Browsing by Subject "Winter"
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Item Development of a Road Condition Recovery Time Estimation System for Winter Snow Events(Minnesota Department of Transportation, 2018-01) Kwon, Eil; Park, ChongmyungThis research develops a Normal Condition Regain Time (NCRT) estimation system, which automatically determines the NCRT at detector stations on the metro-freeway network for given snow events. The NCRT process is based on the findings that the speed level during the recovery process reaches a stable free-flow-speed (FFS), whose value is generally lower than the pre-snow FFS at a same location. Further, the speed-density (U-K) relationship of the traffic flow after snow is cleared exhibits a similar but shifted-down pattern of the normal-day U-K relationship at a given location. In this study, the after-snow traffic condition with a stable but shifted-sown pattern of the normal-day U-K relationship is defined as the ‘wet-normal’ condition, and the NCRT is defined as the time when the U-K data during a snow event starts to follow the wet-normal U-K pattern at a given station. The NCRT estimation system first collects the traffic and weather data for the metro-freeway network and determines the normal-day U-K relationships for the detector stations whose traffic data include both uncongested and congested regions. The normal-day U-K relationships are then applied to calibrate the wet-normal U-K patterns at given locations using the traffic data collected during snow events. Finally, the NCRTs are determined for each station by comparing the U-K data trajectory during a given event with the wet-normal U-K pattern at given locations. The NCRT estimation system has been applied to a set of the sample snow events.Item Exploring the hidden diversity of winter-emerging Chironomidae (Insecta: Diptera)(2021-12) Durnin, TessaChironomidae are a diverse family of flies found on every continent, including Antarctica. As immatures they occupy streams, rivers, lakes, and wetlands and emerge as terrestrial adults. They are biological indicators of water quality and have species-specific tolerance to pollution and disturbances. At least 5,000 species are described, however, projections estimate 20,000 chironomids when including cryptic and yet to be defined species. Cryptic species are one of two or more biological groups that are morphologically identical to one another, are incapable of interbreeding, and are genetically distinct. Driftless Area groundwater-dominated trout streams of southeastern Minnesota provide perfect habitat for cryptic chironomid diversity. During winter, these streams remain open and ice-free all season long because of constant inputs of relatively warm groundwater (~9° C), providing a stable environment in favor of morphological stasis, making the identification of closely related species difficult. Diamesa mendotae Muttkowski and D. nivoriunda Fitch are two commonly encountered winter-emerging chironomids of the Driftless Area. I used molecular methods to explore genetic diversity of these two winter-emerging flies. Cryptic winter-emerging chironomid identification will help sustain trout habitat conservation, create more accurate freshwater management practices, and advance our knowledge of Dipteran evolution.Item Growing Winter Tourism: Four touchstones for growing revenue in winter months.(2023) LeMier, DeeDee, A.; Hoelting, Joyce; Tuck, Brigid; Leys, Becca; Petel, AshleyItem An Investigation of Seasonal Performance Variations in Taconite Plants(University of Minnesota Duluth, 2009) Ersayin, SalihThe objective of this study was to analyze several sets of historical data representing winter and summer conditions using conventional and simulation tools to provide a better understanding of the cause, and to come up with ideas to alleviate the problem. The Coleraine Minerals Research Lab had historical plant data representing summer and winter conditions in a taconite plant. Two parallel lines (Lines 10 and 13) in the Minntac Plant were sampled during the winter and summer of 1995. Data included size structures of the streams in the magnetic separation circuit and head chemistries. However, limited information about the operating conditions was available. Particularly, certain essential data were missing, namely, prevailing hydrocyclone geometry and complete operating conditions during the summer sampling surveys. Nevertheless, it was anticipated that a simulation-aided analysis of this database could still reveal possible causes of performance deterioration during winter months, and could provide clues for performance enhancement to alleviate this negative effect.Item Profile of 2007 Saint Paul Winter Carnival Attendees(University of Minnesota Tourism Center, 2007) Hinds, Nikki; Salk, Raintry; Schneider, Ingrid E.In 2006, the University of Minnesota Tourism Center (UMTC) and Center for Urban and Regional Affairs (CURA) were contracted to profile visitors to Saint Paul Winter Carnival. Several visitor characteristics were of interest beyond demographics, including information sources, spending habits, and experience at Saint Paul Winter Carnival. To that end, a visitor questionnaire was developed and administered to Saint Paul Winter Carnival visitors.Item Winter warm spikes reduce cold-adapted insect longevity and reproduction(2022) Bodmer, Hannah; Nyquist, Corrie; Vondracek, Bruce; Ferrington, LenThe aquatic fly family