Dependence of salinity and oxygen concentrations in the Baltic Sea on large-scale atmospheric circulation

Zorita, Eduardo; Laine, Ari O.

doi:10.3354/cr014025

Cited by 55 publications

(42 citation statements)

References 25 publications

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“…This produces a barotropic pressure gradient and hampers the flow of high-saline water through the Danish Straits into the Baltic proper . A similar long-term sensitivity for stronger westerly winds for the Baltic Sea was shown by Zorita and Laine (2000).…”

Section: Evolution Of Water Temperature Sea Ice and Salinitysupporting

confidence: 52%

The climate in the Baltic Sea region during the last millennium simulated with a regional climate model

et al. 2012

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Abstract. Variability and long-term climate change in the Baltic Sea region is investigated for the pre-industrial period of the last millennium. For the first time dynamical downscaling covering the complete millennium is conducted with a regional climate model in this area. As a result of changing external forcing conditions, the model simulation shows warm conditions in the first centuries followed by a gradual cooling until ca. 1700 before temperature increases in the last centuries. This long-term evolution, with a Medieval Climate Anomaly (MCA) and a Little Ice Age (LIA), is in broad agreement with proxy-based reconstructions. However, the timing of warm and cold events is not captured at all times. We show that the regional response to the global climate anomalies is to a strong degree modified by the large-scale circulation in the model. In particular, we find that a positive phase of the North Atlantic Oscillation (NAO) simulated during MCA contributes to enhancing winter temperatures and precipitation in the region while a negative NAO index in the LIA reduces them. In a second step, the regional ocean model (RCO-SCOBI) is used to investigate the impact of atmospheric changes onto the Baltic Sea for two 100 yr time slices representing the MCA and the LIA. Besides the warming of the Baltic Sea, the water becomes fresher at all levels during the MCA. This is induced by increased runoff and stronger westerly winds. Moreover, the oxygen concentrations in the deep layers are slightly reduced during the MCA. Additional sensitivity studies are conducted to investigate the impact of even higher temperatures and increased nutrient loads. The presented experiments suggest that changing nutrient loads may be more important determining oxygen depletion than changes in temperature or dynamic feedbacks.

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Section: Evolution Of Water Temperature Sea Ice and Salinitysupporting

confidence: 52%

The climate in the Baltic Sea region during the last millennium simulated with a regional climate model

et al. 2012

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“…A strong meridional sea level pressure gradient over the North Atlantic causes positive rain fall anomalies, increasing river runoff and decreasing salinity. Due to the weakened stratification, deep water oxygen concentrations increase (Gerlach 1994;Zorita and Laine 2000). An increase in precipitation will also result in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…Salinity and oxygen concentration in the Baltic Sea also depend strongly on large-scale atmospheric circulation (Zorita and Laine 2000). A strong meridional sea level pressure gradient over the North Atlantic causes positive rain fall anomalies, increasing river runoff and decreasing salinity.…”

Section: Introductionmentioning

confidence: 99%

A Multivariate Baltic Sea Environmental Index

Dippner

Kornilovs

Junker

2012

AMBIO

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Since 2001/2002, the correlation between North Atlantic Oscillation index and biological variables in the North Sea and Baltic Sea fails, which might be addressed to a global climate regime shift. To understand inter-annual and inter-decadal variability in environmental variables, a new multivariate index for the Baltic Sea is developed and presented here. The multivariate Baltic Sea Environmental (BSE) index is defined as the 1st principal component score of four z-transformed time series: the Arctic Oscillation index, the salinity between 120 and 200 m in the Gotland Sea, the integrated river runoff of all rivers draining into the Baltic Sea, and the relative vorticity of geostrophic wind over the Baltic Sea area. A statistical downscaling technique has been applied to project different climate indices to the sea surface temperature in the Gotland, to the Landsort gauge, and the sea ice extent. The new BSE index shows a better performance than all other climate indices and is equivalent to the Chen index for physical properties. An application of the new index to zooplankton time series from the central Baltic Sea (Latvian EEZ) shows an excellent skill in potential predictability of environmental time series.

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“…In the Bornholm Basin, deep temperature observations reveal waters of warm and cold inflows ) that can be later traced in the In the Gulf of Finland, a sub-region with a free connection to the Baltic Proper and the highest freshwater discharge per unit sea volume, changes in salinity and stratification generally follow those of the Baltic Proper, but are not fully synchronous (e.g. Zorita and Laine 2000). On the basis of monitoring data for the period 1965-2000, Laine et al (2007) found a continuous decrease in salinity and density stratification until the early 1990s, after which there was a slight increase.…”

Section: 3mentioning

confidence: 99%

Recent Change—Marine Circulation and Stratification

Elken

Lehmann

Myrberg

2015

Regional Climate Studies

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This chapter describes recent change in the circulation and stratification of the Baltic Sea. A recent warming trend in sea-surface waters has been clearly demonstrated by in situ measurements, remote sensing data and numerical models. Trends in sea-surface temperature (SST) for the past three to four decades based on remote sensing data generally agree with trends determined from in situ observations. Models suggest the current warming within the Baltic Sea lies within the range experienced during the past 500 years. The salinity and stratification of the deep waters are strongly linked to the major inflows of North Sea water that occur sporadically and bring high-saline water into the deep layers of the Baltic Sea. The major inflows normally occur during winter and spring and bring cold oxygen-rich waters into the deep basins. Since 1996, large inflows have also occurred during summer, bringing in warm low-oxygen water. IntroductionChanges in thermohaline characteristics and stratification of the water column are usually analysed on the basis of data from repeat hydrographic observations, originating from shipborne monitoring programmes and/or permanent coastal and offshore oceanographic stations. Such datasets are described in recent books by Feistel et al. (2008) and Leppäranta and Myrberg (2009). In situ observations are often irregular in space and time, especially for offshore areas; therefore, trends and variability in the ocean state can only be determined by careful pre-processing of the data to address issues such as data homogenisation and the suppression of aliasing errors. In recent decades, horizontal undersampling by in situ measurements has been partially offset by the remote sensing of sea-surface properties from satellites; with these data free of spatial aliasing errors due to their high horizontal resolution. Satellite-derived cloud-free products for sea-surface temperature (SST) have been reasonably accurate since the 1980s. Many of the papers published over the past decade that address trends and variability in the circulation and stratification of the Baltic Sea are based on remote sensing data, often in combination with in situ observations and the results of numerical modelling. Improvements in the physical and numerical features of the models, accompanied by model validation studies, have increased confidence in the realism of the model results. Models provide dynamically balanced gridded datasets over decades or longer, including information for 'noisy' variables such as currents, transport and mixing fluxes. This chapter analyses the recent peer-reviewed literature, extending the findings from earlier review (Box 7.1).

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Dependence of salinity and oxygen concentrations in the Baltic Sea on large-scale atmospheric circulation

Cited by 55 publications

References 25 publications

The climate in the Baltic Sea region during the last millennium simulated with a regional climate model

The climate in the Baltic Sea region during the last millennium simulated with a regional climate model

A Multivariate Baltic Sea Environmental Index

Recent Change—Marine Circulation and Stratification

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