The Inflow of Highly Saline Water into the Baltic Sea

Matthäus, Wolfgang; Nehring, Dietwart; Feistel, Rainer; Nausch, Günther; Mohrholz, Volker; Lass, Hans Ulrich

doi:10.1002/9780470283134.ch10

Cited by 70 publications

(63 citation statements)

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“…While there are no MBI data due to WWII (Matthäus et al, 2008), the study by Ahlnäs (1961) supports strong MBIs during that period, combined with reduced river discharge (Hansson et al, 2011).…”

Section: Long-term Changes In Seawater Temperatures Salinities and Smentioning

confidence: 99%

“…Occasional saline water inflows (major Baltic inflows) from the North Sea (Matthäus et al, 2008) and continuous inflow of freshwater from the rivers (Ahlnäs, 1961;Hansson et al, 2011;Väli et al, 2013) keep the stratification strong.…”

Section: Measurement Site and General Characteristicsmentioning

confidence: 99%

“…The ice data used in this study are based on 8564 manually analyzed ice maps from the period 1914-2016. NAO data were taken from Jones et al (1997) with updates from Osborn (2004Osborn ( , 2006Osborn ( , 2011. MBI data were taken from Matthäus et al (2008), with the latest updates from Mohrholz et al (2015) and Nauman et al (2018).…”

Section: Observations and Other Datamentioning

confidence: 99%

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100 years of atmospheric and marine observations at the Finnish Utö Island in the Baltic Sea

et al. 2018

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Abstract. The Utö Atmospheric and Marine Research Station introduced in this paper is located on Utö Island (59 • 46.84 N, 21 • 22.13 E) at the outer edge of the Archipelago Sea, by the Baltic Sea towards the Baltic Proper. Meteorological observations at the island started in 1881 and vertical profiling of seawater temperature and salinity in 1900. Since 1980, the number of observations at Utö has rapidly increased, with a large number of new meteorological, air quality, aerosol, optical and greenhouse gas parameters, and recently, a variety of marine observations. In this study, we analyze long-term changes of atmospheric temperature, cloudiness, sea salinity, temperature and ice cover. Our main dataset consists of 248 367 atmospheric temperature observations, 1632 quality-assured vertical seawater temperature and salinity profiles and 8565 ice maps, partly digitized for this project. We also use North Atlantic Oscillation (NAO), major Baltic inflow (MBI) and Baltic Sea river runoff data from the literature as reference variables to our data. Our analysis is based on a statistical method utilizing a dynamic linear model. The results show an increase in the atmospheric temperature at Utö, but the increase is significantly smaller than on land areas and has taken place only since the early 1980s, with a rate of 0.4 • C decade −1 during the last 35 years. We also see an increase in seawater temperatures, especially on the surface, with an increase of 0.3 • C decade −1 for the last 100 years. In deeper water layers, the increase is smaller and influenced by vertical mixing, which is modulated by inflow of saline water from the North Sea and freshwater inflow from rivers and by wind-driven processes influenced by the local bathymetry. The date when air temperature in the spring exceeds +5 • C became 5 days earlier from the period 1951-1980 to the period 1981-2010 and the date when sea surface water temperature exceeds +4 • C changed to 9 days earlier. Sea ice cover duration at Utö shows a decrease of approximately 50 % during the last 35 years. Based on the combined results, it is possible that the climate at Utö has changed into a new phase, in which the sea ice no longer reduces the local temperature increase caused by the global warming.

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Section: Long-term Changes In Seawater Temperatures Salinities and Smentioning

confidence: 99%

Section: Measurement Site and General Characteristicsmentioning

confidence: 99%

Section: Observations and Other Datamentioning

confidence: 99%

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100 years of atmospheric and marine observations at the Finnish Utö Island in the Baltic Sea

et al. 2018

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“…Dates of observed MBIs are taken from Mattha¨us et al (2008) and updated by R. Feistel (personal communication, October 2013). Moreover, time series of salinity based on measurements are used for the centre of the Bornholm Basin (name of the station is BY5) and the Gotland Deep (BY15).…”

Section: Experimental Setup and Datamentioning

confidence: 99%

An algorithm based on sea-level pressure fluctuations to identify major Baltic inflow events