Chironomidae contains many cold-adapted, winter-active species in the Northern Hemisphere. Cold-adapted chironomid larvae develop underwater but emerge in winter as terrestrial adults to reproduce. Climate change will likely impact these winter-active adults as winter air temperatures increase. Previous studies have found constant exposure to high temperatures reduces survivorship of adult Diamesa mendotae, a cold-adapted chironomid in Minnesota. My research sought to understand how climate change could affect D. mendotae and other cold-adapted chironomids by exposing D. mendotae to high temperatures for short intervals. Here I show short-term exposure to high temperatures decreased adult D. mendotae longevity, reduced egg laying, and increased larval hatch success, but did not noticeably alter adult behaviors. Mean longevity of adult D. mendotae ranged from 14.7-24.3 days at constant 6°C, 12.3-16.8 days after exposure to 22°C for 24h, and 10.5-17.4 days after exposure to 22°C for 48h. D. mendotae eggs were also more likely to complete embryogenesis and hatch as larvae at constant 6°C than after 22°C exposure. However, D. mendotae exhibited similar behaviors over their lifespan in constant 6°C and 22°C exposure treatment groups. Taken together, I found impacts of winter short-term high temperature spikes on D. mendotae. Disruptions in D. mendotae and cold-adapted insect populations by winter warming may have broad ramifications f0r groundwater-fed stream ecosystems. This study highlights the need for further research on cold-adapted insect survivorship after short-term temperature spikes to understand seasonal impacts of climate change beyond mean annual temperature increases.Item Winter-emerging chironomidae (Insecta: Diptera) in Minnesota trout streams(2012-12) Anderson, Alyssa MaeThe Chironomidae (Diptera) is among the few aquatic insect families with species that are reliably able to grow, develop, and emerge as fully functional adults throughout the cold winter months that characterize the midwestern United States. However, few studies document their role in trout streams during this time of year. The intent of this dissertation is to enhance the field of Chironomidae research by focusing on the winter dynamics of these insects, including their response to severe flood events, their incorporation in the winter diet of trout, and the morphological and molecular description of three new cold-adapted Chironomidae species. The resistance and resilience of the winter chironomid community was assessed following a severe flood that impacted many streams in southeast Minnesota during the late summer of 2007. Methodology included collections of chironomid surface-floating pupal exuviae from 18 southeast Minnesota streams; streams were selected to include representation of localities that incurred moderate to extreme levels of flooding disturbance. These data were compared to data from the same localities during prior winters. Significantly more taxa emerged during the winter after late-summer flooding as compared to historic collections, and the number of species emerging in winter was positively correlated with rainfall severity, indicating the winter-active Chironomidae are resistant to late summer spates. This indicates that chironomids are an available winter food resource to stream trout recovering from devastating floods. In attempt to examine the importance of Chironomidae and other winter-active aquatic insects to the winter diet of brown trout (Salmo trutta L.), stomach contents were collected from trout inhabiting three southeast Minnesota streams; these data were compared to organisms collected in the stream drift and benthos. Results indicated that trout diets differ by stream and by fish size, with larger trout feeding heavily on Trichoptera and Physella, and smaller fish relying more on Gammarus and Chironomidae larvae. Stomach contents were more similar to the benthos than the drift, indicating a greater reliance on benthic feeding during winter. Trout in all streams selected Trichoptera and Chironomidae over other prey, and appeared to maintain sizeselective predation throughout winter. Winter-emerging Chironomidae appear to enhance the trout diet in all streams, and chironomid larvae were particularly dominant in the diet of one trout population. Three new chironomid species within the genus Micropsectra, a genus commonly found in the winter trout diet, were discovered from a study of five Minnesota streams. These species, Micropsectra neoappendica, n. sp., Micropsectra penicillata, n. sp., and Micropsectra subletteorum, n. sp., were described using morphological and molecular methods, along with one additional species, Micropsectra xantha Roback, which was redescribed. Two of the new species initially appeared identical to species known from the Palearctic, however molecular data indicated they are genetically distinct. Subsequently, reexamination of morphological characters revealed slight, but consistent diagnostic differences. These results emphasize the importance of using molecular tools in conjunction with traditional morphological techniques when studying Chironomidae diversity, especially when relying on diagnoses from other regions. The culmination of these studies sheds light on the dynamics of winter-emerging Chironomidae in southeastern Minnesota trout streams, their distribution and abundance, and the larger role they play in stream communities.