| 1. |
- Almroth, Elin, 1977, et al.
(author)
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Effects of resuspension on benthic fluxes of oxygen, nutrients, dissolved inorganic carbon, iron and manganese in the Gulf of Finland, Baltic Sea
- 2009
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In: Continental Shelf Research. - : Elsevier BV. - 0278-4343. ; 29, s. 807-818
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Journal article (peer-reviewed)abstract
- The effect of resuspension on benthic fluxes of oxygen (O2), ammonium (NH4+), nitrate (NO3−), phosphate (PO43−), silicate (Si(OH)4), dissolved inorganic carbon (DIC), total dissolved iron (Fe) and total dissolved manganese (Mn) was studied at three different stations in the Gulf of Finland (GoF), Baltic Sea during three cruises in June–July 2003, September 2004 and May 2005. The stations were situated on different bottom types in the western, central and eastern part, respectively, of the open GoF. The fluxes were measured in-situ using the autonomous Göteborg benthic lander. To simulate resuspension events, the stirring speed was increased in two of the four chambers of the lander after approximately half of the incubation time. The other two chambers were used as control chambers. Clear effects of resuspension were observed on the oxygen fluxes where an increase of the consumption was observed in 88% of the cases and on average with 59% (stdev=53). The NH4+ fluxes were affected in 50% of the cases (4 out of 8 incubations) at stations with low bottom water oxygen concentrations, but in no cases where the bottom water was oxygenated (0 out of 9 incubations). The NH4+ fluxes decreased by 26±27% in 2005 and by 114±19% in 2003. There was no clear effect of resuspension on the fluxes of any of the other solutes in this study. Thus, resuspension events did not play a significant role in release/uptake of NO3−, PO43−, Si(OH)4, DIC, Fe and Mn in GoF sediments. However, increased oxygen consumption as a result of resuspension may lead to spreading of anoxic/suboxic bottom water conditions, and thus indirectly to increased benthic release of phosphate, ammonium and iron.
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| 2. |
- Arneborg, Lars, 1969
(author)
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Turnover times for the water above sill level in Gullmar Fjord
- 2004
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In: Continental Shelf Research. - : Elsevier BV. - 0278-4343. ; 24:4-5, s. 443-460
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Journal article (peer-reviewed)abstract
- Daily hydrographic measurements between 1954 and 1986, monthly environmental monitoring data from the last decades, and high-resolution data from 2001 are combined to obtain statistics on the exchange of the water above sill level in Gullmar Fjord, Sweden. The analyses show: (i) that the average turnover time is 16-26 days for the water above the halocline (S < 28), and 40 days for the intermediate water below the halocline, (ii) that the exchange is dominated by baroclinic currents caused by vertical fluctuations of the halocline outside the fjord, and (iii) that the statistics for the turnover times are relatively independent of year and season. One implication of these results is that a coupling between climate variations and water quality in Gullmar Fjord, cannot be explained in terms of variations in the water exchange. (C) 2004 Elsevier Ltd. All rights reserved.
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| 3. |
- Ben Mustapha, Selima, et al.
(author)
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Spatial and temporal variability of sea-surface temperature fronts in the coastal Beaufort Sea
- 2016
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In: Continental Shelf Research. - : Elsevier BV. - 0278-4343 .- 1873-6955. ; 124, s. 134-141
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Journal article (peer-reviewed)abstract
- An analysis of 11 years of sea surface temperatures images allowed the determination of the frontal occurrence probability in the southeastern Beaufort Sea using the single-image edge detection method. Results showed that, as the season progresses, fronts become more detectable due to solar heating of the surface layer. Some recurrent features can be identified in the summer time frontal climatology such as the Mackenzie River plume front, the Cape Bathurst front, the Mackenzie Trough front and the Amundsen Gulf front. These areas may be playing an important role in the biological processes acting as drivers to local enhanced biological productivity.
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| 4. |
- Castillo, M. I., et al.
