NORCE Research Archive
Not a member yet
3811 research outputs found
Sort by
Multiscale model diagnostics
Get PDFI consider the problem of model diagnostics, that is, the problem of criticizing a model prior to history matching by comparing data to an ensemble of simulated data based on the prior model (prior predictions). If the data are not deemed as a credible prior prediction by the model diagnostics, some settings of the model should be changed before history matching is attempted. I particularly target methodologies that are computationally feasible for large models with large amounts of data. A multiscale methodology, that can be applied to analyze differences between data and prior predictions in a scale-by-scale fashion, is proposed for this purpose. The methodology is computationally inexpensive, straightforward to apply, and can handle correlated observation errors without making approximations. The multiscale methodology is tested on a set of toy models, on two simplistic reservoir models with synthetic data, and on real data and prior predictions from the Norne field. The tests include comparisons with a previously published method (termed the Mahalanobis methodology in this paper). For the Norne case, both methodologies led to the same decisions regarding whether to accept or discard the data as a credible prior prediction. The multiscale methodology led to correct decisions for the toy models and the simplistic reservoir models. For these models, the Mahalanobis methodology either led to incorrect decisions, and/or was unstable with respect to selection of the ensemble of prior predictions.publishedVersio
Underground hydrogen storage (UHS) in natural storage sites: A perspective of subsurface characterization and monitoring
Get PDFWith the long-standing efforts of green transition in our society, underground hydrogen storage (UHS) has emerged as a viable solution to buffering seasonal fluctuations of renewable energy supplies and demands. Like operations in hydrocarbon production and geological CO2 storage, a successful UHS project requires a good understanding of subsurface formations, while having different operational objectives and practical challenges. Similar to the situations in hydrocarbon production and geological CO storage, in UHS problems, the information of subsurface formations at the field level cannot be obtained through direct measurements due to the resulting high costs. As such, there is a need for subsurface characterization and monitoring at the field scale, which uses a certain history matching algorithm to calibrate a numerical subsurface model based on available field data. Whereas subsurface characterization and monitoring have been widely used in hydrocarbon production activities for a better understanding of hydrocarbon reservoirs, to the best of our knowledge, at present it appears to be a relatively less touched area in UHS problems. This work aims to narrow this noticed gap, and investigates the use of an ensemble-based workflow for subsurface characterization and monitoring in a 3D UHS case study. Numerical results in this case study indicate that the ensemble-based workflow works reasonably well, while also identifying some particular challenges that would be relevant to real-world problems.Underground hydrogen storage (UHS) in natural storage sites: A perspective of subsurface characterization and monitoringpublishedVersio
Standardisation and diversification–policy tools to govern early childhood education and care
Get PDFPolicy tools have become widespread in education, which indicates efforts to standardise content and professional practices. However, such standardisation might be in contrast to Nordic early childhood education and care (ECEC) traditions of diversity and local variation. We therefore study the distributors and enactment of policy tools in ECEC in light of content regulations and calls for evidence-based practices in ECEC through comparative case studies of 14 Norwegian centres. We identify the tools that are used in ECEC centres and analyse how they are enacted by staff. The material consists of documents from ECEC centres and semi-structured interviews with heads and staff. By employing a theoretical framework based on discursive institutionalism, we find that efforts are being made to standardise didactical practices. The tools are distributed by a range of actors, but our analysis reveals that staff shape and develop tools through coordinative discourses.publishedVersio
Machine learning reveals regime shifts in future ocean carbon dioxide fluxes inter-annual variability
Get PDFThe inter-annual variability of global ocean air-sea CO2 fluxes are non-negligible, modulates the global warming signal, and yet it is poorly represented in Earth System Models (ESMs). ESMs are highly sophisticated and computationally demanding, making it challenging to perform dedicated experiments to investigate the key drivers of the CO2 flux variability across spatial and temporal scales. Machine learning methods can objectively and systematically explore large datasets, ensuring physically meaningful results. Here, we show that a kernel ridge regression can reconstruct the present and future CO2 flux variability in five ESMs. Surface concentration of dissolved inorganic carbon (DIC) and alkalinity emerge as the critical drivers, but the former is projected to play a lesser role in the future due to decreasing vertical gradient. Our results demonstrate a new approach to efficiently interpret the massive datasets produced by ESMs, and offer guidance into future model development to better constrain the CO2 flux.Machine learning reveals regime shifts in future ocean carbon dioxide fluxes inter-annual variabilitypublishedVersio
