnalds, Olafur Gestur; Chairperson, Graduate Committee: Gerald A. NielsenRadiocesium levels in soils were measured at eleven sites throughout Montana. Cesium was mostly confined to the top of the soil profile. Both lateral and vertical displacement of cesium was attributed to mechanical movement of soil particles. The areal activity of cesium was strongly correlated to annual precipitation (R^2 = 0.92). An equation is given to predict cesium activity from annual rainfall. Methods of calculating soil erosion and deposition are discussed and performed for a wind erosion study site in Pondera County and a small watershed in Teton County. The results indicate that deposition at the wind erosion study site can be quantified. Soil deposition of 70 to 1290 m^3 ha^-1 was measured on the leeward sides of a fence and tree windbreaks while an average of 450 m^3 was lost from the windward sides. An average of 740 m^3 ha^-1 was lost since 1962 from an adjacent wind eroded field. This amounts to 34.8 Mg ha^-1 yr^-1. Soil loss since about 1962 ranged from 300 to 820 m^3 ha^-1 within the upper areas of the watershed studied. A pond at the outlet of the watershed and deposition areas at the toeslope accounted for a relatively small fraction of the soil loss within the watershed. Most of the losses are likely to be from wind erosion. Length of slopes or position within the field were more related to erosion than was steepness of slopes, Estimates of erosion rates based on 137Cs ranged from 16.5 Mg ha^-1 yr^-1 at the summit of the watershed to 45.1 Mg ha^-1 yr^-1 at the midslope. Predictions by conventional methods (wind erosion equation and the Universal Soil Loss Equation) agreed rather closely with the estimates from 137Cs.Item Wind-electric power generation in Montana(Montana State University - Bozeman, College of Engineering, 1976) Obermeier, John LeeItem Amorphous character in twenty western Montana forest soils with apparent eolian influence(Montana State University - Bozeman, College of Agriculture, 1977) Ottersberg, Robert JosephItem Sand dunes of the Darhat Valley Mongolia : understanding their origins, dynamics, and impacts on soils and vegetation(Montana State University - Bozeman, College of Agriculture, 2001) O'Connell, Patrick HaroldItem Wind as an ecological factor in the McMurdo Dry Valleys, Antarctica(Montana State University - Bozeman, College of Agriculture, 2012) Sabacka, Marie; Chairperson, Graduate Committee: John C. Priscu.; John C. Priscu, Hassan J. Basagic, Andrew G. Fountain, Diana H. Wall, Ross A. Virginia and Mark C. Greenwood were co-authors of the article, 'Aeolian flux of biotic and abiotic material in Taylor Valley, Antarctica' in the journal 'Geomorphology' which is contained within this thesis.; John C. Priscu, J. E. Barrett, Diana H. Wall, Ross A. Virginia and Diane McKnight were co-authors of the article, 'Aeolian fluxes of carbon, nitrogen and phosphorus among landscape units in the Taylor Valley, Antarctica' in the journal 'Arctic, antarctic and alpine research' which is contained within this thesis.; John C. Priscu was a co-author of the article, 'Spatial distribution of microorganisms in the McMurdo Dry Valleys, Antarctica' in the journal 'Polar biology' which is contained within this thesis.; Alexander B. Michaud and John C. Priscu were co-authors of the article, 'Spatial scaling of cyanobacterial diversity in the Taylor Valley, Antarctica' in the journal 'Polar biology' which is contained within this thesis.The aim of this work was to investigate the role of wind on the ecology of the McMurdo Dry Valleys in Antarctica (MDV), one of the coldest and driest deserts on Earth. The MDV landscape consists of a mosaic of permanently ice-covered lakes, ephemeral streams, exposed soils, and glaciers, all of which contain habitats dominated by microorganisms. Data on wind-driven flux of sediments and associated organic matter were collected using passive aeolian traps and dynamic mass erosion particle counters to investigate the timing, direction and magnitude of aeolian sediment transport. Combination of genomic techniques and phenotypical fingerprinting (pigment analysis) was used to examine microbial diversity over a wide variety of wind-eroded habitats across the MDV landscape to elucidate the role of wind dispersal on the contemporary distribution of microorganisms across the MDVs. Sediment entrainment occurs predominantly within 20 cm of the ground surface and has character of saltation bursts that occupy <3% of the total time within a year. The high-energy winter föhn winds uplift sediments in the upper parts of the MDVs and transport them down-valley where they are deposited onto the surface of perennially ice-covered lakes and surrounding soils. The sediment that enters the water column of the lakes does not provide a significant source of organic carbon for bacterioplankton communities compared to the in situ production by phytoplankton but can be a source of new microbial propagules. The aeolian material is low in organic matter (<1% dw) but is composed of a relatively large numbers of cyanobacterial taxa (~20 OTUs) that can be found in all other MDV habitats. In conclusion, wind distributes microorganisms across the MDV landscape but local environment selects for specific taxa. Predicted climate warming will increase the importance of wind transport, which will affect nutrient cycling and connectivity among MDV ecosystem components.Item The Sinc-Galerkin method for problems in oceanography(Montana State University - Bozeman, College of Letters & Science, 2003) Koonprasert, Sanoe; Chairperson, Graduate Committee: Kenneth L. BowersThe model for a wind-driven current with depth-dependent eddy viscosity is developed as a complex velocity formulation and a coupled system formulation. The numerical solutions, calculated by a Sinc-Galerkin method, are compared. A fully Sinc-Galerkin method in both space and time for a partial differential equation with time-dependent boundary conditions is developed. This entirely new technique is applied to the model for a wind-driven current with time-dependent viscosity. Several numerical examples are used to test the performance of the method. This fully Sinc-Galerkin method is then applied to the spin-up and the episodic wind stress oceanography problems.