(author)
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Subtidal dynamics in a deep fjord of southern Chile
- 2012
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In: Continental Shelf Research. - : Elsevier BV. - 0278-4343. ; 49, s. 73-89
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Journal article (peer-reviewed)abstract
- This study presents results from an unprecedented program of measurements performed in Reloncavi Fjord (RF), Chile. This fiord is located around 41 degrees 35'S, 72 degrees 30'W, making it one of the most equatorward fiords in the world. The main objectives of this study were to describe and quantify the mean circulation inside the Fjord and to evaluate its along- and cross-fjord subtidal momentum balance. The depth of the fjord is about 450 m near the mouth and lacks a well defined sill. There, the mean flow showed a three layered structure. Surface (< 5 m depth) and deep (> 100 m depth) outflow layers delimited an inward-flowing layer. The along-fiord wind stress (tau(y)) shifted markedly during the beginning of the austral spring (September 2008). In winter, the mean tau(y) was predominantly out-fjord, similar to the mean along-fiord currents (nu) observed in the upper layer. In contrast, the spring tau(y), was mainly toward the fjord head, i.e., opposite to the surface current. During periods of large up-Fjord winds (tau(y) > 0.04 N m s(-2)) surface currents were reversed. Near the surface (depths <5 m), nu and tau(y) were well correlated in spring. The horizontal baroclinic pressure gradient force was typically of order 10(-5) m s(-2) at the surface, both along- and cross-Fjord. The estimated magnitudes of the other terms in the along-fjord momentum equation indicated that advective terms were the most relevant But near Puelo, where the fiord abruptly bends and the main river flow enters the fiord, both the advective and frictional forces were relevant, particularly in February 2009. In the cross-fjord component of the momentum equation, the Coriolis term < f nu > was the most relevant in winter. At Puelo the advective term < u(partial derivative u/partial derivative x)> was the most important in summer. The importance of the Coriolis force in the cross-fjord momentum balance suggested that v may approximately be in geostrophic balance. The correlation between the mean along-fjord geostrophic velocities and the mean observed currents had an R-2 > 0.79 for all measurements and reached R-2 similar to 0.85 in winter. (C) 2012 Elsevier Ltd. All rights reserved.
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| 5. |
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| 6. |
- Green, Mattias, 1971, et al.
(author)
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Physical oceanography and water exchange in the Northern Kvark Strait
- 2006
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In: Continental Shelf Research. - : Elsevier BV. - 0278-4343. ; 26:6, s. 721-732
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Journal article (peer-reviewed)abstract
- The Northern Kvark connects the very fresh Bothnian Bay to the slightly saltier Bothilian Sea in the northern Baltic Sea. Intense field experiments were made in the strait in May 2003 and October-December 2004 to describe the physical oceanography of the strait. Three different hydrographic regimes were identified and first-order analyses were made on each regime, neglecting friction, rotation, and horizontal gradients. The strait is shown to be barotropically blocked about 45% of the time. The rest of the time there is vertical stratification, which can be described either by two homogenous layers or by linear density and velocity profiles. The flows in the two stratified regimes are shown to be hydraulically controlled. (C) 2006 Elsevier Ltd. All rights reserved.
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| 7. |
- Hjalmarsson, Sofia, 1980, et al.
(author)
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Distribution, long-term development and mass balance calculation of total alkalinity in the Baltic Sea
- 2008
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In: Continental Shelf Research. - : Elsevier BV. - 0278-4343. ; 28:4-5, s. 593-601
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Journal article (peer-reviewed)abstract
- During the 20th century, extensively hydrographic investigations had been performed in the Baltic Sea. One of the parameters that have been determined during these historic investigations of the Baltic Sea is the total alkalinity (AT). In this study, this large data set is used together with a specifically developed box model to estimate the in- and outflows of salinity and AT within the different sub-basins. The Baltic Sea receives large amounts of freshwater through river runoff, and AT can be used as a chemical signature of the runoff as its concentration depends on the mineralogy of the drainage basin. Rivers entering the southern part of the Baltic Sea are draining areas rich in limestone, therefore having higher AT than rivers entering the northern part of the Baltic Sea where granite dominates the bedrock. The mean AT in rivers entering a specific region of the Baltic Sea is achieved by the intercept of the regression line when salinity is plotted versus AT for the corresponding data. In this study, the focus is on the Gulf of Finland and the Gulf of Bothnia where the longest time series data are available. There is a common trend with an increase in AT in rivers entering the Gulf of Finland and a decrease in AT in rivers entering the Gulf of Bothnia.