The added value of simulated near-surface wind speed over the Alps from a km-scale multimodel ensemble
Get PDFThe advancement of computational resources has allowed researchers to run convection-permitting regional climate model (CPRCM) simulations. A pioneering effort promoting a multimodel ensemble of such simulations is the CORDEX Flagship Pilot Studies (FPS) on “Convective Phenomena over Europe and the Mediterranean” over an extended Alps region. In this study, the Distribution Added Value metric is used to determine the improvement of the representation of all available FPS hindcast simulations for the daily mean near-surface wind speed. The analysis is performed on normalized empirical probability distributions and considers station observation data as the reference. The use of a normalized metric allows for spatial comparison among the different regions (coast and inland), altitudes and seasons. This approach permits a direct assessment of the added value between the CPRCM simulations against their global driving reanalysis (ERA-Interim) and respective coarser resolution regional model counterparts. In general, the results show that CPRCMs add value to their global driving reanalysis or forcing regional model, due to better-resolved topography or through better representation of ocean-land contrasts. However, the nature and magnitude of the improvement in the wind speed representation vary depending on the model, the season, the altitude, or the region. Among seasons, the improvement is usually larger in summer than winter. CPRCMs generally display gains at low and medium-range altitudes. In addition, despite some shortcomings in comparison to ERA-Interim, which can be attributed to the assimilation of wind observations on the coast, the CPRCMs outperform the coarser regional climate models, both along the coast and inland.publishedVersio
How the public understands and reacts to the term “climate anxiety”
Get PDFThe term climate anxiety has increasingly appeared in the academic literature and popular discourse since 2019, typically when discussing young people's negative emotional responses to climate change. This paper reports results from a nationally representative survey of the Norwegian public (N = 2040) that investigated whether people respond differently to descriptions of young people “having climate anxiety”, compared with being “concerned” or “worried” about climate change. Results from the survey experiment showed stronger support for politicians taking young people's climate concern or climate worry into consideration when designing new climate policy as compared with young people's climate anxiety. Analyses of an open-ended question asking what people think of when they hear or read the term “climate anxiety” showed that most respondents (52%) provided neutral descriptions (e.g., worry about climate change impacts), 27% viewed climate anxiety as unfounded, irrational, or excessive, and equal proportions of respondents critiqued the term specifically for contributing to such negative associations (6%) or referred to climate anxiety as a reasonable and rational reaction (6%). These findings indicate that among some audiences, using the term climate anxiety may provoke reactance and be perceived as distracting from political actions to mitigate climate change. Our results give important insights into the potential consequences of the terms we use when reporting on climate distress.publishedVersio
Habitatkartlegging og bestandsundersøkelser av storørret i Sævareid- og Oselvvassdraget
Get PDFPå oppdrag fra Statsforvalteren i Vestland, med støtte fra Sogn og Fjordane Energi, gjennomførte NORCE LFI habitatkartlegging, elfiske og gytefisktelling med fokus på storørret i to elver i Oselvvassdraget (Eimhjellevatnet) og åtte elver i Sævareidvassdraget. I Sævareidvassdraget virker storørretbestanden å være i relativt god tilstand, men det er usikkert hvor stor og robust bestanden egentlig er. De undersøkte elvene i vassdraget var Kikedalselva, Gjønaelva, Eidselva, Orraelva, Skogseidelva, Tomraelva, Drageidkanalen og Hjortedalselva. Habitatkartleggingene viste at tilstanden i elvene var ganske bra, men den viktigste gyteelva (Orraelva) er kraftig endret fra naturtilstand grunnet kanalisering. Under gytefisktelling ble det kun observert storørret i Eidselva og Orraelva, med henholdsvis 47 og 162 individer hver. Det er tidligere observert storørret i flere av de andre elvene, men hovedbidraget i produksjon av storørretunger kommer altså fra de to største elvene. Det er svært populært med fritidsfiske i vassdraget, med ca. 1500 fiskekort solgt årlig i gjennomsnitt siden 2019 (inkludert ukeskort, årskort og garnkort). Det foreslås en rekke endringer i reglementet for å sørge for at man tar vare på bestanden og kan ha et høstbart overskudd også i fremtiden. Videre foreslås det at man gjennomfører undersøkelser som kan avdekke gytehyppighet og genetisk struktur hos storørreten i dette vassdraget, samt en plan for habitatbedrende tiltak i Orraelva. I Eimhjellevatnet (også kalt Storfjorden) er storørretbestanden trolig redusert sammenlignet med tidligere nivåer, men det fanges ifølge lokalbefolkning årlig storørret i innsjøen. Inntrykket er allikevel at bestanden har blitt redusert. Det ble ikke observert noe storørret på tellingene, og heller ikke gytegroper fra storørret. Habitatkartleggingene viste at både Ytsteelva og Heimeelva hadde flere velegnede gyteområder og relativt få fysiske inngrep, men begge elvene er regulerte av magasinkraftverk og mangler minstevannføring enten deler av (Heimeelva) eller hele (Ytsteelva) året. Dette kan ha bidratt til redusert ungfiskproduksjon i elvene, og det foreslås derfor at ytterlige undersøkelser gjennomføres og at det innføres minstevannføring i begge elvene. I tillegg foreslås det endringer i fiskereglementet for å øke bestanden av storørret i vassdraget.publishedVersio
