Ann Kristin Sperrevik

Ann Kristin Sperrevik
Norwegian Meteorological Institute · Department of Research and Development

PhD

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18
Publications
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264
Citations

Publications

Publications (18)
Article
Full-text available
Effective ocean management requires integrated and sustainable ocean observing systems enabling us to map and understand ecosystem properties and the effects of human activities. Autonomous subsurface and surface vehicles, here collectively referred to as “gliders”, are part of such ocean observing systems providing high spatiotemporal resolution....
Article
Full-text available
This paper reviews physical mechanisms, observation techniques and modelling approaches dealing with surface currents on short time scales (hours to days) relevant for operational oceanography. Key motivations for this article include fundamental difficulties in reliable measurements and the persistent lack of a widely held consensus on the definit...
Conference Paper
This work focuses on the physics of ocean in the coastal zone of the Lofoten-Vesterlen (LoVe) region, with the main goal of developing a combined high-resolution ocean and atmosphere model to use it to understand the dynamics of observed oceanic systems and their attribution to spatial/temporal variability in this region. In order to provide an enh...
Article
Full-text available
Observed vertical profiles of buoyant particles, in this case pelagic Northeast Arctic (NEA) cod eggs, occasionally deviate from the vertical diffusion‐buoyancy balance by displaying subsurface maxima. Here, we present a mechanism that may explain this phenomenon by combining in situ measurements of NEA cod eggs and concurrent environmental conditi...
Technical Report
Full-text available
A regional ocean model setup with data assimilation (DA) for the shelf sea off Nor-way has been set up at the Norwegian Meteorologial Institute (MET Norway). The model domain includes the Skagerrak in the southeast, the northern parts of the North Sea, the Shelf sea off western Norway including the shelf slope, and parts of the Barents Sea in the n...
Article
A high-resolution reanalysis of the circulation in the Kattegat and Skagerrak is used to investigate the mechanisms that control the variability in the onset of the Norwegian Coastal Current. In the reanalysis, the authors have used all available in situ and remote sensing observations of salinity and temperature and use surface current observation...
Article
Full-text available
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 observations from a series of intensive field campaigns, and obtain a more realistic distribution of water masses both in the horizont...
Article
Full-text available
The value of global (e.g. altimetry, satellite sea-surface temperature, Argo) and regional (e.g. radars, gliders, instrumented mammals, airborne profiles and biogeochemical) observation-types for monitoring the mesoscale ocean circulation and biogeochemistry is demonstrated using a suite of global and regional prediction systems and remotely-sensed...
Article
Full-text available
High-frequency (HF) radar-derived ocean currents are compared with in situ measurements to conclude if the radar observations include effects of surface waves that are of second order in the wave amplitude. Eulerian current measurements from a high-resolution acoustic Doppler current profiler and Lagrangian measurements from surface drifters are us...
Article
Full-text available
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, with a baroclinic slope current in a periodic channel, and a realistic case for the coast of Vesterålen in northern Norway. In t...
Article
Full-text available
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, with a baroclinic slope current in a periodic channel, and a realistic case for the coast of Vesterålen in Northern Norway. In t...
Article
Full-text available
The Ocean and Sea Ice Satellite Application Facility (OSISAF) of the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) distributes satellite observations operationally. In this paper, we describe the development of a combined optimal interpolation and nudging (COIN) scheme in the Norwegian Meteorological Institute t...
Article
Full-text available
During the 4th International Polar Year 2007–2009 (IPY), it has become increasingly obvious that we need to prepare for a new era in the Arctic. IPY occurred during the time of the largest retreat of Arctic sea ice since satellite observations started in 1979. This minimum in September sea ice coverage was accompanied by other signs of a changing A...

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