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Evaluation of probabilistic forecasts in Uppsala and its potential use in winter road maintenance / Utvärdering av probabilistiska väderprognoser i Uppsala och den potentiella användningen inom vinterväghållningJohansson, Elisabet January 2023 (has links)
Efficient winter road maintenance is crucial for safety and societal function during the winter months in Sweden. This report aims to evaluate the MetCoOp ensemble system CMEPS and investigate its potential use as a basis for formulating criteria for snow removal that accounts for forecasted weather. Today the criteria for activating snow removal in Sweden are static, meaning they start after a set amount of snow and should end within a set time span. The verification metrics rank-histogram, continuously rankprobability score, reliability diagram, and Brier score were used to evaluate temperature and solid precipitation. Observations used as verification were taken at the measuring station Geocentrum in Uppsala during the winters of 2020/2021, 2021/2022, and November-December 2022. The analysis shows the temperature forecast to be under-dispersive and with a cold bias. The ensemble system is shown to be less reliable for predicting temperatures below 0 °C the first 24 hours after the forecast is issued. Still, the forecast generally performs better for short lead times. The forecast overestimates solid and liquid precipitation. The wet bias is greatest for short lead times and long accumulation times. Short lead times are most reliable regarding solid precipitation over 1mm and 3mm. The first 24-30 hours are most important for an application in winter road maintenance, and based on how the forecast system performs for these lead times in this study, it would need calibration. For larger amounts of snow, new criteria could help adjust the starting time and time limits. Before implementing such criteria, practical questions as if dynamic criteria would lead to an improvement and how high the probability threshold should be must be answered. The sample size is also found to be too small, and further analysis is required, especially with data allowing for evaluation of higher thresholds. / En ensembleprognos består av flera prognoser som genom att baseras på något olika information beskriver ett antal möjliga framtida väderutfall. Idag används sannolikhetsprognoser i många delar av samhället då det ger möjligheten att se vilken sannolikhet en viss väderhändelse har. I det här arbetet har ensembleprognosen bestående av 30 medlemmar från MetCoOp utvärderats för temperatur och snö. I rapporten diskuteras även om det finns potential för att sannolikheter om det framtida vädret kan användas i kriterier för att bestämma när åtgärder för snö och is ska påbörjas och avslutas. Effektiv snöröjning och halkbekämpning är samhällsviktiga uppdrag som är kostsamma och kräver mycket planering. Sannolikhetsprognoser används redan som en hjälp för de som jobbar med vinterväghållning, främst för halkbekämpning, men kriterierna är idag fasta och snöröjning påbörjas när en viss mängd snö är uppmätt. Observationer av temperatur, nederbörd och nederbördstyp från mätstationen Geocentrum i Uppsala för vintrarna 2020/2021, 2021/2022 samt november-december 2022 har använts som verifikation. Prognosen har utvärderats med hjälp av rank-histogram, CRPS, reliability diagram och Brier score. Det framgick att temperaturprognosen hade liten och otillräcklig spridning, speciellt för korta ledtider. Ensemblesystemet visade samtidigt ofta för låga temperaturer. Analysen indikerade att mängden fast nederbörd överskattades av prognosen speciellt för 24-timmar ackumulation. Prognosen visade sig vara mest pålitlig för att prognosticera snö över 1mm och 3mm för korta ledtider. Studien visade även på att modellen överskattade regn vilket innebär att ensemblen har svårt att uppskatta nederbörd i allmänhet och inte snö i synnerhet. Prognosen visade sig inte vara pålitlig för att förutsäga om temperaturen 12 och 24 timmar efter observerat snöfall var konsekvent under 0 °C. Analysen är mindre pålitlig på grund av få snöfall under perioden i Uppsala. För att dra säkra slutsatser behöver ytterligare data analyseras med fler snöfall. Det finns dock potential att använda ensemblen från MetCoOp för att formulera kriterier för snöröjning, speciellt om den kalibreras. Med dynamiska kriterier skulle start- och sluttider kunna justeras så att de var anpassade till större snömängder. Det krävs ytterligare undersökning om hur inställningen bland yrkesverksamma ser ut och hur kriterierna skulle se ut i praktiken.
