Abstract. Through the Faroese Channels -the collective name for a system of channels linking the Faroe-Shetland Channel, Wyville Thomson Basin, and Faroe Bank Channel -there is a deep flow of cold waters from Arctic regions that exit the system as overflow through the Faroe Bank Channel and across the Wyville Thomson Ridge. The upper layers, in contrast, are dominated by warm, saline water masses from the southwest, termed Atlantic water. In spite of intensive research over more than a century, there are still open questions on the passage of these waters through the system with conflicting views in recent literature. Of special note is the suggestion that there is a flow of Atlantic water from the Faroe-Shetland Channel through the Faroe Bank Channel, which circles the Faroes over the slope region in a clockwise direction. Here, we combine the observational evidence from ship-borne hydrography, moored current measurements, surface drifter tracks, and satellite altimetry to address these questions and propose a general scheme for the Atlantic water flow through this channel system. We find no evidence for a continuous flow of Atlantic water from the Faroe-Shetland Channel to the Faroe Bank Channel over the Faroese slope. Rather, the southwestward-flowing water over the Faroese slope of the Faroe-Shetland Channel is totally recirculated within the combined area of the Faroe-Shetland Channel and Wyville Thomson Basin, except possibly for a small release in the form of eddies. This does not exclude a possible westward flow over the southern tip of the Faroe Shelf, but even including that, we estimate that the average volume transport of a "Circum-Faroe Current" does not exceed 0.5 Sv (1 Sv = 10 6 m 3 s −1 ). Also, there seems to be a persistent flow of Atlantic water from the western part of the Faroe Bank Channel into the Faroe-Shetland Channel that joins the Slope Current over the Scottish slope. These conclusions will affect potential impacts from offshore activities in the region and they imply that recently published observational estimates of the transport of warm water towards the Arctic obtained by different methods are incompatible.
Abstract. Through the Faroese Channels – the collective name for a system of channels linking the Faroe–Shetland Channel (FSC), Wyville Thomson Basin (WTB) and Faroe Bank Channel (FBC) – there is a deep flow of cold waters from Arctic regions that exit the system as overflow through the FBC and across the Wyville Thomson Ridge. The upper layers, in contrast, are dominated by warm, saline water masses from the Atlantic. In spite of intensive research over more than a century, there are still open questions on the passage of these waters through the system with conflicting views in recent literature. Of special note is the suggestion that there is a flow of Atlantic water from the FSC through the FBC, which circles the Faroes over the slope region in a clockwise direction. Here, we combine the observational evidence from ship-borne hydrography, moored current measurements, surface drifter tracks, and satellite altimetry to address these questions and propose a general scheme for the Atlantic water flow through this channel system. We find no evidence for a continuous flow of Atlantic water from the FSC to the FBC over the Faroe slope outside of the shelf. Rather, the southwestward flowing water over the Faroese slope of the FSC is totally re-circulated within the combined area of the FSC and WTB, except possibly for a small release in the form of eddies. Also, there seems to be a persistent flow of Atlantic water from the western part of the FBC into the FSC that joins the Slope Current over the Scottish slope. These conclusions will affect potential impacts from offshore activities in the region and they imply that recently published observational estimates of the oceanic heat transport towards the Arctic obtained by different methods are incompatible.
PurposeThe aim of the study was to perform a systematic review and best knowledge synthesis of the present literature concerning biomechanical risk factors for developing first‐time and recurrent patella dislocation. MethodsThe study was performed as a systematic review following PRISMA guidelines. PubMed and EMBASE were systematically searched. Studies investigating participants with risk factors for first‐time as well as recurrent patella dislocation were included. The records were screened, and data extracted independently by two researchers supervised by a third independent assessor. The study was registered in PROSPERO. ResultsA total of 6233 records were screened, and 50 studies met the inclusion criteria. The biomechanical risk factors: trochlear dysplasia, increased tibial tuberosity–trochlear groove distance (TT‐TG), and patella alta were found to be statistically significantly associated with patella dislocation in several publications and were thus recognized as risk factors for patella dislocation. The soft‐tissue stabilizers: longer and thinner MPFL ligament, increased number of type 2C and decreased number of type 1 muscle fibers, and joint laxity were found to be statistically significantly associated with patella dislocation in a few publications, but due to limited evidence, no conclusion was made on this matter. ConclusionThere is strong evidence in the literature that abnormalities of bony stabilizers, trochlear dysplasia, increased TT–TG distance, and patella alta are risk factors for patella dislocation. There is less evidence that soft‐tissue stabilizers are risk factors. The study emphasizes the importance of a thorough investigation of bony stabilizers in clinical decision‐making. Level of evidenceLevel IV.
