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dc.contributor.advisorEdvardsen, Kåre
dc.contributor.authorSamuelsen, Eirik Mikal
dc.date.accessioned2017-12-01T09:11:53Z
dc.date.available2017-12-01T09:11:53Z
dc.date.issued2017-11-20
dc.description.abstractA ship travelling in sub-freezing conditions may encounter sea spray, rain, fog or snow freezing onto various parts of it. Such ship icing is a well-known threat for those individuals who have served on ships operating in a cold marine climate. As de-icing techniques may be energy consuming, accurate prediction of icing is also desirable from a financial point of view. Throughout the last 60 years there have been several efforts trying to model this elusive phenomenon. However, the lack of accurate field observations poses questions to the accuracy of the state-of-the-art modelling approaches including the parameterization of the physical processes of the models. As a consequence, the current study presents and utilises icing data obtained from ship observations in Arctic-Norwegian waters supplemented with high-resolution reanalysis data. On the basis of a unique data set derived from observations recorded on a particular ship type of the Norwegian Coast Guard, a completely new icing model has been developed. Verification of this Marine Icing model for the Norwegian COast Guard (MINCOG) and comparison to currently-applied methods in operational weather forecasting, reveals higher accuracy of MINCOG compared to the other methods. Furthermore, the study stresses the importance of including wave information separately into marine-icing models rather than incorporating it in the wind-speed parameter. A major finding of the study is that nature dictates an upper limit to the degree of icing that may arise from wave-ship interactions, since high waves and very low air temperatures rarely coexist. It is also highlighted that the inclusion of snow may be important for ship icing to transpire, and that icing ensues most frequently during cold-air outbreaks from the ice. In addition, when a more general approach is applied to the icing problem, a prediction method utilising the temperature at 850 hPa provides a potential for forecasting icing several days or weeks ahead in time. The prediction models presented in this study may be incorporated in an ensemble prediction system (EPS) providing the officer of a ship an early warning about the risk of icing and the probability of an expected growth rate of icing.en_US
dc.description.abstractEt skip som beveger seg i omgivelser med temperaturer under 0 grader, kan oppleve at sjøsprøyt, regn, tåke eller snø fryser på ulike deler av skipet. Slik skipsising er en velkjent trussel for de som har jobbet på skip som opererer i et kaldt maritimt klima. Siden avising kan være energikrevende, er nøyaktig isingsvarsling ønskelig også fra et økonomisk ståsted. I løpet av de siste 60 årene har det vært mange forsøk på å modellere dette kompliserte fenomenet, men mangelen på gode feltobservasjoner gjør at man må stille spørsmål ved nøyaktigheten til dagens modelleringsmetoder inkludert parameteriseringen av modellenes fysiske prosesser. Som en følge av dette presenterer og anvender dette studiet isingsdata fremkommet av skipsobservasjoner fra Arktisk-Norske farvann. Med utgangspunkt i et unikt datasett utledet av observasjoner utført på en bestemt skipstype fra Den norske Kystvakt, har en helt ny isingsmodell blitt utviklet. Verifikasjon av denne maritime isingsmodellen for Den norske Kystvakt (MINCOG), og sammenligning med andre metoder brukt i operasjonell værvarsling, avslører at MINCOG verifiserer bedre enn de andre metodene. Videre understreker studien viktigheten av å inkludere bølgeinformasjon separat i isingsmodeller brukt over sjø, og ikke inkludert som en del av vindstyrken. Et hovedfunn i studien er at naturen setter en øvre begrensning for mengden ising som kan oppstå på grunn av bølge-skip interaksjoner fordi høye bølger og veldig lave lufttemperaturer sjeldent opptrer samtidig eller i de samme områdene. Det er også fremhevet at snø kan være en viktig faktor for at ising skal kunne forekomme, og at ising oppstår hyppigst i forbindelse med kaldluftsutbrudd fra isen. Hvis man bruker en overordnet tilnærming til isingsproblematikken, vil en prediksjonsmetode som utnytter temperaturen i 850 hPa, gi et potensiale for å varsle ising dager eller uker framover i tid. Prediksjonsmodellene som presenteres i studien kan bli inkludert i et ensemblevarslingssystem (EPS) som kan gi en skipsoffiser et tidlig forvarsel om risikoen for ising og en sannsynlighet for forventet isingshastighet.en_US
dc.description.doctoraltypeph.d.en_US
dc.description.popularabstractA ship travelling in sub-freezing conditions may encounter sea spray, rain, fog or snow freezing onto various parts of it. Since such icing may be hazardous, prediction of this phenomenon is incorporated into general weather forecasting. However, there has been little knowledge about the quality of the icing predictions since there are only a few or insufficient icing data sets previously documented. In order to verify the existing models, unprecedented icing data in conjunction with sea- and weather-condition information are utilized. New and more accurate models are developed based on historical ship observations in Arctic-Norwegian waters. An interesting finding is the fact that nature dictates an upper limit to the degree of icing that may arise from wave-ship interactions since high waves and low temperatures rarely coexist. It is also highlighted that snow may be important for icing to occur, and that most icing events arise when cold winds are blowing off the sea ice.en_US
dc.description.sponsorshipNorwegian Research Council through the MAROFF program [grant number 226404], UiT - The Arctic University of Norway, Norwegian Meteorological Institute.en_US
dc.descriptionThe papers III and IV of this thesis are not available in Munin. <br> Paper III: Samuelsen, E. M.: "Ship-icing prediction methods applied in operational weather forecasting." (Manuscript). Published version available in <a href=http://dx.doi.org/10.1002/qj.3174> Q.J.R. Meteorol. Soc. 2018</a> <br> Paper IV: Samuelsen, E. M., Graversen, R. G.: "Weather situation during observed ship-icing events off the coast of Northern Norway and the Svalbard archipelago." (Manuscript).en_US
dc.identifier.isbn978-82-8236-274-0 (trykt) og 978-82-8236-275-7 (pdf)
dc.identifier.urihttps://hdl.handle.net/10037/11801
dc.language.isoengen_US
dc.publisherUiT Norges arktiske universiteten_US
dc.publisherUiT The Arctic University of Norwayen_US
dc.rights.accessRightsopenAccessen_US
dc.subject.courseIDDOKTOR-004
dc.subjectVDP::Mathematics and natural science: 400::Geosciences: 450::Meteorology: 453en_US
dc.subjectVDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Meteorologi: 453en_US
dc.titlePrediction of ship icing in Arctic waters - Observations and modelling for application in operational weather forecastingen_US
dc.typeDoctoral thesisen_US
dc.typeDoktorgradsavhandlingen_US


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