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Tour expansion in snow removal problemTarasova, Anna January 2022 (has links)
The process of removing snow from the streets of cities in an optimal way can pose quite a challenge. In order to optimize the path of the snow removing vehicle, the city can be translated into a graph with nodes as crossings and links as roads. Once the city is modelled as a graph, all nodes with degree one can be eliminated and the snow removal time is added to the closest node. An optimization problem can then be solved in order to find a vehicle path in this reduced graph. The purpose of this thesis is to give an algorithm to reconstruct the reduced graph and then dictate the proper vehicle path in this reconstructed graph. The algorithm is constructed by reversing the node elimination process, piecing together the original graph and traversing the graph to get information about what to do on the eliminated links and nodes. The obtained algorithm is presented in this thesis.
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Calibration of Snowmaking Equipment for Efficient Use on Virginia's Smart RoadShea, Edward 16 September 1999 (has links)
Virginia's Smart Road, to be completed by early 2000, is a test bed for numerous research activities including snow and ice control, remote sensor testing, snow removal management, safety and human factors, and vehicle dynamics. An all-weather testing system will feature 75 automated snowmaking towers. In order to provide timely and repeatable weather scenarios, equipment operators will need to understand fully the limitations and capabilities of the snowmaking system.
The research presented herein addresses the hydraulic and hydrologic variables and design methodology to implement efficient snowmaking at a transportation research facility. Design variables include nozzle configuration, water pressure and flowrate, compressed air pressure and flowrate, tower orientation, snow inducer concentration, water and compressed air temperature, and ambient weather conditions. Testing and data collection was performed at the Snow Economics, Inc. research and development site at Seven Springs Mountain Resort in Champion, PA. The results of this work will be used to guide the operators of the Smart Road on the most efficient use of the snowmaking equipment. / Master of Science
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Optimization Methods for Snow Removal of Bus StopsHüni, Corina January 2023 (has links)
Snow removal is an important optimization problem in countries with snowfall. Bus stops can only be cleared after the adjacent street is cleared. The problem of optimizing snow removal for bus stops in an urban area is a special case of the Travelling Salesman Problem with Time Windows, where each stop only can be cleared after a certain time has passed. The solver Gurobi is used to solve the mathematical model of this problem to optimality. A local search and a tabu search is implemented. The results of the mathematical model are compared to the results of the implemented tabu search method. The results show that if a solution needs to be produced quickly, the tabu search provides better solutions than Gurobi. / Snöröjning är ett viktigt optimeringsproblem i länder med snöfall. Busshållplatsen kan bara röjas efter att den angränsande vägen är röjd. Problemet att optimera snöröjning av busshållplatser i en stad är ett Handelsresandeproblem med tidsfönster, där varje hållplats bara kan röjas efter att en tid har gått. I arbetet har vi implementerat en tabusökning för att hitta snabbt hitta bra tillåtna lösningar till problemet. För att utvärdera prestandan hos tabusökningen har vi också implementerat en matematisk modell och använt Gurobi som lösare. Resultaten visar att tabusökningen är snabbast på att hitta tillåtna lösningar av god kvalité.
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A Preliminary Assessment of Snowfall Interception in Arizona Ponderosa Pine ForestTennyson, Larry C., Ffolliott, Peter F., Thorud, David S. 05 May 1973 (has links)
From the Proceedings of the 1973 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - May 4-5, 1973, Tucson, Arizona / A preliminary assessment and ranking of the relative significance of five processes that may contribute to snow removal from ponderosa pine forest canopies was made, including wind erosion of canopy snow, snowslide from the canopy, stemflow, vapor transport from melt water, and vapor transport of canopy snow. The first three represent delayed delivery rather than net water loss. A snow load index was obtained through use of time lapse photography of the study site canopy, while incoming solar radiation and atmospheric processes were monitored. The snow load index was expressed as a ratio of forest canopy area covered with snow to the total canopy area. Results obtained over a 4-day period following a six-hour snowstorm showed that snow removal by snowslide and wind erosion was of significant importance, while vapor transport of melt water and canopy snow, stemflow, and dripping of melt water was of comparatively minor importance.
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