Schimanke¹,

Dieterich

Meier

2014

Tellus A: Dynamic Meteorology and Oceanography

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A B S T R A C T Major Baltic inflows are an important process to sustain the sensitive steady state of the Baltic Sea. We introduce an algorithm to identify atmospheric variability favourable for major Baltic inflows. The algorithm is based on sea-level pressure (SLP) fields as the only parameter. Characteristic SLP pattern fluctuations include a precursory phase of 30 days and 10 days of inflow period. The algorithm identifies successfully the majority of observed major Baltic inflows between 1961 and 2010. In addition, the algorithm finds some occurrences which cannot be related to observed inflows. In these cases with favourable atmospheric conditions, inflows were precluded by contemporaneously existing saline water masses or strong freshwater supply. Moreover, the algorithm clearly identifies the stagnation periods as a lack of SLP variability favourable for MBIs. This indicates that the lack of inflows is mainly a consequence of missing atmospheric forcing during this period. The only striking inflow which is not identified by the algorithm is the event in January 2003. We demonstrate that this is due to the special evolution of SLP fields which are not comparable with any other event. Finally, the algorithm is applied to an ensemble of scenario simulations. The result indicates that the number of atmospheric events favourable for major Baltic inflows increases slightly in all scenarios.

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“…250 m, where this study was carried out. With irregular intervals of several years major inflow events take place and saline water from the North Sea flows over the sills and fills up the deeper basins and the last major inflow event was in January 2003 (Matthäus et al, 2008). During stagnation periods be-tween major inflow events the deeper basins are anoxic and sulfidic from the sediment up to the pycnocline.…”

Section: Introductionmentioning

confidence: 99%

Denitrification in the water column of the central Baltic Sea

Dalsgaard

Brabandere

Hall

2013

Geochimica et Cosmochimica Acta

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Removal of fixed nitrogen in the water column of the eastern Gotland Basin, central Baltic Sea, was studied during two cruises in September 2008 and August 2010. The water column was stratified with anoxic sulfidic bottom water meeting oxic nitrate containing water at the oxic-anoxic interface. Anammox was never detected whereas denitrification was found in all incubations from anoxic depths and occurred immediately below the oxic-anoxic interface. Sulfide (H 2 S + HS À + S 2À ) was in most cases the only electron donor for denitrification but, in contrast to previous findings, denitrification was in some situations driven by organic matter alone. Nitrous oxide (N 2 O) became an increasingly important product of denitrification with increasing sulfide concentration and was >80% of the total N gas formation at 10 lM sulfide. The potential rates of denitrification measured in incubations at elevated NO À 3 or sulfide concentrations were converted to in situ rates using the measured water column concentrations of NO À 3 and sulfide and the actual measured relations between NO À 3 and sulfide concentrations and denitrification rates. In situ denitrification ranged from 0.24 to 15.9 nM N 2 h À1 . Assuming that these rates were valid throughout the anoxic NO À 3 containing zone, depth integrated in situ denitrification rates of 0.06-2.11 mmol N m À2 d À1 were estimated. The thickness of this zone was generally 3-6 m, which is probably what can be maintained through regular turbulent mixing induced by internal waves at the oxic-anoxic interface. However, layers of up to 55 m thickness with low O 2 water (<10 lM) were observed which was probably the result of larger scale mixing. In such a layer nitrification may produce NO À 3 and once the O 2 has been depleted denitrification will follow resulting in enormous rates per unit area. Even with an active denitrification layer of 3-6 m thickness the pelagic denitrification per unit area clearly exceeded sediment denitrification rates elsewhere in the Baltic Sea. When extrapolated to the entire Baltic Proper (BP) denitrification in the water column was in the range of 132-547 kton N yr À1 and was thus at least as important as sediment denitrification which has recently been estimated to 191 kton N yr À1 . With a total external N-input of 773 kton N yr À1 it is clear that denitrification plays a significant role in the N-budget of the BP.

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The Inflow of Highly Saline Water into the Baltic Sea

Cited by 70 publications

References 0 publications

100 years of atmospheric and marine observations at the Finnish Utö Island in the Baltic Sea

100 years of atmospheric and marine observations at the Finnish Utö Island in the Baltic Sea

An algorithm based on sea-level pressure fluctuations to identify major Baltic inflow events

Denitrification in the water column of the central Baltic Sea

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