Öregrund, Sweden
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Lundin M.,Harmangers Maskin och Marin AB | Calamnius L.,Harmangers Maskin och Marin AB | Hillstrom L.,University of Gävle | Lunneryd S.-G.,Institute for Coastal Research
Fisheries Research | Year: 2011

A sustainable fishery in the Baltic and Bothnian Seas requires the development and introduction of fishing gear which fishes selectively and at the same time excludes raiding seals. The purpose of this study was twofold: firstly to test and evaluate rigid grids as a method for retaining only larger herring in a pontoon trap, and secondly to analyze which factors were influencing the selection process. The results demonstrate that it is indeed possible to sort herring by size in a pontoon fish chamber. The efficiency of excluding undersized herring was at best 27%, using a selection grid covering just over 0.1% of the fish chamber wall. The factors which have most effect on the selection were the quantity of fish in the trap, the season of the year, the time of day and the presence of seals. © 2010 Elsevier B.V.

Esper J.,Johannes Gutenberg University Mainz | Schneider L.,Johannes Gutenberg University Mainz | Krusic P.J.,University of Stockholm | Luterbacher J.,Justus Liebig University | And 6 more authors.
Bulletin of Volcanology | Year: 2013

The drop in temperature following large volcanic eruptions has been identified as an important component of natural climate variability. However, due to the limited number of large eruptions that occurred during the period of instrumental observations, the precise amplitude of post-volcanic cooling is not well constrained. Here we present new evidence on summer temperature cooling over Europe in years following volcanic eruptions. We compile and analyze an updated network of tree-ring maximum latewood density chronologies, spanning the past nine centuries, and compare cooling signatures in this network with exceptionally long instrumental station records and state-of-the-art general circulation models. Results indicate post-volcanic June-August cooling is strongest in Northern Europe 2 years after an eruption (-0.52 ± 0.05 °C), whereas in Central Europe the temperature response is smaller and occurs 1 year after an eruption (-0.18 ± 0.07 °C). We validate these estimates by comparison with the shorter instrumental network and evaluate the statistical significance of post-volcanic summer temperature cooling in the context of natural climate variability over the past nine centuries. Finding no significant post-volcanic temperature cooling lasting longer than 2 years, our results question the ability of large eruptions to initiate long-term temperature changes through feedback mechanisms in the climate system. We discuss the implications of these findings with respect to the response seen in general circulation models and emphasize the importance of considering well-documented, annually dated eruptions when assessing the significance of volcanic forcing on continental-scale temperature variations. © 2013 Springer-Verlag Berlin Heidelberg.

Esper J.,Johannes Gutenberg University Mainz | Frank D.C.,Swiss Federal Institute of forest | Frank D.C.,University of Bern | Timonen M.,Finnish Forest Research Institute | And 12 more authors.
Nature Climate Change | Year: 2012

Solar insolation changes, resulting from long-term oscillations of orbital configurations, are an important driver of Holocene climate. The forcing is substantial over the past 2,000 years, up to four times as large as the 1.6 W m -2 net anthropogenic forcing since 1750 (ref.A), but the trend varies considerably over time, space and with season. Using numerous high-latitude proxy records, slow orbital changes have recently been shown to gradually force boreal summer temperature cooling over the common era. Here, we present new evidence based on maximum latewood density data from northern Scandinavia, indicating that this cooling trend was stronger (-0.31 °C per 1,000 years, ±0.03 °C) than previously reported, and demonstrate that this signature is missing in published tree-ring proxy records. The long-term trend now revealed in maximum latewood density data is in line with coupled general circulation models indicating albedo-driven feedback mechanisms and substantial summer cooling over the past two millennia in northern boreal and Arctic latitudes. These findings, together with the missing orbital signature in published dendrochronological records, suggest that large-scale near-surface air-temperature reconstructions relying on tree-ring data may underestimate pre-instrumental temperatures including warmth during Medieval and Roman times.

Rottgers R.,Institute for Coastal Research | Doxaran D.,Laboratoire Doceanographie Of Villefranche | Dupouy C.,CNRS Mediterranean Institute of Oceanography (MIO) | Dupouy C.,CIRAD - Agricultural Research for Development
Optics Express | Year: 2016

The accurate determination of light absorption coefficients of particles in water, especially in very oligotrophic oceanic areas, is still a challenging task. Concentrating aquatic particles on a glass fiber filter and using the Quantitative Filter Technique (QFT) is a common practice. Its routine application is limited by the necessary use of high performance spectrophotometers, distinct problems induced by the strong scattering of the filters and artifacts induced by freezing and storing samples. Measurements of the sample inside a large integrating sphere reduce scattering effects and direct field measurements avoid artifacts due to sample preservation. A small, portable, Integrating Cavity Absorption Meter setup (QFT-ICAM) is presented, that allows rapid measurements of a sample filter. The measurement technique takes into account artifacts due to chlorophyll-a fluorescence. The QFT-ICAM is shown to be highly comparable to similar measurements in laboratory spectrophotometers, in terms of accuracy, precision, and path length amplification effects. No spectral artifacts were observed when compared to measurement of samples in suspension, whereas freezing and storing of sample filters induced small losses of water-soluble pigments (probably phycoerythrins). Remaining problems in determining the particulate absorption coefficient with the QFT-ICAM are strong sample-to-sample variations of the path length amplification, as well as fluorescence by pigments that is emitted in a different spectral region than that of chlorophyll-a. ©2015 Optical Society of America.

