The Baltic Sea Tracer Release Experiment: 1. Mixing rates

Holtermann, Peter; Umlauf, Lars; Tanhua, Toste; Schmale, Oliver; Rehder, Gregor; Waniek, Joanna J

doi:10.1029/2011jc007439

Cited by 39 publications

(94 citation statements)

References 30 publications

(68 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…3b). These dispersion results are in accordance with the findings from the tracer release experiment described by Holtermann et al (2012). Small tracer amounts emanating from the Gotland Deep may, however, also be found in the Gulf of Finland and the Gulf of Bothnia.…”

Section: Dispersion Of the East Gotland Deep Water Tracersupporting

confidence: 82%

“…The tracer release experiment by Holtermann et al (2012) was performed in the years 2007Á2009 when our model, in accordance with the in-situ data, indicates a relatively modest inflow period. This can be noticed both in the annual (Fig.…”

Section: 23mentioning

confidence: 88%

“…The tracer release experiment by Holtermann et al (2012) showed that the lateral dispersion of deep water occurs on time scales of a few months. The model results from the present study show that most of the spreading of the East Gotland deep water tracer takes place along the bottom layers of the Baltic and that significant concentrations (5Á10% of the initial concentrations) of the tracer may be found to the north and the west of the island Gotland 2 yr after the tracer initiations (Fig.…”

Section: Dispersion Of the East Gotland Deep Water Tracermentioning

confidence: 99%

“…In Section 2, the model setup and details about the tracer methods are presented. The results of the modelled tracer dynamics are discussed in Section 3 and compared to the in-situ tracer experiment in 2007Á2009 by Holtermann et al (2012) and the data analysis of the inflow in 2003 by Schneider (2011). Finally the horizontal and vertical dispersion of the tracers are discussed and some concluding remarks are given.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Impact of saltwater inflows on phosphorus cycling and eutrophication in the Baltic Sea: a 3D model study

Eilola¹,

Almroth‐Rosell

Meier

2014

Tellus A: Dynamic Meteorology and Oceanography

View full text Add to dashboard Cite

A B S T R A C TThe impact of dense saltwater inflows on the phosphorus dynamics in the Baltic Sea is studied from tracer experiments with a three-dimensional physical model. Model simulations showed that the coasts of the North West Gotland Basin and the Gulf of Finland, the Estonian coast in the East Gotland Basin are regions where tracers from below the halocline are primarily lifted up above the halocline. After 1 yr tracers are accumulated at the surface along the Swedish east coast and at the western and southern sides of Gotland. Elevated concentrations are also found east and southeast of Gotland, in the northern Bornholm Basin and in the central parts of the East Gotland Basin. The annual supplies of phosphorus from the deeper waters to the productive surface layers are estimated to be of the same order of magnitude as the waterborne inputs of phosphorus to the entire Baltic Sea. The model results suggest that regionally the impact of these nutrients may be quite large, and the largest regional increases in surface concentrations are found after large inflows. However, the overall direct impact of major Baltic inflows on the annual uplift of nutrients from below the halocline to the surface waters is small because vertical transports are comparably large also during periods without major inflows. Our model results suggest that phosphorus released from the sediments between 60 and 100 m depth in the East Gotland Basin contributes to the eutrophication, especially in the coastal regions of the eastern Baltic Proper.

show abstract

Section: Dispersion Of the East Gotland Deep Water Tracersupporting

confidence: 82%

Section: 23mentioning

confidence: 88%

Section: Dispersion Of the East Gotland Deep Water Tracermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Impact of saltwater inflows on phosphorus cycling and eutrophication in the Baltic Sea: a 3D model study

Eilola¹,

Almroth‐Rosell

Meier

2014

Tellus A: Dynamic Meteorology and Oceanography

View full text Add to dashboard Cite

show abstract

“…A common practice is to calculate the diffusivity using the constant flux parameter Γ = 0.2 (e.g., Osborn, 1980;Moum et al, 2002Moum et al, , 2004Burchard, 2009;Holtermann et al, 2012). On the other hand, Shih et al (2005) proposed a parametrization for the mixing efficiency that depends on the turbulent activity, or the buoyancy Reynolds number (Re b = ǫ νN 2 ), leading to mixing efficiency significantly lower than Γ = 0.2 when the turbulence is fully developed (Re b > 100).…”