<p>The Faroe Islands is a small mountainous island group in the north east Atlantic Ocean, located far from any other mainland. The closes adjacent land being Shetland ~300 km away. One electrical power company exists on the islands, distributing power to the ~50.000 citizens. Approximately half of the electrical power comes from renewable energy sources (wind and hydro) and the other half from oil [1]. The political goal is to have the electrical system running 100% on renewable energy sources by 2030. This will presumable be achieved by implementing a significant amount of wind power [2]. The climate in the Faroe Islands is very windy, making it a good area for harvesting wind energy.</p> <p>As wind is a fluctuating power source, analyzing the wind field and its characteristics is of great importance, when planning implementation of a significant amount of wind power into the power grid. Smoothening of the wind power can be achieved different ways, one being with spatial dispersion of wind farms seen in other studies [3,4]. The spectral characteristics and the smoothening effect of spatial dispersed sites based on wind farm data and meteorological wind speed measurements in the Faroe Islands was shown in a poster presentation at EMS2019 [5]. However, implementing more wind farms requires knowledge of new sites. There have been made NWP calculations of the wind in the Faroe Islands for the period July 2016 to June 2017. NWP are beneficial in the way that they give valuable information at unknown sites, which may be used for wind farm planning. However, NWP calculations are based on a given setup of a simplified reality. Hence, validating any NWP model is needed.</p> <p>There exists wind measurements at various heights from two meteorological masts at the time period of the mentioned NWP model calculations in the Faroe Islands. The aim of this study is to compare auto- and cross-spectral characteristics of the sets of modelled and measured data. The results will give an insight on the value of NWP derived data for grid integration studies in a region with complex topography.</p> <div><br /> <div> <p>[1] Framlei&#240;sluroknskapur 2018, SEV, (see http://www.sev.fo/Default.aspx?ID=67)</p> </div> <div> <p>[2] Hansen, H., Nielsen, T., Thomsen, B., and Andersen, K., 2018, Energilagring p&#229; F&#230;r&#248;erne, Teknisk opsamlingsrapport. Dansk Energi. (see http://www.os.fo/media/1187/1-teknisk-opsamlingsrapport-energilagring-paa-faer-erne.pdf)</p> </div> <div> <p>[3] Beyer, H. G., Luther, J., and Steinberger-Willms, R., 1993, Power fluctuations in spatially dispersed wind turbine systems, Solar Energy, Vol. 50, No. 4, pp. 297-305.</p> </div> <div> <p>[4] Pearre, N. S. and Swan, L. G., 2018, Spatial and geographic heterogeneity of wind turbine farms for temporally decoupled power output, Energy, Vol. 145, pp. 417-429.</p> </div> <div> <p>[5] Poster presentation at the European Meteorology Society annual meeting 2019, 9-13 September, Copenhagen, Denmark.</p> </div> </div>
Abstract. Hourly modeled wind turbine power output time series – modeled based on outputs from the mesoscale numerical weather prediction system Weather Research and Forecasting Model (WRF) – are used to examine the spatial smoothing of various wind farm portfolios located on a complex isolated island group with a surface area of 1400 km2. Power spectral densities (PSDs), hourly step-change functions, and duration curves are generated, and the 5th and 95th percentiles and the standard deviations of the hourly step-change functions are calculated. The spatial smoothing is identified from smaller high-frequency PSD amplitudes, lower hourly fluctuations, and more flat duration curves per installed wind power capacity, compared with single wind turbine outputs. A discussion on the limitation of the spatial smoothing for the region is included, where a smoothing effect is observed for periods of up to 1–2 d, although it is most evident at higher frequencies. By maximizing the smoothing effect, optimal wind farm portfolios are presented with the intention of minimizing overall wind power fluctuations. The focus is mainly on the smoothing effect on the 1–3 h timescale, during which the coherency between wind farm power outputs is expected to be dependent on how the regional weather travels between local sites, thereby making optimizations of wind farm portfolios relevant – in contrast to a focus on either lower or higher frequencies on the scale of days or minutes, respectively, during which wind farm power output time series are expected to be either close to fully coherent due to the same weather conditions covering a small region or not coherent as the turbulences in separate wind farm locations are expected to be uncorrelated. Results show that an optimization of the wind farm capacities at 14 pre-defined wind farm site locations has a minimal improvement on the hourly fluctuations compared with a portfolio with equally weighted wind farm capacities. However, choosing optimized combinations of individual wind farm site locations decreases the 1–3 h fluctuations considerably. For example, selecting a portfolio with four wind farms (out of the 14 pre-defined wind farm site locations) results in 15 % lower 5th and 95th percentiles of the hourly step-change function when choosing optimal wind farm combinations compared with choosing the worst wind farm combinations. For an optimized wind farm portfolio of seven wind farms, this number is 13 %. Optimized wind farm portfolios consist of distant wind farms, while the worst portfolios consist of clustered wind farms.
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