Blar i Bergen Open Research Archive på forfatter "Christensen, Kai Håkon"
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A combined stokes drift profile under swell and wind sea
Breivik, Øyvind; Christensen, Kai Håkon (Journal article; Peer reviewed, 2020)A combined directional Stokes drift profile for swell and wind sea is presented. The profile can be used to calculate the shear under crossing seas and as such is relevant for Langmuir turbulence and Stokes–Coriolis forcing, ... -
A comparison of Langmuir turbulence parameterizations and key wave effects in a numerical model of the North Atlantic and Arctic Oceans
Ali, Alfatih; Christensen, Kai Håkon; Breivik, Øyvind; Bertino, Laurent; Malila, Mika Petteri; Raj, Roshin Pappukutty; Chassignet, Eric P.; Bakhoday Paskyabi, Mostafa (Peer reviewed; Journal article, 2019)Five different parameterizations of Langmuir turbulence (LT) effect are investigated in a realistic model of the North Atlantic and Arctic using realistic wave forcing from a global wave hindcast. The parameterizations ... -
Constraining energetic slope currents through assimilation of high-frequency radar observations
Sperrevik, Ann Kristin; Christensen, Kai Håkon; Röhrs, Johannes (Peer reviewed; Journal article, 2015-03-11)Assimilation of high-frequency (HF) radar current observations and CTD hydrography is performed with the 4D-Var analysis scheme implemented in the Regional Ocean Modeling System (ROMS). We consider both an idealized case, ... -
Current shear and turbulence during a near-inertial wave
Röhrs, Johannes; Halsne, Trygve; Sutherland, Graig; Dagestad, Knut-Frode; Hole, Lars Robert; Brostrøm, Gøran; Christensen, Kai Håkon (Journal article; Peer reviewed, 2023-04-11)Surface currents and turbulent mixing were observed during a near-inertial wave (NIW) using an accousting doppler current profiler (ADCP) and satellite-tracked drifters. Drifter trajectories sampled at three depth levels ... -
A dataset of direct observations of sea ice drift and waves in ice
Rabault, Jean; Müller, Malte; Voermans, Joey; Brazhnikov, Dmitry; Turnbull, Ian; Marchenko, Aleksey; Biuw, Martin; Nose, Takehiko; Waseda, Takuji; Johansson, Malin; Breivik, Øyvind; Sutherland, Graig; Hole, Lars Robert; Johnson, Mark; Jensen, Atle; Gundersen, Olav; Kristoffersen, Yngve; Babanin, Alexander; Tedesco, Paulina Souza; Christensen, Kai Håkon; Kristiansen, Martin; Hope, Gaute; Kodaira, Tsubasa; Martins de Aguiar, Victor Cesar; Taelman, Catherine Cecilia A; Quigley, Cornelius Patrick; Filchuk, Kirill; Mahoney, Andrew R. (Journal article; Peer reviewed, 2023)Variability in sea ice conditions, combined with strong couplings to the atmosphere and the ocean, lead to a broad range of complex sea ice dynamics. More in-situ measurements are needed to better identify the phenomena ... -
Evaluating the leeway coefficient of ocean drifters using operational marine environmental prediction systems
Sutherland, Graig; Soontiens, Nancy; Davidson, Fraser; Smith, Gregory C.; Bernier, Natacha; Blanken, Hauke; Schillinger, Douglas; Marcotte, Guillaume; Röhrs, Johannes; Dagestad, Knut-Frode; Christensen, Kai Håkon; Breivik, Øyvind (Journal article; Peer reviewed, 2020)The water following characteristics of six different drifter types are investigated using two different operational marine environmental prediction systems: one produced by Environment and Climate Change Canada (ECCC) and ... -
Impact of data assimilation on Eulerian versus Lagrangian estimates of upper ocean transport
Sperrevik, Ann Kristin; Röhrs, Johannes; Christensen, Kai Håkon (Peer reviewed; Journal article, 2017)Using four-dimensional variational analysis, we produce an estimate of the state of a coastal region in Northern Norway during the late winter and spring in 1984. We use satellite sea surface temperature and in situ ... -
Long-Term Statistics of Observed Bubble Depth Versus Modeled Wave Dissipation
Strand, Kjersti Opstad; Breivik, Øyvind; Pedersen, Geir; Vikebø, Frode Bendiksen; Sundby, Svein; Christensen, Kai Håkon (Journal article; Peer reviewed, 2020)Air bubble penetration depths are investigated with a bottom‐mounted echosounder at a seabed observatory in northern Norway. We compare a 1‐year time series of observed bubble depth against modeled and estimated turbulent ... -
Modelling alongshore flow in a semi-enclosed lagoon strongly forced by tides and waves
Taskjelle, Torbjørn; Barthel, Knut; Christensen, Kai Håkon; Furaca, Noca; Gammelsrød, Tor; Hoguane, Antonio Mubango; Nharreluga, Bilardo (Peer reviewed; Journal article, 2014-09-26)Alongshore flows strongly driven by tides and waves is studied in the context of a one-dimensional numerical model. Observations from field surveys performed in a semi-enclosed lagoon (1.7 km×0.2 km) outside Xai-Xai, ... -
Ocean wave tracing v.1: a numerical solver of the wave ray equations for ocean waves on variable currents at arbitrary depths
Halsne, Trygve; Christensen, Kai Håkon; Hope, Gaute; Breivik, Øyvind (Journal article; Peer reviewed, 2023)Lateral changes in the group velocity of waves propagating in oceanic or coastal waters cause a deflection in their propagation path. Such refractive effects can be computed given knowledge of the ambient current field ... -
Resolving regions known for intense wave–current interaction using spectral wave models: A case study in the energetic flow fields of Northern Norway
Halsne, Trygve; Bohlinger, Patrik; Christensen, Kai Håkon; Carrasco, Ana; Breivik, Øyvind (Journal article; Peer reviewed, 2022)Oceanic current forcing in spectral wave models have recently been demonstrated to have a large impact on wave heights at scales between one and up to several hundred kilometers. Here we investigate the impact of such ... -
The "shallow-waterness" of the wave climate in European coastal regions
Christensen, Kai Håkon; Carrasco, Ana; Bidlot, Jean-Raymond; Breivik, Øyvind (Peer reviewed; Journal article, 2017-07-20)In contrast to deep water waves, shallow water waves are influenced by bottom topography, which has consequences for the propagation of wave energy as well as for the energy and momentum exchange between the waves and the ... -
Wave measurements using open source ship mounted ultrasonic altimeter and motion correction system during the one ocean circumnavigation
Ølberg, Judith Thu; Bohlinger, Patrik; Breivik, Øyvind; Christensen, Kai Håkon; Furevik, Birgitte Rugaard; Hole, Lars Robert; Hope, Gaute; Jensen, Atle; Knoblauch, Fabian; Nguyen, Ngoc Thanh; Rabault, Jean (Journal article; Peer reviewed, 2024)This study reviews the design and signal processing of ship borne ultrasonic altimeter wave measurements. The system combines a downward facing ultrasonic altimeter to capture the sea surface elevation as a time series, ... -
Wave Modulation in a Strong Tidal Current and Its Impact on Extreme Waves
Halsne, Trygve; Benetazzo, Alvise; Barbariol, Francesco; Christensen, Kai Håkon; Carrasco, Ana; Breivik, Øyvind (Journal article; Peer reviewed, 2024)Accurate estimates of extreme waves are central for maritime activities, and stochastic wave models are the best option available for practical applications. However, the way currents influence the statistics of space–time ...