Lu X.,Institute for Coastal Research | Soomere T.,Tallinn University of Technology | Soomere T.,Estonian Academy of Sciences | Stanev E.V.,Institute for Coastal Research | Murawski J.,Danish Meteorological Institute
Ocean Dynamics | Year: 2012

Application of the preventive techniques for the optimisation of fairways in the south-western Baltic Sea and the Kattegat in terms of protection of the coastal regions against current-driven surface transport of adverse impacts released from vessels is considered. The techniques rely on the quantification of the offshore domains (the points of release of adverse impacts) in terms of their ability to serve as a source of remote, current-driven danger to the nearshore. An approximate solution to this inverse problem of current-driven transport is obtained using statistical analysis of a large pool of Lagrangian trajectories of water particles calculated based on velocity fields from the Denmark's Meteorological Institute (DMI)/BSH cmod circulation model forced by the DMI-HIRHAM wind fields for 1990-1994. The optimum fairways are identified from the spatial distributions of the probability of hitting the coast and for the time (particle age) it takes for the pollution to reach the coast. In general, the northern side of the Darss Sill area and the western domains of the Kattegat are safer to travel. The largest variations in the patterns of safe areas and the properties of pollution beaching occur owing to the interplay of water inflow and outflow. The gain from the use of the optimum fairways is in the range of 10-30 % in terms of the decrease in the probability of coastal hit within 10 days after pollution release or an increase © Springer-Verlag 2012.

Jorgensen L.L.,Institute of Marie Research | Planque B.,Institute of Marie Research | Thangstad T.H.,Institute of Marie Research | Certain G.,Institute of Marie Research | Certain G.,Institute for Coastal Research
ICES Journal of Marine Science | Year: 2016

The development of ecosystem-based fisheries management over the last two decades has increased attention on the protection of vulnerable resources that are of little or no economic significance including bycatch of benthos in bottom trawling. Current knowledge on the response of benthic communities to the impact of trawling is still rudimentary. In the present study, we used data collected in the Barents Sea during 2011 to assess the vulnerability of benthic species to trawling, based on the risk of being caught or damaged by a bottom trawl. Using trait table analysis, we identified 23 "high-risk" benthic species, which include "large weight and upraised" taxa as "easily caught" by a bottom trawl. We further identified a "low-risk" category containing 245 taxa/species and a "medium-risk" category with 80 species. A clear decline in biomass was noted for all three categories when comparing trawled vs. untrawled areas. This suggests that trawling significantly affects the biomass of all species, but predominantly the "high-risk" taxa. Some Barents Sea regions were particularly susceptible to trawling due to the dominance of the "high-risk" species, including Geodia sponges in the southwestern Barents Sea, basket stars (Gorgonocephalus) in the northern Barents Sea, sea pen (Umbellula encrinus) on the shelf facing the Arctic Ocean, and sea cucumber (Cucumaria frondosa) in shallow southern areas. These findings can guide management decisions to meet targets set by the United Nations Convention of Biological Diversity and the OSPAR Commission ("Protecting and Conserving the North-East Atlantic and its Resources"). We specifically recommend management action in the southwestern and the northwestern Barents Sea and on the Arctic shelf facing the Arctic Ocean. © 2015 International Council for the Exploration of the Sea 2015. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Acosta Navarro J.C.,University of Stockholm | Smolander S.,University of Helsinki | Struthers H.,Linköping University | Zorita E.,Institute for Coastal Research | And 5 more authors.
Journal of Geophysical Research: Atmospheres | Year: 2014

We investigated the millennial variability (1000 A.D.-2000 A.D.) of global biogenic volatile organic compound (BVOC) emissions by using two independent numerical models: The Model of Emissions of Gases and Aerosols from Nature (MEGAN), for isoprene, monoterpene, and sesquiterpene, and Lund-Potsdam-Jena- General Ecosystem Simulator (LPJ-GUESS), for isoprene and monoterpenes. We found the millennial trends of global isoprene emissions to be mostly affected by land cover and atmospheric carbon dioxide changes, whereas monoterpene and sesquiterpene emission trends were dominated by temperature change. Isoprene emissions declined substantially in regions with large and rapid land cover change. In addition, isoprene emission sensitivity to drought proved to have significant short-term global effects. By the end of the past millennium MEGAN isoprene emissions were 634 TgC yr-1 (13% and 19% less than during 1750-1850 and 1000-1200, respectively), and LPJ-GUESS emissions were 323 TgC yr-1(15% and 20% less than during 1750-1850 and 1000-1200, respectively). Monoterpene emissions were 89 TgC yr-1(10% and 6% higher than during 1750-1850 and 1000-1200, respectively) in MEGAN, and 24 TgC yr-1 (2% higher and 5% less than during 1750-1850 and 1000-1200, respectively) in LPJ-GUESS. MEGAN sesquiterpene emissions were 36 TgC yr -1(10% and 4% higher than during 1750-1850 and 1000-1200, respectively). Although both models capture similar emission trends, the magnitude of the emissions are different. This highlights the importance of building better constraints on VOC emissions from terrestrial vegetation. Key Points We have investigated terpene emissions in the past millennium Land cover and CO2 govern isoprene emission in industrial time Monoterpene and sesquiterpene emissions have been driven by temperature ©2014. American Geophysical Union. All Rights Reserved.

