| 1. |
- Testor, Pierre, et al.
(författare)
-
OceanGliders: A component of the integrated GOOS
- 2019
-
Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 6
-
Forskningsöversikt (refereegranskat)abstract
- The OceanGliders program started in 2016 to support active coordination and enhancement of global glider activity. OceanGliders contributes to the international efforts of the Global Ocean Observation System (GOOS) for Climate, Ocean Health and Operational Services. It brings together marine scientists and engineers operating gliders around the world: (1) to observe the long-term physical, biogeochemical, and biological ocean processes and phenomena that are relevant for societal applications; and, (2) to contribute to the GOOS through real-time and delayed mode data dissemination. The OceanGliders program is distributed across national and regional observing systems and significantly contributes to integrated, multi-scale and multi-platform sampling strategies. OceanGliders shares best practices, requirements, and scientific knowledge needed for glider operations, data collection and analysis. It also monitors global glider activity and supports the dissemination of glider data through regional and global databases, in real-time and delayed modes, facilitating data access to the wider community. OceanGliders currently supports national, regional and global initiatives to maintian and expand the capabilities and application of gliders to meet key global challenges such as improved measurement of ocean boundary currents, water transformation and storm forecast.
|
|
| 2. |
- Ringkjøb, Hans-Kristian, et al.
(författare)
-
Short-term solar and wind variability in long-term energy system models - A European case study
- 2020
-
Ingår i: Energy. - : Elsevier Ltd. - 0360-5442 .- 1873-6785. ; 209
-
Tidskriftsartikel (refereegranskat)abstract
- Integration of variable renewables such as solar and wind has grown at an unprecedented pace in Europe over the past two decades. As the share of solar and wind rises, it becomes increasingly important for long-term energy system models to adequately represent their short-term variability. This paper uses a long-term TIMES model of the European power and district heat sectors towards 2050 to explore how stochastic modelling of short-term solar and wind variability as well as different temporal resolutions influence the model performance. Using a stochastic model with 48 time-slices as benchmark, the results show that deterministic models with low temporal resolution give a 15–20% underestimation of annual costs, an overestimation of the contribution of variable renewables (13–15% of total electricity generation) and a lack of system flexibility. The results of the deterministic models converge towards the stochastic solution when the temporal resolution is increased, but even with 2016 time-slices, the need for flexibility is underestimated. In addition, the deterministic model with 2016 time-slices takes 30 times longer to solve than the stochastic model with 48 time-slices. Based on these findings, a stochastic approach is recommended for long-term studies of energy systems with large shares of variable renewable energy sources. © 2020 The Authors
|
|
| 3. |
- Stipa, Tapani, 1968-
(författare)
-
Freshwater, density gradients and biological processes in cold, brackish seas : aspects of the biogeophysical fluid dynamics characterising the Baltic Sea
- 2002
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The dominant component in the ocean water is freshwater. In this thesis its mixing and the freshwater-induced dynamics are discussed, with cold, brackish basins such as the Baltic Sea especially in mind. A mathematical framework is derived to allow for a consistent way of adding freshwater effects to the governing equations. The conservation equations in the presence of mixing by small-scale, irreversible molecular processes or large-scale stirring patterns are derived and the resulting differences are discussed. The lateral advection of freshwater from coastal sources is demonstrated on the basis of observations from the Gulf of Riga and Gulf of Finland. The advection is found to take place as a well-defined coastal current, in particular during spring when a minimum in the climatological wind stress is found. The baroclinic stability of a coastal current of this type is studied analytically and numerically, and a functional dependence between the cross-shore eddy transports and the bottom slope is derived. The role of edge waves in the stability problem and their sensitivity to bottom boundary characteristics is emphasized, and their biological relevance is discussed.Spatial temperature anomalies are shown to be dynamically passive at low temperatures in the Baltic. Observations and a numerical simulation confirm that the density gradients in off-shore areas of the Northern Baltic result from lateral gradients of freshwater. Under these conditions, the phytoplankton spring bloom results from freshwater-induced stratification.As opposed to non-reactive freshwater, many effluents that are carried to the sea by coastal freshwater discharge are transported exactly like freshwater, but being biologically reactive they have a limited range of transport. The biological reaction rate, in turn, is modified by the physical processes dealt with in this thesis, as shown from the observations and numerical results. The range of influence and eventual fate of such effluents is of relevance for the coastal societies. A requisite theoretical biogeophysical basis for socioeconomic inferences concerning coastal eutrophication is thus provided by the freshwater dynamics discussed this thesis.
|
|
