A5041935370- Oceanographic and Atmospheric Processes
- Arctic and Antarctic ice dynamics
- Climate variability and models
- Ocean Waves and Remote Sensing
- Geology and Paleoclimatology Research
- Tropical and Extratropical Cyclones Research
- Meteorological Phenomena and Simulations
- Marine and environmental studies
- Marine and fisheries research
- Atmospheric and Environmental Gas Dynamics
- Fluid Dynamics and Turbulent Flows
- Methane Hydrates and Related Phenomena
- Marine and coastal ecosystems
- Geological formations and processes
- Geological Studies and Exploration
- Coastal and Marine Dynamics
- Climate change and permafrost
- Coastal wetland ecosystem dynamics
- Reservoir Engineering and Simulation Methods
- Cryospheric studies and observations
- Marine Biology and Ecology Research
- Solar and Space Plasma Dynamics
- Marine and coastal plant biology
- Underwater Acoustics Research
- Geometric and Algebraic Topology
University of Oslo
2007-2024
Norwegian Meteorological Institute
2015-2024
Akvaplan-niva
2024
University of Oxford
2023
University of Bergen
2015
Norwegian Institute for Water Research
2006-2008
Norwegian Polar Institute
2002-2003
University of British Columbia
2000
Abstract Eddy‐resolving regional ocean model results in conjunction with synthetic float trajectories and observations provide new insights into the recirculation of Atlantic Water (AW) Fram Strait that significantly impacts redistribution oceanic heat between Nordic Seas Arctic Ocean. The simulations confirm existence a cyclonic gyre around Molloy Hole near 80°N, suggesting most AW within West Spitsbergen Current recirculates there, while colder westward mean flow south 79°N primarily...
A simplified diagnostic model of the time-mean, large-scale ocean circulation in Nordic Seas and Arctic Ocean is presented. Divergences surface Ekman layer are extracted from observed climatological wind stress fields. Similarly, divergences caused by meridional thermal transport (relative to bottom) calculated an density field. These known quantities then used force model's bottom geostrophic velocities. Both scaling arguments direct observations show that for long time scales currents...
Abstract Observations of ocean currents in the Arctic interior show a curious, and hitherto unexplained, vertical temporal distribution mesoscale activity. A marked seasonal cycle is found close to surface: strong eddy activity during summer, observed from both satellites moorings, followed by very quiet winters. In contrast, subsurface eddies persist all year long within deeper halocline below. Informed baroclinic instability analysis, we explore origin evolution seasonally ice-covered...
Abstract The vigorous mesoscale eddy field around the Lofoten Basin west of northern Norway is thought to be related shedding from Norwegian Atlantic Current flowing along coast. Here we study baroclinic instability in current with a particular focus on influence topography. flow over steepest part continental slope found most unstable. growth characteristics cannot understood Eady theory alone but require consideration interior potential vorticity gradients. A fully developed macroturbulent...
Abstract. Lagrangian coherent structures (LCSs) are transient features in the ocean circulation that describe particle transport, revealing information about transport barriers and accumulation or dispersion regions. The method of finite-time Lyapunov exponents (FTLEs) uses data to approximate LCSs under certain conditions. In this study FTLEs used characterize flow field a high-resolution regional forecast system. Generally, trajectory simulations, such as trajectories, inherit uncertainty...
Lofoten and Vesterålen region in Northern Norway contains the main spawning areas for Northeast Arctic (NEA) cod. A large embayment, partially sheltered from continental slope open ocean by Lofoten-Vesterålen archipelago, called Vestfjorden approximately 60 % of NEA cod this region. The dynamical processes that control transport paths times eggs larvae out embayment are major importance, not only fish stock, but general marine ecosystem This study investigates net impact nonlinear tidal...
Ocean flows interacting with topography are critical for shaping large-scale circulation in polar regions such as the Arctic Ocean, where strong topographic steering shapes flow along continental slopes. Flow over sloping corrugations exhibits an asymmetric response to prograde versus retrograde forcing, stronger and more laminar case (here, forcing aligns wave propagation, while opposes it). Previous studies attribute this asymmetry increased form stress forcing. To further investigate...
Abstract The Arctic Ocean is a key component of Earth's climate system, and an understanding ocean dynamics in this region central for predicting how the responding to changing climate. In study, we examine circulation high‐resolution numerical model Nordic Seas. Based on what observed simulation, reexamine existing idealized linear estimating time‐variable large‐scale basins, test it against highly nonlinear model. integral relation derived from momentum equations assumes that around closed...
