Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Snow avalanche identification using Sentinel-1: detection rates and controlling factors(Montana State University - Bozeman, College of Letters & Science, 2021) Keskinen, Zachary Marshall; Chairperson, Graduate Committee: Jordy Hendrikx; Jordy Hendrikx, Karl Birkeland and Markus Eckerstorfer were co-authors of the article, 'Snow avalanche identification using Sentinel-1 backscatter imagery: detection rates and controlling factors' submitted to the journal 'Natural hazards and Earth system sciences' which is contained within this thesis.Snow avalanches present a significant hazard that endangers lives and infrastructure. Consistent and accurate datasets of avalanche events is valuable for improving forecasting ability and furthering knowledge of avalanches' spatial and temporal patterns. Remote sensing-based techniques of identifying avalanche debris allow for continuous and spatially consistent datasets of avalanches to be acquired. This study utilizes expert manual interpretations of Sentinel-1 synthetic aperture radar (SAR) satellite backscatter images to identify avalanche debris and compares those detections against historical field records of avalanches in the transitional snow climates of Wyoming and Utah. This study explores the utility of Sentinel-1 (a SAR satellite) images to detect avalanche debris on primarily dry slab avalanches. The overall probability of detection (POD) rate for avalanches large enough to destroy trees or bury a car (i.e., D3 on the Destructive Size Scale) was 64.6%. There was a significant variance in the POD among the 13 individual SAR image pairs (15.4 - 87.0%). Additionally, this study investigated the connection between successful avalanche detections and SAR-specific, topographic, and avalanche type variables. The most correlated variables with higher detection rates were avalanche path lengths, destructive size of the avalanche, incidence angles for the incoming microwaves, slope angle, and elapsed time between the avalanche and a Sentinel-1 satellite passing over. This study provides an initial exploration of the controlling variables in the likelihood of detecting avalanches using Sentinel-1 backscatter change detection techniques. This study also supports the generalizability of SAR backscatter difference analysis by applying the methodology in different regions with distinct snow climates from previous studies.Item Results of a micro pulse differential absorption LIDAR for temperature profiling and analysis code(Montana State University - Bozeman, College of Engineering, 2021) Cruikshank, Owen Daniel; Chairperson, Graduate Committee: Kevin S. RepaskyThermodynamic profiling of the lower troposphere is necessary for the study of weather and climate. The micropulse DIAL (differential absorption lidar), or MPD, presented here is designed to fill the need. The MPD is eye-safe and can run autonomously for continuous measurements compared to technologies with similar measurement capabilities like Raman lidar. Using a temperature-sensitive absorption line of O 2, the MPD system can measure the absorption of O 2 in the lower troposphere as a function of range and convert that measurement to temperature as a function of range. This process relies on a perturbative correction to the absorption retrieval to account for the fact that the O 2 absorption spectral linewidth is similar to the molecular Rayleigh scattering linewidth. An ancillary measurement of the ratio of aerosol backscatter to molecular backscatter is required for the correction. The integrated high spectral resolution lidar (HSRL) uses a heated potassium vapor notch filter to make the aerosol-to-molecular ratio measurement. An analysis program in MATLAB was written to take in raw lidar data and produce a temperature product of range and time. Results presented from a campaign at the Atmospheric Radiation Measurements program Southern Great Plains site in Oklahoma in spring 2019 show temperature comparisons with radiosonde measurements with a mean difference between radiosonde and MPD measurements of -1.1K and a standard deviation of 2.7 K. Further results from an instrument on the Montana State University campus in Bozeman and at the National Center for Atmospheric Research in Boulder, Colorado have shown that the MPD instrument can produce measurements autonomously for periods of weeks to months.Item Biocorrosion of 1018 steel in sulfide rich marine environments: a correlation between strain and corrosion using electron backscatter diffraction(Montana State University - Bozeman, College of Engineering, 2014) Martin, Joshua Daniel; Chairperson, Graduate Committee: Paul E. GannonMicrobially induced corrosion (MIC) of steel due to the presence of sulfide is a leading cause of pit formation of carbon steel in fuel-seawater environments. While extensively studied, the exact causes of pitting corrosion in naval fuel tanks when exposed to MIC in the presence of fuel and seawater are not completely understood. This thesis focuses on the role that cold-rolling of carbon steel plays on corrosion while subjected to sulfidogenic, suboxic corrosive environments. Particularly, the effects of microscopic residual strain found within 1018 steel on the anodic dissolution of the metal is studied in different MIC sulfide environments using EBSD, AFM, FE-SEM, EDX, and electrochemistry. It is found that regions of increased plastic deformation of the crystalline lattice as a result of cold rolling correlate to an increase in anodic dissolution rates of 1018 steel coupons cut parallel to rolling direction. Image overlay provides a verification of the location of corrosion of samples to the same locations found in EBSD mapping taken prior to corrosion, ensuring the predictive value of EBSD analysis in establishing locations of accelerated corrosion. The effect of different corrosion environments on the corrosion rate of steel is measured through electrochemistry. Values obtained through these measurements are applied using mechanochemical theories to predict the localized dissolution rate of the steel due to strain using computational methods. Mechanochemical analysis of the strained areas results in predicted corrosion rates within an order of magnitude of the corrosion rates measured using AFM for the exposed time period at the same locations. Areas exhibiting increased corrosion rates occur in areas exhibiting increased strain as measured by EBSD analysis. Further electrochemical results show an increase in corrosion rates for suboxic sulfide rich systems containing low levels of oxygen, when compared to anaerobic sulfide environments. Variations in corrosion current density as a function of oxygen presence, as measured by electrochemistry, accurately predict variations in mechanochemical corrosion rates of strained areas well within an order of magnitude. Results from this study support the use of EBSD as a means to further the understanding of pitting corrosion as a function of material properties.