Gassmetning og biologiske effekter i Skibotnelva
Get PDFGassovermetning fra Skibotn kraftverk er dokumentert med verdier opp til 183 % TDG i periode 2021 – 2023. Historiske målinger av gassmetning i kraftverksutløpet viste maksnivåer mellom 106 og 184 % TDG i en periode mellom 2006 – 2011. Målinger i perioden 2021 – 2023 viste gassmetningsnivåer med risiko for akutt fiskedød både ved stasjon i kraftverksutløp, men også ved stasjoner 4,8 km og 8,2 km nedstrøms utløpet. Høye gassmetningsverdier inntraff i sammenheng med drift av Skibotn kraftverk og hovedårsak er sannsynligvis luftinndrag ved bekkeinntak. Resultater av ungfiskundersøkelser og bunndyr viste lavere tettheter nedstrøms enn oppstrøms kraftverksutløpet, noe som kan være en effekt av gassovermetning, men også av andre habitatforhold eller reguleringseffekter. Fortynning med ikke-overmettet vann fra restfeltet demper påvirkningen av gassovermetning fra Skibotn kraftverk, men det forblir usikkert hvor stor strekning som rammes før vannet er tilstrekkelig fortynnet eller utluftet. Det anbefales derfor å fortsette overvåking av gassmetning i Skibotnelva og å utvide stasjonsnett med målinger på begge sider av elv ca. 900 m nedstrøms kraftverksutløpet, ved tilløp av Kvitlielva. Dette vil også hjelpe å belyse biologiske effekter og årsakssammenheng mer detaljert. Følgende avbøtende tiltak vurderes som egnet til å redusere gassovermetning: Struping eller ombygging av bekkeinntak, fremskynding av fortynning og lufting ved økt turbulens i elva og tilpassing av driftsmønster. Også nye teknologier og metoder slik som utlufting ved ultralyd kan fungere, men her er det fortsatt forskningsbehov.publishedVersio
Stratospheric influence on the winter North Atlantic storm track in subseasonal reforecasts
Get PDFExtreme stratospheric polar vortex events, such as sudden stratospheric warmings (SSWs) or extremely strong polar vortex events, can have a significant impact on surface weather in winter. SSWs are most often associated with negative North Atlantic Oscillation (NAO) conditions, cold air outbreaks in the Arctic and a southward-shifted midlatitude storm track in the North Atlantic, while strong polar vortex events tend to be followed by a positive phase of the NAO, relatively warm conditions in the extratropics and a poleward-shifted storm track. Such changes in the storm track position and associated extratropical cyclone frequency over the North Atlantic and Europe can increase the risk of extreme windstorm, flooding or heavy snowfall over populated regions. Skillful predictions of the downward impact of stratospheric polar vortex extremes can therefore improve the predictability of extratropical winter storms on subseasonal timescales. However, there exists a strong inter-event variability in these downward impacts on the tropospheric storm track. Using ECMWF reanalysis data and reforecasts from the Subseasonal to Seasonal (S2S) Prediction Project database, we investigate the stratospheric influence on extratropical cyclones, identified with a cyclone detection algorithm. Following SSWs, there is an equatorward shift in cyclone frequency over the North Atlantic and Europe in reforecasts, and the opposite response is observed after strong polar vortex events, consistent with the response in reanalysis. However, although the response of cyclone frequency following SSWs with a canonical surface impact is typically captured well during weeks 1–4, less than 25 % of the reforecasts manage to capture the response following SSWs with a “non-canonical” impact. This suggests a possible overconfidence in the reforecasts with respect to reanalysis in predicting the canonical response after SSWs, although it only occurs in about two-thirds of the events. The cyclone forecasts following strong polar vortex events are generally more successful. Understanding the role of the stratosphere in subseasonal variability and predictability of storm tracks during winter can provide a key for reliable forecasts of midlatitude storms and their surface impacts.publishedVersio
Fiskebiologiske undersøkelser i Eidfjordvassdraget. Årsrapport for undersøkelser i 2023
Get PDFDet er utført fiskebiologiske undersøkelser i Eidfjordvassdraget siden 2004. Denne rapporten er rapport for undersøkelsene gjort i 2023 og ettervinteren 2024, men inneholder også data for hele undersøkelsesperioden. Undersøkelsene er utført for å overvåke bestandene av laks og sjøaure i vassdraget, og for å evaluere tiltak for å styrke fiskebestandene. Undersøkelsene viser at gytebestandene av både laks og sjøaure har økt i årene etter 2010 sammenliknet med årene før. Gytebestandsmålet for laks har også vært nådd i enkelte av de siste årene, men bestandsstørrelsen har variert mellom år og forvaltningsmålet er ikke nådd. Bestanden av sjøaure kan i de senere årene karakteriseres som god, og er en av de mer solide i fylket. Tiltakene som så langt har vært gjennomført, har bidratt til at miljøbetingelsene i vassdraget har blitt bedre, men det anbefales at enkelte av tiltakene styrkes.publishedVersio