Stanev E.V.,Institute for Coastal Research | Lu X.,Sun Yat Sen University | Grashorn S.,Institute for Coastal Research
Ocean Modelling | Year: 2015

The dynamics in the transition zone between the North Sea and Baltic Sea are analyzed here using data from a 22-year-long climatic simulation with a focus on the periods 1992-1994 and 2001-2003 when two recent major inflow events occurred. Observations from gauges and in situ measurements are used to validate the model. Parameters, which cannot be easily measured, such as water and salt transports through straits, have been compared against similar previous estimates. The good performance of simulations is attributed to the finer resolution of the model compared to earlier set ups. The outflow in the Kattegat, which is an analogue of the tidal outflows, tends to propagate to the North over the shallows without showing a substantial deflection to the right due to the Earth's rotation. The inflow follows the topography. The different inflow and outflow pathways are explained as a consequence of the specific combination of bathymetry, axial and lateral processes. The circulation in Kattegat is persistently clockwise with an eastern intensification during inflow and a western one during outflow regimes. The tidal wave there propagates as Kelvin wave, keeping the coast on its right. The flows in the two main straits reveal very different responses to tides, which are also highly asymmetric during inflow and outflow conditions. The circulation has a typical two-layer structure, the correlation between salinity and velocity tends to increase the salt transport in the salinity conveyor belt. The transversal circulation in the entrance of the Sound enhances the vertical mixing of the saltier North Sea water. The long-term averaged ratio of the water transports through the Great Belt and the Sound is ~2.6-2.7 but this number changes reaching lower values during the major inflow in 1993. The transports in the straits are asymmetric. During inflow events the repartition of water penetrating the Baltic Sea is strongly in favor of the pathway through the Sound, which provides a shorter connection between the Kattegat and Baltic proper. The wider Great Belt has a relatively larger role in exporting water from the Baltic into the North Sea. A demonstration is given that the ventilation of the Baltic Sea deep water is not only governed by the dynamics in the straits and the strong westerly winds enhancing the eastward propagation of North Sea water (a case in 1993), but also by the clockwise circulation in the Kattegat acting as a preconditioning factor for the flow-partitioning. © 2015 Elsevier Ltd.

Wang X.H.,University of New South Wales | Bhatt V.,University of New South Wales | Bhatt V.,Institute for Coastal Research | Sun Y.-J.,University of New South Wales
Ocean Dynamics | Year: 2013

Two mutually exclusive ocean models, Ocean general circulation model for the Earth Simulator (OFES) and the Bluelink ReANalysis (version 2.1; BRAN2.1), and the spin-up model (SPINUP4) of BRAN2.1 were used to investigate seasonal variability of the East Australian Current (EAC). These model outputs were tested against satellite and in situ data. The seasonally averaged sea surface temperature (SST) in the OFES and SPINUP4 shows a negative bias of 1 C. However, the OFES, SPINUP4, and BRAN2.1 have a similar seasonal cycle in SST. The annual mean EAC transport computed at 28 S from the three models shows a good agreement with annual mean transport computed using the in situ data. However, they have considerable differences in terms of annual cycle. A better performance of the BRAN2.1 in simulating the temperature field is a result of data assimilation. The advection of heat across the open boundaries contributes ∼50 % of the heat content change in the region. This study suggests that the advection by the EAC plays a significant role in heat content change of the region. © 2013 Springer-Verlag Berlin Heidelberg.

Rttgers R.,Institute for Coastal Research | McKee D.,University of Strathclyde | Utschig C.,Institute for Coastal Research
Optics Express | Year: 2014

The light absorption coefficient of water is dependent on temperature and concentration of ions, i.e. the salinity in seawater. Accurate knowledge of the water absorption coefficient, a, and/or its temperature and salinity correction coefficients, T and S, respectively, is essential for a wide range of optical applications. Values are available from published data only at specific narrow wavelength ranges or at single wavelengths in the visible and infrared regions. T and S were therefore spectrophotometrically measured throughout the visible, near, and short wavelength infrared spectral region (400 to ∼2700 nm). Additionally, they were derived from more precise measurements with a point-source integrating-cavity absorption meter (PSICAM) for 400 to 700 nm. When combined with earlier measurements from the literature in the range of 2600 - 14000 nm (wavenumber: 3800 - 700 cm-1), the coefficients are provided for 400 to 14000 nm (wavenumber: 25000 to 700 cm-1). © 2014 Optical Society of America.

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