Lagrangian modeling of water circulation in the Lofoten Basin |
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| Institution: | 1. St. Petersburg State University, 7–9, Universitetskaya nab., St. Petersburg 199034, Russia;2. NIERSC, Nansen International Environmental and Remote Sensing Centre, 14th line, 7, St. Petersburg 199034, Russia;3. Arctic and Antarctic Research Institute, Bering str., 38, St. Petersburg 199397, Russia;4. Pacific Oceanological Institute of the Russian Academy of Sciences, 43 Baltiiskaya St., 690041 Vladivostok, Russia;1. Razi University, Kermanshah, Iran;2. Swedish Meteorological and Hydrological Institute, Norrköping, Sweden;3. Institute of Geophysics, University of Tehran, Iran |
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| Abstract: | Lagrangian particle tracking is implemented for the Lofoten Basin of the Norwegian Sea. The ocean dynamic fields are obtained from the GLORYS 12V1 reanalysis available by the Copernicus Marine Environment Monitoring Service. Spatial distributions of the Lagrangian particles during May-November 2014 are analyzed for two depth layers: the sea-surface (0.5 m) and 266 m. The results show a significant impact of the Norwegian Coastal Current (NCC) on the thermohaline structure of the upper Lofoten Basin, underestimated previously. The NCC penetrates deep into the central Lofoten basin as far as the longitude 0°. In the subsurface layer, the area over which the NCC influences water structure is comparable to the area of the Norwegian Atlantic Slope Current (NASC), as well as to that of the Norwegian Atlantic Frontal Current (NAFC). The NCC maximum influence on the surface water of the Basin is reached in August. The inflow of the NCC is associated with relatively fresh water intrusions (0.5–2‰ fresher than the surrounding waters) moving from the coast to the central part of the Basin. The NASC and NAFC form two main sources of the Atlantic Water in the Lofoten Basin. At 266 m level, the NASC and NAFC waters dominate water structure in the basin. Herewith the NASC influence prevails over that of the NAFC, the latter being limited to the western periphery of the Basin. At this level, the NCC is observed only along a narrow band following the eastern coast. During summer, the core of the Lofoten Vortex (LV) at 266 m is mainly composed of the NAFC water. This fact contradicts the previous point of view of the dominance of the NASC in the LV core at all depth levels. Using two types of Lagrangian maps, we highlighted the summer and the autumn periods in the LV annual lifecycle. The summer LV is characterized by high orbital velocities, which are several times higher than those of the currents along the basin boundaries. The monthly mean orbital velocities in the LV reach 35 сm s?1. To the end of autumn, the LV weakens with the monthly mean orbital velocities below 10 cm s?1. |
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| Keywords: | The Lofoten basin The Norwegian Sea The Lofoten Vortex Numerical modeling Lagrangian tracking |
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