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| 8. |
- Hordoir, Robinson, et al.
(author)
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Freshwater outflow of the Baltic Sea and transport in the Norwegian current : A statistical correlation analysis based on a numerical experiment
- 2013
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In: Continental Shelf Research. - : Elsevier. - 0278-4343 .- 1873-6955. ; 64, s. 1-9
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Journal article (peer-reviewed)abstract
- Based on the results of a numerical ocean model, we investigate statistical correlations between wind forcing, surface salinity and freshwater transport out of the Baltic Sea on one hand, and Norwegian coastal current freshwater transport on the other hand. These correlations can be explained in terms of physics and reveal how the two freshwater transports are linked with wind forcing, although this information proves to be non-sufficient when it comes to the dynamics of the Norwegian coastal current. Based on statistical correlations, the Baltic Sea freshwater transport signal is reconstructed and shows a good correlation but a poor variability when compared with the measured signal, at least when data filtered on a two-daily time scale is used. A better variability coherence is reached when data filtered on a weekly or monthly time scale is used. In the latest case, a high degree of precision is reached for the reconstructed signal. Using the same kind of methods for the case of the Norwegian coastal current, the negative peaks of the freshwater transport signal can be reconstructed based on wind data only, but the positive peaks are under-represented although some of them exist mostly because the meridional wind forcing along the Norwegian coast is taken into account. Adding Norwegian coastal salinity data helps improving the reconstruction of the positive peaks, but a major improvement is reached when adding non-linear terms in the statistical reconstruction. All coefficients used to re-construct both freshwater transport signals are provided for use in European Shelf or climate modeling configurations.
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| 9. |
- Joensson, Bror F., et al.
(author)
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A Lagrangian-trajectory study of a gradually mixed estuary
- 2011
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In: Continental Shelf Research. - : Elsevier BV. - 0278-4343 .- 1873-6955. ; 31:17, s. 1811-1817
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Journal article (peer-reviewed)abstract
- When modelling is used for investigating estuarine systems, a choice generally has to be made between applying simple mass-balance considerations or using a process-resolving three-dimensional (3-D) numerical circulation model. In the present investigation of the Gulf of Finland, a gradually mixed estuary in the Baltic Sea, it is demonstrated how Lagrangian-trajectory analysis applied to the output from a 3-D model minimizes the disadvantages associated with both of the modelling techniques referred to above. This formalism made it possible to demonstrate that the main part of the Gulf is dominated by water originating from the Baltic proper, and that the most pronounced mixing with fresh water from the river Neva takes place over a limited zone in the inner part of the Gulf. Dynamical insights were furthermore obtained by using the Lagrangian formalism to construct overturning stream-functions for the two source waters.
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| 10. |
- Jönsson, Anette, et al.
(author)
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Bottom type distribution based on wave friction velocity in the Baltic Sea
- 2005
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In: Continental Shelf Research. - : Elsevier BV. - 0278-4343. ; 25:3, s. 419-435
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Journal article (peer-reviewed)abstract
- Surface waves play an important role for the sediment distribution in the shallow Baltic Sea. This paper presents the large-scale spatio-temporal distribution of wave-induced bottom friction velocity, u*, based on modelled wave data for the years 1999 and 2000. The highest values of u* are found along the eastern coasts of the Baltic Proper and Bothnian Sea—areas characterised by long fetches for the dominant winds. Temporally, the dynamics follow that of the wind climate with higher velocities during winter and lower during summer. A smooth bottom is assumed for the calculations. To test this assumption, u* is compared to other estimates of u* assuming rough bottoms. The spatio-temporal patterns are similar, although the present approach gives a slight underestimation of u* at areas with coarse grain sizes. To compare the results, the co-variation between the u* distribution and bottom type distribution from a digitised sediment map is analysed. It shows upon a good agreement. This is also found when comparing critical levels for resuspension found in the literature with the same from modelled u*. In addition, other processes important for bottom stress, such as mesoscale eddies and coastal jets, are discussed.
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