Section: Mooring Datamentioning

confidence: 99%

Behavior and mixing of a cold intermediate layer near a sloping boundary

2015

View full text Add to dashboard Cite

As in many other subarctic basins, a cold intermediate layer (CIL) is found during ice-free months in the Lower St. Lawrence Estuary (LSLE), Canada. This study examines the behavior of the CIL above the sloping bottom using a high resolution mooring deployed on the northern side of the estuary. Observations show successive swashes/backwashes of the CIL on the slope at a semi-diurnal frequency. It is shown that these upslope and downslope motions are likely caused by internal tides generated at the nearby channel head sill. Quantification of mixing from 322 turbulence casts reveals that in the bottom 10 m of the water column, the timeaverage dissipation rate of turbulent kinetic energy is ǫ 10 m = 1.6 × 10 −7 W kg −1 , an order of magnitude greater than found in the interior of the basin, far from boundaries. Near-bottom dissipation during the flood phase of the M 2 tide cycle (upslope flow) is about four times greater than during the ebb phase (downslope flow). Bottom shear stress, shear instabilities and internal wave scattering are considered as potential boundary mixing mechanisms near the seabed. In the interior of the water column, far from the bottom, increasing dissipation rates are observed with both increasing stratification and shear, which suggests some control of the dissipation by the internal wave field. However, poor fits with a parametrization for large-scale wave-wave interactions suggests that the mixing is partly driven by more complex non-linear and/or smaller scale waves.Frédéric Cyr Institut des sciences de la mer de Rimouski, Université du Québecà Rimouski, Rimouski (Québec) Canada.

show abstract

Close coupling of N‐cycling processes expressed in stable isotope data at the redoxcline of the Baltic Sea

Frey

Dippner

Voß

2014

Global Biogeochemical Cycles

View full text Add to dashboard Cite

Over the past decades, the hypoxic state of the central Baltic Sea has deteriorated because of eutrophication, but little is known about the extent to which related factors such as nitrogen removal have been altered. The Baltic Sea is a stratified semi-enclosed basin with a large, anoxic bottom water mass in its central Gotland Basin and highly active microbial nitrogen transformation processes at the redoxcline, the interface between oxic and anoxic waters. In this study, we identified and quantified the dominant transformation processes of reactive nitrogen by exploiting fine resolution profiles of δ 15 N NO3 , δ 18 O NO3 , and δ 15 N NH4 through the pelagic redoxcline between 60 and 140 m. Our results showed increasing δ 15 N NO3 and δ 18 O NO3 values with decreasing nitrate concentrations, but the associated low apparent isotope effect (ε =~5‰), as inferred from a closed system Rayleigh model, was not consistent with the high ε (~25‰) characteristic of denitrification in the water column. These findings could be explained by substrate limitation. The observed δ 18 O NO3 :δ 15 N NO3 ratio of 1.38:1 rather than the usual 1:1 ratio typical for denitrification-dominated systems could be explained by the occurrence of both nitrification and denitrification. We then developed a numeric reaction-diffusion model, according to which a realistic denitrification rate of 14 nmol N L À1 d À1 was estimated, and a nitrification rate of 6.6 nmol N L À1 d À1 confirmed. Our study not only demonstrates the value of stable isotope data for investigating nitrogen transformation processes but also highlights that care is needed in interpreting systems with closely coupled processes such as those at ocean redoxclines.

show abstract

The Baltic Sea Tracer Release Experiment: 1. Mixing rates

Cited by 39 publications

References 30 publications

Impact of saltwater inflows on phosphorus cycling and eutrophication in the Baltic Sea: a 3D model study

Impact of saltwater inflows on phosphorus cycling and eutrophication in the Baltic Sea: a 3D model study

Behavior and mixing of a cold intermediate layer near a sloping boundary

Close coupling of N‐cycling processes expressed in stable isotope data at the redoxcline of the Baltic Sea

Contact Info

Product

Resources

About