The varying depth-integrated currents in the Nordic seas and Arctic Ocean are modeled using an integral equation derived from shallow-water equations. This assumes that mass divergence surface Ekman layer is balanced by convergence bottom layer. primary flow component follows contours of f/H. model employs observed winds realistic topography has one free parameter, coefficient (linear) drag. data used for comparison situ current meters, satellite altimetry, a primitive model. current-meter...
Abstract Bekkby, T., Rinde, E., Erikstad, L., Bakkestuen, V., Longva, O., Christensen, Isæus, M., and Isachsen, P. E. 2008. Spatial probability modelling of eelgrass (Zostera marina) distribution on the west coast Norway. – ICES Journal Marine Science, 65: 1093–1101. Based modelled measured geophysical variables presence/absence data Zostera marina, we developed a spatial predictive model for Z. marina. Our analyses confirm previous reports show that finding marina is at its highest in...
Large‐scale budget calculations and numerical model process studies suggest that lateral eddy heat fluxes have an important cooling effect on the Norwegian Atlantic Current (NwAC) as it flows through Nordic Seas. But observational estimates of such been lacking. Here, wintertime surface in eastern Seas are estimated from drifter data, satellite data eddy‐permitting model. Maps flux divergence advective along path NwAC. Integrating over temperature classes yields consistent for three sets;...
Abstract The Beaufort Gyre (BG) is a large‐scale bathymetrically constrained circulation driven by surface Ekman convergence that creates bowl‐shaped halocline and stores significant portion of the Arctic Ocean's freshwater. Theoretical studies suggest in gyre interior, equilibrated balance between pumping counteracting mesoscale eddy transport energized baroclinic instability. However, strongest anticyclonic flows occur over steep continental slopes, and, despite bathymetric slopes being...
Abstract A weak planetary vorticity gradient and density stratification in the northern North Atlantic Nordic seas lead to time-mean currents that are strongly guided by bottom topography. The topographic steering sets up distinct boundary with strong property fronts prone both baroclinic barotropic instability. These instability processes generate a macroturbulent eddy field spreads buoyancy other tracers out from into deep basins. In this paper we investigate particular role played...
Several studies have documented relationships between wave exposure and distribution, density, size of marine species. Hence, this factor is at a high level in the hierarchical habitat classification system EUNIS one Water Framework Directive water typology criteria coastal waters. Isæus (2004) Isæus, M. 2004. Factors structuring Fucus communities open complex coastlines Baltic Sea. Doctoral thesis, Department Botany, Stockholm University, Sweden. Downloadable from...
Abstract The Ocean and Sea Ice Satellite Application Facility (OSISAF) of the European Organisation for Exploitation Meteorological Satellites (EUMETSAT) distributes satellite observations operationally. In this paper, we describe development a combined optimal interpolation nudging (COIN) scheme in Norwegian Institute that assimilates OSISAF sea-ice concentration (SIC) into coupled sea-ice–ocean Regional Modeling System (ROMS). modifies modeled SIC at every time-step, based on difference...
Abstract Chaotic intrinsic variability is a fundamental driver of the oceanic variability. Its understanding key to interpret observations, evaluate numerical models, and predict future ocean climate. Here we study deep convection in northwestern Mediterranean Sea using an ensemble eddy‐resolving hindcast simulation over period 1979–2013. We find that mostly forced but also, considerable extent, intrinsic. The can dominate total locally single winter. It also makes up significant fraction...
Abstract Observations from the past decades have promoted idea of a long-lived anticyclonic vortex residing in Lofoten Basin. Despite repeatedly recorded intense anticyclones, observations cannot firmly decide whether signature is single or succession ephemeral vortices. A persisting for requires some reinvigoration mechanism. Wintertime convection and merging been proposed candidates. We examine Basin dynamics using high-resolution regional ocean model. The model initialized coarser state...
Most of the ocean’s kinetic energy is contained within mesoscale eddy field. Models that do not resolve these eddies tend to parameterize their impacts such parameterized transport buoyancy and tracers reduces large-scale available potential spreads tracers. However, parameterizations used in ocean components current generation Earth System (ESMs) rely on an assumption a flat floor even though observations high-resolution modelling show sensitive vorticity gradients associated with sloping...
Abstract Oceanic mesoscale eddy mixing plays a crucial role in Earth’s climate system by redistributing heat, salt, and carbon. For many ocean models, eddies still need to be parameterized. This is often done via an diffusivity , which sets the strength of turbulent downgradient tracer fluxes. A well-known effect modulation presence background potential vorticity (PV) gradients, suppresses direction PV gradients. Topographic slopes can induce such suppression through topographic However,...